Energy efficient buildings (new constructions or renovated existing buildings) can be defined as buildings that are designed to provide a significant reduction of the energy need for heating and cooling, independently of the energy and of the equipments that will be chosen to heat or cool the building.

This can be achieved through the following elements:

  1. bioclimatic architecture: shape and orientation of the building, solar protections, passive solar systems
  2. high performing building envelope: thorough insulation, high performing glazing and windows, air-sealed construction, avoidance of thermal bridges
  3. high performance controlled ventilation: mechanical insulation, heat recovery

Only when the building has been designed to minimise the energy loss, it makes sense to start looking at the energy source (including renewable energy) and at the heating and cooling equipments. We designate this approach as the Trias Energetica concept.

The trias Energetica Concept

Following the principles of the Trias Energetica concept we have developed the following 5-step approach:

Bioclimatic architecture takes into account climate and environmental conditions to help achieve thermal and visual comfort inside. Bioclimatic design takes into account the local climate to make the best possible use of solar energy and other environmental sources, rather than working against them. Bioclimatic design includes the following principles:

  • The shape of the building has to be compact to reduce the surfaces in contact with the exterior; the building and especially its openings are given an appropriate orientation (preferably towards the south); interior spaces are laid out according to their heating requirements ;
  • Appropriate techniques are applied to the external envelope and its openings to protect the building from solar heat in winter as well as in summer; passive solar systems collect solar radiation, acting as “free” heating and lighting systems; the building is protected from the summer sun, primarily by shading but also by the appropriate treatment of the building envelope (i.e. use of reflective colours and surfaces).

Thermal insulation is a low-cost, widely available, proven technology that begins saving energy and money, and reducing emissions the moment it is installed.

Well installed insulation ensures energy efficiency in every part of the building envelope including ground decks, roofs lofts, walls and facades. It is also well suited for pipes and boilers to reduce the energy loss of a building’s technical installations. Insulation is as relevant in cold regions as in hot ones. In cold/cool regions, insulation keeps a building warm and limits the need for energy for heating whereas in hot/warm regions the same insulation systems keep the heat out and reduce the need for air conditioning.

  • An exterior wall is well insulated when its thermal resistance (R value) is high, meaning the heat losses through it are small (reduced U value). Insulation is a key component of the wall to achieve a high R value (or a low U value) for the complete wall. The thermal resistance R of the installed insulation products has to be as high as possible.
  • To limit the thickness of the insulation within acceptable dimensions, Saint-Gobain Isover constantly improves the thermal conductivity of its materials (lower lambda value) thus allowing increased thermal resistance within the same space.

Air tightness reduces air leakage – the uncontrolled flow of air through gaps and cracks in the construction (sometimes referred to as infiltration, exfiltration or draughts).

Air leakages need to be reduced as much as possible in order to create efficient, controllable, comfortable, healthy and durable buildings With more stringent building regulations requiring better energy efficiency , air tightness is an increasingly important issue.

  • Details that are vital to achieving good air tightness need to be identified at early design stage. The next and equally important step is to ensure these details are carried over into the construction phase. Careful attention must be paid to sealing gaps and ensuring the continuity of the air barrier. It is far simpler to design and build an airtight construction than to carry out remedial measures in a draughty home.
  • Saint-Gobain Isover has developed systems with innovative accessories that allow appropriate installation of the insulation while guaranteeing excellent air tightness and allowing proper moisture management (see the Vario system presentation).

Consequences of air leakages : cold outside air may be drawn into the home through gaps in the walls, ground floor and ceiling (infiltration), resulting in cold draughts. In some cases, infiltration can cool the surfaces of elements in the structure, leading to condensation. Warm air leaking out through gaps in the dwelling’s envelope (exfiltration) is a major cause of heat loss and, consequently, wasted energy.
Most existing buildings, even those built recently, are far from being airtight and because of unwanted air infiltration generate huge costs to owners and occupants, in environmental, financial and health terms.
A leaky dwelling will result in higher CO2 emissions. The additional heat loss will mean that a correctly sized heating system may not be able to meet the demand temperature. Draughts and localised cold spots can cause discomfort. In extreme cases, excessive infiltration may make rooms uncomfortably cold during cooler periods. Excessive air leakage can allow damp air to penetrate the building fabric, degrading the structure and reducing the effectiveness of the insulation. Air leakage paths often lead to dust marks on carpets and wall coverings that look unsightly.

Ventilation is the intended and controlled ingress and egress of air through buildings, delivering fresh air, and exhausting stale air through purpose-built ventilators in combination with the designed heating system and humidity control, and the fabric of the building itself.

  • If you do not insulate properly and ventilate too little, you can risk warm humid air condensing on cold, poorly insulated surfaces which will create moisture that allows for moulds and fungi to grow.
  • A controlled ventilation strategy will satisfy the fresh air requirements of an airtight building. Air infiltration or opening of the window cannot be considered an acceptable alternative to designed ventilation.
  • As the saying goes: ‘build tight, ventilate right.’
Back to FAQ list