Green building

marker Publication Date: 2020-12-08
Tinyhouse, passive housing, kerterre, ecological renovation, timber-frame house, straw insulation, rammed-earth house, whitewash... you have probably heard some of these concepts which all have in common to be related to green building.
But what exactly is green building or sustainable construction?

Green building is the construction or renovation of a building in the most environmentally friendly way, while considering its entire life cycle, from its design to its dismantling.

The green construction approach can concern both rehabilitation sites and construction of new buildings.
Buildings can be of all sizes, from single-family houses to larger projects (eco-districts or industrial zones).

A necessary global approach

To successfully complete a green building project, a systemic approach integrating all aspects and their interactions is necessary.
Thus, the entire life cycle of the building must be considered, enabling the building to respect the environment during the design, construction, use, renovation and demolition phases.

It is also essential to include all the housing industry stakeholders in order to be able to assess the environmental and social impacts of each decision taken during the project, a detailed knowledge of local stakeholders is therefore essential.

The budget for green building is not necessarily higher: a well-designed project using local materials will drastically reduce expenses (construction operators using these less conventional types of materials may, on the other hand, be rarer, requiring more time and commitment).
When it integrates more complex technologies (solar collectors, mass stove, innovative materials, centralized management, etc), the additional costs of the construction project can be important. On the other hand, these additional costs will be balanced in a few years through the achieved savings in energy and maintenance, that is way we should consider the project in all the phases of its life cycle.

The criteria defining a green building

Many criteria define a green-built housing:
  • Consideration of local environmental constraints
  • Efficient use of energy and water
  • Pollution and waste reduction
  • Use of renewable energies
  • Use of non-toxic, ethical and sustainable materials
  • Indoor air quality

These criteria must be considered as a whole.
Indeed, a passive house, that is to say a house which has an energy consumption fully compensated (by solar energy or by the calories emitted by its occupants and the devices operating inside), may not be a green building assuming that it is built with fired bricks, a very energy-intensive material.
The use of organic paints, which emit pollutants in the home could also be compatible with a passive house, without guaranteeing healthy air for its occupants, a necessary condition for defining a green building.

Now let us see these 6 criteria in more detail:

Consideration of environmental constraints

When designing a green building project, a precise study of local conditions must be made to define the specific conditions of the land (its type, orientation and morphology, surrounding objects such as trees or other buildings…) and the climate (direction and force of the winds, hours of sunshine, temperature scales, types and frequency of precipitation…).

From the identified local conditions, it will be possible to design the building so that it integrates these data: the arrangement of the rooms and windows will, for example, enable to limit the energy needs of the house by capturing the heat and sunlight. The living rooms will therefore be logically arranged to the south, while reducing the glass surfaces exposed to the north. Studying the architecture of traditional buildings can be of great help in learning a lot about local conditions and in maintaining harmony in buildings.

It is also important to take into account what is already present in the area when arriving on a given site, with the aim not to occupy it but to integrate it: the pre-existing ecosystems must be protected as much as possible in order to not to disturb or destroy natural habitats while installing a new building.

Tinyhouse green construction
The trailers of Sieben Linden are a kind of tinyhouse: these houses, very small, limit their footprint allowing them to reduce their environmental impact. These houses remain comfortable and are built using healthy materials that respect nature.

Efficient use of energy and water

The efficient use of energy and water in the building both reduces dependence on external sources of supply (thereby increasing its resilience , makes financial savings and reduces the environmental impact.

The two most important items of energy consumption in a building are usually heating and hot water production.
In order to limit the use of energy for heating, passive solar energy capture techniques, heat recovery ventilations or high thermal inertia walls are examples of techniques to reduce energy consumption.
Hot water can be produced using thermal solar panels coupled to a hot water tank.

The water required in a building is generally of two types: potable water for consumption and domestic water for other uses. Capturing rainwater is an effective solution to reduce the consumption of non-potable water that can be used for showers, washing clothes and dishes...
Finally, the use of equipment with low electricity and water consumption allows significant savings in these resources.

Maison surface sud
With its large south-facing glass front, this building in Sieben Linden has drastically reduced its consumption of wood thanks to an insulation of 70 cm under the roof, large thermal solar panels combined with a heat storage tank and a ventilation system with heat recovery.

Pollution and waste reduction

The choice of construction materials will be decisive in reducing the production of end-of-life waste: some materials can indeed return to nature without any prior treatment, while others will need to be treated via processes that are sometimes very complex, polluting and energy intensive.
A mud house whose walls are layers of compacted raw earth will thus gradually return to the earth under the effect of weather.

Very frequently, green constructions also integrate waste treatment systems:
  • Natural wastewater treatment systems allow the natural treatment of grey water from the building
  • Composting toilets compost human waste
  • Composters allows to compost kitchen waste

The Kerterre is a house which fits in perfectly with its surroundings. It is entirely made with natural materials: hemp, earth and lime. These materials will not need treatment during when demolishing the house and will be spread in nature (source image:

Renewable energies use

After having studied the natural resources available on the building site, it will be possible to determine the systems best suited to locally produce energy in order to meet the needs of the building and its occupants.
Many production solutions exist including:
  • Thermal solar panels are used to produce domestic hot water and help with the heating of the building.
  • Heat pumps are useful for the production of heat, the supply of domestic hot water and the cooling of buildings by capturing thermal energy from the air, water or the ground
  • Biomass boilers produce heat through the combustion of waste and renewable materials
  • Digesters allow the production of biogas from decomposing organic matter
  • Photovoltaic panels for the production of electricity
  • Hydraulic turbines which use the force of water for the production of electricity
  • Wind turbines for the production of electricity from the force of the wind

Solar panels
Solar thermal panels equip a large majority of green-built houses, thus allowing the production of hot water and sometimes also part of the heat needs.

Non-toxic, ethical and sustainable materials use

The choice of building materials, which must be efficient, ethical and environmentally friendly, is essential.
In general, we are looking for a durable material that is:
  • Mechanically resistant, for structural materials (floor, walls, roofs)
  • With high thermal capacity, thus avoiding thermal bridges
  • A good humidity regulator in the house
  • Fire resistant
  • Saving energy and greenhouse gas emissions for its production
  • Locally available in sufficient quantities
  • Non-toxic so that it does not impact the health of workers, residents and the environment
  • Able to return to earth gradually under the effect of weather, without human intervention

So, sustainable building materials can be diverse:
  • For the structuring materials, we will use in particular stones, earth (via bricks or rammed-earth) or wood (wooden-frame house) which will enable to limit the use of fired bricks and concrete, whose production is very energy intensive.
  • For insulation, hemp, straw, wood fibre, sheep's wool or cellulose insulation are good alternatives to glass fibre, whose ecological footprint is bad.
  • Natural paints and wall treatment with lime, linseed oil, water are good regulators of the rooms humidity and allow good protection of surfaces, while avoiding volatile organic compounds emitted by standard paints and glues which pollute the indoor air.
  • Certain materials known to be pollutants are avoided as far as possible: this is particularly the case of PVC, a material that is difficult to recycle and emits volatile organic compounds that are hazardous to health.

Hjortshoj ecoconstruction
A long experimentation work on the use of construction materials has been carried out by the inhabitants of the community of Hjortshøj. This house built with rammed earth (raw earth compacted in layers) is protected by tuya claddings (some of which are protected with linseed oil) and walls coated with lime.

Indoor air quality

As we saw in the paragraph dealing with materials, indoor air quality is very dependent on the used construction materials. Indeed, certain materials can diffuse pollutants that can degrade the quality of the air inside a building.
Walls designed using materials that allow moisture to pass through enable good humidity regulation in the house, for the comfort of its occupants.