German language video, Lustenau, Austria.
Passive heating in Austria. Temperature all-year around guaranteed to be between 22-26 C, hence the qualifier “2226”. Office building with 100 work places. Humans themselves are “hot” and serve as heat sources of 80 Watt. And so are devices like computers, lights, coffee machines, printers, etc. The trick is to keep this modest amount of generated heat inside the walls, that are no less than 76 cm thick.
The windows are deep inside, to prevent that too much solar heat will penetrate into the building in the summer, eliminating the need for cooling with energy devouring air conditioners. If inside, the temperature gets too hot or the air too stuffy, valves in the outer walls are simply opened. No complicated network of pipes and pumps is installed. The resulting building is cheap and simple and hence low-maintenance.
So where’s the catch? An important point is to let go of the superfluous wish to completely control the temperature at say 22 C. By tolerating the temperature to vary between 22 and 26 C, you gain a lot of freedom to eliminate both heating and cooling and leave it to inhabitants to decide to work in a t-shirt or pullover. Another important point is the relatively large thermal mass inside the building, that acts as a buffer and temperature stabilizer.
German language video with English subs. Example Luzerne, Switzerland.
German language video, Burgenland, Austria. If works for detached homes too.
[source] Building elements for a 2226 building