Our retrofit of a 1950s semi-detached house in Monkstown, Co. Dublin has just been certified Ireland’s first (and the world’s fifth) project. Besides the retrofit of the existing house to the EnerPHit standard the house has also a new extension to the Passive House standard.
The project has brought the house from a BER of G to A3, reducing its primary energy use by an impressive 89.7%.
PHPP calculations yield a space heating demand of only 17 kWh/m²yr and a heat load of 12 W/m². After several tests the airtightness was measured at 0.93 ACH at 50 Pascal.
Existing hollow block walls have been externally insulated with 150mm Baumit Platinum EPS with a mineral render finish. The cavity of the ground floor brick wall to the front was filled with platinum bonded blown bead, before external insulation was installed with a finish of brick slips exactly matching the existing brick. The original internal wet plaster finish has been renovated and extended, and it forms the main air barrier. In rooms adjoining the party wall, 50mm insulated plasterboard has been used additionally to minimise thermal bridging. The average U-value of the walls is 0.13 W/m²K.
In the attic 350mm cellulose was blown between and over joists (U = 0.10 W/m2K).
Before adopting EnerPHit we had intended to insulate under the suspended timber floor in the usual manner. In moving to EnerPHit we realised that the resulting U-values would not be good enough. In any case as the insulation depth increased beyond the joist depth the repeat thermal bridges would get worse. Instead we stripped out the joists and tassel walls, laid a radon barrier on the original subfloor and built up 300mm of EPS300, then poured 150mm of concrete with 70% GGBS (i.e. Ecocem) cement mix on top. This gave us a retrofit floor U-value of 0.11 W/m2K.
Windows are triple-glazed Future Proof uPVC from Munster joinery.