We renovated this 1960 Glencullen bungalow to Passive House standard in 2009, the before and after PHPP's (energy calculations) for the project show that the energy demand was reduced by 93% by improving air-tightness by a factor 20, by insulating to Passive House standards, by fitting a Passive House approved HRV system and by fitting triple glazed Passive standard windows. 15m2 of Solar Panels were also fitted with a 2000L buffer tank to provide hot water and contribute to the heating requirement.
The wall cavities were pumped with 100mm EPS bead and the walls were externally insulated with 200mm of EPS External Insulation. 400mm of EPS Polystyrene bead was pumped under the existing wooden floor which allowed the floor vents to be closed off, 300mm of Cellulose was pumped into the roof at a density of 60kg/m3 to prevent summer overheating and reduce temperature fluctuations. The new extension was built using Externally Insulated QuinnLite blocks. The house was air-tightened to below 1 air-changes using internal plaster and by taping the OSB boards lining the inside of the roof.
Triple glazed German 0.80 U-value wooden windows were fitted, these protruded outside the existing walls and the frames were covered on 2 sides by the External Insulation to eliminate Cold Bridging.
A Passiv Haus certified Paul HRV system was installed to provide fresh air and to keep the RH% low, but return air temperatures of 14 degrees at minus 10 outside was too cold and caused draughts in the house, so we will remove the Paul HRV unit and replace it with a more efficient FiWi HRV unit. A 15m2 Solar panel array tilted at 70 degrees facing towards the Winter Sun was fitted with a 2000L buffer tank for space and hot water heating. The Buffer-tank is also periodically heated by a small 4kW wood burning stove!
Cold Bridge reduction details- to avoid Cold Spots, Condensation and draughts
The External Insulation was dropped 500mm down below the internal Finished Floor Level to reduce the Cold Bridge between the wall and the floor to an acceptable level and to prevent the base of the wall getting too cold and causing Condensation. The dpc was luckily 300mm below FFL allowing us to pump EPS bead down to this level helping to reduce the wall/floor CB to 0.062 and reducing the heat loss to 0.9kW/(m�.a) at the wall/floor junction. The client is moving away from an Oil heating system which required 2 fills per year to a more sustainable lifestyle. They resisted the urge to put in a gas boiler back up heating system.
The 3 graphs below show the effect of the study we undertook to eliminate the wall/floor Cold Bridge;
The External Insulation stopped at Finished Floor Level in this first 1st simulation below, you can see the 13.8 degree temperature at the wall/floor junction, if the Relative Humidity rose to over 75% then you would get condensation at this point.
The External Insulation was dropped 500mm below the Finished Floor Level in this Simulation, you can see the temperature at the wall/floor junction has risen to 15.5 degrees, if the Relative Humidity rose to over 83% then you would get condensation at this point.
The External Insulation was dropped 500mm below the FFL and EPS bead was pumped into the below FFL cavity in this Simulation. At 16.1 degrees, the Relative Humidity would need to rise to over 85% to get condensation at the wall/floor junction. We used this method because of the improved temperature where the joist meets the wall.