Ulf Köpcke
Bibliographic info:
12th International BUILDAIR Symposium, 25-26 June 2021

Purpose of the work
An airtight design of the heat-transferring building envelope has become a standard requirement for new buildings. An n50-value of approximately 1 is now quite common for new buildings in Germany. Property developers and building contractors are thus all the more adamant that any notices of defect put forward in spite of such good air exchange rates be dismissed on the merits. Phrases such as "generally accepted construction tolerances", "permissible irregularities" or a plain statement that an air exchange rate of zero isn't feasible anyway, are increasingly being put forward during disputes about air leaks. This presentation will outline the legal frameworks in German law that are relevant for such discussions.
Method of approach
I will analyze situations and issues that typically arise in practice within the context of applicable provisions in contracts for work and services.
Content of the contribution
An airtight building envelope is a requirement that is set out as a work to be performed under building code law. Applicable standards are high. Originally specified in the German Energy Savings Ordinance they are now part of the German Energy Savings and Renewables Act (Gebäudeenergiegesetz - GEG). The heat-transferring building envelope and its joints must have a permanently airtight design in accordance with generally accepted good engineering practices. Avoidable leakages are always at variance with the work to be performed as required by law. Discussions about tolerances or permissible irregularities basically lead to the question as to whether there is such a thing as "air leaks that are fit for purpose" when discussing the airtightness of buildings - i.e. leaks which do exist but do not impair the building envelope's fitness for purpose in any way or hardly at all. I will demonstrate that this reasoning is hardly acceptable from a legal point of view. More importantly, however, I will point out that the law on contracts for works and services deals with such cases by objecting that certain claims to remedy defects are not reasonable, instead of simply acknowledging any tolerances that are put forward. Such objections to claims which do not seem to be reasonable can always be put forward.
From a legal point of view a concept such as "leaks fit for purpose" seems to be too far-fetched to make claims. Acknowledging some kind of generally accepted tolerances to assess the airtightness of a building envelope thus doesn’t seems to work either in legal terms.
If the contractors have delivered building envelopes that meet high quality standards and are airtight, any disputes on the relevance of any remaining leaks should be settled mainly by analyzing whether the request to remedy defects is reasonable, or not. It is up to building practice, building theory and construction lawyers to develop criteria and categories which can be used onsite to analyze and settle such issues.

For further information please contact Rechtsanwalt Ulf Köpcke at: koepcke.u@t-online.de