Some years ago we embarked on a project to build a Passive House for a retired couple, who had been living in an old farm house at the time. The couple had contemplated renovating there old house, but after intensive planning this appeared to be too much work and too expensive. After visiting a Passive House we had previously designed the couple decided that was exactly what they wanted.
During the construction of house we used our own timber frame design, which has since been accredited by the Passive House Institute in Germany as a certified Passive House component. The exterior of the building was finished in block and plaster, which we discovered is suitable for our weather conditions after been testing throughout the years. The interior of the house is completely moisture diffusible which, again, is most suited to our humid climate. Rather than focussing on additional insulation, we concentrated on thermal bridging and air tightness as this is a much better approach and more economically viable.
The heating for the three-bedroom bungalow is provided by a condensing oil boiler and wood burning stove which also heats the house. The condensing boiler is a Grant Vortex condensing boiler with an average efficiency of 92%. The wood burning stove is a Stratford EB 9 stove with an efficiency of 67%, providing 4.5kW to the space and 7kW to the water/boiler.
The bungalow has been designed to maximise solar gain, and as a result, intuitive heating controls each room accordingly and will only turn on when required. A mechanical recovery system provides a change of air every 2.5 hours, and it even includes an extract in the hot press to benefit from the moisture of slightly damp clothes. The MVHR that was used was by Vent-Axia Kinetic Plus B with a heat recovery of 91%, a humidity sensor and summer bypass. This approach is an integral aspect of meeting Passive House standards, and as a result, the annual heating bill for the retirement bungalow stands at just £70 or 45 gallons of oil for heating and hot water.
For future projects our company would continue to be interested in designing to a Passive House Standard as we believe it is the way forward for building in the construction industry.