5 Things To Know When Buying Energy Efficient Windows For Your Portland Home

Can you feel the heat coming through your windows on a sunny day?Details about energy efficient windows for your Portland Oregon home

Ever feel cold air seeping in during the winter?

If the answer is yes to these questions, it may be time for you to replace the windows in your Portland Oregon home with energy efficient windows.

If you live in an older home, your windows are probably single pane aluminum windows, which are not very energy efficient.

You can save energy and money by replacing the windows in your home

There’s many kinds of windows so let’s talk about what you need to know before making an investment in new windows.

Let’s start by discussing the various elements of a window and explain which components are used to make a specific window more energy efficient. For example, a window can have a number of layers (single, double or triple paned) and that, combined with the other factors we’ll talk about, determine the efficiency of the window.


Glazing is a fancy word for the glass in the window.  Now, not all glass is created equal as the glass itself can have different types of coatings that affect the window’s U-factor (sometimes called the U-value).

What’s the U-factor?

It’s the degree of insulation against the outdoors or in other words, it measures the rate of heat loss or heat transfer.  U-factors (or U-value) usually range from 0.25 to 1.25.  This is what you need to remember-the lower the U-factor, the greater the window’s resistance to heat flow and the better it insulates.


Low-e stands for low emissivity or low emittance and it is a crucial component in the energy efficiency of a window.  Low-e refers to the window’s ability to reflect (rather than absorb) heat so that your home stays cooler.  Low-e coatings are virtually invisible to the naked eye as they are made from microscopic metal or metallic oxide particles applied to the glass.

How does low-e coatings work?

The low-e coating suppresses radiant heat flow out of the window but allows solar radiation.  Let’s explain that in simpler terms.  In summer, the coating keeps the sun’s heat from entering your home and in the winter, it keeps the heat inside your home by minimizing heat loss through the windows while allowing solar heat gain from the sun to enter.

If you want to read more about low-e, read our past blog post about windows with low-e glass.


Spacers separate the sheets of glass in a window to increase its insulation abilities.  The design and material used are significant to preventing condensation and heat loss.

A single pane window obviously has no spacers but double-pane windows have 2 layers of glass and it’s the gap between the layers that creates a barrier to heat flow.

The efficiency of a window can be increased by adding another layer so that 2 separate insulating chambers are formed and that’s when you get a triple-pane window (pictured here), which is even more efficient than a double-pane window.

4-Gas fills

Double or triple-pane windows have either Argon, Krypton or a combination of the two in-between the layers of glass to increase insulation and slow heat transfer.   Here’s a fact for you-these types of windows often don’t work at high altitudes because the difference in air pressure can cause the gas to leak out.

5-Frame construction

How the window frame is constructed is important as the materials used can greatly affect its efficiency.  For example, insulation-filled vinyl frames and fiberglass perform better than wood, wood-clad or vinyl that is not insulated.

Aluminum and steel frames are the worst performers as they are rapid conductors of heat.  A lot of older windows have aluminum frames though these are the very windows you are looking to replace so you probably already knew that.

Now that you know the 5 components of a window, you can make a better decision when it comes time to replace your windows.  In upcoming posts, we’ll go over signs to look for when making the decision to replace your windows, your options for replacement and go over what questions you should ask when choosing a company.

May 3, 2017