HFCs: The global-warming agent you're probably not thinking of. One pound of HFC is equivalent to nearly a ton of cabon dioxide (1500x GWP), and they can't be photosynthesized away.
Some environmentally-conscious individuals choose premium-efficiency heating, cooling, and insulation products with the goal of saving energy and carbon usage. But, premium insulation products such as extruded polystyrene (XPS) and sprayed polyurethane foam (SPF) are blown with HFC that will all leak out, if not now, when the building is demolished. Even the best air conditioners and heat pumps today are filled with HFC, and while technicians are EPA-mandated to recover it, leaks do occur, and not all countries regulate it tightly.
Fortunately, there are some improvements:
- Polyisocynurate (polyiso) and expanded polystyrene (EPS, or styrofoam, or beadboard) are NOT made with HFC/CFC anymore but with pentane, which is only 7x as bad as CO2, which sounds bad, but is negligible compared to the 1500x of HFCs.
- Open-cell foams, and even some closed-cell foams, are blown with "water" (in reality, CO2)
- PepsiCo is phasing out HFC refrigerants, using hydrocarbons and CO2: http://www.refrigerantsnaturally.com/about-us/members/pepsico/
- And transcritical CO2 looks like a promising refrigerant for general heating/cooling: https://en.wikipedia.org/wiki/EcoCute