Window Shopping: What to Look for in Replacement Windows

Looking to install new windows? Here's what you'll need to know about glass, frames and window installation

Credit: Flickr / Brian Williams

Flickr / Brian Williams

Glass, frame and installation are the key considerations for replacement windows

If window replacement is on your home improvement to-do list, this guide will help shed light on various types of new windows, glass and frames you’ll want to consider

When you bought your house, your key considerations may have been location, location, location, but when it’s time to buy new energy-efficient replacement windows, the three key words are glass, frame and installation.

It’s possible to get a replacement window made in almost any configuration, but it’s what you don’t see that really counts with new windows. 

Types of Glass in New or Replacement Windows

Technology has really flexed its muscles when it comes to glass in new window installations. The newest technology is low-E³, which is glass coated with three layers of low-emission coating. Low-E² glass, with two layers of protection, is still available. 

“It reflects the heat back to its source,” says Mark Brandow, sales manager at Centra Windows. “The biggest payoff is in the winter. The heat in the house hits the window and goes back into the house.”

There are three main types of window glass for replacement windows: hard coat lowE, soft coat lowE and Argon gas.

Hard coat lowE is a thin metallic layer applied to glass while it is extremely hot, during the float process.

Although it is more durable than soft coat, few manufacturers still use this process.

  • Pros: Any type of lowE coating, including hard coat, provides better insulation than regular glass. And hard coat is the most affordable coated glass.
  • Cons: Hard coat lowE windows have a lower R-value so they don’t insulate as well as soft coat lowE windows do.

Soft coat lowE is a differently composed micro-thin metallic layer applied after the glass has cooled.

It performs better than hard coat and is the most widely used glass in the window industry today.

  • Pros: Soft coat lowE is widely available, limits UV rays coming through your window, and keeps the heat in during the winter and out in the summer, making you more comfortable and saving you money.
  • Cons: Coated glass is more expensive than regular glass.

Argon gas is an inert gas that acts as a low thermal conductor (which means it slows the transfer of heat and cold).

Its abilities are enhanced when applied to lowE glass.

  • Pros: Argon adds an extra layer of insulation to a sealed unit. The gas used between panes is odourless, colourless and non-toxic, and remains inside the glass for many years under normal use.
  • Cons: Many agree that argon gas will dissipate out of the window over time, though that rate of dissipation is unknown.

IMAGE: iStockphoto / uplifted

New Windows – Single, Double or Triple-paned?

Since single-glazed windows don’t exist anymore, look for the type of spacer used in double-paned units. Two panes of glass are sealed around airspace; the seal is where you gain performance.

With triple-paned windows, there are three sheets of glass. The main benefit of multiple glazing (or multiple layers of glass) in your replacement windows is that air is a good insulator, so air trapped between layers of glass reduces heat loss and reduces noise, and a warmer inside window means less condensation when it’s cold outside.  

  • Pros: Double-glazed windows with an E coating give the same performance as triple-glazed standard windows but with less weight and a lower cost.
  • Cons: Triple panes are expensive and the extra cost only warranted in extreme climates or when trying to achieve very high energy ratings. Triple-pane windows are also heavier, so they limit the size of window that can be made.

In between the panes of glass are spacers. Structural foam spacers are top choices; they move as the glass expands and contracts. Aluminum and stainless steel are next best. 

Low-conductivity spacers can improve the thermal performance of a lowE, gas-filled window, door with a window, or skylight by as much as 20 percent.

Whatever type of window you choose, it is a major purchase for your home and cost may play a factor in your window and frame choice.

Replacement Window Frames

The window frame has more to it than meets the eye. “Cold air transfers through chambers. The more chambers, the longer it takes cold air to enter the house,” says Brandow. Some windows have 10 chambers in each frame. Others have seven. A bad window? Only two.

The outside – the piece you see – is typically vinyl, but it could also be made from wood, aluminum or a combination of wood and aluminum.

Vinyl windows have great thermal characteristics with strong welded corners. They are easy-to-clean and their multi-chambered construction reduces cold and heat transfers.

  • Pros: Vinyl windows are very low maintenance, clean easily with a cloth and never need painting. And they come in a wide range of prices and sizes.
  • Cons: Once you choose a colour, you are stuck with it for the life of the vinyl window as they cannot be painted.


Wood replacement windows have decent thermal characteristics and are strong, high-maintenance and very expensive.

  • Pros: Wood windows keep the heat in, and have a beautiful look that cannot be replicated with vinyl.
  • Cons: Wood windows are more expensive. They are also bulky, so they will take up a bit more room. Wood windows also need a lot of upkeep and are susceptible to peeling and cracking.

Plain aluminum windows are affordable, strong and low maintenance, but have poor thermal characteristics.

Aluminum wood-clad replacement windows, when you add aluminum to wood, have decent thermal characteristics. You also decrease the maintenance required to keep your windows looking great, but the high cost may be prohibitive.

  • Pros: These types of windows are strong and low maintenance.
  • Cons: These new windows are also more expensive than just wood.

IMAGE: iStockphoto / happyborder

Replacement Window Installation

As with any home renovation, check references and the Better Business Bureau for membership and complaint status when buying replacement windows. While you’re at the computer, get an electronic clearance letter from WorkSafeBC; it only takes a minute and confirms the business’s status.

Finally, ask if employees or subcontractors will perform the window installation. Typically, says Brandow, employees are paid an hourly wage and quality is top-of-mind; subcontractors are paid by the piece so speed is paramount.

“Ask if the company does a background check on employees. Do they have an apprenticeship program? Are the installers certified? What are the warranties? Look for lifetime warranties and read the fine print on the frame, seal and installation,” says Brandow.

Protect Your Investment

The bottom line is that windows are made of glass, and glass breaks. Consider an after-market film for security, solar protection or a better outlook.

Safety film is a sacrificial barrier, says Charm Prophet, GM of EWS Films Inc. It’s a thin, clear product applied to the inside of glass, which reduces the risk of flying shards should Mother Nature or the kid next door toss something through your new windows.

A better solution might be security laminate – a thicker, transparent, multi-layer barrier that deters break-ins. “Its top-grade polyester adhesive does all the work, once cured,” says Prophet. “It won’t stop an entry – but it slows it down.”

Solar film battles a different enemy – the sun. It can block 98 per cent of harmful UV rays and increase heating and cooling efficiency.

For a truly unique and stylish choice, try decorative film. Your new windows can look like cut crystals, an Arizona sunset, or a dreamscape of butterflies. Decorative film still lets in the light, but otherwise offers you total privacy.


Image courtesy Trove


Originally published in BC Home magazine. For monthly updates, subscribe to the free BC Home e-newsletter, or purchase a subscription to the bi-monthly magazine.