Our original plan was to build a house certified to the PassivHaus standard in order to reduce our energy usage and thereby our overall carbon footprint. We added PV panels to the design so that we could match our energy consumption with renewables. The PassivHaus principle uses building materials that are highly energy efficient together with a construction process that produces a building that is virtually airtight. The house is heated by mechanical ventilation. This system can draw heat from a thermal store when the temperature of the air being drawn into the house is below the desired comport level. The window design and layout takes full advantage of solar gain in the winter when the sun is low in the sky but allows virtually no solar gain during the summer when additional heat would be unwelcome.
We have lived in our PassivHaus for over two years and we love it. We are often asked whether living in an airtight construction means not being able to open the doors and windows. The answer is we are free to open the doors and windows whenever we like, and we do. In deep winter we keep everything closed as you would in any house and on very hot days we close doors and windows to keep the house cool. For the rest of the year we use windows and doors the way we would in any other house.
The ambient temperature remains consistent throughout the house and throughout the year. The mechanical ventilation means that there is no condensation. The resultant environment is calm and very comfortable.
In terms of energy efficiency the house has performed very well. Our annual consumption is c.9,500 kWh and the solar PVs produce over 9,800 kWh per year. Clearly the PVs produce more than we need in the summer and less than we need in the winter but across the year we have achieved our aim of being energy neutral.
DH – The homeowner