by Martha Gail Moore

Windows in our homes are our all-important look into nature or at least outside. But those glass panes could be a big reason your energy bills are so high. About 45% of energy used in homes is for heating and cooling, according to the U.S. Green Building Council.

So how do you choose the right windows for your home? Here are some tips to help you decide which windows would be best for your renovation and energy efficiency.

Factors to consider

  1. What does your city code require?
  2.  What are the available materials?
  3.  What’s your climate like?

What does your city building code require?

The first thing to do is to check the city building code requirements. Yes, if you’re replacing windows, you need a building permit.  Depending on your city’s energy conservation goals, this could mean more expensive windows. However, the energy efficiency over the life of the window will more than make up for the pricier windows.

What are the available materials? What is their energy efficiency?

How do you decide what material to use for the frames? You can choose from aluminum, composite, fiberglass, vinyl, or wood. Each of these has its good and bad points, from how well they insulate to how costly they are.  Aluminum is one of the cheaper options, but is not the most energy efficiency, since it conducts heat and cold more easily. Today, there are some very good options in vinyl and it’s easier on the pocketbook, too.

If your home has historical significance, it might make sense to keep the wooden frames. If keeping the integrity of your wooden windows is of utmost importance, then storm windows could be a good and economical option. They can be mounted either inside or outside the existing windows. Even insulating around existing windows and caulking can make a difference.

How do you choose the glass?  There’s an organization that has different ratings for windows called the National Fenestration Rating Council (NFRC). They require several ratings on the label that are really important things to check for. Two of the most important terms are the U-value or factor and the solar heat gain coefficient (SHGC). U-value measures the glass’s resistance to losing heat and how well it insulates, while SHGC measures how much heat the window allows through it. You want both these numbers to be low, e.g. between .2 and 1.3 — the lower the number the better.

A third term to look for is low-emissivity glass or low-E. Emissivity means the ability to reflect heat. This is achieved by applying a coating to the glass at the manufacturing plant. There are two methods and different materials are used in each one.

The method used in double-paned windows allows for more sunlight to pass through the windows and is superior in reflecting the sun’s rays. These windows are made with a special silver coating on the glass and they can be filled with argon gas between the layers for even further insulation. Single-paned windows also have a low-emissivity film applied to them, if the price of double-paned windows ends up being too costly.

What’s your climate like?

If you live in a rainy climate and need as much natural light as possible from your windows, visible transmittance (VT) might be very important to you. This rating shows the amount of light that the glass lets in.  Choose a higher number if you want the most daylight to be able to pass through the window. There’s also condensation resistance that is important if you live in a humid climate.

Another rating to check is the design pressure (DP) or wind rating. Depending on where you live and what your city code calls for, this could range from DP 20 to DP 50, the latter being glass that can withstand hurricane-force winds.

All the best-rated windows won’t do much to help reduce your energy consumption though if they are not installed properly. Get an excellent window contractor with references galore to install your windows.

Remember that the extra cost for energy efficiency in your windows will more than pay for itself in lower energy bills within as little as a few years.  Enjoy natural light and energy savings with new insulated windows.

Let us know in the comments section what you think the best windows are and how much they have helped you reduce your energy bills.