There is no doubt that a growing number of people worldwide are striving to make buildings considerably more environmentally friendly than ever before. For new home builders, essentially this means constructing houses using eco friendly materials in a way that makes them energy efficient.

When it comes to eco friendly windows, there are several factors to consider. These relate to the material used for the frame as well as insulation and their ability to keep the rays of the sun in or out of the home, depending what is required. It’s got to do with comfort as much as it has to do with reducing our carbon footprint and going green for our planet, because it’s the right thing to do. And there’s another factor too; homes that are energy efficient are cheaper to run.

In addition to all of this, some country’s governments offer incentives to encourage less enthusiastic home builders to think and act green. In the US there are at least eight different financial incentives from tax credits and home loans for replacing old windows with energy efficient windows, to tax rebates for installing a solar hot water heater. There are also local incentives in most US states. Manufacturers and green-savvy builders can earn energy-efficient tax credits as well.

In Canada, the Office of Energy Efficiency at Natural Resources Canada offers federal grants and incentives as part of its ecoENERGY Retrofit program – even though this is more relevant to upgrades and refurbishment than new homes.

Because the man (or woman) in the street has not got the technical know-how to judge whether windows – and other products – are eco friendly, the US Environmental Protection Agency and the US Department of Energy launched a joint program to improve energy efficiency products and practices. Called ENERGY STAR, it awards products specific ratings. So by using products with an ENERGY STAR rating, you know that they meet the strict energy efficiency guidelines that have been laid down by the EPA and the US Department of Energy.

In 2010 alone, North Americans saved enough energy to avoid greenhouse gases that would have been caused by 33-million cars. According to ENERGY STAR, they also saved close to US$18-billion on combined utility bills.

In addition to ENERGY STAR ratings, Canada has an EnerGuide rating service (the ERS) that determines the level of efficiency in homes according to a scale numbered from zero to 100. The higher the rating the better, indicating that the house is well insulated and airtight, well insulated and doesn’t need the owner to buy any additional energy. It is easy to see how windows will help to boost any house up the ratings. The ideal for a brand new house is a rating of at least 80 – if possible higher.

Energy efficient factors

Windows are among the growing list of products that qualify for use of the international ENERGY STAR energy efficiency symbol. However different climatic zones have different needs in terms of suitability. What makes a window good for a northern Canadian home will be rather different to one that meets the needs of a home in northern Australia. There are also variations within single countries. For example Canada alone has been divided into four climate zones as explained on the Natural Resources Canada web site: So the most suitable eco friendly window for your home will depend on where you live.

Whether you are buying windows from an outlet like Lowes ( or Home Depot (, or directly from one of the manufacturers, there are some other things to look out for as well.

First there is the U-factor which is a measure of how well a window prevents heat from escaping and how well it insulates. Ratings range for 0.20 to 1.20 and the lower the number, the better the U-factor.

Then there is the solar heat gain coefficient (SHGC) which measures the ability of windows to block out sunlight and maintain a cool interior environment. The lower the SHGC, the better it is able to block the heat.

Another rating is visible transmittance (VT) which is a measure of the amount of visible light that is transmitted through the window. The higher the value the more light you will see, and the less artificial lighting you will need.

The R-value measures resistance to heat loss. Since windows can, according to Natural Resources Canada, account for up to 30% of the heat lost from a house, it is clear how important the R-value factor is. High R-value windows are the most energy efficient.

According to Serious Windows (, the most cost effective energy saving option is R-5 windows. As their experts point out, windows are one of the biggest sources of heating and cooling energy loss in our homes.

Then there is the air leakage factor. This measures the quantity of air that can escape through the window. While a well made window will be air-tight, a cheap, badly made window may well have gaps and cracks at the joints, and air will pass through these even if the window is shut.

Condensation resistance (CR) is another factor that should be considered. This measures the ability of the window to resist moisture forming on the glazed surface. CR is rated as a number between zero and 100 and the higher the number, the more resistant it will be to condensation.

Lastly there is a design pressure (DP) rating which measures the pressure the window is able to withstand when it is closed and locked. This is an important security factor as well as an issue that relates to air entering and leaving the house, and of course the effect strong winds might have. The higher the DP rating, the more pressure the window will be able to withstand.

Eco friendly materials

Marvin ( and, is a window manufacturer that has outlets throughout the USA and Canada. The company prides itself on producing energy-efficient products and their windows meet or beat the tax-credit ENERGY STAR guidelines. In addition to this, they also use quality recycled materials and make a point of recycling all their manufacturing by-products.

Window frames are made of lumber or aluminum-clad wood. Products are FSC and/or SFI certified. The FSC (Forest Stewardship Council) certification is, of course one that shows lumber was sourced from a sustainable, well-managed forest. The SFI (Sustainable Forestry Initiative) also certifies that you are buying wood that comes from a certified sustainable source.

So if you are looking for eco friendly windows that are made of wood, make sure you look out for both of these certifications.


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