An efficient air conditioner will almost pay for itself in energy savings.
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It's used as foam insulation, upholstery stuffing, shiny wood-floor sealant, and more. This synthetic polymer is strong, lightweight, and versatile. It is highly effective as an insulator, which earns it green points, though it is obviously not eco-friendly from a resource standpoint, since it's petroleum-based. Polyurethane foam insulation was traditionally blown in with CFCs or HCFCs, which are known ozone depleters. Today, more eco-friendly blowing agents are used with this material, and it's a component of structural insulated panels (SIPs), a construction element that is generally smiled upon by green builders.

Many homeowners know very little about their heating and cooling equipment-until something goes...