Ok, so its our own record, but we’ve had the lowest calendar year energy usage for our demo house so far. I’m putting it down to 3 changes over last year – a) slightly lower occupancy with the children being out at school b) a very mild 12 months c) some remediation work to some thermal bridges identified with a thermal imaging camera.  Below are two of the picture for thermal bridges that have now been rectified.

Results

So what were the results?  Here is a table that shows the 12 month figures:

• Gas units: 4,771kWh
• Electricity units imported: 2,464kWh
• Electricity generated: 2,073kWh
• Gas cost excluding standing charge: £144
• Electricity cost excluding standing charge: £298
• Net costs (gas/electricity/standing charge/FIT/RHI): -£550 – yes that’s right, its a big negative number!

Charts – month by month

This chart shows how the gas and electricity imports and generation vary month by month.  Heating is off in the summer and solar thermal provides most of the hot water but we still use a little gas for cooking:

This graph shows how all the costs vary throughout the year.  You can see we only have 4 months where we pay more than we get back.

Compared to previous years…

As you can see there was a healthy drop the first year when we put on the front door! We’re really please the house is continuing to perform above expectations.

What does that mean in terms of energy use per square meter?

There are different ways of accounting for energy and CO2 depending on which conversion factors are used and how you account for exported energy.  We used to show the results of our examplar project on the publically supported Low Carbon Building Database but for some reason despite it being one of the most cost effective and outright effective projects it has been removed.

We are continuing to track if on CarbonBuzz. This is what CarbonBuzz shows:

Using our calculations, if we net off the exported electricity we make it: 38kWh per m2

And CO2 per year

Gas: 0.97 tonnes

Electricity import: 1.38 tonnes

Electricity export: -0.56 tonnes

Net: 1.78 tonnes or 446kg per person.