Passivhaus Petflap

We often receive enquiries from people interested in fitting a Petflap in a Passivhaus or other low-energy home. Until recently we have had only anecdotal information to offer, but now the Petflap is undergoing accredited testing.

passivhaus petflap
By Jayswipe – James N, Public Domain,

In September 2020 we were approached by the Passive House Academy New Zealand. They were looking for evidence of the Petflap’s performance. When we weren’t able to provide more than anecdotal and informal test results, their Director offered to help. We have tried before to arrange testing in the UK but never got anywhere due to the nature of the product. We were quite happy to send a Petflap to New Zealand if it got us the data!

We established that we needed two types of test: an evaluation of the Petflap’s intrinsic thermal properties, and a test with air blowing on it to see how much got through. These are respectively the U-value and the air leakage rate.

To calculate the U-value you need to know the thermal value of each component. In theory, you’ll have access to information giving you the thermal performance of each material. We approached all our suppliers but none had been provided with this information, so we had to go with generic values. Because of this, the result is a conservative one. The U-value was calculated to 3.521 W/(m²K).

We were all set to have the air leakage tests run in February. This involves sealing the Petflap into a unit and then blowing air at it and measuring how much gets through. The testing lab is in Auckland, and Auckland went into lockdown just as the lab was ready to go with it. We wish them all the very best and look forward to receiving our test results with they’ve caught up with their backlog.

Please get in touch if you would like us to email you with the information when we have it.