My oil filled radiator at 850 watt will maintain the main living room temperature should we have a problem with the boiler, it would take a silly time to get there if room allowed to cool, but it would maintain the heat. And this is with no other heating. I am looking for inferred output to make a room at 18ºC air temperature feel like 20ºC, and my living room uses 8 x 6 watt LED bulbs, and 3 x 20 watt strip lights which are not normally at full output, they light a display cabinet which adds to lighting in the room, so would say around 60 watt of LED lighting, that is if tungsten around 15 lumen per watt, and LED around 85 lumen per watt then would need 340 watt of tungsten light to equal what I had today, or the government has been issuing wrong figures. Likely actually would need 180 watt as I think we got more than 15 lumen per watt, so around 3 x 60 watt bulbs, which may not have given enough inferred to reach the feel like 20ºC may have needed to set air temperature up to 19ºC but the point is air changes don't loose that heat, it warms furniture and people, but not the air, so is more efficient as less losses.
I know with the last house in the days of tungsten the living room thermostat was set to 18ºC all day, from 7 am to 10:30 pm and a simple time clock in the garage with the boiler turned off the heating at night, but when we went to CFL I found in the evening when we were just sitting down, 18ºC was too cool, and I had to swap the basic thermostat for a programmable thermostat, and get rid of the time clock, so the air temperature rose to 20ºC in the evening, this resulted in the bedrooms getting too warm, so then I had to fit TRV's to bedroom radiators to stop bedrooms overheating.
Not saying this was a bad thing, but it did mean moving from tungsten to CFL was a lot more expensive than the government made out. Since heating my home with gas, using the CFL did save money, not convinced it would have done if I was using electric to heat the home.
Also the bulb sizes did not equate to what we were told.
As new build 2 x 100 watt, this was changed to 6 x 40 watt to get better spread, with two chandeliers, some times we did use 60 watt bulbs, would buy assorted packs, but on going to CFL we used 6 x 11 watt which looked rotten as too tall for the design of the chandeliers, so swapped to 10 x 8 watt Philips golf bulbs with a new chandeliers these were really far too dim, but we had paid so much for the bulbs, and told would last years, two rooms so 16 bulbs in all, within a year 6 had failed, and we had used cheaper larger bulbs in one room. as the continued to fail, replaced with 3 watt candle LED, which to start with looked better, but found room looked bright, likely colour temperature, but could not read a book in that light, so mother had a smaller room so used 3 watt in her house, and went to 5 watt in mine, so starting at 200 watt, and ended up at 50 watt, so if the LED is 85 lumen per watt, then tungsten was more like 20 lumen per watt.
The problem is tungsten was shining in all directions, LED is not, so the light reflects off walls and ceiling in a different way, so there was no direct comparison. And at the end of the day, in the days of tungsten I was renewing a bulb some where in the house once a fortnight, and today maybe one every 6 months, so all in all LED are better.
But I still do not see how they save energy, money yes as heat with oil now, but energy no.
So to heat a home with fan heaters is far more energy efficient than to heat with storage radiators as the fan heaters only heat the room when required, where the storage radiator can never switch fully off, but money wise then buy energy at night and using in the day with some thing like economy 7 will save money if the room is used 24/7. As what hourly usage the fan heater would become cheaper, would depend on air changes in the room, and the heat lost through fabric of the building.
However that was not the question, it seems the question is what the government approved software considers as the best option. And looking at homes and comparing it seems using storage radiators instead of gas with drop most homes from D to E band. Seems they are pushing heat pumps, but only electric, if you use a motor to transfer heat powered by 35 sec gas oil, the government has just changed the rules, and you have to use road taxes diesel instead.