2. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. The Efficient Windows Collaborative: An Explanation of 2003 “Glitch” Window change to Chapter 13 of the Florida Building Code

3. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Introduction and Background

4. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Aesthetics Does it have the right style? How will it look after being outside for 5 years? Windows have to meet lots of requirements… Structure Does it leak? Is it easy to open? Safety Is it big enough to escape thru? What is the best sill height? Does it need safety glass? Energy Does it keep in the cool? Does it keep out the hot?

5. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Energy is different because it’s difficult to see… For aesthetics and safety, you can see if you’ve received what you expected. With structure, you can see some, but we rely on ANSI/AAMA/NWWDA testing for details. With energy, we can see the results of energy transfer, but we really can’t see the transfer itself.

6. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Evaluating energy efficiency is more complicated than it used to be We used to be able to tell energy efficiency from components. It used to be that: –W–Wood kept heat in better than vinyl which kept it in better than aluminum. –I–Insulated glass also kept heat in better than single pane. –T–Tints kept out heat better than clear glass. With advanced technology, technologies are invisible: –G–Glass doesn’t have to be dark to keep out heat. –W–Warm edge spacers, thermal breaks and gases help keep heat in. So today, what you see is not necessarily what you get.

7. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. HistoryHistory In the1980s, a code official in the Pacific Northwest started investigating claims of energy efficiency in windows. Radically different representations of efficiencies were discovered. Led to the formation of the National Fenestration Rating Council to create a standardize testing methodology for whole window energy performance.

8. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. U-Factor or how well a window keeps the heat in Defined as the rate of heat loss is indicated in terms of the U-factor (U-value) of a window assembly. The insulating value is indicated by the R- value which is the inverse of the U-value. The lower the U-value, the greater a window's resistance to heat flow and the better its insulating value. A low U-factor is helpful whenever heating is needed. An U-factor of 0.75 or less is recommended in warm climates.An U-factor of 0.75 or less is recommended in warm climates.

9. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Solar Heat Gain Coefficient (SHGC) or how well a window keeps the heat out Defined as the fraction of incident solar radiation admitted through a window, both admitted through a window both directly transmitted, and absorbed and subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a window's solar heat gain coefficient, the less solar heat it transmits. In heating-dominated climates, a high SHGC increases passive solar gain for the heating, but reduces cooling season performance. A SHGC of 0.40 or less is recommended in warm climates.A SHGC of 0.40 or less is recommended in warm climates.

10. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Tested values allow for unbiased comparison Windows with the same efficiency get the same tested U- factor and SHGC values regardless of the combination of material components. U-factors and SHGCs can be compared without bias toward components. U-factors and SHGCs also can be used to obtain more accurate measurement of a home’s overall energy usage. NFRC 100 (U-factor) and NFRC 200 (SHGC) have been adopted by the International Energy Conservation Code (IECC) and the Florida Building Code as the methodology for window performance.

11. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. What about a window that isn’t tested? FBC and IECC provide approximate values for windows that are not tested based of a generic configuration of components. These values are called defaults and are generally worse- case. If you to receive credit for the extra value from more advanced technologies (beyond a lower energy bill), testing is needed.

12. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Up-selling on energy was really tough For years in Florida, sales have focused on structural aspects of windows because of hurricane preparedness. Energy educators said upgraded windows were not cost effective. In a way, they were right…

13. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Current and Future Energy Parameters for Windows in the Florida Building Code

14. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. This is where things get muddy Chapter 13, Section 104.4.5 said defaults were one set of numbers (from Appendix B, Section 2.1.2 and 3.1). However, a different set of defaults was actually used in the calculations. So U-factor UsedCodeCode Single pane clear1.00.70 Single pane tint1.00.60 Double pane clear0.50.61 Double pane tint0.50.53 1.300.75 1.300.64 0.870.66 0.870.55 Used SHGC

15. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. This difference hid the impact of efficient technologies Untested windows received about 30% credit on U-factor and 10% on SHGC. Even though the SHGC difference is only 10%, its effect is comparable to the 30% U-factor difference because of the importance in controlling excess heat in Florida. Therefore comparisons against tested (generally upgraded) windows showed much less improvement than was expected. These results reinforced calculations done by energy educators who recommended upgrades on other products such as insulation and HVAC equipment because simulations showed greater results with these products.

16. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. On June 30, 2003 in Florida, U-factor and SHGC defaults will revert to those found in the Florida Building Code.

17. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. What should you do? Find out if your windows are tested to NFRC 100/200. –Many companies have NFRC tested/certified products, but don’t provide the information where there isn’t any demand. If they meet or exceed the old defaults, you’ll simply need to change the way you fill out the forms (see next slide). Even if they meet or exceed in only one value, it’s worth your while to see how or if the windows you are currently buying will affect the overall calculation before changing your current house plans. 1997 DefaultsU-factorSHGC Single pane clear1.0 or less0.70 or less Single pane tint1.0 or less 0.60 or less Double pane clear0.5 or less 0.61 or less Double pane tint0.5 or less 0.53 or less

18. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Enter SHGC here Enter U-factor here

19. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. If NFRC 100/200 values are not available, Energy Code Calculations should be completely redone. New forms can be found at http://www.dca.state.fl.us/fhcd/fbc/committees/energy/ener gy_forms/1_energy_forms.htm This will allow builders to figure out what other measures need to be taken to make up the efficiency deficit by using unlabeled windows. Alternate measures include but are not limited to higher SEER HVAC, higher EF water heater, more ceiling insulation, or airtight duct testing. To avoid delay in permitting, recalculate before June 30. This page only applies if windows are not NFRC tested.

20. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. www.efficientwindows.org This information was brought to you by:

21. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. A international coalition of: –window, door, skylight and component manufacturers, –research organizations, –federal, state and local government agencies and –others interested in expanding the market for high- efficiency fenestration products. EWC is a non-profit market transformation project of the Alliance to Save Energy. Efficient Windows Collaborative

22. © EWC 2000 All rights reserved. Revised May 2003. Regional Representative Efficient Windows Collaborative A project of the Alliance To Save Energy And… Class 1 Residential Energy Rater 530 AZS Consulting And… Volunteer Educator Florida Energy Extension Service University of Florida Arlene Zavocki Stewart

23. Efficient Windows Collaborative © EWC 2000 All rights reserved. Revised May 2003. Selecting a Window the EWC way 1.Look for the Energy Star Look for a product that qualifies for the Energy Star in your area. 2.Look for Energy Efficient Window Properties on the NFRC Label The key window properties are U-factor, Solar Heat Gain Coefficient (SHGC), and Visible Transmittance (VT). The NFRC label provides the only reliable way to determine the window properties and to compare products. 3.Compare Annual Energy Costs for a Typical House The annual energy use from computer simulations for a typical 2000-square-foot house in your region can be compared for different window options. 4.Estimate and Compare Annual Energy Costs for Your House Using a computer program such as RESFEN to compare window options is the only method of obtaining reasonable estimates of the heating and cooling costs for your climate, house design, and utility rates.