How efficient old heat pump. Frosty Morning?

with well designed and built houses you simply don't need much heating in places like auckland.

My house is over 150 years old, so it's not well designed or built. However I have improved it a lot. Walls and ceilings are insulated, and there's a variety of window insulation.

I visited a place today that has two heat pumps going all day and night, and they had four windows open all the time.

thats just crazy unless they are only open for a short time.
not a bad idea to heat the place up and then open the windows to air it out.

otherwise if you have a place thats reasonably well sealed then a balanced ventilation system with a heat recovery unit would work really well.
at least halve the heat loss of those open windows.

When we lived in Tokoroa, the coldest place ever, other than Siberia or Russia LOL, we had difficulty getting our new heatpump to turn on until we came to the conclusion that we would need to turn it on in the late afternoon and leave it on all all night. As long as it was operting before the frost descended, it would keep operating, but if we left it till the early hours to turn on and warm the house for when we rose, it was a waste of time.
We also discovered that it had not been fully gassed up when installed, and that was in itself, part of the problem.
Servicing is another MUST, they can't operate when full of dust.

Ive gone off heat pumps, to many issues, ugly, noisy. When you have a lager house and need a large system they are stupidly expensive - I was quoted 32k but apparently I will save hundreds in power. Happy with the 27kw I get out of my 5k fireplace.