What Is An Energy-efficient Building?
Energy-efficient buildings (new buildings or renovated existing buildings) can be characterized as buildings built to significantly reduce the energy requirement for heating and cooling, irrespective of the energy and the facilities chosen to heat or cool the building.
Via the following elements, this can be achieved:
Bioclimatic architecture: building form and orientation, solar shields, passive solar systems.
To help achieve thermal and visual comfort within, bioclimatic architecture takes climate and environmental conditions into consideration. Bioclimatic architecture takes account of the local atmosphere in order to allow the best possible use of, instead of operating toward, renewable energy and other environmental sources. The following principles constitute bioclimatic design:
- In order to minimize the surfaces in contact with the outside, the form of the building must be compact; the building and, in particular, its openings must be angled correctly (preferably to the south); the interior spaces must be organized according to their heating requirements;
- In order to shield the building from solar heat in winter as well as in summer, appropriate techniques are applied to the exterior envelope and its openings; passive solar systems absorb solar radiation, serving as ‘free’ heating and lighting systems; the building is shielded from the summer sun, mainly by shading but also by the appropriate treatment of the building envelope (i.e. use of reflective colours and surfaces).
High-performance building envelope: thorough insulation, glazing and windows of high performance, air-sealed construction, thermal bridge avoidance.
Thermal insulation is a low-cost, widely usable, proven technology that, when built, starts to save energy and money and minimize emissions. Well designed insulation guarantees energy efficiency in any aspect of the building envelope including ground floors, roofs lofts, walls and facades. It is also well suited for pipes and boilers to reduce the energy loss of a building’s technological installations. In cold areas, insulation is as important as in hot ones. Insulation keeps a building warm in cold/cool regions and limits the need for heating energy, while in hot/warm regions, the same insulation systems hold the heat out and minimize the need for air conditioning.
- When its thermal resistance (R value) is high, the exterior wall is well insulated, which means that the heat losses through it are minimal (reduced U value). To obtain a high R value (or a low U value) for the complete wall, insulation is a key component of the wall. The thermal resistance R of the isolation items mounted must be as high as possible.
- Saint-Gobain Isover constantly improves the thermal conductivity of its materials (lower lambda value) to limit the thickness of the insulation within appropriate dimensions, thereby enabling increased thermal resistance within the same room.
Regulated ventilation for high performance: mechanical insulation, heat recovery
Air tightness decreases air leakage through gaps and cracks in the construction by uncontrolled air flow (sometimes referred to as infiltration, exfiltration or draughts). In order to create efficient, controllable, comfortable, healthy and durable buildings, air leakages must be reduced as much as possible. With more stringent building regulations requiring better energy efficiency, air tightness is an increasingly important issue.
Consequences of air leakage: through holes in the walls, ground floor and ceiling (infiltration), cold outside air can be drawn into the house, resulting in cold draughts. In certain cases, penetration, leading to condensation, may cool the surfaces of elements in the system. A significant cause of heat loss and, subsequently, wasted energy, is warm air escaping out through gaps in the envelope of the dwelling (exfiltration).
Most existing buildings, including those constructed recently, are far from being airtight and, in environmental, financial and health terms, generate enormous costs for owners and occupants because of unnecessary air infiltration.
In conjunction with the engineered heating system and humidity control, and the fabric of the building itself, ventilation is the intended and regulated entry and exit of air into buildings, providing fresh air and exhausting stagnant air through purpose-built ventilators.