We live in a fairly well-insulated house which uses district heating for the central heating. The individual radiators are controlled by a smart thermostat system. The hot water in the radiators comes directly from the district heating, so the supply temperature to all he radiators is in excess of 70°C. This is obviously unnecessarily high for a well-insulated house.
For the gas-fired central heating typical for my country (the Netherlands), there is a lot of push to lower the water temperature to save on carbon emissions. Obviously, this makes the heater more efficient by being able to cool the exhaust a bit further.
However, I can't seem to find if lowering the temperature* also has additional advantages not specific to a gas heater. For example, right now our radiators are typically very hot in a small area and pretty much cold for the rest, just because that's enough to heat the house. That probably means that we might be losing quite a bit of heat to the outside near the hot spot on the radiator. Also, the crawl space containing some of the pipes gets nice and toasty, although there more insulation might be more cost effective. Finally, I suppose the heat is less evenly distributed through our living room, which might be less comfortable.
I'm billed purely in GJ received, measured as flow times delta T. I'm wondering if I can lower my (billed) energy consumption by lowering the radiator temperature.
*I'm thinking of using a water/water heat exchanger that cools the supply water against the used, cooler water, using a thermostatic mixing valve to bypass the heat exchanger to bring in more hot water if necessary. This way I won't have to use a circulation pump.