The battle of the panes - double-glazing vs multi-glazing

If you are serious about getting the best quality, best energy-savings and best value in today’s window replacement market, then you really need to do your own homework, and draw your own conclusions.

This blog entry is intended to give you an impartial look at the variables and factors affecting the most current window prices and performance. We hope this information provided will help you decide which option are best for your family and your home.

Glass Efficiency

Before you start, here are a number of glass attributes that affect a window’s efficiency.

1. The number of (glazes) panes of glass
2. The thickness of the glass
3. Coatings on the glass
4. Space between the glass
5. The Material separating the glass (spacers)
6. The gas between the glass
7. The frame holding the glass in place

Lots to consider. Unfortunately, these attributes are rarely published and available to the average consumer. That’s why Energy Ratings are so important, they are the only standardized unbiased measurements (tested and measured by a neutral authority) available to help you make an honest comparison between windows.

Measuring Energy-Efficiency

The best resource for honest energy-efficiency measurements are available from the NRC Canadian Government-sponsored Energy Star website, here you can search for windows by a variety of queries.

Below are the main energy-efficiency ratings as they pertain to glass. Keep in mind that window manufacturers typically provide customers with several glass options to help produce the desired result (e.g. less light, less heat, more insulation…) which can lower or raise energy-rating values.

1. U-factor (UF) - heat loss through frames, spacer and glass
2. Solar heat gain coefficient (SHGC) - heat transmitted and absorbed that is subsequently released inward
3. Visible transmittance (VT) - is the amount of light in the visible portion of the spectrum that passes through a glazing material

Energy-efficiency is great, but what about home comfort?

In Ottawa (climate zone 3) the energy-efficiency prime directive is focused on keeping heating costs down in the winter as statistics show heating costs far outweigh cooling costs. However, in many cases, energy-efficiency may mean a sacrifice in home comfort.

Unfortunately, some of the things that make a window more efficient can also result in less desirable effects:

• Excessive heat in a room in the summer
• Excessive brightness in a south-facing window all year round
• Furniture damage due to UV rays

This is exactly why most window manufactures give you varying levels of glass options and why when you are buying windows, even though there are manufacturing standards, you cannot really make apples-to-apples comparisons.

Comparing double-glazed windows to triple-glazed windows

OK, so which is better, triple or double glazing? For purposes of understanding the statements below, we’ll pretend we are using the same glass, gas and spacer attributes for both the triple and double-glazed windows. Here are the facts.

If you would like to know more, give us a call or send us a request for more information. We’d be happy to address all of your questions or concerns.