Energy Use
The first winter has been a little disappointing with energy use higher than I had hoped but none the less it is still very low. The house has been lovely to live in, everything clean, new and warm.
I have been monitoring total energy use since before I moved in and am gradually getting better at recording it. I am now monitoring the MHRV and some appliances seperately too.
I can project the total energy use for the first year with some degree of certainty as 10,000 to 10,500 kWh. In Passive house terms this equates to 42 to 44 kWh/m2/y well less than half of their allowance.
I have analysed and been able to project the total energy use for heating and hot water for the first year in occupation as between 11 and 12 kWh/m2/y. I cant as yet separate out the hot water element.
Total energy use spreadsheet
Energy use spreadsheet - update and tidy occasionally
Several people have asked me if my house how my will stay cool in the summer. I tell them that the high levels of insulation that I have will help to keep the heat out.
I can open my window shutters during the night in the summer which we usually keep closed overnight in the winter. This maximises the heat loss during the hours of darkness and although a small effect helps keep us cooler. I can run the MHVR system with a higher flow rate at night again maximising the heat loss from there. I can also use nighttime cooling. In winter it runs slower at night. The house has very high thermal mass and so the temperature changes very slowly and so we are somewhat isolated from sudden changes in outdoor temperatures.
The biggest and best way to keep the house cool is to close the external window shutters while the sun is shining on them and cut out the solar gain completely. This works brilliantly well, much better than I had expected and I hope to write some computer control software to manage this process. I did have to fit low energy bulbs in the lounge main light in May as it had has some incandescent bulbs in for the winter months, naughty I know but as we have no formal heating maybe I could be forgiven.