Energy Efficient Housing in Germany

Some friends of mine live in Königs Wusterhausen, in the outskirts of the Berlin area. This is a lovely lovely area bordered by lakes and forests. Of course, given its location, it gets quite cold in winter

They have built a highly energy efficient house there, which contains a number of great features that I would love to incorporate in an upcoming home renovation back in Adelaide.

Australian houses generally just don’t get built with energy efficiency in mind to nearly the same extent as in Europe. This house, in particular, is bristling with highly efficient features.

One of the glaring omissions in Australia in most houses is highly insulated windows and doors. Almost all European buildings employ double (or even triple) glazed windows and doors, and they have excellent seals around the openings, so that when they are closed, the rooms remain hugely more temperature stable with far less energy required to maintain their temperature. Or course, the walls are super-insulated as well!

This approach doesn’t just work well in cold climates; Such highly insulated environments are equally good at helping a house in a hot-summer climates such as Adelaide to be kept at a comfortable temperature as well.

I have included a little gallery in this post showing of some of the great ‘technical’ energy efficiency features of this house in the gallery below.

Key aspects of this are:

  • An efficient and zero-air-exchange wood stove. This draws external air through the combustion chamber and exits the air via a flue, without exchanging that air with the air inside the house. Above the heating chamber is a box full of stones which act as thermal mass to allow the unit to keep heating the room even once the wood has burned out. The properly has about a decade of wood stored there, salvaged from prior clearing of the site. Because the house is so efficient at holding in its heat, this is extremely effective to heat the primary living space in the house.
  • A ground-source heat pump that uses deeply buried tubes to access constant temperature underground. It uses this fixed temperature source to heat (or cool) water for multiple purposes in an extremely energy efficient manner.
  • Two separate water heating chambers in the water heat-pump unit generate hot water for domestic purposes and (separately) heats or cools water for use in the hydronic (underfloor water pipe) water system, allowing for room heating/cooling via control of the temperature of the floor slab
  • The house is so super-insulated that the hydronic system can effect house heating by operating at only around 24 degrees Celsius, in order to raise the room temperature to a typical level of 21 degrees. This means the system warms the house without the floor becoming hot to the touch. In a less well insulated house, the floor would have to be heated via a much higher water temperature, in order to offset heat leakage through the windows and walls (and with a consequently much higher energy draw required).
  • The hydronic system has individual thermostats controlling individual flow valves, allowing each room to be maintained at a separate temperature using this single hydronic system.
  • An air/air heat exchanger is connected to air loops in each main room. The system uses a closed-loop approach and offers an essentially silent and draught-free air-handing outcome.
  • This unit circulates the in-building air through a heat exchanger that implements thermal exchange between the internal house air and an external air access loop, in order to modify the temperature of the in-house air. This is much more efficient than drawing outside air into the house and having to heat or cool it across the full differential between outside ambient and the desired internal temperature.
  • Triple-glazed windows and doors and super-insulated walls
  • LED and compact fluorescent lighting throughout

We have found one (great) local Australian manufacturer of double glazed “German Grade” super insulated doors and windows in Australia, run (not surprisingly) by an expatriate German gentleman named Tony Paarhammer. His company is Paarhammer – and it is a company I strongly recommend to anyone who wants to do glass doors and windows properly.

The ground-source water heat-pump and air-air heat exchange system are new to me, and if I can’t find local suppliers I intend to source these from Germany for our own house renovation in the future.

Likewise the hydronic control system; We have a hydronic system in our house today but it only has a single whole-of-house thermostat which turns the whole system on or off. This generates an outcome that is quite compromised (due to the lack of individual room temperature control and the consequential difficulty in balancing the system to generate an acceptable temperature in all rooms at once). The individual thermostat approach also allows rooms to be turned ‘off’ and ‘on’ at will, with obvious additional energy savings as a result.

You can read a lot more about the building of this house on the blog that chronicles the build process.

That site is here:   (in its original German)

You can also access it this way:   (Google auto-translated to English)