Another little power station goes live in West Bridgford

Although I've been somewhat preoccupied with air tightness of late, other things are happening. Today, the new PVs were hooked up to the electricity meter and we are now generating energy and feeding it to the grid. Now all we need is some sun....

Compared with all the other work we've had done, the 2 visits from the team at Carbon Legacy to install the PVs have been most straightforward. What is there to say? Day one and the panels appear on the roof, day two and the cables link to the inverter and from there to consumer unit and meter.

The amount of electricity which we hope the system will produce in a year should be a little over 3,000 kWh.    This will hopefully equate to a significant proportion of our total annual energy use (electricity plus gas) once the low energy refurbishment is complete. (I'm expecting total energy use to be between 6,000 and 9,000 kWh a year - watch this space!)

For comparison, the original estimate for annual energy use in the "as bought" state (based on a SAP energy model) was 36,000 kWh. In fact, energy-saving habits meant that we only used about 24,000 kWh of gas + electricity in a year.

This is like a mini version of the UK's energy challenge. The Department of Energy and Climate Change anticipate that the UK could face energy shortages by 2015. Hence the interest in generating more renewable energy in one form or another. However, there's a very long way to go to meet ever-growing demand for energy, especially with certain older power stations reaching the end of their lives soon.

However, if homes, business etc. were very energy efficient and used MUCH LESS energy (through additional energy-saving habits, insulation, more efficient appliances and equipment, etc), then the scale of the challenge would be reduced - and the chance of power outages in 2015 would also be reduced.

Gas, Electricity and Water use in Year 1

We now have over 12 months of gas, electricity and water readings, taken on the same day every month so we can compare seasonal variations.

During the first winter (in Feb 2010), the gas boiler broke down for 2 weeks. This reduced the gas bill a little, but increased the electricity bill significantly as we brought in one electric heater so we could at least keep one room warm.

In a house like ours with an Energy Performance Certificate (EPC) rating of E and no eco-features at all, you might expect our annual gas, electric and water use to look something like this:

EPC/SAP estimated gas use - 32700 kWh
Average UK electricity use - 3500 kWh
Average UK water use - 140-150 litres per person per day

However, our actual use in 2010 was this:
Year 1 gas use - 21315 kWh
Year 1 electricity use - 1927 kWh
Year 1 water use - 94.5 cubic metres = 94,500 litres, or 64 litres per person per day

What this means is that we've reduced our bills significantly through being careful not to waste energy or water. In other words, we've done the "free" stuff. If we want to reduce energy and water use further we'll need to spend some money.

That said, I'm quite surprised how big the difference is between our actual use and the "UK average".

Our gas use is about 35% less than average for this kind of house as suggested by the Energy Performance Certificate (SAP calculation).
Our electricity and water use are approximately half of the UK average.

That's a lot of money and CO2 we're saving every year before we even start to make home improvements.