New Regs May Change Your Window Choices

By Arlene Stewart

Year 2006 will bring many changes for Florida builders when it comes to energy efficiency.  It’s a good time to revisit your window choices because products that were not cost effective yesterday, just might be today with the changing market conditions cause by a federal HVAC change. 

So why talk about HVAC in a window tip column?  Because increased HVAC efficiencies are the reason for the change. 

You should know by now that the new Federal minimum SEER is 13.  This national change will cause an overall efficiency increase of 10-15% in the energy code.  (If you haven’t heard, go get a copy of Big HVAC and Window Changes are on the Horizon from the April/May 2005 edition of Florida Home Builder Magazine). Some companies have stockpiled the lower efficiency SEER 10 equipment, interpreting this measure as only applying to manufacturing requirements.  Others are taking advantage of Florida Building Code requirements that will not incorporate this HVAC change until August 2006 at the earliest.  Still others are interpreting the federal requirement as being absolutely effective on January 23, 2006, regardless of how the state may implement it.  They think that if builders do not immediately use both a SEER 13 and meet the overall 10-15% increase (that the SEER caused), that builders will have seven months of liability for not meeting national and state requirements. 

No matter what you think, one thing is certain.  Energy code requirements will go up sometime this year. 

Windows will be important when meeting those requirements.  Builders in Florida have traditionally been told that window upgrades were not cost effective.  In this changing market, windows may now be your most cost effective option.

So what should you know?

There are two measures for thermal performance: U-factor and SHGC. 

• U-factor measures how much heat is transferred through an assembly. Simply put, U-factor measures how well windows keep the heat IN.  It is the inverse of R-value.  However, windows do not use R-values for thermal performance because there are many different R-values for each component of the window.  If you do see an R-value for a window, chances are that it is a structural design pressure rating or it is just for one component like glass or framing.  Don’t get confused. Demand the whole window performance value as required by the building code.
   
• SHGC stands for solar heat gain coefficient and it measures how much of the sun’s radiation can be reflected or absorbed by the window.  Unfortunately, most national literature focuses on U-factor because most of the country is more concerned about keeping heat in the home.  We want the opposite in Florida: we want to keep the heat out. So, SHGC is more important than U-factor in Florida.
   
• Lower is better when it comes to energy efficiency in windows.  The US Department of Energy recommends SHGC 0.4 or less and U-factors 0.65 or less for Florida.  Using windows with even lower numbers (and better performance) can help even more on your energy calculations.
   
• The National Fenestration Rating Council (NFRC) maintains the national standard for testing and rating energy performance in windows.  NFRC is cited in the Florida Building Code where only whole window product performance is allowed.
   
• Ask your window dealer if the windows you are already using are NFRC-tested and certified. Over 80 percent of window products in the US are NFRC-tested but builders in Florida simply do not use the numbers in the energy calcs.  You may find you are in better shape than you thought you were.  For a complete list of certified products, go to www.nfrc.org.
   
• Ask for performance, not for components.  If you ask for SHGC and U-factor performance, you can compare apples to apples without becoming an expert on technology. Don’t just ask for low-E windows: low-E can be engineered for any climate zone. An unqualified request might result in a great window for Minnesota showing up on your doorstep. 
   
• If you transition from clear to solar control windows, make sure you tell your HVAC contractor.  Building America projects have shown that there should be a minimum half-ton reduction in HVAC size when switching from clear to solar control windows.  That will certainly help your bottom line.  More importantly, cooling, comfort and moisture problems may result if the HVAC system is not reduced to the proper size.
   
• Make sure you ask about solar control in impact windows too.  There are numerous choices in both single pane (monolithic) and double pane applications.  In fact, monolithic impact products with solar control can be more efficient than ordinary single pane ones.  Impact windows with really low SHGCs can be a great choice for energy efficiency and safety.
   
• What kinds of efficient window choices are out there?  The Efficient Windows Collaborative provides non-biased information on windows, technology and performance.  At their website www.efficientwindows.org, you can find fact sheets that compare the cost savings of generic window products for Florida.  Once you decide on window performance that might suit your needs, you can click on a link to see who in your area supplies similar windows.

Arlene Zavocki Stewart is nationally known energy advocate, promoting the use of state-of-the-art window and glazing technologies to construct high performance homes and buildings.  She is also FHBA’s Area II Vice President for 2006.

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