I cut my gas use, turned down the thermostat. (I bought a 100 year old house that was last modernized in the 60's, just before gas prices shot up.)
But then I noticed moisture buildup on the inside of the roof. Screws sticking through the roof had water dripping from them. I turned the radiators back to full and the thermostat up again.
I'm restructuring the house, so not everybody will see it so clearly as I do, but we have to watch out. Our houses, particularly old ones are constructed to only stay nice with a good heat source inside during winter, in every room. Hot air will transport moisture out and keep it from depositing. If things cool down, fungi and moisture are a big risk. Hot humid air you breath out will find a cold spot to deposit it's moisture. It may take years before you find out where that is, and from experience I can tell you it can get quite disgusting when you finally rip out some plating.
The answer is: good, vapor tight (at the hot side, cold side should be open to vapor, or completely waterproof/tight!) insulation combined with good ventilation. That last one is very important, I also heard from people that closed their ventilation ducts... until water was dripping down the windows, or moist spots appeared in their wooden floors. Btw, a CO2 monitor can provide a good proxy measurement for your ventilation, imo.
Watch out people, you can save a lot on gas, but invite a lot of new problems. Don't go too crazy.
When I renovated my house (temperate EU climate), this was actually mandatory: active ventilation and breathing vapor shield in front of the insulation layer.
Indeed, older houses rely on "gravity ventilation", as my architect described it: high-temp heating is used to move stale air around by induction, plenty of nooks and crannies together with the density gradient would suck in fresh air.
When you renovate partially, adding insulation layers and plugging holes, you need to open up the windows for about 5-10 minutes once or twice a day. Paradoxically, the heat loss is mitigated because the fresh air is typically drier, which heats up easier.
I'm doing it all myself so there is no real "mandatory", contractors will do it properly of course and by the rules (at least they should, but I sometimes wonder how careful they are taping all small holes on the inside of the insulating layer with aluminum tape, etc). People doing it themselves, I feel, just put mineral wool everywhere. Quite unwise, I hear some alarming stories.
But I really spend a lot of time reading and thinking. I am insulating my roof, insulated the ceiling. But CO2 buildup is very rapid in the living room now, even though there are 2 large ducts in the wall leading directly outside (easily >1500 PPM while cooking and the 4 of us in the room). So I'm looking at installing stuff like this now: [0]. Imo such things are very necessary and I feel that many people "modernizing", insulation their own house are inviting a lot of issues.
But then I noticed moisture buildup on the inside of the roof. Screws sticking through the roof had water dripping from them. I turned the radiators back to full and the thermostat up again.
I'm restructuring the house, so not everybody will see it so clearly as I do, but we have to watch out. Our houses, particularly old ones are constructed to only stay nice with a good heat source inside during winter, in every room. Hot air will transport moisture out and keep it from depositing. If things cool down, fungi and moisture are a big risk. Hot humid air you breath out will find a cold spot to deposit it's moisture. It may take years before you find out where that is, and from experience I can tell you it can get quite disgusting when you finally rip out some plating.
The answer is: good, vapor tight (at the hot side, cold side should be open to vapor, or completely waterproof/tight!) insulation combined with good ventilation. That last one is very important, I also heard from people that closed their ventilation ducts... until water was dripping down the windows, or moist spots appeared in their wooden floors. Btw, a CO2 monitor can provide a good proxy measurement for your ventilation, imo.
Watch out people, you can save a lot on gas, but invite a lot of new problems. Don't go too crazy.