Replacement Windows Buyers Guide To Understanding Window Performance: Thermal Efficiency

Throughout February, Windows on Washington is presenting a four part series examining the essentials of window performance. Our aim? To help you make an informed decision when selecting custom replacement windows.

In Part One , we discussed Visible Transmittance.

In Part Two, we examine thermal efficiency and how heat loss can affect the energy efficiency of your home.

Thermal Efficiency Explained

Each home has some element of thermal mass. These are the parts of your home that absorb and store heat energy. During summer, thermal mass absorbs heat during the day and releases it at night. In winter, the same thermal mass can store the heat from the sun or internal heaters to release it at night, helping the home stay warm.

The Thermal Efficiency of your windows plays an enormous part in this process, and therefore the comfort and energy efficiency of your home. Windows, especially older single pane varieties, become a vehicle for temperature transfer; the exchange of thermal energy between environments. In simple terms, it means that during winter older style windows allow too much heat to escape – up to 40%. Meanwhile in summer, outside heat can enter your home with little resistance if your house features windows with poor thermal efficiency.

Thermal Efficiency: It’s up to U

Thermal efficiency is the measurement of how well the window resists the movement of energy through it.  The measurement of this efficiency is represented by U-Factor.

The U-Factor measurement demonstrates the rate of heat loss of each window. The lower the factor, the more resistance to heat flow.  A window with a lower U-Factor will keep more heat inside during the winter and more ambient heat outside in the summer, improving the energy efficiency of your home.

Today, windows come in a massive array of varieties. Double and triple pane glass offers unprecedented energy savings, while high-tech finishes and coating prevent temperature transfer.

But not all windows are created equal. House design and window orientation play a big part in determining which product offers you the best energy efficiency.

The Okna 500 and 800 have U-Factors that far exceed the current and proposed Energy Star Qualifications. U-Factors ranging from 0.15 to 0.26 are far superior to other common window types which usually offer a U-Factor of 0.30.

Things To Consider When Upgrading Your Windows

• The energy performance rating of different windows
• The climate of where you live
• The orientation of your home in relation to the sun
• The placement of windows around your home

Don’t Forget The Frame

The window frame itself plays a vital role in regulating internal temperature, working with the glass to prevent heat transfer. Frames come in a variety of materials, including aluminium, vinyl, fiberglass and metal. Energy efficiency is best achieved when the window frame matches your selected window and it’s finishing.

Always Use A Professional

Remember that a high-performing window is only effective when properly installed. Windows on Washington only offers the highest quality replacement windows on the market. Always use a professional to install your windows to ensure safety, and maximum value for money.

Find out more

Contact Windows on Washington to request a free estimate to see which products would suit your home. You can also download this free ebook that teaches you how the right windows, air sealing and insulation can improve the energy efficiency of your home.