your comment about average yearly temperatures is of course correct, but in this case it biases in favour of GP: * It's colder than average today, to reducing

your comment about average yearly temperatures is of course correct, but in this case it biases in favour of GP: * It's colder than average today, to reducing the setpoint has more effect vs an annual average. If sun takes part of the heating, then the ratio of dT to gas saved is even bigger. * The formula actually does work that way, maybe you're thinking of a different formula? i.e. Q (flow of heat) is a function of some heat transfer coefficient (U), area (A) and the temperature difference (dT) between inside and outside. So the (simple) correlation between dT and gas consumption to maintain a temperature is linear. This will be influenced by e.g. wind (increases U, therefore gas consumption) and other factors of course. Anyway, it's winter. If there is any time where you can reasonably reduce your gas consumption by lowering the thermostat, it's today. In fact, I'll try this now and see if it works. Maybe time to start a movement. (Also note that residential heating and office account for roughly a third of gas consumption in e.g. the Netherlands. Reducing that by 20% is still 7% reduction in total, and potentially a 17.5% reduction in Russian gas given the current gas mix)