An exterior envelope encases the living area of your home. This outer shell – which includes the floor, walls, and ceiling – is far from uninterrupted. Building material changes, wiring and plumbing penetrations, exhaust vents, windows, doors, and other home features create openings in the exterior envelope. Outdoor air can enter your home through these openings, impacting heating and cooling efficiency.
Windows have a particular impact on home efficiency because they’re quite large and are made of glass, which is a very poor insulator. This means that the entire window – not just where the frame meets the wall – affects air and temperature transfer in and out of your home.
Energy efficient windows are more expensive than basic options, but they should still be your first choice. When you choose windows with a higher efficiency rating, here’s how you benefit:
- Lower your heating and cooling costs by keeping conditioned air inside where it belongs, while keeping hot humid air outside.
- Decrease your home’s carbon footprint and do your part for the environment.
- Increase your HVAC system’s lifespan by reducing the workload.
- Make your home feel comfortable with fewer drafts and a more even temperatures from room to room.
- Reduce condensation to control moisture that could cause mold growth or home structure problems.
- Preserve the color of your furniture, carpet, and paint with window coatings designed to keep UV rays out.
Many features come together to make a window more energy efficient. They impact the window’s energy performance rating, which succinctly conveys how efficient the window is in different categories. The most prominent energy-saving features of high-performance windows include:
- Two panes of glass with a low-solar Low-E coating to slow heat transfer through the window
- Argon gas filling between the panes to act as an invisible insulating blanket
- Insulating window frame material
- Low conducting spacers to hold the window panes a precise distance apart, thus reducing heat flow and minimizing condensation
- Professional installation that includes foaming, caulking and weatherstripping to eliminate air leaks around the frame