HOW TO PICK THE BEST WINDOW

“What is the best window?”
I get asked all the time “What is the best window?”  I wish there were a single answer, but there isn’t.  What we really need to ask is “What is the best window for you?” and the answer could be very simple, or it could be extremely complicated.

Frame Material
The first option I look at is the frame material.  The basic materials for frames are vinyl, aluminum, fiberglass, wood, clad wood, composites, or a combination of any of these.  All of these materials have their own positive and negative attributes.

Pricing
One of the other top priorities is the budget.  In very general terms, pricing tends to go like this:
           
Frame - Price Point
Clad Wood - Mid to very high
Wood - Mid to very high
Fiberglass - Mid to high
Composites - Mid to high
Aluminum - Mid
Vinyl - Low to mid

Color
My next thing to consider is color.  A lot of today’s windows have very few color options.  Some products are paintable, some are not.  It is best to choose a factory finish because repainting adds all new complications, such as how to paint weatherstripping.

Energy Efficiency
Energy efficiency is where thing can get really complicated.  Most of the available data is on U Value, which is helpful, but fails to address energy efficiency as a whole.  There are several other important factors to consider when thinking about energy efficiency.  

•      Visible Transmittance (VT) – Measures how much light comes through the glass.  The higher the value, from 0 to 1, the more daylight the glass lets in.  Visible Transmittance is measured over the 380 to 760 nanometer portion of the solar spectrum.
•      Shading Coefficient (SC) – Defines the amount of heat gain through the glass compared to a single pane of clear 1/8” (3 MM) glass.
•      Solar Heat Gain Coefficient (SHGC) – Defines the fraction of solar radiation admitted through the glass both directly transmitted and absorbed and subsequently released inward.  The lower the value, the less heat is transmitted through the glass.
•      Relative Heat Gain (RHG) – The amount of heat gain through a glazing incorporating U-Factor and Solar Heat Gain Coefficient.
•      Transmission Ultra-Violet Energy (TUV) – The transmission of short wave energy in the 300-380 nanometer portion of the solar spectrum.  The energy can cause fabric fading.
•      Transmission Damage Function (TDW) – The transmission of UV and visible light energy in the 300-600 nanometer portion of the solar spectrum.  The value includes both the UV and visible light energy that can cause fabric fading.  This rating has also been referred to as the Krochmann Damage Function.  This rating better predicts fading potential than UV transmission alone.  The lower the Damage Function rating, the less transmission of short wave energy through the glass that can potentially cause fabric fading.  Fabric type is also a key component of fading potential.
•      Percent Relative Humidity Before Condensation – Occurs at the center of glass, taken using center of glass temperature.
•      Inside Glass Surface Temperature (IGST) – Temperature is taken at the center of the glass.

Other factors to look at include Performance Rating, Design Pressure Rating (DP), and Certified Air Infiltration Rates.  All reputable brands will have this information available but with many it may be difficult or impossible to get.  

In general, some of the best energy upgrades are insulated glass, low E coating, and gas filled units.  There are several types of low E coating on the market today which vary in performance and HAVE TRADE-OFFS.  Gas filled units are another option (with argon being the most common one) but gases have nowhere near the effect that low E coating has.

Triple pane glass is also available in some off-brand windows, but most major window companies don’t believe the benefits of these windows outweigh the high cost and dramatic daylight transmission reduction.  You would need approximately twice the square footage of triple pane windows to let in the same amount of daylight, and daylight, after all, is the reason we put in windows in the first place.

Things to Avoid
One of the most disturbing trends in today’s window and door market is the high pressure/exclusive product sales scheme.  Even some of the large retail chains and major window and door manufacturers have chosen to use these deceptive, “tin men” tactics.  

Here are some of the things you should watch out for:

•      “If you sign today we will give you a large discount!”
•      “If you sign up and we can use your house as a display house we will give you a deal.”
•      “We have an exclusive window or door!”

These are all indicators of a less-than-reputable company.  If a company has a quality product it will stand up against the competition without needing huge price drops or outrageous claims.  A manufacturer with a great product will have no problem getting contractors, builders, and architects to use it.  Dealers of quality windows and doors do not need to resort to these kind of tactics in order to sell their products.