I could imagine that President Trump should put this question and even answer it with no, it is not. Indeed, it is clear that too much thermal insulation takes more from the environment that the energy saved during the life time of the building brings back to the environment. Or in other words, which thickness is the break even point? We answer the question for GLAPOR cellular glass.
Passive houses have generally two requests:
- The building envelope has to be airtight
- The U-value should be between 0.15 and 0.1 W/m²K
It is clear that large GLAPOR cellular glass boards are the most ideal thermal insulation to obtain airtightness. But for an U-value of 0.15 W/m²K, we need 36cm GLAPOR PG600 boards, which is acceptable as wall thickness. Today, value down to U=0.12 W/m²K are already requested in Europe at some places. But is this ecologic? We answer this question with the UBP-system of Switzerland.
For U=0.15 W/m²K, we need at least to use the house 13.5 years to pay back the environment for the production of the thermal insulation. For U=0.1 W/m²K, we have already 30 years. In Sweden for the roof, I found the following on Wikipedia:
In Sweden, to achieve passive house standards, the insulation thickness would be 335 mm (about 13 in) (0.10 W/(m²·K)) and the roof 500 mm (about 20 in) (U-value 0.066 W/(m²·K)).
For U=0.066 W/m²K, we need already a lifetime of 70 years, while except GLAPOR, thermal insulation manufactureres does not give a lifetime more than 50 years. And the UBP for all other thermal insulation boards is worse than GLAPOR, saying that even more than 70 years are needed with these materials even up to 150 year.
This is a nice example of eco-fundamentalism, when laws forces people to demolish the the environment. Small U-values can only be approved with thermal insulations with a very long life time and we should ask ourselves: Is this needed? In my opinion, below U=0.05 W/m²K (125 years), Trump should be right.