Passive house: what it is and how it works
A house where internal heating is guaranteed by the heat generated by electrical appliances and people living in it. A house that recovers energy in an alternative way, through a mechanical ventilation system. Here is the goal of Passivhaus.
Passive house concept isn’t new, indeed. Even if In Italy it is known for a quite short time , in Germany it has already existed since 1989. In those years, two North-European universities decided to collaborate to devise a new generation of sustainable houses.
These houses should have exploited the quality of the building materials and the solar exposure, to cut down on energy requirements for internal heating. The outset of Passive houses resulted from that intuition.
Francesco Nesi, construction physicist and president of Zephir ( a private research institute founded in Trento in 2001 which represents the Passivehaus Institute) explains what a passive house is: a passive house is not built only with natural materials or with hi tech and expensive materials. Most of the initial costs, approximately the 6 %, is amortized over ten years thanks to energy saving.
Passivehaus is a house able to guarantee internal heating with a very low heating source recycling the heat generated by electric appliance and the body heat from the residents and by the means of alternative energy sources. A geothermal heat pump set into a mechanical ventilation system allows the recovery of the energy generated into the house.
A Passive House allows related energy savings of up to 90%. Passive Houses use less than 1.5 litres ( about 15 kwh) per square meter of living space per year – far less than what a traditional house use only for the heating (10/12 litres) ,
Of course, a passive house beyond the use of renewable energy, needs: a correct sun exposure, the help of a natural ventilation, the use of a water heat recovery system and photovoltaic panels.
Costs can be reduced thanks to economic energy monitoring systems and suitable doors, windows and shutters.
There is also the possibility to limit energy waste in traditional buildings.
All over the world passive houses are more than 50 thousand, but only a few thousands are certified Passivehaus. In Italy there are about a hundred, for the most part in the North even if they are spreading also in the rest of the country. You can visit a Passivhaus , taking part in a Passivhaus day or visiting Bonapace Hotel in Torbole (province of Trento) the first certified Passivhaus hotel in Europe and the second in the world.