[jmrm]

People doesn't give the massive importance the isolation has. Some years ago we remodelled our home and added XPS (Extruded Polystyrene) to insulate the roof of the house. After that we use the AC only three or four days in the year, and before that we had to use it at least a complete summer month. That house is in the south-interior of Spain, so heat is no joke here.

If somebody are constructing or remodelling any house I recommend it to add any insulation they can in any shape, in less than five years you'll recover what you spend, and if you add PV panels for electricity or a thermosiphonic system to heat water, you'll recover the investment in about 10 years, with a healthy amount of available health in the devices to continue saving money with a proper maintenance.

[franciscop]

What people definitely don't give enough importance is CO2 buildup as well. The more isolated a place is, and smaller, the more environment friendly it is BUT the more likely it is to build up CO2, which leads to headaches.

I installed a CO2 meter both at my current home, and at my parent's home for when I go back for Christmas. In my home, it's a fairly big open place so it takes ~2 days of closed windows (0-3C outside) to reach 2000PPM (recommended under 1000, above 2000 starts affecting you, 5000 is the legal limit[1]). However, at my family home where I grew up it's a tiny room and it reaches 3000-4000 just by sleeping there with the window and door closed. So the headaches of "visiting family" might in big part be explained by this.

PS, incidentally in Spain!

[1] https://www.kane.co.uk/knowledge-centre/what-are-safe-levels...

[Arbalest]

These are starting to catch on, as someone else said Heat Exchanger, but that's a more general concept and this is the thing you'd actually want https://en.wikipedia.org/wiki/Energy_recovery_ventilation

[shostack]

I suspect I'm experiencing some of this in a small home with poor circulation. Any suggestions for inexpensive room monitoring sensors?

[franciscop]

I just bought one on my local Amazon version by searching "CO2 meter". While true numerical accuracy is "who knows", on rest/full ventilation it shows 400PPM and blowing at it (even gently) shows the CO2 increases drastically, as expected, so I'm happy with it.

[hazza_n_dazza]

that is why you need a Heat Exchanger

[fouc]

It seems like historically people underestimated the insulation value of polyurethane because apparently it doesn't necessarily do well on the conventional R-value score.

Apparently a solid inch of sprayed polyurethane can provide 90% insulation, and 2 inches gets you to 99% insulation.

https://www.monolithic.org/blogs/presidents-sphere/r-value-f...

[fullstop]

> That house is in the south-interior of Spain, so heat is no joke here.

I looked up a few areas (Ciudad Real) to see what you meant by heat, but it seems quite similar to a good portion of the northern USA. This makes sense, I suppose, given the similar latitude.

[SOLAR_FIELDS]

Insulation is so, so important. I work out of my garage currently and Texas winters get reasonably chilly and of course summers are hot. I'm lucky enough that my garage is actually under a room in my house such that it's insulated (as you imply, roof insulation is one of the most important places to insulate). Even simply adding padded insulation and trim to the exterior door and garage door made it viable enough to stay cool in the summer with zero extra cooling and warm in the winter with a small infrared heater.

[voisin]

What about windows? I find buildings with few or small windows to be unmanageably dreary, but the math works out that no matter how insulated you make the walls if you have a good amount of glazing on the walls the effective R value drops quite low.

[jmrm]

You always can use isolated glass panels and wood or plastic frames to prevent that: https://www.energy.gov/energysaver/window-types-and-technolo...

I personally have gas filled glass panels and are pretty good at that, but I wish I had also those that have an IR filter coating that prevent IR heat from entering and from exiting the house. That was a lot more expensive when I installed mine.