Hilsdon Holmes current governing body ATTMA has launched a dedicated Passivhaus testing standard, which we are delighted to become affiliated.
While the general principles of a passively heated or cooled house are not new, a scientific approach to passive design has gathered momentum in recent decades, with an industry recognised standard, developed from research carried out by Dr Wolfgang Feist, introduced in the 1980’s.
The key principles of Passivhaus design are:
- Good levels of insulation with minimal thermal bridging
- Excellent levels of airtightness
- Good indoor air quality
- Passive heat gains through solar radiation and internal heat sources
The reason that a Passivhaus is required to be of a highly airtight construction is because the level of airtightness for a building will directly affect the heating demand. As a result, the financial and environmental costs of maintaining a good level of thermal comfort in less airtight properties is greater.
For the majority of newbuild properties, it is only necessary to test the airtightness as part of the completion assessment. For a building to comply with the Passivhaus standard, air permeability should be no more than 0.6 volumetric air changes per hour. To ensure the finished properties would comply with such a high degree of airtightness, Hilsdon Holmes conduct air tightness tests at both first fix stage (when the main building services are installed prior to dry lining), and for the standard final test for compliance with Passivhaus standard and building regulations.
Our testers have an excellent understanding of airtightness construction, so we can offer comprehensive advice on potential problem areas, and practical guidance when locating leakage during first fix tests. This cooperative approach to first fix testing has resulted in plots achieving very low results.
Ensuring a completely airtight seal around the testing frame is critical when it is placed into the properties external door opening. Due to the extremely airtight standard of a Passivhaus, our testers have developed methods to ensure a completely airtight seal around both the blower door frame and the fan drum.