12 May - net zero day

[RedRhino]

Well I'm chuffed to bits with the performance of our new self-build house. 

With another 6 weeks to go before mid-year our 2026 electric bill has balanced out. By mid-year we should be in credit by about £150, so maybe £300 for the whole year. 
That is for DHW, heating and domestic load. 2 people in permanent residence, with guests, 200m^2, thermostat set at 21.5c throughout. 

We run a sauna but not an EV.
Contributing factors in approximate order of importance: 

1. High levels of insulation in floor, walls, and roof (MBC high performance timber frame)
2. Very good air tightness (0.8)
3. Large solar array 3kw facing SE and 6kw facing SW with no overshading from trees / chimneys etc
4. Octopus Flux tariff
5. Tesla Powerwall 3 battery
6. 5kW ASHP
7. UFH
8. Triple glazing

 

Each item has value in itself, but they also complement each other e.g. the UFH reduces heating temps which increases the efficiency of the ASHP which reduces demand which . . . 

I just need to tell Octopus that they need to set up a Direct Debit to pay me : ) 

[Alan Ambrose]

Congrats. Also, good to think there’s light at the end of the tunnel. 😀

[SteamyTea]

2 hours ago, RedRhino said:

Well I'm chuffed to bits with the performance of our new self-build house. 

With another 6 weeks to go before mid-year our 2026 electric bill has balanced out

I have not followed your build, but goes to show that it is, I assume, just a case of solid and sensible engineering.

[RedRhino]

Exactly that - just balanced decisions and good execution with the freedom that only new-build gives which is to consider everything in the round. 
For instance, we knew we were having a large solar array from the very beginning, so we told the architect we wanted a rectangular roof to best fit rectangular panels.

[SteamyTea]

2 minutes ago, RedRhino said:

For instance, we knew we were having a large solar array from the very beginning, so we told the architect we wanted a rectangular roof to best fit rectangular panels.

Always narks me a bit when people say that want PV, then don't fit it because of cost. I suspect very few fit it later.