Residential Energy Code FAQ
Information for a General Audience on Building Energy Codes
Specific Information on the Georgia Residential Energy Code
Information for a General Audience on Building Energy Codes
Energy codes are part of a larger set of legal requirements governing the construction of buildings that protect individuals from substandard living and working conditions. In particular, building energy codes lower a building’s operating costs, while also making it healthier and more comfortable for its occupants.
Building energy codes are important for a number of reasons:
- Building energy codes save consumers money. A home that does not meet the energy code’s minimum requirements results in years of wasted energy and high operating costs for the owner. Energy-efficient buildings that use less energy put that money back into the owner’s pocket.
- Building energy codes result in healthier and more comfortable buildings. Energy-efficient buildings typically achieve a higher rate of homeowner satisfaction. Because the code reduces the amount of air that enters the home from places like the crawlspace, attic and outside, occupants breathe healthier air and are more comfortable year-round due to appropriate humidity levels. Because these homes are more comfortable, builders typically receive fewer callbacks, and the home’s value is increased.
- Energy codes bolster the local economy. The money that consumers save from lower operating costs can be spent on other goods and services in the local economy. Workplaces can also reinvest the money saved on operating costs in other areas of need.
- Energy codes reduce our dependence on foreign energy. Buildings consume 40 percent of energy used in U.S. Because energy codes improve the energy efficiency of our homes and workplaces, the U.S. does not have to import as much energy from foreign countries.
Georgia’s new energy code became effective on January 1, 2011. For residential buildings, the 2009 International Energy Conservation Code, along with the Georgia State Supplements and Amendments, make up the current energy code.
For commercial buildings, builders may use one of two compliance pathways: either Chapter 5 of the 2009 International Energy Conservation Code, along with the Georgia State Supplements and Amendments, OR the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 90.1-2007.
Please visit Southface’s comprehensive list of energy code resources and links.
5. Why does the energy code require thorough air sealing, continuous insulation, high performance windows, and duct sealing?
- Air Sealing – The energy code requires builders to air seal a home thoroughly and specifically points out a number of typical problem areas where air may leak into a home. Because heat and moisture can enter or escape a home through these penetrations, it is critical that these penetrations are sealed to increase a home’s efficiency, comfort and durability.
- Continuous Insulation – Properly insulating a house goes a long way towards making it energy efficient. Installed correctly with an air barrier, the insulation ensures that heat is less effective at moving between a home and the outside. Therefore, a more comfortable living temperature is less expensive to maintain in a well-insulated house.
- High Performance Windows – While they provide wonderful daylight and views, windows act somewhat like holes in a building's insulation, letting heat easily pass through their thin glass. To minimize this effect the energy code requires that windows have double panes and a special coating to keep out much of the sun's heat and improves the window’s insulating properties.
- Duct Sealing – Duct leakage is often the single biggest waste of energy in a home. Because conditioned air can leak out or unconditioned air can be pulled in, the energy code requires that these holes be sealed in order to save homeowners money and reduce pollutants from entering the home.
The Georgia residential energy code ensures that all aspects of a building’s thermal envelope (walls, windows, ceilings, floors and foundation) are both well-insulated and air-sealed effectively. To ensure air-sealing is executed appropriately, the energy code requires that builders pass a blower door test to verify that the home is not “leaky.”
The residential energy code also ensures that the HVAC system is sized properly, and that its ductwork is efficient and properly installed. For example, the energy code requires that builders seal their ductwork with mastic, and that the ductwork passes a leakage test.
Finally, the energy code requires that a home’s lighting is efficient. It requires that 50 percent of the light bulbs in permanent fixtures are either efficient (e.g., CFL or fluorescent) or controlled by occupancy or vacancy sensors.
As a general rule of thumb, every new residential construction project must meet code requirements, whether it is a new, single-family home, a gut renovation project, or an addition to an existing home. There are a few special cases and subtleties, which are clarified in section 101 of the 2009 IECC.
Builders are required to place a certificate on or near the panel box or the main air-handler showing major component R-values, U-factors, windows’ Solar Heat Gain Coefficients (SHGCs), equipment efficiencies, load calculations, and envelope and duct testing results. If a builder follows the prescriptive energy code, compliance can be verified by comparing the values in the certificate to those in the prescriptive code.
9. What are the biggest changes to the 2011 Georgia energy code?
- Duct and Envelope Testing: Every new, single-family home must have a blower door test and duct pressurization test conducted by a certified duct and envelope tightness (DET) verifier. These tests empirically confirm that a home’s building envelope and ductwork is properly air-sealed. Sealing the envelope and ductwork are key to ensuring that a home does not lose excessive heat in the winter or gain too much in the summer. For more information about these tests and who can conduct them, visit the duct and envelope tightness FAQ.
- Duct Sealing: In addition to passing an air-tightness test, ductwork must also be sealed with mastic. The new code does not allow the use of building cavities as either return or supply ducts.
- Lighting: For the first time, the new energy code addresses lighting in residential construction, requiring that half of all bulbs in permanent fixtures are efficient (e.g., CFLs or fluorescent bulbs) or are tied to an occupancy or vacancy sensor.
- Insulation and Windows: The new code has stricter window requirements, and it mandates basement insulation throughout most of Georgia. The code also has specific provisions for installing insulation along the roofline.
Specific Information on the Georgia Residential Energy Code
10. How can I attend a training on the Georgia residential energy code?
Southface is offering energy code trainings throughout Georgia until June 30, 2011. For a list of upcoming residential energy trainings and to see the free training materials, visit the Southface training center. If you do not see a training that meets your needs, contact the Georgia Department of Community Affairs for a list of other residential energy code trainers in the state.
11. What is the building thermal envelope, and why is it important?
The building thermal envelope separates a home’s living space (conditioned space) from unconditioned or outside spaces. In a typical residence, the building envelope consists of the roof, walls, windows and foundations. Examples of unconditioned spaces include attics, vented crawlspaces, garages, and basements with ceiling insulation and HVAC supply registers. The energy code ensures that the building thermal envelope consists of two elements: an air barrier and insulation are both continuous and touching. A good building thermal envelope is the most important step in building an energy-efficient, healthy and comfortable building.
12. Which parts of the Georgia energy code are unique to Georgia?
Periodically, Georgia evaluates the most recent version of the energy code (in this case, the 2009 IECC) and makes changes to supplement and clarify the energy code. While reviewing the 2009 IECC, Georgia strengthened the code substantially. Georgia has:
- removed the visual inspection option from the code, effectively requiring blower door testing of the envelope for single-family homes
- specified testing protocols and clarified who can conduct the envelope and duct pressurization tests
- required mastic on all ductwork and banned the use of building cavities as ducts
- increased the required insulation levels in attic kneewalls and clarified insulation levels for attic access
- increased the stringency of the window requirements so that the windows’ SHGC is consistent statewide and the U-factor requirement in South Georgia is the same as in Atlanta
- developed a series of graphics to illustrate the air-sealing and insulation requirements
- established minimum insulation thresholds for those builders who choose to use REScheck for simple trade-offs in demonstrating code compliance
- eliminated the use of grid-tied power attic ventilators (except for solar-powered fans)
- eliminated the use of new and replacement electric furnaces
- required additional information on the compliance certificate to be posted on the electrical panel box or air handler
There are three pathways a builder can take to meet the requirements of the energy code. The most common method is the prescriptive approach. This is the “just tell me what the answer is” pathway, which gives exact insulation and window requirements a builder must use. The “REScheck” pathway allows builders to conduct simple trade-offs (e.g., use lower levels of ceiling insulation but improve windows) using REScheck, a free software tool. The simulated performance pathway is the most complicated approach. This pathway allocates a total allowable energy use for a building, as determined by a modeling software, and the builder chooses the materials and equipment to meet this target. No matter which pathway a builder takes, he or she must meet the mandatory requirements in the energy code (e.g., duct and envelope testing).
14. What are the prescriptive requirements in the energy code, and are they the same in North Georgia and South Georgia?
The energy code breaks the country into several different climate zones by county. Georgia spans Climate Zones 2, 3 and 4. North Georgia is in Climate Zone 4, and South Georgia is in Climate Zone 2, while the majority of the state falls in Climate Zone 3. Depending on your climate zone, you will encounter different levels of insulation and window requirements. The prescriptive requirements for each climate zone are located in Table 402.1.1 of the Georgia State Supplements and Amendments. The prescriptive requirements in the new energy code are very similar to the old energy code. However, the new energy code requires improved basement wall insulation in Climate Zones 3 and 4, as well as improved window requirements statewide.
In Climate Zones 2 and 3 (South Georgia to Atlanta), R-30 insulation is required prescriptively by the Georgia energy code. In Climate Zone 4 (North Georgia), R-38 is required. If using blown insulation, a ruler must be installed for every 300 square feet of attic space. In addition, Georgia requires R-5 insulation for vertical attic access doors and pull-down stairs, and R-19 insulation for hatches and scuttle-holes. All of these doors must be weather stripped to prevent air-leakage.
A wind-wash baffle and dam must also be installed. The code specifies that a minimum of a 1 inch of space must be provided between the insulation and the roof sheathing and at the location of the vent. The baffle must also extend over the top of the insulation inward, until it is at least 4 inches vertically above the top of the insulation. Dams are required to prevent blown insulation from blocking the soffit vent. Georgia has created diagrams to demonstrate these details. See Appendix A of Georgia’s Supplements and Amendments.
For attics that house HVAC systems, Georgia has amended the code so that builders do not have to use REScheck to conduct a trade-off analysis for slightly lower levels of insulation under HVAC attic platforms. In the new Georgia energy code, R-19 is acceptable under HVAC attic platforms (32 square feet per HVAC system plus a 32-inch walkway).
The energy code specifies the use of R-8 insulation for ductwork in the attic and R-6 insulation for ductwork in a home’s other unconditioned spaces (e.g., crawlspace). The energy code does not contain any insulation requirements for ductwork located within the building thermal envelope.
The Georgia energy code specifies that all ductwork must be sealed with mastic. Silver, UL181 tape may be used to assemble ductwork but may not be used as the primary sealant (mastic is required on top of the tape). All new duct systems must also pass a duct tightness test. For more information on this test, see the DET FAQ.
The prescriptive code requires R-30 insulation in your roofline, but a builder can use REScheck to conduct a simple trade-off analysis. The Georgia energy code does not allow for trade-offs in insulation levels below a certain point. For example, if a roofline is insulated with spray-foam (air-impermeable insulation), it must be at least R-19. If a building is insulated with fiberglass batts or cellulose (air-permeable insulation), it must also be at least R-19, plus R-5 in Climate Zones 2 and 3, or plus R-15 in Climate Zone 4 rigid foam board insulation (air-impermeable) above or below the roof decking to prevent condensation. For more information, see the 2010 Georgia Amendment to Section 806.4of the 2006 International Residential Code, “Unvented attic assemblies.” Georgia has also created diagrams to demonstrate these details. See Appendix A of Georgia’s Supplements and Amendments.
18. Do I have to install R-30 in underfloor insulation over a garage or crawlspace?
No. Prescriptively, floors over unconditioned interior spaces must be R-19 in Climate Zones 3 and 4, or R-13 in Climate Zone 2. However, insulation in cantilevered floors over outside air must be R-30 to meet the prescriptive code. In addition, the band area above an exterior wall must be blocked. All underfloor insulation must be installed to maintain permanent contact with the underside of the decking.
Section 402.4.3 requires that new wood-burning fireplaces have gasketed doors and outdoor combustion air. Although the final decision rests with the code official, this requirement has been interpreted to only apply to masonry-built, wood-burning fireplaces and not factory-built, wood-burning fireplaces, as installing gaskets would violate the UL rating on the factory built fireplace. For more information, see the clarification on this provision from the International Codes Council.
The code prohibits the use of a new or replacement electric furnace as a home’s primary heating system. Standard grid-connected power attic ventilators are also prohibited.
21. How do I air-seal a home so that it meets the code’s mandatory air sealing requirements?
Georgia has created an air sealing and insulation guide that details the measures needed to meet the new code’s mandatory air sealing requirements. The guide is located in Appendix A of Georgia’s Supplements and Amendments.
22. What is the difference between a mass wall and a basement wall, and what are the insulation requirements for both?
A mass wall is a heavy wall that is more than half above grade wall and is constructed of a fairly massive material (e.g., concrete, block, insulated concrete forms, masonry cavity, non-veneered brick , adobe, compressed block, rammed earth, and solid logs). A basement wall is a wall that is more than half below grade and encloses conditioned space. Insulation requirements for basement walls and mass walls depend on the location of the insulation and the type of insulation (whether it is continuous or insulation installed in a cavity). Requirements also vary by climate zone. Below is a table detailing the insulation requirements in the energy code.
||Insulation Location and Type||Climate Zone 4||Climate Zone 3||Climate Zone 2|
||Interior - Continuous||R-10||R-5||R-0|
|Basement Wall||Interior - Cavity||R-13||R-13||R-13|
|Mass Wall||Exterior or Integral- Continuous||R-5||R-5||R-4|
||Interior - Continuous||R-10||R-8||R-6|
Encapsulating a crawlspace (closing vents, insulating the walls and installing a vapor retarder on the floor) is a great way not only to save homeowners money on insulation costs but also to improve the comfort of a home through improved humidity control. The energy code and IRC both have provisions for encapsulating a crawlspace.
The energy code requires the installation of a Class I vapor retarder on the floor of the crawlspace, that is sealed and overlaps 6 inches at any seams and extends 6 inches up the stem wall. The energy code also requires that one insulate the walls of the crawlspace to certain levels (R-10 in Climate Zone 4, R-5 in Climate Zone 3 or R-0 in Climate Zone 2). A 3-inch inspection strip at the top of the crawlspace wall is required for termite inspections.
To properly encapsulate a crawlspace, one must remove all crawlspace vents and other leaks into the crawlspace from unconditioned spaces. To remove all vents, the builder must satisfy an IRC exception to vent provisions (2006 IRC section R408.3), which allows for installing a continuous exhaust (e.g., via radon vent), provides ducted supply air or offers another mechanism for directly conditioning the air (e.g., with a dehumidifier).
Certain crawlspaces are not candidates for encapsulation. These are crawlspaces with drainage problems, combustion safety issues or pest control issues. For more information about encapsulating a crawlspace, visit www.crawlspaces.org.
Technically, the energy code does not require that windows be tested using the National Fenestration Rating Council (NFRC) procedures. However, if the window is not NFRC-rated, builders must use Tables 302.1.3 in the 2009 IECC to assign a default SHGC and U-Factor. Because none of the windows in the default table meet the requirements of the prescriptive energy code, one must use the 15-square-foot exemption in the code for non-compliant windows (e.g., decorative windows) if following the prescriptive approach.
25. How do I insulate and air-seal an attic kneewall according to the requirements of the energy code?
The energy code requires that the attic kneewall be air-sealed and insulated to R-18. A builder can use three different methods to meet the insulation requirement for attic kneewalls:
- Install R-13 cavity insulation with R-5 insulated sheathing.
- Install R-15 cavity insulation with R-3 insulated sheathing.
- Install R-19 compressed into a 2 × 6 cavity.
The attic side of the knee wall must also have a sealed air-barrier. For detailed graphics showing where one must air-seal, see Appendix A of Georgia’s Supplements and Amendments.
26. Where can I get a copy of RESchecK?
REScheck is a free software tool that can be downloaded from the Department of Energy’s website at: www.energycodes.gov
27. Where can I get a copy of the mandatory compliance certificate?
An electronically fillable version of the mandatory compliance certificate is posted on Southface’s website. To view and save the form, you will need Adobe Reader, which can be downloaded for free at www.adobe.com.
28. When do I have to install a programmable thermostat?
The new energy code requires a programmable thermostat to operate a furnace. If installing a heat pump, a smart thermostat or lockout feature is necessary to prevent unnecessary strip heat from being activated.
When installing an HVAC system, one must size it according to the mechanical section of the IRC, which requires the use of ACCA Manual J or approved equivalent, i.e., ASHRAE Fundamentals.
A minimum of 50 percent of bulbs in permanent fixtures must be high-efficacy ,or be controlled by occupancy or vacancy sensors. The energy code considers compact fluorescents, T8 or T5 fluorescents, and most LED as high-efficacy. Incandescent, halogen and T12 fluorescent bulbs are not considered high-efficacy. Lights may also meet certain lumen/W requirements (e.g., efficient LEDs) listed in the energy code.
Interested in Learning More?
Southface offers the following energy code training classes:
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