The latest eco-efficient double glazing has a remarkable gas inside the units. It's fantastic at trapping heat. Sulphur hexafluoride, it's called, and it has to be synthesised as it's not naturally occurring. It will not break down in the atmosphere for over 3000 years, and its Global Warming Potential in that time is something like 500,000 times what CO2 is.
And modern eco- houses are designed to last 30 years ?