22 ms·

I disagree. Airtightness is far more important than insulation. Insulation is worthless if air currents can simply carry the heat and bypass the insulation. An

I disagree. Airtightness is far more important than insulation. Insulation is worthless if air currents can simply carry the heat and bypass the insulation. And unless you're building an ICF house, some minor thermal bridging is unavoidable. But it does not matter because you can just insulate more somewhere else to make up for it. Exterior foamboard insulation around the entirety of the house is already quite common and cost-effective.

mikeyouse 5y ago
This is exactly right - there are calculators that assess the heat/cooling load of your home (https://www.borstengineeringconstruction.com/Heat_Loss_Analysis_Calculator.html https://www.borstengineeringconstruction.com/Heat_Loss_Analy... for a basic one) and with sensible insulation + leaky buildings that were common in the past, the heat loss to air infiltration can approach the total load you'd otherwise need. Using that calc - with typical R-Values for an old building of 1,000sq ft + ACH50 of 10 (converted to 0.5 for this since ACH50 values are at pressure) with a 0º outdoor temp and a 70º inside temp, the heating load would be 50k BTU. Doubling the insulation on the walls, doubling the R-Value of the windows, and doubling the roof insulation has the same impact as bringing the leakiness to an ACH50 of 3. One of those can be done with a few tubes of caulk, a few rolls of weather stripping, and some cans of spray foam. The other involves removing siding/drywall/roof material. Everyone in building science will tell you that the "best dollars" on saving heating/cooling costs are spent in making your home tighter.