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Frequently Asked Questions

Frequently Asked Questions

A passive house consumes very little energy thanks to a very good thermal insulation of its external envelope and its airtightness. It is good to live in a passive house. Especially thanks to the ventilation system that allows a constant renewal of the indoor air. 

To be certified, a Passive House must comply with the following criteria:

  • Heating requirements ≤ 15 kWh/m².year or maximum load for heating ≤ 10 W/m²
  • Cooling requirements ≤ 15 kWh/m².year or maximum cooling load ≤ 10 W/m²
  • Airtightness n50 ≤ 0.6 /h
  • Primary energy needs ≤ 120 kWh/m².year or renewable primary energy needs ≤ 60 kWh/m².year
  • Overheating limitation 
  • Interior thermal comfort
  • Indoor air quality
  • Good sound insulation
  • Reduction of the electricity bill for heating
  • Preserves non-renewable resources (oil, gas, etc.)
  • Contributes to the reduction of CO2 emissions through its high energy performance

According to a study conducted by the Passive House Institute, the additional investment cost for a passive house compared to a traditional construction would be about 5%. On the other hand, it is necessary to study each case in detail. Indeed, insulation needs will differ from one climate to another, and this will have an influence on initial costs. 

The Passivhaus label is a German label for the energy performance of buildings. It is a global construction concept whose main objective is to do without conventional heating. This label ensures that a house will offer thermal comfort, high indoor air quality and low energy consumption. 

A common misconception about passive houses, which can frighten many people, is that it is forbidden to open windows, otherwise the energy performance of the house would be lost. 

In a conventional house without ventilation we strongly recommend to open windows regularly to ventilate. However, in a passive house it is not mandatory, but not prohibited. In a passive house, the air is constantly renewed thanks to efficient ventilation and adapted filters, reducing in particular the risk of allergies among occupants. 

A passive house is not necessarily made of wood, as it is a performance standard and not a specific construction method. As long as the building meets the requirements in terms of energy demand, comfort, airtightness, each one is free to choose how to achieve them. We can find passive houses wood, brick…

A passive house is a long-term sustainable investment. Indeed, in a passive house, heating needs are 4 to 10 times lower than those in a standard house. Such a house allows you to save on your electricity bill for heating. Moreover, as electricity prices will increase, the inhabitants of such houses will not be affected by this price increase. 

A bioclimatic house is designed and built in such a way as to adapt and integrate into its environment. Bioclimatic concept takes into account environmental factors from the design phase. These are the climate, the land orientation, the exposure to prevailing winds and the existing vegetation on the land. Most of the windows are located in the South, to take maximum advantage of solar gains and reduce the need for conventional heating. To avoid overheating in summer, natural (vegetation) or artificial shading devices (sunbreakers, adjustable shutters, etc.) should be installed.

The first passive constructions appeared in Germany, and were designed for a cool temperate climate. However, the standard is applicable to the majority of the world’s climates. There are indeed certified passive buildings in more than 40 countries around the world.  This is the proof that the principles of passive houses are valid in any climate. 

To date, 4 houses have been certified in Portugal an about forty projects are under development. In Europe, about 4000 buildings are certified (including more than 2000 in Germany). 

For more details visit the database.