EnergyRealist

This short article from Germany talks about another alternate approach to building an energy efficient house.  What gets my attention is not so much the technical detail (more on that below), but that the German news is filled with this sort of discussion.

At the opposite end of the spectrum from a single house there is debate about an “energy concept” – the equivalent of the much needed comprehensive energy policy in the US.  That the Germans, who have embraced the idea of sustainable energy so well, still do not have an integrating concept shows just how difficult the economics and politics are.  Atomic power plants are under some major scrutiny – Just how long will they run?  Will some have to shut down because of mandated safety enhancements (including having to withstand a direct impact from a loaded passenger jet)?  Will there be a tax on nuclear fuel elements to pay for disposal and reprocessing?  It all sounds familiar.

(A much longer discussion on Germany and nuclear power can be read at this Bulletin of the Atomic Scientists site. )

The large tank being lowered into the house (Sueddeutsche Zeitung, Kappen)

At the small end of the scale this house in Moosburg (pronounced Mohsburg), in Bavaria, is an attempt at building an energy efficient house as simply as possible.  It still needs a lot of people to work together.  The local authorities helped out by granting variations from standard building practice and allowed the house to be located at an angle in the lot to gain the needed north-south orientation.  Heat comes via 64 sqm (690 sqft) of solar collectors feeding, via heat exchangers, into a 14200 liter (3750 US gallons) storage tank.  The more usual dimensions for collector and tank are 30 (320 sqft) to 70 sqm (750 sqft) of collector and only 150 to 250 liters (40 to 70 US gallons) of storage. The super large tank is integrated into the stairwell of the house. The southern roof pitch is a steep 67º to get the best angle for winter sun.

Unlike many energy efficient houses this one relies on well sealed 49cm (19 inches) thick masonry walls, instead of masonry plus 30cm (12 inches) of Styrofoam as insulation.  To an environmentally conscious owner the impact of producing that Styrofoam, and the glues and antifungal paints needed to install it are a definite negative.  In addition to the solid construction the design avoids thermal bridges; for instance, the balcony is suspended by steel cables, instead of being cantilevered from the house.

Supplemental heating will be a wood stove (just wood, not pellets or anything high tech.).  The owner claims that 1 to 2 hours of wood fire will generate enough stored hot water for 2 to 3 days of no sun.

[The approach of using solar energy – solar thermal in this case – to raise the storage medium (water) by a small amount makes a lot of sense.  I often wonder about the wisdom of converting sun light to electricity (at low efficiency) and then turning that highly concentrated (low entropy) energy into warm air or water.  See Energy 101 for a slightly more detailed discussion and references.]