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What can we learn from Germany?

20/01/2013 13:25:58

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A new NHBC Foundation report has been published.  "Lessons from Germany's Passivhaus Experience", ref. NF47, was authored by Cutland Consulting Ltd, and the following is the Executive Summary of that report, reproduced by kind permission.  The full publication is available on the NHBC Foundation website.

The rise in popularity of Passivhaus in Germany has been largely due to a specific combination of social, political and financial circumstances:

• Social: The German population has a strong interest in the environment and an associated inclination to take action. While people in Germany have traditionally lived mostly in rented accommodation, an increase in home ownership is occurring; a general enthusiasm for high product specifications and attention to detail means that building or buying a low energy home is seen as an attractive option.

• Political: In addition to national regulations for the energy performance of buildings, many individual cities have chosen to set their own energy and environmental standards which mandate an even higher performance. Failure to comply is treated as a regulatory offence and fines are issued.

• Financial: The cost of building a Passivhaus home in Germany is now estimated at 3 to 8% more than building a home to the building regulations (known in Germany as EnEV), and there is a variety of assistance available for financing this cost. Government and local loans are available at significantly discounted interest rates, and grants are available depending on the level of energy efficiency achieved.

Passivhaus is often described as a ‘comfort standard’ as well as an energy standard, and studies of occupant satisfaction in 736 dwellings in Germany and Austria are reviewed in this report. Overall the occupants were generally positive about Passivhaus with 92% of them indicating that their expectations had been met.

Germany’s experience suggests, however, that educating occupants in the correct operation of the home and its ventilation system is vital – especially in order to avoid overheating in summertime. This is not a Passivhaus-specific problem; the trend towards more airtight homes in the UK as well means that mechanical ventilation with heat recovery (MVHR) is likely to become the dominant form of ventilation in new homes.

No claim has been made that building Passivhaus homes is easy; the demanding energy performance and quality assurance requirements present a challenge to the designer and builder alike. Some observers question whether Passivhaus is a realistic solution for the volume market, although a number of large scale projects are continuing to inform the debate.

All certified Passivhaus homes built in the UK have to verify compliance with building regulations as well as the Passivhaus quality assurance procedure, which can add time, effort and cost. This problem is less significant in Germany because the Passivhaus Planning Package (PHPP) software also produces an energy compliance report for the requirements of the EnEV.

The high level of compliance of Passivhaus dwellings has led to suggestions that the formal certification process could help to narrow the gap between designed and built performance - although some elements of the process may be hard to apply to volume house building. It has been suggested by some UK proponents that Passivhaus certification be afforded the status of ‘deemed to satisfy’ the energy component of the UK building regulations.

January 2013

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