23 May Victorian terraced house produces more energy than it imports and is net zero carbon
So, we finally had enough data after two and a half years of living in our retrofitted Victorian terraced house to work out if we actually achieved our aim of generating more power than we imported and being net zero carbon. I’d always wanted to generate more power than we imported, or was it generate more power than we used? The latter being a very tall, and unlikely, outcome in an old Victorian house that was not retrofitted to a passive standard.
You see I recently looked at the design and access statement for planning and that said we were going for enerPHit (like passive house but for retrofits). That strategy changed when we’d got planning and the best advice we could get from friends and collaborators sustainable developer Pete Halsall and architect Sean Griffiths said “Don’t try to make it airtight or you could have problems with the building fabric”. So we retreated from trying to seal every nook and cranny and insulate for the arctic to trying to let the house still breathe whilst making it as energy efficient as possible. There were also cost implications of the passive/enerPHit plan…what if we spent all of that time, effort and money and it didn’t work as planned? It’s no easy thing to do and we didn’t have specialist builders either.
The results are, in nearly all respects, much better. Precisely because we aren’t too far off being enerPHit, whose standards allow for a maximum 25 kWh/m2/year. Our reduction from around 400 kWh/m2/year to around 65 kWh/m2/year is 37.5% lower than the average Superhome (as designated by the Energy Saving Trust). Whilst the house is also well below the 60% reduction in carbon emissions that make your house a Superhome (of which there are only about 200 in the UK) and is almost certainly Net Zero Carbon (with the stove being the only emissions producer and that burns fifty per cent coffee grounds logs that produce fewer emissions than kiln dried wood and stop the grounds going to landfill where they emit methane which is twenty times more harmful that CO2).
However, the most important thing is that we have demonstrated that a standard Victorian terraced house doesn’t need to be fully passive or enerPHit and thus require the huge investment that that entails in order to be far more energy efficient than most other old houses in the UK need to be (I think I saw the figure 24% somewhere but don’t take that as gospel).
The extra bedroom clad in PV, a battery, Octopus Agile, (Update: 18 Feb 2022. The fuel cost crisis made the price we paid max out at 35p per kWh so we switched to Tesla plan for 11p per kWh in/out but it means Tesla control the battery!) the removal of gas and some serious insulation installation would probably get most houses down to a level of emissions that, if done at sufficient scale, would transform the UK’s domestic energy use profile. An extra bedroom would help with the housing crisis, increase density, boost property value and increase rentable value.
You can see the slides that I used to talk about this to the Zero Carbon Dorset project in an online session with two other eco-builders (much more experienced than me) last week HERE. If you want all of our house retrofit data (including planning, drawings and system/operations) you can now download it all for a small fee from this website.
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