LISTEN...

Windows and doors are typically the weakest spot in the building envelope. When you're looking at replacing existing units with new ones, consider using something with higher energy efficiency.

Windows and doors are measured for thermal conductivity in U-Value, or how much heat loss the assembly is expected to have - Remember: a lower U-Value is better.

In terms of energy efficiency, these are the important parts to consider for a window unit:

1. Glazing - The quality of glass and the number of panes.
2. Spacers - The strips that separate the glass in between each pane and around the entire perimeter of the glass.
3. Sash - The part surrounding and holding the glass. The sash may move up and down, or swing like a door or awning.
4. Frame - The part that holds the sash. The frame is stationary in the rough opening and it will attach to air, thermal and moisture control layers.
5. Weather and Air Seals - These are strips of squishy but durable materials that surround the perimeter of frames and sash. When the window is closed and locked, these seals should make the unit airtight.
6. Hardware - Hinges, cranks, locks and other metal parts that control the opening action and locking of a window.
7. Inert Gas - Gas such as argon or krypton is injected in between the panes of glass, to slow the passage of heat through the glazing assembly.
8. Low-E Coatings - These are "low emissivity", transparent coatings applied to glazing faces to reflect heat either into or out of a building.