Your roof is your home’s crowning glory — after all, it keeps you warm in winter, cool in summer and dry year-round. It’s also the finishing touch that makes your house look complete. But the truth is, most of us take our roofs for granted.

Windows, like appliances, can be Energy Star certified. It’s the job of the National Fenestration Rating Council (NFRC) — a nonprofit organization that rates the energy efficiency of windows, doors and skylights — to test windows and determine if they qualify for the Energy Star program. To do this, the organization developed a rating system that quantifies a window’s performance, including the amount of solar heat it lets in and the amount of air it lets out.

Going green has long been more than just a trend in North America, and the government is encouraging sustainable choices and green home improvements with incentives and subsidies. Energy-efficient windows installation tops the list of go-to home renovations and can reduce energy bills by 7% to 15% annually.