Which are the fundamental aspects of the Passivhaus construction method?
The Passivhaus method construction is reaching a higher level of relevance among property developers around Europe. Passivhaus is based on the optimization of existing resources through passive construction techniques. These kind of buildings reduce heating and cooling needs by 75% in comparison with a regular building. The little extra energy they require can easily be covered from renewable energy sources, becoming a construction with a very low energy cost.
In Spain, the main organization that promotes this way of construction is Plataforma de Edificación Passivhaus (PEP). According this organization, the concept is based mainly in five essential principles:
One of the most important factors to build an efficient building is the thermic insulation. A Passivhaus project must have excellent insulation, which is beneficial both in winter and summer. Depending on the climate, the thickness of the thermal insulation must be optimized in terms of cost and energy efficiency improvement.
A low thermal transmittance by the proper composition of walls, decks and ceilings is basic.
Right election of windows and doors
A high quality of windows and doors is a key factor to get a brilliant level of insulation. In fact, they are considered as the “weak points” of the buildings. Not only is relevant the quality of materials, the thickness or the level of light reflection provided by the windows. It is also essential to analyze where these elements should be put it and be careful with the installation process during the building works.
Absence of “thermal bridges”
Unwanted losses or gains of energy not only occur in general elements such as walls or ceilings, but also occurs in corners, shafts, joints, etc. For this reason, during the construction process must be considered the use of materials with the higher thermal resistance if the insulation layer is interrupted. But obviously, if possible, try to do not interrupt the insulation layer is a priority.
A specific attention of the joints between constructive elements is important to detect potential “thermal bridges” in early stages of the building works.
Installation of mechanical ventilation with heat recovery
People and appliances generate heat, this is reused by the ventilation system, by preheating incoming clean air before expelling the stale air.
The amount of energy needed to get a proper thermic condition of the spaces is very small thanks to the mechanical ventilation. The needs in terms of heating could be covered just with a small stove without the need for a conventional system of radiators or underfloor heating. This represents important economic savings.
In a conventional construction, air flow can occur through windows, gaps or cracks causing interior condensation during the colder periods of the year, and of course causing also a certain level of thermal discomfort among the property users.
In a passive building, the level of insulation is as high as possible, achieving a considerable efficiency of the mechanical ventilation system. This is possible by taking maximum care of the execution of the joints during construction process.