Had nearly decided on an MG5 as our new car, but just learnt it doesn’t have a heat pump. Some models do have heated seats though. Interested to hear folks experience of this EV or others without heat pumps to get a picture of how much more of an impact on range that makes in winter. Thanks 🙏
Chuffed though I am, I doubt it. A moderately sized new build Passive House with a heat pump working reasonably well should certainly use less electricity for space heating than we do, so it would just need an efficient hot water system as well. Get monitoring your systems people!
In fact, our house was recently recognised as having the lowest heating costs on the heatpumpmonitor.org site, which raises an interesting question, could we have the lowest heating costs in the UK?
Total space heating electricity usage (some of which is actually heat for the hwhp): 756 kWh
Total water heating electricity usage: 336 kWh
Total hot water usage: 18,000 litres (about 50 per day). Mostly at 52°C, but we boost to 60°C when we have visitors and need the extra capacity.
Relatively low hot water usage for now, I expect this to change as the children get older!
The last three points mean that our hot water reheat times are quick enough that all the hot water heating is during the 4 cheap hours per night.
The hot water heat pump has a reasonable efficiency all year round, since it is 'stealing' heat from the house at ~20°C.
Our hot water demand is low because we have shower-water heat recovery, very efficient (radial 10mm) distribution and 6l/min showers. Surprisingly the showers are among the nicest I've used.
We've been able to demand shift quite successfully. 52% of the electricity used by the air to air heat pump was in the middle four hours of the night when the electricity is just 9 p/kWh (although the rest was at 29 p/kWh).
We've got a higher occupancy density (5 people in 105m2 treated floor area) than PHPP assumes for certification on a house of this size, this will reduce our space heating demand somewhat.
I think the A2A is more efficient than the SCOP of 3 I guessed it would be. I can't monitor heat output, but comparing modelled heat demand & electricity usage I think we're getting a SCOP of 4 or 5. Much <4 would imply unbelievable fabric efficiency and much >5 would be stretching thermodynamics.
