Yes!
You'd be surprised how little it changes room temperature.
A lot of the thermal mass is conserved in the walls, furniture and people in the building.
You'd be surprised how little it changes room temperature.
A lot of the thermal mass is conserved in the walls, furniture and people in the building.
That adds a lot of thermal mass as well.
One thing I've definitely noticed is that as I improve the insulation in one area of the house, other areas will get colder.
The reasoning is that the worst insulated spots in my house were near to the thermostat. Now they they can maintain heat decently, the further way areas are allowed to cool more before the heat kicks on.
The first tool someone should buy when investigating the thermal efficiency of their house is one of the cheap ($30- $50 if I remember right) infrared thermometers.
The temperature of your house is likely 5-10F off from what your thermostat claims, particularly the further you get from the thermostat.
Found that out the hard way when three years ago during our first Winter here, the water to the kitchen was frozen for most of the month of January. Thankfully our house has PEX piping, so no burst pipes for us.
Sealing and insulating those areas has made a tremendous difference, even in the interior areas of the house. Since the subfloor is wide open, a cold breeze from one spot can suck the heat out of the entire floor with surprising effectiveness.
You're correct that it doesn't make sense to insulate between floors, but you do need to insulate the entire exterior wall area, which includes the wall space between floors.
As you say, air has little mass and very little thermal mass, solids have a lot more thermal mass so the equalized temperature after briefly exchanging all the air for cold air is basically the same as the original.
But physiologically and psychologically, human comfort levels are based not on the air temperature and convection or conduction with the air but on the mean radiant temperature, the temperature of an ideal enclosure of uniform emissivity and temperature that creates the same radiant heat transfer rates as whatever non-uniform surfaces are in the area.
Sit with your face in a sunbeam in a cold house, and you'll feel like it's pleasantly warm even if the heating of the sunbeam is doing less than the motion of cold air wicking away heat. Open your garage door on a still winter day, standing in the warm air with one wall removed, exposing you to sub-freezing temperatures, and you'll feel cold even if the air is still warm. Stand in the high-temp air blast of a torpedo heater in a cold shop, with the ceiling, concrete floor, walls, and other equipment still frigid, and you'll feel cold even as the hot air melts the plastic bits on your clothes. Blast the AC in a hot car, and you might be breathing air at 40F/5C from the vents, but you'll still feel hot until the vehicle interior trim is cooled by the air.