Home Replacement Windows: What's Your R-Value?

Today, everyone from President Obama to Green Building Advisor Martin Holladay is talking windows – those that save money and save energy.

At a Home Depot store in Virginia, Obama explained how retrofitting buildings and investing in “energy-efficient windows and doors” is the biggest bang for the buck for economic growth, environmental initiatives and energy efficiency.

Martin posted a fantastic summary and is leading a great discussion on Windows That Perform Better Than Walls.

His technical explanations dive deep into the relationships and qualities of insulation values (R-value or U-value) and solar gain and a concept that we specialize in, and the critical art of directional “tuning” glass values based on a building’s position in relation to the sun. He discusses different standards such as Canada’s ER (Energy Rating) method and Passive House - one specifically that emphasizes the fine balance of solar energy gains and losses, super-insulation, advanced window technology, air tightness, and ventilation.

It is pretty simple. This chart details the amount of money you can save replacing your home's old single pane windows (an R-value of 1.0) with other windows on the market. Super-insulating windows of higher R-values can help you save the highest percentage of heating and cooling costs when compared to other "energy-saving" windows available today.  Even compared to typical ENERGY STAR® windows (they are usually dual pane low-e windows with an insulating value of R-2.5 to R-2.8 depending on geography).

The data for this chart is based on the U.S. Department of Energy's RESFEN model and is an average taken from 5 typical cities across the U.S.: