Recently, a commenter requested advice on making window doors more efficient. Susan Meredith, co-founder of Go Green Squads, actually wrote a section in her book (Beyond Light Bulbs: Lighting the Way to Smarter Energy Management) about what qualities windows and doors should have to be more efficient.

According to Meredith, the main considerations with windows and doors include “heat radiating from the sun, heat conducting through the windowpane and frame, light, and airflow” (Meredith 56). The choices you make depend on what kind of house you want.

Things to pay attention to:

1. The SHGC Rating

How much heat can enter through the windows is measured by a solar-heat-gain coefficient (SHGC). The higher the rating, the more heat can get into your house.

2. The U-factor

The U-factor measures how much non-solar-heat flow is conducted through glass, frame and spacer materials for windows and glass doors.  A low U-factor prevents heat from escaping in cold weather and absorbs less heat during hot weather—Treating windows with certain types of coating such as low-E (emissivity) and using curtains and blinds can help reduce the U-value. Low-E is always better in hot climates, but is trickier in cooler climates because low solar-gain glazings perform better in summer but higher solar-gain glazings perform better in winter.

3. Frame material

Some materials are stronger conductors than others, causing heat to pass through more easily (this is bad). Aluminum, for instance, has high conductivity unless it is layered with nonconductive material.

4. Triple-Pane it

More layers provide better insulation. “Double-paned or even triple-paned windows reduce the amount of heat that transfers through while still allowing light through” (Meredith 56).

5. Location

The placement and shading of windows has a significant effect on the temperature of your home. For more heat, place more windows or remove the shade from windows on the west and south sides of the building. To keep things cool, cover those on the west and south and expose those on the east and north sides. You can also open windows on opposite sides of the room or ventilate through a high window in order to increase airflow. Putting windows in stairwells can further cool the building.

So, here is a quick summary of what you should go for, depending on whether you are a polar bear hoping for a fresh, icy abode, or a camel partial towards a toastier environment.