Traditionally we turn off heating at night, and have it lower in the day than in the evening, and we have used a combination of convected air and inferred from the lights, the big problem with inferred is it can pass through glass and is hard to control, however because it heats the body directly it does not raise the temperature of the air, so using inferred you lose less heat with air changes. So in the British house we would set the central heating air temperature to around 18°C ample when moving around during the day, in the evening air temperature remained at 18°C but the inferred made it feel as if it was 21°C.
When the tungsten bulbs are removed and replaced with LED we feel cold in the evening so we compensate by lifting the air temperature to 20°C unless we manually change the setting we will also have it at 20°C during the day, so we end up with the house 2°C warmer for around 16 hours because of moving to LED.
With hot air heating as used in many other countries we can have one central thermostat that controls the whole house, so changing the standard thermostat for a programmable thermostat with very little cost you can get the house to just have it a little warmer in the evening, but still cooler during the day, however we use a hydraulic system which was considered better, as we could set each room at a different temperature so save on energy, it also means areas of the room can remain cool, like next to windows, the hot air system results is needing loads of plants to keep humidity from getting too low, and is expensive because the air is circulated, I know first house I had was hot air heated with vents in every door for the return air. But although a TRV is quite cheap, they are not easy to keep altering to get the duel temperature, we are forced with the standard model to select one temperature and leave it at that.
To be able to alter the temperature automatically between day and evening we need to swap all the TRV heads for electronic types which start at around £25 each, even then there is a problem as some thing needs to tell the boiler in summer when not required. Ideal is for the eTRV to tell a hub which in turn tells the boiler, however to do that the TRV heads are around £60 each, there is a cheap method using a wall thermostat, however the wall thermostat at around 0.5°C and the standard TRV at around 2°C can be set to work together,
but with a eTRV the TRV range is much reduced, around 1°C so to get the two working together is near impossible, so if working on the cheap the room with the wall thermostat has to stay at the same temperature day and evening as that room needs to have a very basic TRV. The whole point is to get what we had with a simple tungsten bulb with the evening boost, with LED bulbs means a lot of work is required on the central heating system. Or we have the house warmer during the day, there are of course some houses where it is easier than others, my 1979 house is open plan down stairs, so a simple programmable thermostat works fine down stairs, and the TRV is just to stop upstairs getting too hot, so after LED bulbs cost around £20 to get the evening boost, but mothers house has doors on every room, so no option but use eTRV's. Son has a wood burning fire he uses in the evening, daughters both have houses with only one living room down stairs so thermostat like in my house is in that main room, TRV's only stop other rooms over heating.
My mothers house with the doors, larger than mine and detached actually uses less gas, because of the doors keeping the heat in the rooms and less circulating air, so it does matter how the house is designed, but be it a vented tumble drier, or heat from lights, the house needs looking at as a whole, the idea of taking any one appliance and testing it in isolation does not work, there will be people with ceiling full of MR16 lamps which need a dedicated air conditioner unit to then keep house cool, my father-in-law uses gas to cook, so house is damp, and kitchen gets really hot, I use an induction hob, so cooking adds very little heat.
