Passivhaus buildings reduce heating and cooling requirements by 75%. The little supplementary energy that they require can be easily covered from renewable energies, becoming a construction with a very low energy cost for the owner and the planet.
5 key points are treated:
A very good insulation of the envelope is beneficial both in winter and in summer: the outer walls, the roof and the sill must have a very low thermal transmission, so that it does not let in the heat of summer, nor the cold of winter.
The holes are the "weak point" of the envelope, so you must pay close attention to its location during the design of the project, to maximize the incidence of the sun, and its proper placement during the work.
The carpentries used also have very low thermal transmission and the windows are double or triple glass filled with an inert gas, the glass being low emissive to reflect the heat inside the house in winter and keep it outside during the summer.
The transmission of energy not only occurs in general elements such as walls or ceilings, but also occurs in corners, axes, joints, etc. Unwanted losses or gains occur and the surface temperatures in these areas are usually lower than the rest of the envelope, which can cause the appearance of mold. It can be built without thermal bridges by:
People and appliances generate heat, this is taken advantage of by the ventilation system, by pre-heating the incoming clean air before expelling the stale air. The amount of energy needed to condition the spaces is so small that we could cover it with a small stove without the need for a conventional radiator or underfloor heating system, with the corresponding economic savings that this implies.
In a conventional construction, the air currents that can be given through windows, holes or cracks cause discomfort in the user and even interior condensations, particularly during the coldest periods of the year.
In a Passivhaus building, the enclosure is as watertight as possible achieving a high efficiency of the mechanical ventilation system. This is achieved by taking maximum care of the execution of the joints during construction.
The tightness of the building is measured with a pressure test, or Blower Door test, which consists of creating a pressure difference between the interior and exterior through a fan placed in the main door. To meet the standard, the result must be less than 0.6 air changes per hour.