Legrand Legrand

Green building - Definition

Green building – Ecological construction


Logo Développement durable Legrand

The notion of Green building varies depending on the specialist. For eco-builders, it means a clean building, using natural materials. They consider that a building must above all adapt to humans, the well-being of its occupants being capital. These partisans of green building condemn the use of toxic substances in the industrial manufacture of construction materials. Experts in energy savings aim to limit the negative impact of human habitat on the environment through ultra-modern technologies and to reduce the amount of energy consumed by buildings, houses and apartments. They recommend enhanced thermal insulation and leading-edge construction techniques. Eco-builders consider a building over its whole lifetime. Not only do they integrate energy savings, they also take into consideration the origin of the materials used and their management (elimination, recuperation) at the end of their life.

Eco-construction, also referred to as sustainable construction or green building, proposes various possibilities of reducing the environmental impact of buildings. Green building is not a specific construction method, but it brings together a set of techniques, materials and technologies which when suitably integrated in a construction project, contribute to enhancing its environmental performance. In an ideal world, eco-construction optimises energy efficiency, limits water consumption, makes maximum use of recycled, recyclable and non-toxic materials. It also generates as little waste as possible during the construction process and subsequent occupation.

In a green building, the structural creation processes respect the environment and make efficient use of resources. This practice is growing and complements the conventional concerns of designing buildings that are economical in energy, sustainable and comfortable. A green building is a clean, sustainable building, designed with natural materials, uses little energy and renewable ones at that, is easy to maintain and available at a reasonable cost.

A green building is designed to reduce the overall impact of the built-up environment on human health and the natural environment, through:
•    The efficient use of energy, water and other resources
•    Protecting occupant health and improving employee productivity
•    Reducing waste, pollution and harm to the environment.

Effectively, a green building can incorporate sustainable materials (reused, recycled, recyclable, or from renewable resources) in its construction, create a healthy interior environment with a minimum of pollutants and functional landscape planning that requires less water (using indigenous greenery that thrives without additional watering).

Clean building

construction saine

Clean building is an eco-construction or green building approach that aims to build in respect of our environment and that of future generations, while offering maximum comfort to occupants.  It is also an approach that involves:
•    The identification of the environmental impacts of projects throughout their lifecycle;
•    The use of architectural and urban-planning techniques that prioritise natural light, integrate bio-climate principles, guarantee good thermal insulation of the whole building envelope and respect applicable legislation;
•    The use of “environmental” or “natural” materials that consume little energy in their manufacture, transport and deployment;
•    The promotion of the use of renewable energies and/or low-pollution fuels;
•    The use of “intelligent” equipment: “Low energy” lighting and household appliances, efficient correctly-sized heating systems.

What is more, there is no clean habitat without a clean building site. To choose the right location, we must always start by considering the influences of the soil (contaminated sites, natural radioactivity, etc.) or the environment (noisome roads, industrial plants emitting toxic emissions, high voltage power lines) that may be troublesome. Installation in the route of a wind corridor, even within a large town, means the site will benefit from a pleasant atmosphere, rich in oxygen.

Green building uses resources efficiently. Its success is to leave fewer traces on the environment through the use of renewable energies and by ensuring high energy yield. This is a balanced solution between construction and a sustainable environment.


The green building

Natural construction

A natural green building construction must satisfy two additional imperatives: the adaptation of the architecture to the landscape and its measurable data, alongside the use of natural materials, which if possible are renewable. The choice of the site must be made according to natural data. In effect, topological data have a great influence on the micro-climate and therefore on the properties of a building site. So in a basin where cold air stagnates, temperatures can be 6°C below those on a flat terrain just a few hundred metres away.

Architectural forms must be inspired by nature, with colours that do not seem artificial. Natural building techniques use the materials that nature provides. When these materials replace polluting synthetic products which consume a large quantity of energy in their manufacture, their use is highly recommended. The term “natural materials” essentially covers local (renewable) raw materials that can be used according to traditional craft methods or modern techniques.

Passive building

The expression “passive building” refers to a construction standard that can be achieved using various types of construction materials. It can also mean a green building construction that guarantees an interior climate as comfortable in summer as it is in winter without a conventional heating system. Taken from the German word “Passivhaus,” this expression concerns both collective and individual habitats. The purpose of the passivhaus is to reduce energy consumption in residential buildings by capturing a passive solar energy contribution, reinforcing building insulation, using renewable energies and recuperating heat.

A passive building consumes no more than 15 kWh/m2/year for its heating and no more than 30 kWh/m2/year for heating, hot water and ventilation. Total consumption (including household appliances) must not exceed 120 kWh/m2/year in primary energy (that which is taken from nature before transformation). The passive building mark includes many specific and technical elements concerning windows, insulation and facade seals, air renewal, etc. Rigorous testing is carried out to obtain the passive building mark.

Individual passive houses are often compact. This is one condition for achieving low energy consumption. To build a passive building, the following requirements must be satisfied:
•    Excellent insulation all over the building, exterior insulation from 25 to 35 cm;
•    High quality triple-glazed windows;
•    Building orientation to capture passive solar energy and large south-facing picture windows;
•    A dual-flow mechanical ventilation system with a heat recuperation rate of at least 75%.
•    Solar thermal units for hot water requirements.

Popular instructions

There remains a great deal of effort to make in promoting eco-construction and renovation with our populations. Today the majority of people recognise the expression Green Building and most consider it with a positive connotation. Among those who perceive eco-construction under a positive light, many are ignorant of the specific nature of such practices. The often ignore what distinguishes them from conventional construction methods, how they are integrated into residential construction and what the selection of ecological options implies for companies and acquirers.

Therefore within the population there is a lack of information, combined with the circulation of several misconceptions. In fact, most people associated a particular architectural style with eco-construction, something modern and contemporary, with the addition of complex systems such as solar panels and water heaters, geothermal systems or green roofs. Promotional communication should accentuate the fact that it is possible to build a high-performance eco-home which neverthless has traditional aesthetics. What is more, subtle or even invisible measures, such as low-emission windows, high-quality ventilation ducts and suitable insulation make a significant contribution to the energy efficiency of a home without changing its physical aspect or rendering the construction process overly complicated.

For optimum operation, ecological methods and technologies must be integrated into a coherent design. The expectations of today’s owners and occupants in terms of maintenance, operation and comfort are very high, which results in corresponding technological and energy costs. An important vector for promoting ecological construction is construction regulations.


Green building – components

Energy efficiency and renewable energy

General considerations

construction saine

Energy efficiency is a major concern and an essential component of green building. It has even become a major factor in its success. A green building must always be fitted with solutions that offer enhanced electrical energy management, reduce consumption and contribute to supplying quality energy.

This efficiency can be materialised in a home through the use of occupancy detectors and full home automation systems. All these solutions help to manage and programme lighting, heating and other uses to optimise their use at a lower cost. In commercial buildings, solutions are multiplied to reduce energy use and contribute to reducing greenhouse gases, both in lighting management, office equipment management, security lighting, infrastructure measurement and surveillance. In such buildings, capacitor banks increase the efficiency of the installation and network analysers make it possible to measure the consumption and quality of the energy.

Renewable energy sources present the advantage of being available in unlimited quantities. Their use is a way of satisfying our energy needs while conserving the environment. The main forms of renewable energy are solar power, wind power, biomass power, geothermal power, hydraulic power, etc.

The energy produced by photovoltaic panels is an undeniable component of renewable energy production, which must satisfy the dual issue of integration into buildings and optimised production. Heavy investment in various clean energy technology projects around the world have been undertaken to improve the efficiency of renewable energies, to reinforce the economy, protect the environment and reduce our dependence on oil products.

Energy efficiency and green building


For the past 10 years, observers have complained about peaks of energy consumption due to air conditioning equipment. Among other factors, they point out unsuitable dimensions, non-existent or unsuitable cleaning and maintenance, the use of obsolete and energy-inefficient technologies. To stop energy waste, air conditioning systems are subject to regular inspections. In effect, a decree and law now require that owners have their units regularly inspected, every 5 years at least, by a certified technician.

In France, this concerns decree 2010-349 of 31 March 2010 and the administrative order of 16 April 2010. These legal texts continue the enactment of the European Directive on Building Energy Performance in French law and the implementation of the Grenelle Environment round table recommendations. The aim is to end wasteful use of energy. Air-conditioning systems and reversible heat pumps with a rated cooling power above 12 kW are equipment for home comfort. Their energy use is not in proportion to actual needs, either because they are incorrectly dimensioned, or that they are not correctly maintained or managed. Cooling systems for computer rooms and industrial use are not concerned by these texts. Waste is not welcome in a green building.

Specific electricity
Logo Développement durable Legrand

Specific electricity corresponds to that required for services that can only be provided through the use of electricity. Items that are not taken into account in specific electricity include hot water, heating and cooking, which can use other types of power. Specific electricity consumption has doubled over the past 20 years and this trend is likely to continue. Choosing energy-efficient appliances is therefore of great importance in a green building.

Efficient appliances will make significant savings on the specific electricity bill. For example, the savings generated by low energy lamps reduces costs by a factor of 4 compared to incandescent lamps. For cooling appliances, the difference in consumption between two different new machines can be anywhere from 1 to 3. Note also that a new appliance can consume up to six times less than an aged appliance.

Energy savings

By energy savings, we mean all economically interesting actions undertaken to reduce energy consumption, by for instance installing suitable equipment in electrical installations. The aim is also to consume energy in an optimal manner (e.g. recuperate heat lost in combustion gases or produce energy from waste). We should be aware that energy savings do not concern just electricity. Adopting some simple daily habits along with a judicious choice of equipment also enables us to control consumption of all other forms of energy (gas, heating fuel, etc.). In a green building, the main priority is to identify energy savings.

Some of the main measures that enable energy savings are:
•    Good thermal insulation of all exterior components (walls, windows, roof, etc.)
•    Eliminate thermal bridges and other energy leaks
•    Good airtight seal on the exterior building envelope
•    Reduction of thermal losses through ventilation
•    Efficiency of a reduced-inertia boiler
•    Optimised electricity management (reduction of installed power ratings, central management, use of lighting control equipment, etc.).

Renewable energy

Solar power systems
Logo Développement durable Legrand

Solar energy is the source of the water cycle and of wind. The plant kingdom, on which the animal kingdom depends, also uses solar energy by transforming it into chemical energy through photosynthesis.
Apart from nuclear power, geothermal energy and tidal power, solar energy is the origin of all other energies on Earth. Solar energy is also inexhaustible on a human timescale and hugely abundant. It is estimated that the Earth receives from the sun about 10,000 times the total amount of energy consumed by all of humanity. Solar power capture technologies can be split into three categories: Solar photovoltaic, solar thermal and solar thermodynamic. The use of solar power is of tremendous importance in a green building.

Solar heating systems can be installed in all types of buildings. Using solar power to pre-heat outside air before it is allowed to enter a building can considerably reduce heating costs both in residential buildings and commercial constructions. Solar heating systems are especially efficient for large buildings such as hospitals, hangars, school and gyms, as well as multi-storey residential buildings. To make solar electricity available on a large scale, scientists and engineers around the world have been trying to develop a low-cost solar cell for many years. Such cells must be very efficient and easy to manufacture, with a high yield.

The vast majority of solar heating systems require the installation of solar walls. Such equipment can be installed on new or existing buildings. Solar walls require very little maintenance, feature no liquids or detachable parts other than the ventilators connected to the ventilation system. Moreover, solar walls can operate under cloudy conditions and at night time, even if their efficiency is much less. The ROI is two years due to the energy savings they produce.

Geothermal power

Geothermal energy is extracted from the ground for use in air conditioning, heating or transformation into electricity. Installing a geothermal heat pump system represents a major investment, but it enables users to make use of an inexhaustible source of energy that will provide 60 to 70% of the power required to heat a building. Geothermal systems can be installed on new houses or renovation projects. This technology can therefore considerably reduce the use of fossil fuels or electricity, which emit much more greenhouse gases and which are generally less financially interesting in the long term. Geothermal technologies are naturally included in green building parameters.

Geothermal systems present some major advantages. Effectively, underground heat is present everywhere on Earth. Geothermal energy comes from an almost continuous source that is not dependent on atmospheric conditions. The ease of extraction of this energy depends on the structure of the geological formations or the composition of the rock beds. This technology is split into two categories: Deep geothermal or near-surface geothermal energy.

Other energy sources

Alongside solar energy and geothermal energy, wind power is the third major source of green building energy. Today wind power is the least expensive clean energy to produce, which explains the strong enthusiasm for this technology. Current research could enable it to keep this comfortable head start for several years to come. Water or hydraulic power is mainly produced by the displacement or accumulation of fresh water or sea water. As it is everywhere, water plays an extremely important role in transporting the Earth’s energy. 

Biomass is generated by photosynthesis, where solar energy is stored by plants in the form of carbohydrates, as they use the carbon dioxide in the atmosphere. In a wide sense, the expression “biomass” refers to all living matter (the total mass of living matter). In terms of energy, biomass refers to all organic material that can become a source of energy in the form of biogas, biofuel or directly by combustion: Wood or organic agricultural or urban waste, etc. Biomass energy is used by the biogas, biofuel and wood industries.

The radiant system is a comfortable heating system. Radiant heating transfers heat directly from the floor to your body as well as heating the ambient air. Radiant heating systems produce uniform temperatures in all rooms or heated floor areas, in all seasons. Radiant heating is also a technique to prevent the transmission of dust and pollen, which are prevalent in warm air heating systems.

Sustainable management

Sustainable water management

Water savings in a green building

The availability of fresh water has become a matter of increasing concern in a context where developed and developing countries are engaged in a race to obtain resources that are inexorably becoming scarcer. A green building must therefore be designed to use water efficiently. Managing waste water, irrigation water and rain water are also essential for a sustainable approach.

The use of mixer taps reduces water consumption as it is easier to control the temperature. Aerator tap fittings reduce the amount of water used without it being noticed during use. Waste through negligence is to be avoided. Even if repairing a leaking tap can be a chore, tens of millions of cubic metres of water are lost every year, just in France, because of inadequate seals on taps.

Thermostatic mixer taps can also generate savings. As water runs at a predetermined temperature, the water that is usually lost when adjusting a shower temperature is saved. An efficient and sustainable water-saving approach also depends on existing knowledge or projections of water use, tracing and preventing leaks. Replacing unsuitable equipment and using water-efficient devices, communicating and raising user awareness are also potential sources for water savings.

Recuperation and use of rain water

Rain water is an inexhaustible natural resource which has its place in the green building. Rain water is collected as it runs off a roof and is stored in a tank. Whether polluted or not, rain water is naturally slightly acidic (pH from 5 to 6), due to its carbon dioxide content, present in the atmosphere. This acidity means it should not be stored in plastic or metal containers. For domestic use, the ideal solution is a concrete or limestone tank that neutralises the natural acidity of rain water.

Rain water is only rarely recuperated and often only used for watering gardens. Its use should nonetheless be systematic both to unblock waste networks and to save on a resource that is becoming scarcer and is weighing on household budgets. A farmer’s common sense has always encouraged them to put a container under the gutter pipe to recuperate rain water. If optimised, rain water collection can enable homes to be autonomous in water use, without it being visible or visually un-aesthetic.

In certain buildings, rain water is recuperated, treated and reused in applications that do not require potable water. This kind of solution helps reduce fresh water needs in the public network, while avoiding the propagation of pollutants by run-off. Other solutions are available, such as green roofs, which not only store rain water, but also provide a green oasis in an urban environment along with many other benefits.

Reduction of waste and toxic substances

Logo Développement durable Legrand

A good green building design helps the occupants to reduce the quantity of waste generated. It also offers solutions such as composting bins, to reduce the volume of matter going to landfills. The green architect also aims to reduce waste in terms of energy, water and materials used for the construction. This considerable reduces the volume of waste sent for disposal during the construction phase. Green building avoids the systematic burial of materials retrieved from buildings at the end of their life by recycling and recuperating them. The extension of the useful lifetime of a structure also enables waste reduction.

The quality of interior air is an important factor in a green building. To do this, it must also seek to reduce volatile organic compounds (VOC) and other air impurities such as microbial contaminants. The ventilation systems must be well-designed to ensure suitable ventilation and air filtration, as well as to isolate certain activities (kitchens, dry-cleaning, etc.) from other applications.

During design and construction, the choice of construction materials and interior finishing products is made to reduce the amount of toxic substances in the building. In effect, many construction materials and cleaning products emit toxic gases such as VOC and formaldehyde. These gases can have a negative impact on occupant health. By avoiding these products, we can increase the quality of the interior environment in a building.

Construction materials used on a green building

Wooden structure

Wood occupies a primordial place in the green building approach. There are many different possibilities in terms of wooden structure. We can opt for walls with solid wood beams, wall with glued and laminated timber, and the wooden frame structure, which are suitable for an urban environment as from the outside they look identical to a conventional construction. The foundations of these constructions are made of concrete.

The benefits reside in the fact that wood is a clean material that generates neither radon nor static electricity. Wood protects itself naturally as it contains polyphenols of vegetal origin, which have a disinfectant effect. It is also an excellent thermal and hygrometric regulator, regulating ambient humidity like other green building construction materials.

One of its many benefits is its lightness. Wood also resists well to traction and compression along the axis of the tree from which it came. It offers high insulation properties, which enables the construction of thinner bearing walls. Wood offers good insulation both in winter and summer by naturally contributing to the thermal inertia necessary to keep warmth inside during the winter and maintain coolness in summer. It can significantly reduce heating consumption in winter.

The insulating load-bearing clay brick

Bricks are becoming more important in the green building approach. The insulating load-bearing clay brick (“monomur” brick) does not need insulating cladding on either the inside or the outside. It is a self-insulating material. The thermal insulation produced is in fact a combination of insulation and thermal inertia achieved by multiple air holes and extending the thermal path crossing the wall. As a resistant and durable heat regulation system and humidity barrier, the insulating clay brick displays admirable performance. Its efficiency is clearly demonstrated today through many tests and studies.

In addition to all these benefits, the insulating clay brick also offers a technology that simplifies its deployment, respects all construction regulations and makes this material a future concept that is increasingly appreciated by builders. It presents a highly reassuring safety rating. In the event of flooding, the characteristics of the insulating clay brick remain intact after drying out, which is not the case with interior insulation. Without additional insulation, the insulating clay brick is totally non-combustible. It emits no toxic gases in the event of fire. Insulating clay brick elements can easily be used to build buildings that must comply with seismic protection regulations.

The clay brick is a natural temperature controller that retains its properties throughout its lifetime. In winter, the brick absorbs heat from the heating system and redistributes it gradually by radiation, reducing energy consumption by about 10% whatever the source. In summer, it naturally regulates the temperature and retains the coolness offered by nocturnal ventilation all day long, due to its excellent thermal inertia, but on condition that heat is not permitted to enter during the daytime by opening the windows.

Cellular concrete

Cellular concrete, sometimes referred to as aerated concrete, is a lightweight concrete that is very interesting for green building. It is a combination of water, siliceous sand, cement, lime and air. The lime reacts in contact with the aluminium powder present to 0.05%, emitting hydrogen gas to create the air bubbles. After hardening, the material is fairly light with a density of 400 Kg/m3 as it contains thousands of trapped air bubbles (up to 80% of its volume), and offers excellent thermal characteristics. Also, the expansion agent produced by recycling after chemical bonding with the lime, forms non-toxic calcium aluminates.

The materials used in its manufacture make it an eco-material as it respects the environment. It is 100% recyclable and can be used to cover rubble without risk of polluting soils.  Cellular concrete offers a high thermal inertia and enables efficient correction of thermal bridges. It also offers exceptional resistance to fire, in excess of 6 hours. Soundproofing taken into account in the HEQ approach is 49 dB.

The sound-damping performance of these blocks satisfies the most stringent requirements of acoustic regulations in effect for exterior walls. Cellular concrete is a natural mineral, non-combustible material. It offers remarkable protection against fire and its frequent use in industry and buildings requiring such protection is highly appreciated. A wall built of cellular concrete is water tight and can breathe. It is a real humidity regulator: It softens dry air by releasing gas and absorbs excessive humidity in a damp atmosphere. It therefore creates a healthy, pleasant atmosphere throughout the home.

A major benefit of cellular concrete and what sets it apart from other materials is how it controls interior temperatures through thermal inertia. The thermal inertia of this material guarantees high attenuation of external temperature variations. It has an excellent capacity to accumulate heat and return it. This can help reduce the amount of time heating is used in half-season and can even offer natural temperature control in summer.

The Euromac2 structure

This construction system comprises two insulating cladding walls made of high density expanded polystyrene, joined by two metal spacers that are reinforced in their lateral parts by flat metal bands. Then concrete is poured inside the cladding up to a height of 3.6 metres in one go. This wall system is totally seismic-protected and has a variable width of 0.25 m to 0.45 m, with excellent acoustic and thermal insulation properties.

Aside its exceptional thermal insulation properties, it offers excellent acoustic insulation and a fire-retardant effect from 90 to 120 minutes, depending on the thickness of the wall. It naturally insulates the outside from the inside, eliminating all thermal bridges and offering full protection to the construction. This type of construction method can be used for high buildings (up to 10 storeys) and underground basements.

With its reinforced insulation concept for all exterior walls and the slow inertia of its walls, Euromac2 (walls, floors, roofs) is particularly effective for BBC (low energy) buildings (Effinergie, Minergie and passive house certificates) and suitable for green building projects.


Green building – Environment and climate

The environment

Natural resources

The conservation of natural resources is the main objective of the green building approach. A natural resource is a raw material, whose properties are used by humans or other species to satisfy a need. Natural resources can be used in their raw state, with possibly some processes that do not alter them (the case of vegetal and animal resources, but also renewable energies from air, wind, water and the sun). They can also be transformed to be used. The latter mostly involves fossil fuels such as coal, oil, natural gas or uranium.

We can distinguish two types of natural resources: Biological resources and energy resources. Natural biological resources are the water we drink, the soils that we cultivate, the air we breathe, the forests that provide oxygen for the atmosphere, along with all plant and animal species. Natural energy resources are by definition those we use to produce energy. They include air, the sun, water, geothermal sources, plants and fossil fuels.

We can observe that natural resources are running out and that their extraction has harmful effects: Soil erosion, deforestation, destruction of natural habitats, biodiversity and disappearance of fish stocks. The exploitation of these resources generates pollution which to all evidence harms most countries and represents an increasingly dangerous threat to the quality of water, soil and air. Our current production, construction and consumption models, along with global climate change are factors that lead to us to wonder if the planet’s stock of natural resources will remain sufficient to satisfy the needs of a world population that is growing in number and increasingly drawn to live in cities.

We often distinguish renewable resources and non-renewable resources. In terms of renewable resources, we consider those that naturally regenerate, or those that are in unlimited quantities. The two distinctions (biological or energy resources, renewable or non-renewable) can be further sub-divided. Effectively, a resource can be biological and renewable (air), biological and non-renewable (red tuna in the Mediterranean, very soon), energy and renewable (sun) or energy and non-renewable (coal).  Today all natural resources are under threat, not just the finite reserves of energy. The most essential is water, which is cruelly lacking in certain regions of the world.

Waste treatment

In France, the law of 15 July 1975 on waste elimination and recuperation of materials defines waste as “any residue of a production process, transformation or usage, any substance, material, product or more generally, any furniture that is abandoned or destined to be abandoned by its owner.” In our current society of consumption, goods circulate quickly and are renewed incessantly due to the existence of disposable goods. Waste is therefore produced in greater quantities and in increasingly complex forms.

There are several waste management principles where use varies according to the country or regions. The hierarchy of strategies (the three Rs): Reduce, Reuse and Recycle: classifies waste management policies according to the priorities we wish to assign. Certain experts in waste management have recently added a fourth R: “Rethink,” which implies that the current system has weaknesses and that a perfectly efficient system would require a whole new vision of waste management.

We now need to consider waste as a resource to be exploited and not as waste that we need to get rid of. The methods used to produce new resources from waste are varied and plentiful: For example we can extract raw materials from waste then recycle them or incinerate them to produce electricity. These methods are in full development, notably thanks to contributions from new technologies.

The recycling of waste as raw materials is becoming increasingly popular, in particular in urban areas where space to open new waste management centres is becoming scarcer. Private individuals are therefore required to participate and selective waste collection is increasingly used. Public opinion is clearly evolving towards a position that in the long term, we cannot just dispose of our waste when raw materials are only available in limited quantities. The green building approach naturally integrates optimised waste management.

Respect for the environment

The commercial and residential construction sector can represent up to 40% of primary energy consumption. Overall, it is also responsible for 20 to 25% of waste dumped and 5 to 12% of total water consumption. The United States Green Building Council considers that on average, green building currently reduces energy consumption by 30%, carbon emissions by 35%, water consumption by 30% to 50%, costs relating to waste by 50% to 90%.

A considerable number of research reports confirm the benefits for health and productivity, environmental properties such as natural lighting, the increased use of natural air for ventilation and humidity reduction, the choice of products with low emission rates for carpets, adhesives, paints and other coatings, as well as interior finishing products. In the USA, the annual cost of sickness related to buildings is estimated at 58 billion dollars. According to researchers, the “ecologisation” of construction could achieve annual savings of 200 billion dollars in the USA, simply by improving worker productivity through the improvements of ambient air in office buildings.

Buildings also influence our quality of life, the deployment of infrastructures and transport networks. Bad land management practices often lead to inefficient use of land, which generates higher energy consumption and increased travel time. This can also result in a loss of productivity, the discharge of polluted run-off water into surface water storage and waste water treatment networks, the loss of farm land, the fragmentation of habitats and financial pressure for local authorities.

Climate change

Reports produced by the world’s leading scientists stress the need to take action on a planetary scale to manage climate change. According to the forecasts of the Intergovernmental Panel on Climate Change (IPCC), if we do not immediately take sufficient measures to limit greenhouse gases, global warming could have irreversible and possibly catastrophic consequences. Every year, the energy used by buildings ejects thousands of megatonnes of CO2 emissions into the atmosphere.

Reports indicate that energy-efficient buildings are one of the fastest and most economical ways of considerably reducing greenhouse gas emissions, and often a source of net economic benefits. An increasing number of organisations, institutions and government entities are demanding a radical improvement in energy yield in the construction sector. In short, the green building approach represents one of the most likely short term methods of considerably reducing emissions responsible for climate change.

According to the IPCC report (ref 2b, 2007, institutional efforts in favour of eco-construction), the building sectors offer the best opportunity to achieve considerable reductions in CO2 emissions. In its fourth evaluation report, the Intergovernmental panel of experts confirms we should be able to eliminate approximately 30% the world’s emissions of greenhouse gases in the construction sector by 2030. With such reductions in energy consumption, renewable sources could satisfy additional energy needs, which would make it possible us to produce buildings with zero net energy consumption and which are carbon neutral. This limitation of CO2 emissions would also improve the quality of interior and exterior air, increase social well-being and secure our energy resources.

Environmental quality

The environmental quality of a green building is its ability to satisfy three complementary requirements:
•    Control the impacts of the building on the exterior environment
•    Create a comfortable and healthy environment for its users
•    Preserve natural resources by optimising their use.
This rule applies to construction but also more widely to urban programmes and land management (business parks, zoning, infrastructures, etc.).

It is a concern that stems from discussions at the Rio summit in 1992, where 164 nations met to talk about sustainable development. The construction of a building can in effect have a major negative impact on the quality of our environment. The building sector consumes: 50% of natural resources, 40% energy and 16% of water.

Green building – Certifications

High Environmental Quality (HEQ)

The HEQ approach

The HEQ approach is proposed to project owners and project managers to make the most appropriate decisions in terms of sustainable development at all phases of construction and the lifetime of a building: Design, construction, use, maintenance, adaptation and deconstruction. Analysis of the solutions that will enable us to achieve the best compromise possible between these occasionally contradictory choices must be done for each operation. Such an approach is not the same from one project to another. Hence it is indeed an approach that aims to favour fully-considered choices made by all stakeholders in construction and future users, in a global cross-functional approach.    

A priori this approach is valid for all building sectors, whether new constructions or renovations. But not all buildings are implicated in the same way. Public buildings are the first concerned, as local authorities wish to show the way ahead in this matter. It is an excellent lever to promote a global cost approach, which is still underused, even though it makes better financial sense over the long term for local authorities, which are both project owners and managers of such buildings.

The role of HEQ in the construction of a green building

The HEQ approach gives project owners a work method that guides them in making the most pertinent choices in terms of a green building approach, according to the criteria that they weigh up themselves according to their priorities and the characteristics of their operation. This approach avoids a vast amount of financial waste as it encourages all stakeholders to work together upstream of an operation to analyse all the data together. Included in this waste we can identify: Design errors identified too late on site and which mean deployments must be reviewed, site delays due to opposition from local residents as a result of insufficient consultation, incorrectly estimated maintenance costs, that harshly penalise the life of the building, irrelevant energy consumption, etc.

To the management and construction of a green building, HEQ provides:
•    A harmonious relationship between the building and its immediate environment, by organising the building site to create a pleasant environment, by using the opportunities offered by the neighbourhood and the site, by reducing the risks of nuisance between the building, the environment and the site.
•    The selection of appropriate construction processes and products
•    Low-nuisance sites
•    Efficient energy, water and activity waste management
•    Advance cleaning and maintenance alongside the integration of maintenance requirements, by deploying efficient technical management and maintenance processes, and by managing the environmental effects of maintenance processes.

With HEQ, buildings offer the following in terms of comfort and health:
•    Hygrothermal comfort: Stability of hygrothermal comfort conditions and homogeneity of hygrothermal atmospheres, hygrothermal zoning, according to use;
•    Acoustic comfort: Acoustic correction, acoustic insulation, attenuation of impact noise and equipment noise, acoustic zoning, according to use;
•    Visual comfort: Satisfactory visual relationship with outside, optimal natural lighting in terms of comfort and energy costs, appropriate artificial lighting as a complement to natural lighting;
•    Olfactory comfort: Reduction of unpleasant odour sources, ventilation to evacuate unpleasant odours;
•    Sanitary conditions: Creation of satisfactory properties of interior atmospheres, creation of optimal hygiene conditions, ease of cleaning and evacuation of activity waste, creation of facilities for reduced-mobility users;
•    Air quality: Management of pollution risks due to construction products, management of pollution risks by equipment, management of pollution risks due to cleaning or improvement, management of risks of polluted new air, ventilation to ensure satisfactory air quality;
•    Water quality: Protection of the collective potable water distribution system and maintenance of potable water quality in buildings, possible improvement of potable water quality, possible treatment of non-potable waste water, management of risks concerning non-potable water networks.

Energy choices in HEQ

The first approach to adopt in terms of green building is to deploy all efforts to control energy requirements: This will enable a bio-climate architecture with orientation of the building, recuperation of solar contributions in winter and protection against over-heating in summer. Concerning the choice of renewable energy sources, no one should be singled out as having priority over another, as there exists no energy solution with zero drawbacks for the environment.

Each case must be analysed and comparative studies in terms of overall cost must be systematic to foster reasoned choices. What is more, we use renewable energies in association with conventional sources (wind power, solar thermal, wood, recuperation of calories from air and water, etc.) each time it is possible.
Lastly, we seek to optimise energy use through the use of systems able to adjust energy use to the strict necessities: Programming, power cuts, etc. Commercial and residential buildings generate about 25% of the world’s CO2 emissions. A constant effort to rationalise energy use in buildings can therefore significantly reduce the drift of the greenhouse effect. A HEQ building can therefore make an appreciable contribution to reducing the greenhouse effect.

LEED certification


LEED certification (Leadership in Energy and Environmental Design) is an international certification system for green buildings. It was established in March 2000 by the US Green Building Council, an American association dedicated to promoting financially-sound buildings that are pleasant to live/work in and offering good environmental performance. It also provides tools to assist building owners and operators in areas with human and environmental impacts. Its sustainable development-based approach relies on excellent performance in six major areas of human health and environment:
•    Environmental organisation of sites
•    Efficient water management
•    Energy and atmosphere
•    Materials and resources
•    Quality of interior environments
•    Innovation and design process.

LEED certification satisfies these fundamental needs while offering recognition for the efforts made to achieve them. It enables the reduction of the building’s impact on the environment while minimising costs associated to its life cycle. LEED certification is granted to buildings that have demonstrated viability by respecting the highest performance standards in terms of environmental responsibility and energy efficiency.

Credit to obtain LEED certification


A certain number of pre-requisites are imposed before the LEED green building assessment and rating is carried out:
•    Prevention of pollution caused by construction activities (erosion control and sediment management);
•    Deployment of basic building energy systems;
•    Minimal energy performance;
•    Reduction of CFCs in HVAC equipment and fundamental management of refrigerants and elimination of halon gases (halogen bromide chemical compounds);
•    Collection and storage of recyclable materials;
•    Minimal performance in terms of interior air quality;
•    Control of ambient tobacco smoke.

The purpose of these pre-requisites is to control and reduce surface erosion and to reduce the negative impact on surrounding water systems and air quality. Attenuation measures are used to protect the surface soil during construction against rain water run-off and the displacement of sand by strong winds. It also imposes measures to prevent the deposit of sand and other materials in rain water evacuation networks. To satisfy these requirements, certain design measures proposing the anti-erosion cladding, temporary or permanent burial of tanks to trap the materials deposited.

LEED credits per domain

Certification is awarded according to the total number of points obtained subsequent to the verifications and examinations. Each domain has a series of credits covering the most important environmental problems. Each credit can give one or more points according to the progress made in terms of the requirements. The criteria are defined in detailed directives for different types of new or existing buildings, schools, healthcare, commercial buildings and the interiors of green building commercial premises. On the basis of an overall score for the building, a certificate is awarded for the category. For levels of recognition can be awarded depending on the result: Certified, Silver, Gold or Platinum.

The environmental categories are sub-divided into credits according to the desired performance objectives. So points are awarded according to the achievement of requirements.

Environmental organisation of sites:
•    Choice of site
•    Alternative transport modes
•    Fluidity on site
•    Minimal disruption caused by site
•    Rain water management
•    Site layout to reduce the effects of a thermal island
•    Reduction of light pollution

Efficient water management
•    Innovative waste water treatment technologies
•    Reduction in water consumption

Energy and atmosphere
•    Optimise energy performance
•    Renewable energies
•    Improve refrigerant management
•    Measure and verify
•    Green energy
•    Protect the ozone layer

Materials and resources
•    Reuse buildings
•    Management of construction waste
•    Reuse of materials
•    Recycled content
•    Regional materials
•    Certified wood

Quality of interior environments
•    CO2 checks
•    Increased ventilation
•    Interior air quality management plan
•    Low-emission materials
•    Control of interior sources of chemical emissions and pollutants
•    System control by occupants
•    Thermal comfort
•    Natural light and views

Innovation and design process
•    Innovation in Design (management system for energy efficiency and reduction of environmental pollutants)
•    LEED accredited professional

BREEAM certification

BREEAM certification (Building Research Establishment Environmental Assessment) evaluates the performance of buildings in terms of the management system, energy, health, well-being, pollution, transport, ground use, biodiversity, materials and water. Points are attributed on each of these aspects according to the performance levels attained. A weighting system consolidates these scores to obtain an overall final score. This score is awarded in the form of a certificate and can then be used for promotional purposes.

The method was developed in the UK to assist building industry professionals to understand and reduce the environmental impact of buildings at each phase of the construction process. Using this method, the Building Research Establishment (BRE) is capable of measuring the impact of specific construction materials in order to produce environmental projects reflecting their performance. It enables environmental profiles to be created for each material used in the construction, based on a life cycle assessment.

LEED and BREEAM certificate systems both use a scoring system. This feature is not used in HEQ certification, yet it enables the comparison of buildings in terms of sustainable development (green building) and takes into account the performance achieved in assessing the value of the property in question.


Sustainable development and the environmental footprint

Sustainable development

Logo CSR Legrand

Sustainable development is based on three essential principles:

The need to reason in terms of sustainable development also affects concerns about the drift in the greenhouse effect and climate change. Sustainable development is not a temporary fad, today it is an imperious necessity and an economic reality that an increasing number of local authorities and businesses are starting to take into account in their strategies and actions.

The construction sector is at the heart of sustainable development. A large number of stakeholders are involved in construction activities: Project managers, project owners, industrials, service providers and institutional bodies work together on a joint project: The sustainable construction and management of our heritage. Eco-construction or green building is the ideal solution for sustainable management. Effectively, the construction of a building has direct and indirect impacts on the environment at all phases in its life cycle. Among these: Use of materials, product transport, building commissioning, use of the building (operation, impacts on current use, maintenance, renovation) and end of life waste (reuse, recycling and energy production).

Environmental footprint

The environmental footprint is a tool used to evaluate the productive surface required by a population to satisfy its consumption of resources and its waste absorption needs. It is a measurement of the pressure that humans put on nature, so that we can evaluate the influence we each have on the environment. It offers each of us the chance to assess our impact on the planet and to reduce our consumption of resources and our production of waste, so as to reduce our footprint and act in favour of sustainable development. 

On a world level, humankind’s environmental footprint is an estimation of the biologically productive land or sea surface required to satisfy all our needs. According to the world’s leading conservation organization, WWF, in its 2010 report, Humankind uses the equivalent of a planet and a half to satisfy its needs. The Earth has exceeded its bio-capacity by 50%. To deal with the most urgent challenges, actions must be taken to reduce our environmental footprint and enable sustainable development. The following actions are recommended:

•    Increase the number of protected zones by 15% in environmentally-sensitive areas
•    Participate in sustainable management of forests. According to the H1 resolution (Helsinki, 1993), this is the management and use of forests and wooded terrains, in such a way and intensity that they are able to maintain their biological diversity, their productivity, their regenerative capacity and their vitality. Such a management approach must preserve the ability to satisfy both now and in the future, the environmental, economic and social functions on a local, national and global level. The rational management of forests must not cause harm to other ecosystems.
•    Stop excessive consumption of water and the segmentation of fresh water ecosystems
•    Eliminate over-fishing and destructive fishing practices (loss of edible fish, destruction of coral reefs, reduction of the diversity and richness of species)
•    Invest in bio-capacity
•    Promote biodiversity and services rendered by ecosystems
•    Solve the problems of priorities between food and energy, generated by agri-fuels
•    Pay attention to the problems raised by allocating land and planning land use
•    Share limited natural resources


Green building – green installations

Electrical panel

General matters concerning electrical panels

Electrical panels can improve energy performance in a home and thereby contribute to sustainable development and the green building approach. In light of its weight in energy consumption, building energy use is a major concern. Innovative solutions now exist to compensate reactive energy and measure building consumption.

The innovative offers brought out by the Legrand group concern the whole electrical panel. Everything from the installation head, to custom equipment boxes is available. As the electrical panel is the core of the electrical installation, it is logical that it is active in the deployment of solutions that aim to support sustainable development.

Reactive power compensation

Reactive power causes more energy to be consumed and in the end contributes to increasing CO2 emissions into the atmosphere and to more costly electricity bills. Under the yellow rate, reactive power is taken into account on an all-inclusive basis in the apparent subscribed rating, which increases the cost of electricity. The aim of compensation is to improve the power factor of an installation. It consists of setting up capacitor banks which are a source of reactive energy. So the power capacitor banks reduce the quantity of reactive energy supplied by the source. It is an eco-efficient solution that can make an immediate contribution to reaching the objectives set by the Grenelle Environment round table.
The conservation of natural resources and enhanced energy efficiency are the fundamental objectives of sustainable development and green building policies. Reactive power compensation can increase the energy efficiency of an installation. It is then possible to achieve a situation where only the active (useful) energy is carried, both on transport and distribution networks, and in customer networks. The use of reactive energy compensation equipment is a major source of savings. Such equipment enables an immediate and significant reduction in energy consumption and CO2 emissions.

The capacitor banks provide the reactive energy necessary for certain equipment to work (ballast, motors, etc.). They enable consumers to subscribe to a less expensive power supply contract with the utility supplier. Low Voltage and High Voltage capacitor banks are designed and sold by the Legrand group in France and around the world. They make a significant contribution to sustainable development.

These capacitors compensate the installation’s reactive energy while reducing energy bills. In effect, they reduce the apparent power required by the installation by around 20%. This can avoid the replacement of a substation that has reached its power capacity or to settle for a subscription that is limited by technical conditions (many subscribers on a single transformer). Capacitors are used in industrial buildings and large commercial buildings. With the same subscription, they can eliminate the reactive energy bill, optimise the subscription and increase the installation yield. In a 1000 m² supermarket, savings can reach €1128 per year. The savings in CO2 amount to 1.6 tonnes a year and the cost is amortised in just 2 years.

Measurement of energy consumption

Measuring one’s electricity consumption, displaying and recording it is the first step towards achieving sustainable savings that are justly considered as part of the green building approach.  Measuring energy use is primordial if we want to take the right decisions in terms of sustainable development. Precise and regular measurements, combined with suitable corrective actions, are the key to efficient control over consumption and energy quality. When we monitor consumption, we make savings from 8 to 12%. So it is possible to set up simple but efficient action plans that will optimise performance.

Electricity meters and Legrand measuring stations meter the electrical power consumed on a single-phase or three-phase circuit. These meters are of course placed downstream of the metering by the power supplier. They display power use in kWh and total and partial active energy. The total and partial reactive power, the instant current and instant voltage etc. are also measured. The digital multi-function measurement stations also measure electrical values of low voltage applications.

The Mosaic programme

Commercial products and solutions

ECO 1 and ECO 2 stand-alone sensor switches
Logo Développement durable Legrand

The Legrand ECO1 and ECO2 stand-alone sensor switches can generate up to 55% energy savings according to a calculation of standard EN 15 193. They operate in automatic On/Off mode and measure the lighting level. Automatic On and Off functions are offered by the ECO1 mode. The ECO2 mode features a voluntary automatic On/Off action, according to standard EN 15 193. These sensor switches are easy to deploy, whether in a false ceiling, as a surface-mounted wall or ceiling fitting or as a flush-mounted unit.

According to a calculation based on standard EN 15 193, in mode ECO2 and for a 100m² area with natural lighting, these sensor switches can make considerable savings: Up to €80/year on green/yellow rate and up to €130/year on blue rate. What is more up to 120 kg of CO2 equivalent of pollution-generating gases can be saved. This example shows the significant role of a lighting management system in a sustainable development construction project. Stand-alone sensor switches generate an ROI within 2 years on average, and sustainable savings thereafter.

Lighting control system
Logo Développement durable Legrand

The lighting control system represents a solution to reduce consumption in commercial applications and improve the global costs in terms of building maintenance. It includes ECO1 and ECO2 stand-alone sensors, the installation on BUS/SCS and stand-alone Radio/Zigbee sensors. This control system uses various lighting control solutions to make energy savings and ensure comfort of use. It is a genuine source of energy bill reductions and makes a valid contribution to sustainable development. The system can be used both in new buildings and renovations.

BUS/SCS sensors can be used individually or for centralised installations. Their deployment is simple and usually done in technical ceilings. These detectors and controls are by default configured intuitively. The settings are calculated either by the programming software or by customising them on the equipment, by touch controls or wireless configuration via the sensors. According to a calculation based on the EN 15 193 standard and for a 100 m² area with natural lighting, BUS/SCS variable controllers in technical ceilings can make substantial annual savings. For 100 m², the savings could reach €100/year on green/yellow rate and up to €160/year on blue rate, or 160 kg of CO2 equivalent/year of pollution-generating gases. BUS/SCS sensors therefore make an efficient contribution to the green building approach.

Stand-alone Radio/Zigbee sensors are generally used in addition to BUS/SCS devices. Such sensors are also used to independently control many different applications with individual controls or centralised control depending on the programming. The Office block equipment with its 230V Radio/Zigbee control will for example, control the office lighting and turn on / cut off PC power in parallel to the BUS/SCS. According to standard En 15 193 and with an ON/OFF lighting control, this type of detection can generate annual savings of up to €80/year at green/yellow rates and up to €130/year on blue rate. This represents 120 kg of CO2 equivalent per year. The BUS/SCS – Radio/Zigbee interface is used to connect a BUS/SCS installation and an additional Radio/Zigbee installation together.

Green sockets

Green sockets are eco-sockets that can equip each work station when connected to specific circuits. These power outlet sockets are easy to use and deploy (flush-mounted, surface-mounted, in the ceiling, in the floor or close by). The Mosaic range of green sockets can reduce the consumption of power outlet circuits by up to 25%. These sockets can shut down PCs (screen and central unit) or put them on standby, cut power to certain machines (photocopiers, network printers, fax machines, beverage dispensers) at night and at weekends.

They exist in different configurations: Small and large columns, floor boxes and blocks, notably office blocks and meeting room blocks. The latter integrate special energy-saving functions. For installations in renovated buildings, custom office blocks can integrate a time switch and RJ 45 outlets. Office blocks, columns and meeting room strips are ideal solutions for flexible commercial workspaces. The pleasing ergonomic and aesthetic features of these blocks offer a dash of elegance to office space. Green sockets are sustainable development equipment, therefore ideal for a green building approach.

Heating and temperature control

Logo Développement durable Legrand

Heating represents almost 65% of the energy bills of main homes in France. Domestic heating is therefore the expenditure item to be considered in priority in the search to identify solutions for reducing electricity and natural gas bills. Gladly, sustainable solutions exist, thanks to the green building approach. So by regulating the temperature, it can be maintained at a selected value (temperature setting) while taking into account heat contributions from other source (sun, cooking equipment, etc.). This is possible through a regulation system that acts on the operation of the heating system.

The programme offers optimal control of the heating. A heating programming device such as an ambient thermostat can control the temperature of rooms according to the time of day. With an electronic weekly programme, this system can control the temperature on oil-fired, gas, and electric heating systems, whether in comfort mode, reduced or no-freeze mode. The system displays the current programme permanently. It can be rapidly connected using automatic terminals and is suited to regulating heat-radiating ceiling units and directly heated floors.

For a decent comfort temperature and to avoid waste, the building code has defined average temperature of housing as 19°C. A temperature of 16 to 17°C is sufficient in bedrooms during the night. It is also important to lower the temperature of a home when it is empty during the day. Changing the set temperature from 20°C to 19°C can reduce energy consumption by almost 7%.

Using a control system can therefore generate waste-free comfort and a reduction in energy consumption from 10 to 25%. Limiting emissions of pollutants and greenhouse gases makes a significant contribution to sustainable development. To ensure optimum performance, attractive energy savings and enhanced comfort, the heating system and installation must be efficient and modern.

In addition to efficient equipment, there are some simple actions that encourage energy efficiency and therefore sustainable development. Respecting boiler maintenance requirements for example, avoids deregulations that can lead to energy over-consumption. To facilitate heat distribution, radiators should not be covered and should be dusted regularly. It is also recommended to adapt the opening/closure of shutters and curtains according to the outside temperature and to the sunlight on glass separations. The Mosaic range offers automatic control of certain of these mechanisms.

Emergency lighting

Logo Développement durable Legrand

Emergency lighting is an obligatory lighting installation for all public buildings and/or workplaces. This type of installation must be implanted in appliance with regulatory requirements to ensure both suitable signage and a minimum lighting level, to enable the evacuation of people in the event of an emergency. This system therefore provides signage for exists and evacuation routes in public buildings and workplaces, in the event the normal power supply is cut off. Its installation must include evacuation route lighting, ambient or anti-panic lighting for open spaces and halls, as well as stand-alone portable lighting for electrical rooms.

The new ECO2 addressable self-testing units satisfy the energy requirements of HEQ-VHEQ buildings. In effect, as they use LEDs, consumption by emergency evacuation lighting has dropped to 0.5W. The LED security blocks feature a low energy electronic circuit. For a total of 500 units, the savings can reach up to €1200/year and 1805 kg of CO2 equivalent on green/yellow rate and double this on blue rate. The units are equipped with addressable technology that enables easy control over the whole installation. In the sustainable development spirit, their labels and plastic light diffusers are recyclable. They are also suitable for HEQ/BBC (low energy) buildings to optimise energy performance.

HV/LV dry-type cast resin transformers

Logo Développement durable Legrand

Transformers are used to reduce the voltage on electric current delivered by a supplier, to an intensity suitable for the user’s electrical equipment. A dry-type transformer, contrary to a submerged transformer, is made up of moulded windings in a vacuum, inside an epoxy resin insulating casing. Cooling is done only by the surrounding air. These transformers offer reduced losses, which generate extensive electricity savings and a significant contribution to sustainable development and the green building approach.

They are designed to optimise energy efficiency. The resulting reduction in electricity use can reach 20% in relation to a conventional dry transformer for a building not in use (nights and weekends). Their use can therefore significantly lower the impact on the environment. This 20% reduction in energy use corresponds to 408 kg of CO2 per year for a 1250 kVA transformer.

In contrast to oil-based transformers, Zucchini transformers use “dry cast resin” technology. They can reduce the limitations, risk of fire and ejection of pollutants into the environment. They are therefore appropriate for sustainable development and do not need to be protected in a dedicated, isolated structure. They can also be more easily recycled at the end of their life. Zucchini transformers reduce energy consumption during phases of no activity in buildings. They can therefore generate significant savings. For a computer centre with two clusters of 250 m², the savings are in the order of €500 per year, or 816 kg of CO2 equivalent, which enables their cost to be amortised in under 5 years.


Logo Développement durable Legrand

Faced with the scarcity of fossil fuel supplies and increasing prices, the development of renewable energy sources, especially solar power, contributes to securing our energy supplies. Photovoltaic solar power is a buoyant sector. The Legrand group is contributing to its progress, notably in terms of safety. By assisting in the timely diversification of our energy resources, photovoltaic techniques are a pillar of sustainable development and the green building approach. Effectively, due to its abundance and inexhaustible supply, much greater use should be made of solar power as a resource.

Legrand proposes protection cabinets and components to protect and cut off DC electricity produced by photovoltaic panels. Safe deployment in residential applications is made easier with suitable solutions that combine UPS and protective devices in a single product. Such equipment can be used to build 3 kWp installations.

For commercial installations, the accent is naturally placed on safety, with MC4 type connections. This type of equipment enables reliable and durable connections. We can add emergency stop slap buttons to enable immediate shutdown. Legrand proposes weatherproof cabinets, protective devices, cut-off devices and UPS up to 14 kWp, both for DC and AC applications.

Photovoltaic energy generates no greenhouse gas pollution or waste. Its potential is infinite and therefore plays a major role in sustainable development. According to the International Energy Agency (IEA), a surface area of 145,000 km² (or 4% of the surface of the driest deserts) would be sufficient to satisfy the whole planet’s electricity needs. The IEA calculation shows that a photovoltaic installation connected to the network will produce an ROI within 1 to 3 years, depending on the amount of sunshine captured by the site.


Green building – Eco-technologies and practices

Heat insulation for a green building


Efficient insulation

In our climates, whether we build new buildings or undertake renovations, seeking the maximum possible reduction in heat loss (thermal efficiency) is one of the main points to take into account in the green building approach. This reduction in heating requirements, absolutely necessary in light of economic, demographic and environmental indicators, is achieved by a three-pronged approach – “sobriety, efficiency and renewable energies.” In relation to the current trend of increasing energy needs, this approach will enable us to reach the “factor 4” objectives (commitment by western governments to reduce their CO2 emissions by a factor of 4 by 2050), by acting on three levers in a precise order, which is implemented as follows in the construction industry:

•    First of all sobriety: Through architectural design that will save space (to be built and heated), reduce heat-loss surfaces, capture and manage free sun heating in winter, protect from the sun in summer. This sobriety in design is backed up by sobriety in use, which is also a major factor in reducing consumption.
•    Then efficiency: Through a building envelope that drastically reduced heat loss in winter and avoids over-heating in summer, which also makes use of the thermal properties of materials, with equipment suited to needs.
•    Lastly and lastly only, the use of renewable energies: As an addition to heating and hot water systems.

The efficiency of the building envelope is depended on three factors: Fully insulated walls, limited gaps in insulation (thermal bridges) and limited parasite air passages. Full insulation is a result of the project design phase: while limiting thermal bridges depends on the choice of construction systems and airtight seals are instantly associated with the quality of deployment work. Efficient insulation should dramatically reduce energy needs, at least within the range of the “factor 4” objectives.

Sustainable insulation

In the conditions of use of the building, materials are often subject to aggressions or unplanned nuisances: Subsidence, damage by rodents, insects, humidity, loss of resilience after flooding, etc. If in theory all materials have a “guaranteed” durability, their sensitivity to all these situations is highly diverse and their real durability, like their performance, depends on the type of construction system in which they are used and the quality of the deployment work.

For really efficient green building insulation, we must choose both the suitable material and use it so as to ensure its resistance over time alongside that of the other elements of the wall associated to it. To know if a material is suited to a particular use, we need to see its full technical documentation which specifies the recommended methods of use. Sustainable insulation is also adapted to the building life cycle. The different sensitivities of insulation material to damage that can affect their durability are:

•    Sensitivity to compression
•    Sensitivity to rodents and insects
•    Sensitivity to humidity (water and water vapour)

Insulation for clean and safe buildings

To have safe green buildings, insulation materials and walls must also have good fire resistant ratings. The fire resistance properties of construction materials are very unequal and light, aerated insulation materials, along with certain sealing materials (membranes) and finishing materials (paint, curtains, etc.) are sensitive materials. But their fire resistant properties are far from being the main factor for insulation materials as they are never left uncovered. The properties of the wall and above all its facing that should be considered from this point of view. In effect, fire resistance and the preservation of mechanical properties of walls featuring inflammable insulation materials are above all dependent on the properties of the facings and structural elements.

The choice of facing materials is therefore essential and determines the fire resistant capacity of insulation materials and walls. These insulation materials must be clean. This type of insulation must enable clean buildings, both for residents and the people who build them.

Pollution associated to such materials and in particular insulation materials may be of several different types:

•    Moulds and pathogens, responsible for infectious diseases and/or allergies;
•    Particle substances and microscopic fibres in suspension in the air, which can be inhaled and may cause serious illnesses: Silicosis, lung cancer, etc.
•    Gaseous substances often emitted by organic materials resulting from petroleum chemistry, present in certain insulation materials, but also in glues, additives, manufacturing agents, finishing and decorative products such as styrene, toluene, benzene, formaldehydes, organic chlorine compounds, etc., known under the generic term of volatile organic compounds (VOC); they are increasingly subject to regulation, especially since the REACH European Directive;
•    Heavy metals responsible for intoxication such as lead, but also wood treatment products (copper, chrome, arsenic) are today much less frequently used;
•    Ionising and non-ionising radiation.

Choice of low-environmental impact materials
Logo Développement durable Legrand

Insulation in a green building must use materials with a low environmental footprint. Life cycle analysis (LCA) is therefore the basic tool used to quantify the impact on the environment of a material, a service, or a building. This codified and managed approach (ISO 14040 standard series) unfortunately remains a matter for specialists, because in trying to be exhaustive, it has become complex and onerous.

For a construction material, an LCA seeks to quantify its cost to the environment, ideally at each stage of its life: Manufacture, transport, deployment, maintenance and end of life. Such an approach therefore enables us to calculate what the material consumes (fuel, coal, water, renewable and non-renewable raw materials, etc.) and emits (pollutants affecting soils, air, water, etc.). Such matters are subject to eco-assessments, LCA, impact studies, etc.

For the choice of eco-insulation materials, the most commonly used environmental indicators are the CO2 assessment and grey energy. Other indicators are used to check that a material that has a good score on the initial criteria does not present serious drawbacks on the others. Take the example of asbestos, which according to the CO2, grey energy and resource scarcity indicators, would have been an eco-material … except that on the toxicity indicator the result is disastrous.

The main environmental assessment indicators are:

•    Human toxicity
•    Photochemical ozone formation
•    Odour
•    Energy consumed
•    Water consumed
•    Depletion of natural resources
•    Inert waste formation
•    Radioactive waste
•    Greenhouse effect
•    Acidification
•    Eutrophication
•    Aquatic eco-toxicity

Insulation materials

Synthetic insulation

In general these are expanded polystyrene, extruded polystyrene and polyurethanes. These insulation materials are produced by the oil industry, most often from one or more by-products of the refinement process. The fact that they are most commonly produced by recycling materials considered to be petrochemical waste (like naphtha, used as a base for polystyrene), does not automatically make them acceptable for a coherent green building approach. Reasons:

•    Their production is energy-intensive, produces vast amounts of CO2 and pollutes natural environments (air, water, stratospheric ozone, etc.).
•    In the usage phase, even though the most toxic products for the environment and human health have been banned, synthetic insulation materials still pose many problems of VOC emissions and are for the most part highly toxic in the event of fire.
•    At the end of their life, no recycling channel is sufficiently organised to ensure the separation of components and/or their elimination without risk to health and the environment.

Nonetheless, all synthetic insulation materials cannot be lumped together in the same class. Polyester fibres are comparatively a good choice (although still limited). Their production generates pollution and is energy-intensive, but their use does not present any notable risks for human health. The fibres are naturally stable and do not release VOCs or toxic gases in the event of fire. They can be reused at the end of the building’s life.

Mineral insulation

These are mineral wools, cellular glass, glass foam, expanded glass, expanded perlite, expanded vermiculite, expanded clay, pumice stone, pozzolana and mineral foam. These insulation materials are made of mineral raw materials (silica, clay, volcanic rock, etc.). They can also include certain products of recycling (glass, blast furnace coke, etc.) In an industrial process where various additives are generally integrated, the raw materials are transformed into fine fibres, rolls, panels, expanded granules, etc. with very variable properties.

Their production uses raw materials that are often abundant in the Earth’s crust, but the high-temperature manufacturing processes are energy-intensive and produce CO2. In the usage phase, products offer varying degrees of stability depending on their textures and densities. At the end of the building’s life, the possibilities of reuse or recycling depend greatly on the nature of these products and above all those associated with them. Mineral insulation materials can therefore only be used for green building applications according to their own properties.

Vegetal and animal origin insulation material

The main vegetal insulation materials used are made of wood or agricultural products. They are commonly used in green building construction and their use is rapidly growing, for several reasons:

•    The resource is renewable and greatly abundant;
•    As they fix CO2, they have the best carbon balance of all insulation materials and are not energy-intensive, except for dense industrial products;
•    Free of specific additives, they are clean for residents if correctly deployed to prevent any abnormal risk of humidity, i.e. in airtight and watertight walls that perspire;
•    Their fire-resistance properties are satisfactory compared to preconceived notions;
•    At the end of the building’s life, they can be reused or valorised as fuel or for some as compost.

But not all vegetal insulation materials are ecologically sound. Cotton wool, for example, when produced from native fibres, is the product of an agricultural industry based on intensive mono-culture that is extremely polluting for soils, destroys food crops and the autonomy of producing country populations. The situation is obviously not the same for recycled cotton.

Animal-origin insulation materials are mainly made of hair such as sheep’s wool, bird feathers and duvets. They are the only thermal insulation materials produced naturally as such. In theory, all animal hairs and feathers could be used to produce insulation materials. But in the current economic context, the resources must be sufficiently concentrated and/or organised.

Deployment techniques

Insulation of external walls

In a building, the wall is the separation with the most contact with the outside, therefore with the most heat exchange possibilities. It is also the most mechanically strained (supporting ceilings and roof, resistance to natural elements such as wind, seismic events, etc.) and the most complex, as it features almost all the passages between inside and outside (doors, windows, etc.). Walls also represent the largest volume of materials. It is therefore not surprising that a building is often referred to by the materials used to build its walls: A stone house, a brick wall, a straw house, etc., i.e. a house with walls built using these materials.

There is a wide range of technical possibilities to provide wall insulation for green buildings. The basic solution is to build insulating walls (assembled on wooden structures and built-up walls). In this family we have:

•    Built-up walls with distributed insulation: Load-bearing clay bricks, cellular concrete bricks and lightweight concrete blocks;
•    Externally-insulated walls: Rendered insulation without air gaps, insulation under cladding with air gap and built-up cavity wall;
•    Internally-insulated walls: Insulation using rendered panels or blocks, insulation attached to wooden structure and insulation with built-up inner partition;
•    Wood walls and wooden frame: Insulated solid wood walls, with a wooden frame and dry insulation filler, lightweight concrete fillers and wooden frames with straw bale filler.

Walls with distributed insulation or clay bricks are built using load-bearing blocks that are self-sufficient from a thermal standpoint in most cases. They are made of lightweight materials: Porous clay with multiple perforations, cellular concrete or light granulate bonded by a cement (stone, expanded clay, etc.). It is possible to do thermal correction on built-up walls by:

•    Laying thin insulation on the inside and/or outside;
•    Applying an insulating rendering on the inside and/or outside;
•    Applying a low-effusivity interior cladding.

Floor insulation

There are three main types of floors, depending on their position in the building and their thermal function between the living areas and the outside:

•    Ground floor surfaces in direct contact with the soil, or floors over an earth platform: High inertia floors (insulation under slab), medium inertia floor (insulation under screed) and low inertia floors;
•    Floors separated from the ground by a non-heated empty space (flooring on non-heated space). This space can be the exterior environment (house on pillars or piles), a temperate environment (crawl space) or a buffer space (cellar, underground, non-heated floor, etc.): Insulation of existing slabs, wood and concrete floors;
•    Intermediate floors between lived-in and heated levels.

The design of floor-level insulation over solid platforms is done according to several main criteria:

•    The desired level of inertia
•    The thermal function of the floor (passive or active with heated flooring);
•    The type of interior covering desired (tiling, concrete, bare earth, wooden parquet, linoleum, etc.).

In all cases, the risks of capillary rising and of thermal bridges must be managed attentively.

In a new green building construction project, the most logical systems from a thermal, economic and environmental viewpoint are in general wooden structure floors, on which the desired inertia can be applied for interior areas with a dry or wet screed. In addition, the thermal limitations for floors between heated levels are often subject to acoustic comfort requirements that must be taken into account. The floors of attics, unheated roof spaces must be taken into account in roof insulation.

Roof insulation

Roofs are extremely important components in the construction of a green building. They help to control the air flows and humidity in a building and also insulate it from exterior temperatures. In most old buildings, the protective function of the roof did not include the thermal insulation role so to speak, which was done on the last floor level, the attic floor. They were referred to as cold roofs.

Today, it is rare that the two functions of protection and insulation are not merged in order to make the whole volume of space under the roof and inside the walls inhabitable. But this gain of space comes with a new role for the roof as an exterior separation. From a thermal management viewpoint, roofs are opaque walls which, for a given surface area, present both heat losses in winter and the risk of overheating in summer.

This tells us that it is the separation that must receive the highest level of insulation, both to prevent the loss of heat in winter and to prevent its entry in summer. Insulating the roof should therefore take into account not only the thickness of the insulation material, but also its density (transmission inertia) and all the thermal bridges and air leakage points. The massive use of wood in any construction approach for its mechanical properties has already helped to reduce thermal bridges due to its relatively low conductivity.

To remedy the effects of transmission inertia on the roof, the first actions to take are in construction:

•    A low-capture covering (plant roof)
•    An air gap under the covering, sized for a real thermal draft, which depending on the gradient, may represent wide spaces (over 10 cm for a 30% gradient) and specific fittings for the entrances and exits of the air flow;
•    A high-inertia interior cladding (ceiling).

The plant roof or green roof is a major ecological benefit for sustainable constructions. It brings together all the benefits of a sustainable construction. Installed on terraces or flattish roofs, a green roof is part of a sustainable development approach as it proposes natural building insulation. In the urban context, a green roof helps restore biodiversity. This solution also offers strong perspectives in terms of biological filtration and cleansing of rain water. It also captures rain water and limits rain water run-off in pipelines. Green roofs in an urban environment also help to reduce CO2 content in the air, while capturing the main culprits of pollution (atmospheric dust and pollen).

The green roof technique can also insulate the building naturally. The mix of earth and rooted plants on roofs produces an airtight and watertight roof but which can also resist wind and fire. For the past few years, the practice of creating green roofs is a de facto part of current sustainable construction practices, the architectural version of the sustainable development philosophy. Green roofs can in effect protect the insulating membranes from UV rays and solar thermal radiation. This natural protection means we can hope the insulating membrane may last from 30 to 50 years.

Picture window insulation

Picture windows are special points in the envelope of the green building as they have multiple functions. From a thermal viewpoint, they are both and alternately sources of heat capture and loss depending on their orientation, the time of day and the season. But they must also provide views of outside, enable people to go in and out (sliding doors), let light in, air in and out at certain times, etc. All these functions make them highly technical components, for which thermal performance must go alongside the other functions we expect of them.

Heat losses from picture windows are caused by two factors: The intrinsic quality of the windows and the quality of their installation. In terms of picture window dimensions, the whole idea is to use as few surrounding frames as possible for a given surface area of window, i.e. prefer large panes and increase the size of picture windows rather than their quantity.  As in relation to two small windows, one large window of an identical surface area:

•    Loses less heat as it features more glazing and less frame
•    Captures more heat because in picture window only the glazing can do so
•    And costs less in frame costs and masonry.

Other light matters in a green building

Plumbing and electricity in a green building

Plumbing is also another important element in comfort, savings and safety in a green building. Its installation is a necessary step in construction. Water is effectively necessary for the comfort of the inhabitants, both for hygiene and drinking. Faced with the challenge of preserving the environment, specialists are slowly succeeding in designing eco-friendly plumbing. This must be designed in such a way to generate as little grey energy as possible and must be coordinated with the rest of the home.

The plumbing materials in a green building must be manufactured using processes that respect the environment. Manufacturers try to use as little carbon as possible and improve the heat insulation of components, to limit heat loss. Specialists are also making efforts in matters of water saving, environmental respect and septic tanks. It is important to maintain plumbing or to change it regularly, to avoid it becoming toxic both to the environment and to human health.

Polyethylene pipes are made of recycled plastic. They are interesting from a sanitary viewpoint, and especially in environmental terms as they are made from recycled products. Unfortunately, they are not very resistant and have difficulty in supporting heat and high pressure. What is more, the use of plastic piping for central vacuum cleaning systems, the cold air inlets for chimneys and gas heating systems, may contribute to reducing draughts in the family environment.

PVC pipes represent a big shock for the environment. The consumption of grey energy in their manufacture is high, their elimination can also cause problems and their reliability is not impressive. PVC becomes brittle under freezing temperatures and its leaktight properties will deteriorate after around thirty years underground but after only 10 years in the sunlight. PVC is produced using oil and salt. It contains plasticizing agents that are hazardous to human health, notably phthalic ester. Also used in its composition are stabilisers based on toxic heavy metals, fire-retardant agents made of chlorinated paraffin which are harmful to health, or antimony derivatives, which are reputedly carcinogenic.  These substances also create problems during their production and elimination.

In a green building, the right choice in tap fittings can make substantial water savings, such as:

•    Mixer taps: Enable considerable hot water savings, therefore of power used to heat the water;
•    Thermostatic tap: With a conventional shower tap, a large quantity of water is lost when adjusting the temperature. With a thermostatic tap, you control the desired temperature on one side using the indications on the appliance, and on the other side the desired water pressure.
•    The flow reducer: This is installed on a shower head at the base of the pipe and can reduce the water flow by half, while maintaining the same spray pressure;
•    Aerator: It is installed on a tap. It prevents leaks and reduces the water flow while maintaining an identical pressure compared to a non-equipped tap. The water volume is reduced by compensated for by air.

It is fully possible to produce your own electricity with ecological production methods, through photovoltaic power, wind turbine power or hydraulic power. It is also possible to select environmentally-friendly electricity from suppliers. The liaison committee for renewable energies and WWF-France have created the EVE mark (Environmental Green Energy) so that consumers can choose between the different suppliers of ecological energy. The idea is to supply, in a fully transparent manner, electricity that is produced in respect of the environment and to promote the development of renewable energies. For its part, Greenpeace has launched its green offer comparison tool, Ecolo Watt.

Plastic plays a major role in high tech and is often taken for granted. The plastics used in making electric components in an installation must be specifically suited to satisfy the conjoined needs of electrical safety and fire safety. The durability of the plastic parts of electrical components enables such products to have a long useable lifetime.

Doors and windows for green buildings

Doors and windows seal a building and therefore must respect very strict criteria. Entrance doors must protect against humidity, freezing, heat and noise. They must also provide safety, durability and energy efficiency. As many of their customers do not trust conventional doors made of wood, manufacturers use aluminium and PVC for the structure, with low-quality insulating foam fillers. This type of door is highly criticised for environmental reasons and traditional wooden doors are to be preferred.

Today there is a vast range of durable and efficient solutions made of plastic materials for doors that are easy to maintain. Despite their low weight, plastic doors are extremely durable. In fact, the spreading use of plastic door products has validated their strength, their energy efficiency and their acoustic value.

Entrance doors with a plastic foam core may inhibit noise and add insulation value, which can help reduce heating and cooling needs. Sealing foam can also be used to draught-proof windows, doors and thresholds, to seal out undesirable air draughts. From an ecological viewpoint, solid wood is the most suitable material. This is because a solid wood panel made of three or four crossed laminated sheets is strong and guarantees good thermal and acoustic insulation.

Windows are a building’s weak points in terms of thermal insulation, including for the green building. In winter, south-oriented windows capture more heat than they lose. Some are partisans of single glazing for south-facing windows, which favour solar contribution to heating; others prefer insulating glazing that reduces heat loss.  Before making a choice, both the glazing and frames must demonstrate good thermal performance. However, a multiple-opening window features two panes that are only separated very rarely (for cleaning), which improves insulation. A double window comprising two panels that open separately. They allow good thermal and acoustic insulation.

Vinyl windows and glass doors enables less electricity to be used for heating and cooling a house or larger building. This energy efficiency helps reduce greenhouse gas emissions from power stations. Also the low maintenance needs of vinyl windows and glass doors eliminate the need for paint, tinting, thinners and paint removers, which harm the air quality.

Interior fittings


Staircases are essential elements in a construction and must satisfy very specific standards in terms of safety. In buildings, staircases that present a certain risk are usually built with heavy materials (in general concrete). The joins between the steps and the stringer, the core or the wall, as well as those between the stringer and the planks, should systematically be acoustically treated, which will considerably limit the propagation of noise in a wooden staircase.

As an eco-material, local wood should be tested for its durability properties. A hard wood such as oak will resist for at least 80 to 100 years, but thin steps made of tender wood are to be avoided. For green buildings, wood is naturally recommended.

Terraces and balconies

Like roofs, green terraces and balconies are becoming an important component for the green building approach. A terrace designed in the spirit of a garden would create a genuine micro-ecosystem, where birds and insects can thrive. Without neglecting the aesthetic aspect or the original motivations, a terrace can also become a kitchen garden. Fruit and vegetables to hand can accompany delicious meals cooked in the kitchen. To achieve this, the space needs to be optimised, and water and utility use regulated. A bin to recycle natural waste (peelings, weeds, branches) will be needed to create green compost. This will rapidly be reused to cover the soil or for compost mixed with soil after long decomposition.

The components of a green terrace are: Vegetation, cleaning plants and shadow plants. They should be set out to reduce heat spots, as recommended by the LEED certification. Different materials are to be used to make such spaces. You will need to identify the purpose and intended use, the assemblies and arrangements necessary. The architecture should therefore be used, not only by the materials that it represents, but also by its volumes, forms and styles. Architecture and landscape are capital factors to succeed in fitting out terraces and balconies.

Air quality inside a green building

A building built in a sustainable development approach also takes into account the long-term and short-term health of its occupants. For this reason, green buildings should fully integrate measures intended to improve interior air quality into their design.

These constructions can result in the selection of materials that do not liberate toxic compounds, not dangerous chemical substances. The adjustment of ambient conditions in terms of ventilation, temperature, humidity and lighting is also to be improved. Healthy interior environments not only ensure the well-being of the occupants, but also guarantee their satisfaction and stimulate their productivity.

Green building – Zero energy home and economic aspects

Zero energy home


Buildings have a relatively long lifetime compared to consumer goods. The selection of green construction methods and materials therefore has an impact over a very long period of time. The choice of construction materials is important insofar that materials with very high thermal inertia must be selected, as they insulate efficiently against the cold in winter an heat in summer. Their environmental performance is also a determinant factor.

An environmental approach to construction always results in savings in terms of maintenance and operating costs. This approach does not forcibly entail additional initial investment. One of the following structural materials must be used to build a green building:

•    Cellular concrete: Load-bearing material offering thermal insulation, of mineral origin. It is durable, recyclable and produces no toxic discharges.
•    Clay bricks (honeycomb brick): Load-bearing clay material offering thermal insulation. Offers high acoustic performance and highly durable. Incurs overconsumption of grey energy in the manufacturing process.
•    Wooden frame: Load-bearing material (requires systematic addition of an insulating material) and CO2 absorbent. A renewable source available in large quantities.

Choice of energy

Here it is not a question of total energy independence from the electricity supplier but to produce as much energy as the building consumes on average over a given period of time.  The green building that produces as much energy as it consumes on an annual basis is equipped with passive solar power features such as south-facing windows.  Combined with solar panels, these systems concentrate the sun’s energy to produce electricity, heating or air conditioning.

In certain countries, solar rays captured by an average house, over a year, are sufficient to satisfy its energy needs and more. It is now possible to reduce the average energy consumption of a green building to zero by using solar power. In a green building, reduced energy consumption must be accompanied by the use of all energy efficiency measures possible.


For heating purposes, it is important to prioritise renewable energies, especially in new construction projects. In this respect, solar power, wood-energy and geothermal sources seem to be the most suitable. With plenty of solar power in a green building, we can propose hot water and a direct heated floor for heating.

These days solar water heating systems are extremely efficient, even if we can regret that the maximum yield is in summer when we need it least. This solar energy is free, clean and inexhaustible. It can cover a part of a green building’s heating needs. In this context we refer to combined solar systems. They can cover from 25% to 60% of annual needs in terms of heating.

The combined solar system is more complex to set up insofar that we need hot water all year round but heating is only needed for several months. Similarly, the temperature of water in the heating circuit is rather low (between 30°C and 50°C) while for hot water it is much hotter (between 45°C and 60°C). To remedy these difficulties, hydro-accumulation systems have been created. This system consists in stocking the heat produced by sensors in a buffer water tank, which we can tap into in the event of necessity. The energy required for heating is distributed around the building either by low temperature radiators or via direct-heated floors.

Wood energy is a renewable energy that contributes to reducing the greenhouse effect and climate change. It recycles the carbon dioxide in the atmosphere which is then absorbed by forests. What is more, its constitutes and excellent method of valorising by-products and waste from the wood industry and participates in rational forest management, therefore to maintaining hydrological and climatic balances.

Geothermal power is also a renewable energy, environmentally-friendly and available on demand. Geothermal heating collects heat from the earth or water, in the case of a geothermal system on a water table, to transform it into useable heat in the green building, via a generator that supplies the heating system. Geothermal heating offers solutions that are suitable to most constructions.

The economic aspects of a green building

Cost of a green building

Usually, the ecological properties of a building are considered as an additional cost. In this vision of things, the construction of a green building is inevitably more expensive that a less eco-efficient solution, as it implies the use of high quality materials, high efficiency materials and a more complex work flow. The approach that consists in considering that the payment of a supplement is inevitable to make a project eco-sound is now fading away to allow more holistic designs and a global vision of project costs and benefits.

Today, research scientists, architects and owners observe that a program that is oriented to sustainable development from the outset may enable us to discover techniques that will bring environmental and social benefits without additional costs. For example, by simply orienting a building to exploit its windows and capture passive solar heat as much as possible, promoters and architects can create their designs with a mind to consume less energy, increase the sustainable development aspects and improve daylight penetration, which can increase employee productivity without incurring additional construction costs.

A green building can even help the owner eliminate expenditure from the outset. The choice of cooling equipment is a good example. In this way, if heat losses on an eco-construction project are reduced to a minimum through efficient lighting and the building envelope is eco-efficient, the building will need a much smaller cooling capacity. This can therefore avoid having to install an additional cooling system and can even reduce the project budget significantly.

The benefits of a green building

The construction of a green building may generate only few additional costs, even none, but that is not due to spontaneous generation. The required evolution in processes to design and construct a building with an integrated approach requires a great deal of effort and must be perceived as having sufficient added value to be adopted by the industry. Rightfully so, owners and promoters wish not only to be assured that a green building will not cost them much more, but they also wish to be sure that it will produce substantial benefits that will justify their efforts.

Of course, one of the benefits of a green building is to be able to use it as a showcase for public relations. People interacting with companies and organisations now expect to see a certain degree of environmental action. A green building conveys a physical and permanent message on a company’s commitment in terms of stewardship and environmental responsibility.

Concerns due to climate change encourage governments to enact laws that impose measures to reduce carbon emissions. Similarly, shareholders are increasingly demanding that businesses manage their environmental and carbon footprints responsibly, as well as anticipating the risks of climate change to which they are exposed. The construction of a green building can help owners to comply with these requirements.

These advantages help demonstrate the value of a building, but do not always suffice to motivate an owner to adopt an eco-construction approach. As with any financial decision, the return on investment is crucial. However, in many cases, eco-construction is a byword for energy savings and potentially significant savings can help the owner to cross the eco-construction line.

When a green building is designed to optimise efficiency and reduce the use of resources to a minimum, it must produce a lower energy bill. It is commonplace that the energy bill be half as much as that for a building built according to minimum standards. This bill will drop even further when on-site generation of renewable energies is included in the project.

Nonetheless, these energy savings generally benefit the building occupants and not the architect or the entrepreneur. To alter this erroneous perception of the cost/benefit ratio, recent studies have attempted to quantify the value (for the owner) of a green building, using measurements done by the whole property sector. Below are some of the conclusions drawn by this study:

•    Ecological buildings sell at a higher price. McGraw Hill measured the price premium on the sale of Energy Star buildings and obtained a result of 12%. Another study estimated the price premium on LEED-certified buildings at 31%.
•    Rents on ecological buildings are higher. By comparing lease contracts on Energy Star buildings with those on non-Energy Star buildings, researchers at Maastricht University observed that rents on eco-efficient buildings were 3.5% higher than others.
•    Ecological buildings are more attractive for occupants. The same study revealed an occupancy rate 6% higher for Energy Star-certified buildings.

Given that available data is increasing and that building owners are succeeding in assessing the benefits of a green building more effectively, an increasing number of projects will follow this path. As part of a new integrated design approach, it is possible to reduce the additional cost of ecological buildings to a negligible level. What is more, the benefits are increasingly visible and tangible. The two variables of this equation are progressively but inevitably leading us towards an era of construction of sustainable buildings. Real estate professionals have realised this and the increase in eco-buildings will results in more sustainable urban habitats all over the world.

By ensuring the continued improvement of the methods of selecting construction locations, design processes, construction methods, operating methods and modernisation techniques, political leaders should support the green building approach. The application of leading edge eco-efficient techniques may generate enormous reductions in the demand for fossil fuels and in greenhouse gas emissions. Design and construction best practices can also assist in resolving environmental problems related to the exhaustion of natural resources, the elimination of waste and the pollution of the air, water and soils. The growing “ecologisation” of the building industry may help to improve human health and prosperity.

In March 2011, the Fukushima accident in Japan was a stark reminder to us all that electricity production involves risks. In light of the environmental limitations and the increasing scarcity of non-renewable resources, the green building approach must pursue its development. This type of eco-construction is not an alternative, but rather the only way of meeting the environmental challenges that we face.
Fortunately, to do this, we can count on the environmental commitment and the continued development of solutions offering maximum energy efficiency, from such organisations as the Legrand group.

Copyright protected by articles L.111-1 and L. 123-1 of the French Intellectual Property Code.


électricité spécifique

Specific Electricity Solutions

Learn more

Efficacité énergétique

Energy efficiency

Learn more

Document de reference 2015

Registration document 2015

Get your PDF

Message of, the CEO

Chairman’s message

Learn more