Passive house »Wohnen & Arbeiten«

The Small Co-generation Unit

	Sachs HKA-Co-generation Unit
	Click on the picture to enlarge:1024 x 768
	BHKW (opened)
	Interior View of BHKW
	Warm Water Connection of the Washing Machines

In the planning period of the houses, it was clear at an early stage, that the Vauban territory would be equipped with a local heating network: An ecologically progressive procedure, particularly with Holz-BHKW which is actualized by Badenova. In principle, we would have chosen this network, however...

Are Local Heating and Passive houses Incompatible?

When a community of a development area chooses a local or long-distance heating network, everyone has an obligation for alignment and use: every owner is obligated to join, since with a low level of participation such a network would not be economicaly or ecologically sensible.

Because the cost of the installation of a heating network is really high, (and because one wants to provide the consumers with cost-effective heating), it is conventionally and legally allowed, to shift the cost of the network (upto 70%) onto the consumers rightaway. Only 30% is paid by the provider, which, from the beginning, has a reliable customer base and a monopoly in the region. The so-called "additional connection costs" are levied per square meter of living area, independent of how much heat would actually be used later.

If we had agreed on the alignment for the local heating, we alone would have had to pay a five-figure sum for the additional connection costs for the whole house. This amount may be acceptable for a house with normal heating standards, since this sum for the most part is more favorable than a comparable installation, for example, a gas boiler. Due to our very low heating needs, this meant that we had to pay more money than we had to for a small gas-operated co-generation plant, with which we sympathized anyway since in that case, we could produce another part of our electricity ourselves and more ecologically than the traditional way allows for.

The logic and the justification -quasi "preamble"- of having to align oneself with the network enabled by the legislator, is "the cost-effective and reliable supply of heat". However, cost-effectiveness would not have been the case for us.

Private Electricity and Heat Production Cheaper than Local Heating!

The direction of the negotiations was clear: The postulated connection price was too high for us; we had built this house also so we could save some money. In the negotiations, we, the city and the energy supplier have agreed on that we, as the passive house residents/owners would come clear from the connection price and the obligation to use the local system. This was only on the condition that we would really build a passivehouse and would not try to avoid the regulations. This was for us, a task that we happily would comply with.

After considering the pros and cons of a local heating system, we can come to the conclusion that local heating systems and particularly the "combined heat and power generation" system has a big and important potential for especially old buildings. However for passivehouses, which already have very small energy requirements, local heating systems do not make economical and ecological sense.