You are not allow to open windows
In summer, a Passivhaus relies on open-able windows. In warm weather, the most effective way of purging of any heat built up during the day is open the windows at night time. During the winter heating season, there is no reason why a window can’t be open but most people will feel less inclined to do so because heat recovery ventilation ensures the internal air is fresher in a Passivhaus than a typical modern build. A few people living in Passivhaus flats and houses, who previously always slept with an open window summer and winter, continue to do so in their Passivhaus home. This reduces the temperature a bit and adds a little to the building’s energy use.
The air is too dry in a Passivhaus
This can be an issue in a Passivhaus, but it is also true in conventional centrally heated buildings, however it can be minimised, provided that the heat recovery ventilation (MVHR) system is specified, installed and commissioned correctly.
Passivhaus buildings overheat in summer
As mentioned above, it is important to open windows at night during warm spells. In the daytime, windows exposed to sunlight should be shaded externally to keep the heat out. The Passivhaus standard requires that the internal temperature does not exceed 25C on more than 90 percent of days annually.
There is no heat source such as a cosy fire or similar focal point - you cannot use wood to heat a Passivhaus
There is no physical need to light a fire in order to feel cosy, as a Passivhaus feels cosy without one. This is why we don’t feel the need to light a fire in a conventional house in summer. You can install a very small wood burner in a Passivhaus; however, using it in all but the coldest winter days could risk overheating unless one was very careful about how much wood was added. If too much wood was burnt, any overheating could easily be remedied by opening windows! A Passivhaus could be designed with areas that are outside the thermal envelope. A wood burner could be used to heat those spaces. While this arguably might defeat the purpose of a Passivhaus, it does give the occupant a choice whether or not to use their wood burner.
