Boosting Efficiency With Windows and Doors

Jeff Wilson replaced half of the windows in his 70-year-old Cape Cod home just five years ago, upgrading from single-pane glass to more efficient double-pane windows. Meanwhile, as Jeff greens his home top to bottom with a Deep Energy Retrofit (DER), he addresses nine leaky windows and a front door, choosing today's gold standard: triple-pane, gas-filled windows.

Triple-pane, gas-filled windows provide three layers of glass and are filled with krypton or argon gas. The gas serves as insulation, preventing heat transfer between panes. This cross-section view shows the technology Jeff chose.

The home's bay and dormer windows are replaced with triple-pane, gas-filled windows that have a warm-edge glazing. This means high-density foam and silicon sealant is applied between the window and frame rather than using a simple metal spacer. This technology will prevent condensation at the window ledge, which leads to mildew and rotting.

You can choose the most efficient windows on the market, but if they aren't installed correctly, you've just wasted time and money. A tight air seal is imperative. Windows must be caulked and taped to prevent any gaps.