Top of Page 8. How does a window, door or skylight qualify for ENERGY STAR?
• To qualify for the ENERGY STAR mark, fenestration products must meet strict technical requirements for both thermal and structural performance. Products are qualified based on either their U-value (rate of heat transfer from a warm area to a cold area) or their Energy Rating (a scale that takes into account a product’s U-value, potential solar gain and airtightness). The colder the climate zone, the more stringent the requirements. Windows, doors and skylights must also have good airtightness to qualify for ENERGY STAR. To ensure the integrity of the ENERGY STAR mark, all product testing is done by accredited laboratories under standardized, quality-controlled conditions.
