Sucker!

As always one thing depends on another, and so on. One of the documents we needed to get for our FIT payments from the PV solar panels, was an EPC (Energy performance certificate) which all new builds require nowadays. And part of this EPC required an air tightness test.

This basically involved a man turning up and sealing the utility/garage door up with a big fan which sucked all the air out of the house..

We didn't all go blue and collapse on the floor, looking like mad healers walking around the house, we did feel any small drafts magnified to huge blasts of air. So any leaks were then sealed as much as possible.

Thank goodness for expanding foam!

A true lesson in where a house leaks though, so hopefully this should minimise our heat loss and keep a toasty house in the winter.
We achieved a high level 'B' on the EPC in the end which is a great result and with a bit of extra sealing achieved our reading for the desired air tightness performance of the house from it's design.

Anoraks only past this point...

The test result is that the house leaks 4 cubic metres per hour per square metre of surface area at 50 Pascals of pressure. (It's the fan that creates the pressure). To give some sort of comparison the minimum standard for air permeability is 10 cubic metres (etc).

The design spec was improved over the minimum standard to reduce the cost of heating the house. As well as lots of expanding foam and sealing tape one of the things we did to reduce the leakage was to specify windows without trickle vents. This would ordinarily mean lots of condensation which is why we installed the MVHR (Mechanical Ventilation Heat Recovery) system. This sucks out stale air from 'wet' rooms and uses the heat from the stale air to warm fresh air that is being blown into all the other rooms.