We extended this house in Glasnevin from 80m2 to 150m2 and did some renovation work to the existing house. The 70m2 Timber Frame Passive Extension arrived to site fully finished and insulated from the factory with the plasterboard on the walls and the windows fitted. With excellent U-values of 0.11 for the roof, walls and floor we expected a really good performance from this extension but the performance has exceeded our expectations.
All the Cold bridges were eliminated using our foundation system and we achived close to Passive levels of Airtightness (0.75) for the Extension and 1.6 in the complete house which shows that taping the joints in the OSB board works really well. The main air losses from the Timber Frame Passive Extension were through the Rationel windows which leaked at the seals. We pumped 400mm of Cellulose into the roof of the existing house and did airtightness work around the windows and ceiling.

The existing house was Externally insulated with 120mm of plastered EPS and a local Heat Recovery Ventilation system was fitted in the wet rooms. We ran this house through the Passiv House Planning Package Software and got an amazing result of 23kwh/m2.a which is bordering on Passive standards.
This house was featured in a Construct Ireland article and has a BER cert giving it a B2 (90kw/m2.a) which shows the inaccuracies of the BER system. If we had increased the insulation thickness in the walls to 220mm, used better windows and had gotten the airtightness of the complete house down to 0.6 we would be at Passive Levels. "This extension follows our ethos which is to reduce the need for heat to a level which makes the heating system irrelevent".

This is the wall build-up we used for the Timber Frame Passive Extension.