Passivhaus Air Testing

What is an Passivhaus Air Testing

A Passivhaus is a building standard for energy efficiency which reduces a building’s ecological footprint. This results in ultra-low-energy buildings that require little energy for space heating or cooling.

Their purpose is to provide a high level of thermal comfort to occupants with minimal environmental impact and extremely low energy costs.

Passivhaus Air Test (otherwise known as Air Tightness Testing; Air Permeability Testing; Air Leakage Testing and Air Pressure testing) is the process used to determine the total conditioned air lost through leaks in a building’s fabric, known as its envelope.

All new developments have been required to have an Air Test as stated in Part L of the building regulations, since 2006.

The final Air Test is always completed towards the end of the construction process and before the occupier has moved in to meet Building Regulations.

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How important is air tightness in Passivhaus?

Compared to conventional constructions, Passivhaus buildings must be extremely airtight. A structures must adhere to “either 0.60 ACH50 (air changes per hour at 50 pascals) based on the building’s volume, or 0.05 CFM50/sf (cubic feet per minute at 50 pascals, per square foot of building enclosure surface area).” To this end, the generally accepted best practice is to test the structure’s air barrier enclosure using the “blower door” method. Ideally, this should be done at the mid-point in construction.

The Passivhaus standard was created so most of the air exchange with the outside occurs by controlled ventilation via a heat-exchanger. This reduces heat loss (or gain, depending on the local climate) to the lowest possible level. Another reason for this arrangement is that Passivhaus requires a great deal of insulation, which can bring challenges with condensation/dew. Control of moisture is made possible through air barriers, and the effective sealing of construction joints and service entry points.

Meeting the Passivhaus standard also involves: