Home Series: Guide to Buying New Windows- Consult with Bruce Coleman, Vancouver Mortgage Broker
Many older homes have wood frames made which tend to deteriorate and often only support single paned windows which can cause loss of energy.
Here is a brief guide on selecting new windows. Keep in mind that you can also get your windows custom made and in styles that reflect your style of home.
How Windows Are Rated
The energy efficiency of windows is reflected in the following terminology:
U Factor – Describes the glazing efficiency alone how it conducts non-solar heat flow. A more comprehensive rating is called the NFRC U- Factor rating describing the efficiency of both the glass/glazing. A lower rating means the window/frame has greater energy efficiency.
Solar Heat Gain Coefficient (SHGC) – Refers to the amount of solar energy and the amount of solar heat passing into the home. A lower rating means less solar heat.
Air Leakage – describes how much moves about the window frame. A lower rating means a tighter more efficient fit.
Windows are rated by the amount of sunlight so you can adjust to suit certain rooms.
Visible Transmittance (VT) – Represented as a fraction. The term refers to the spectrum of light which you see. A higher VT rating means more visible light.
Light to Solar Gain (SHGE) – This is the ratio of the Solar Heat Gain Coefficient (SHGE) to the Visible Transmittance (VT) and refers to the efficiency of the window glass or glazing.
Choosing Window Frames
Here are the types of window frames to choose from including:
Wood Window Frames – Many older homes have wood frames which are not energy efficient and subject to the elements. You can buy wood frames, but keep in mind they need be regularly maintained
Metal Window Frames
Metal frames require minimal maintenance because they are light and durable, but they tend to be a poor conductor of heat and have negligible insulation. They have to be installed correctly to adjust these issues.
Vinyl and Fibreglass Window Frames
Most vinyl frames incorporate Polyvinyl Chloride and should preferably have ultraviolet light stabilizers to prevent erosion. They resist moisture and do not require painting.
Composite Window Frames
These use composite wood products such as strand lumber or particle board but can resist moisture and less decay than standard wood frames.
There are many types of window glazing and glass so you select the ones you need for different rooms and for different effects. Your choices include:
Gas Filled – Uses inert gas such as Krypton or Argon between the window panes to provide greater resistance to both heat and air flow.
Tinting – Tints absorb heat and limit the amount of solar radiation and heat transfer. You have a variety of options
Coatings – Coatings are also varied so can opt for the following:
Low-emissivity coating which regulates heat transfer for windows that have insulated glazing.
Reflective coating which blocks light but will admit more heat.
Spectrally selective coatings that filter out between 40 – 70% of heat but permit a full range of light to enter.
Insulated Windows – Have two or more panes of glass. They are hermetically sealed and can be very energy efficient.
When buying new windows, just remember that you don’t have to select one uniform type so give some thought about what you want to achieve when you go shopping for new windows.