Is it for heat pumps that work slower? It still implies to me that insulation is lacking.
I'm still somewhat dubious of 'better' thermostats though. I just turn it on when I feel cold. I don't see how a thermostat could improve on: 'The heat only goes on when it's cold enough for me to turn it on'.
Theoretically it could use feedback from all the thermostat valves (and adjust the burner to keep the most-open valve near (but not at) 100% flow), but that requires feedback from all valves rather than just an outdoor temperature probe and a parametric mapping curve that depends on radiator style, desired indoor temperature, and building insulation.
The lower the level the more efficient it is. It's better to run the boiler on low for 3 hours, vs high for 1 hours.
How do you know if to run the boiler on low or high? You check the outdoor temperature. You also do a backup: If the boiler has been running for more than an hour, increase the temperature slightly every 15 minutes. Once it goes off, reset the temperature to the one determined by outdoor temperature.
I've got cavity wall insulation, 30cm of insulation in the loft and recentish double glazed windows and the bedrooms stay warm enough at night with just body heat and residual heat. The heating on goes on in the evenings (still hasn't gone on yet) unless it's really cold. I don't think any of those are particularly onorous jobs to undertake.
My house has something called ETICS* (basically a thick outer layer of polystyrene with a weather resistant paint. Ugly stuff, but it works wonders!), mineral wool insulation in the attic (which I'm supplementing just in case), underfloor insulation with extruded polystyrene and of course double glazed windows. We don't turn on the heat until it's 3 degrees or less outside. Thermostats and stuff like in the article bring too small benefits to really consider.
Ultimately my direct debit for gas electricity is only £10pm at the mo after the govt bung so my house is about as good as I'm going to get it anyway.
For those of us with solid walls it's expensive and very disruptive to install internal/external wall cladding. I happen to live in an area where I'm not even allowed to install external cladding.