How Residential Windows and Doors Can Affect Climate Change

• Eleven U.S. states still do not have a building energy code.
• Only twelve states enforce a current version of the residential model energy code (2006) as it relates to windows and doors.
• Twenty-three years after commercialization, only 58% of residential windows and doors sold in the United States contain energy-efficient LoĒ glass.
• Second generation LoĒ² (low-e squared) products are now commonly available in every state with adequate production capacity already installed to handle 100% of the nation’s window demand.
• LoĒ² glass contains two layers of silver, which selectively transmit visible light and reflect solar heat and far infrared, making it efficient in both hot and cold climates.

The cost is minimal.

• Efficient LoĒ² windows cost about $15 more per window than clear double-pane windows, on average.
• Builders experience an additional cost of about $350 per average house (2,500 ft² of floor space, 22 windows) for these energy-efficient window products.  But with proper engineering, builders would save up to $1,000 in first-time HVAC costs.

The energy savings are huge.

Currently, the residential windows and doors sold with energy-efficient glass (58%) are reducing peak energy demand enough to eliminate the need for eight new 200 MW coal-fired power plants each year.

If the remaining inefficient windows and doors (42%) sold each year were required to have LoĒ² glass:

• Peak U.S. energy demands would be reduced sufficiently to eliminate the need to construct six additional new 200 MW coal-fired power plants each year.
• Greenhouse gas emissions (CO₂) from heating and cooling U.S. homes would be reduced by 2.5 million tons each year.
• The annual CO₂ emissions prevented by converting an average house to energy-efficient LoĒ² windows and doors equate to the difference between the volume of CO₂ emitted by driving an SUV versus a small hybrid vehicle.
• More than 50% of all windows manufactured in the United States are installed as remodeling or replacement windows in older homes.  If these were energy-efficient windows, the improved energy performance would become actual reductions in the total U.S. consumption.

The future appears even brighter.

• The third generation of LoĒ window and door products (LoĒ³ pronounced low-e cubed) is now entering the market.  These products incorporate a triple layer of silver with still more efficient solar selectivity.
• If all windows and patio doors in the U.S. were required to use this third generation of LoĒ products, greenhouse gas emissions (CO₂) from heating and cooling U.S. homes would be reduced by 7.0 million tons each year.
• This would amount to eliminating two new coal-fired power plants per year, or a total elimination of eight new coal-fired power plants per year.

Next: Neutralizing our own carbon footprint