Windows are an important part of every building and we put together this guide to explain them.

There are three main elements of windows that are important for anyone looking to buy windows: type, material, and glazing

01 TYPE

These are the most common types of windows on the market today. Each type operates a bit differently.

Single Hung - Single hung models have an operable bottom sash that allows air flow into the space.

Double Hung - Both the top and bottom sashes move on double hung windows.

Casement - Casement windows open along the edge of the window - the other edge is hinged. The window is opened and closed using a hand crank on the interior side.

Awning - The window sash opens at the bottom of the window with a hinge along the top edge.  

Sliding - Sliding windows open horizontally. One or both of the sashes can be operable on this window type.

Fixed - Like the name suggests - this type of window does not open.

The type of window used plays a role in a home’s energy efficiency. It takes more energy to heat and cool a space if outside air is actively leaking inside. Any window that opens has the potential to leak. Due to this fact, fixed windows are the most energy efficient. Casement and awning windows seal pretty well. The sliding mechanism on the other types of windows tends to allow more air through. This becomes more important if extreme wind and weather conditions are common at the building location - most of the time a quality sliding window type will be fine.

02 MATERIAL

Windows are being made out of many different materials these days. Below we will explain some of the most popular materials used and their relative benefits.

Wood

Wood windows offer the best insulating properties of the different window materials discussed here. They are also considered to be the most beautiful type. They require more upkeep than the other materials and are the most expensive option.

Vinyl

Vinyl is less expensive than the other options here but window manufacturers offer different grades of vinyl windows. Higher grades are recommended as lower grades tend to leak more air. Premium grade vinyl windows can end up being expensive. 

Fiberglass

Fiberglass is more expensive than vinyl but less expensive than wood. It is stronger, more energy efficient, and more durable than vinyl.

Aluminum

Aluminum is lightweight and stronger than other options but allows for a lot of heat transfer. The other window materials offer far better insulation. Aluminum will sometimes be used as a cladding material with wood underneath. This does help to insulate the window but water tends to get behind the aluminum and cause the wood to rot.

03 GLAZING

There are a few ways to increase the energy efficiency of a window through it’s glass construction. Insulation can be added with multiple-pane windows and there are coatings that decrease heat transfer.

Number of Panes

Windows can have multiple layers of glass. Double-pane and triple-pane windows have air or gas sealed between the panes which helps by adding insulation to the glass. If the seal is broken, however, condensation can form between the panes. There is also a definite cost increase when multiple panes are used.

Low-E Glass

Low-E stands for low emissivity. This is a very thin coating applied to the glass that allows light through but reflects heat. This coating keeps heat from passing through the window making it useful in all seasons.

Windows are also tested for their energy efficiency. These measurements will be available to anyone shopping for windows. Two of these values are the solar heat gain coeffient (SHGC) and U-value.

SHGC (Solar Head Gain Coefficient)

This value indicates the amount of energy from the sun that passes through the window assembly. A higher SHGC allows more heat from the sun through. A lower value is more energy efficient.

U-Value

The U-value is the rate at which heat moves through the window. A lower value indicates a more insulated window.

EnergyStar has recommended values for the SHGC and U-value based on location. Check it out here.