ENERGY STAR PERFORMANCE GUIDELINES OVERVIEW
ENERGY STAR Qualified Homes Page No. Certification Process 4 National Performance Path Requirements and Notes 5 Builder Option Package (BOP) and Notes 7 Thermal Bypass Inspection Checklist 10 Thermal Bypass Guide 12 ENERGY STAR Performance Requirements 21 ENERGY STAR Manual J Load Calculation Requirements 23
ENERGY STAR QUALIFIED HOMES ENERGY STAR homes use a number of innovative technologies, such as climate-appropriate insulation, high-performance windows, airtight envelope and ducts, efficient heating and cooling equipment, plus on-site inspections and testing to verify compliance. ENERGY STAR NATIONAL REQUIREMENTS To qualify as ENERGY STAR, a home must meet the minimum requirements specified below, be verified and field tested in accordance with the RESNET (Residential Energy Services Network) standards by a RESNET accredited provider, and meet all applicable state building codes. I. Homeowners/builders may choose one of two ways to qualify their home as an ENERGY STAR energy-efficient home. A traditional Home Energy Rating A Home Energy Rater simulates the home s energy use; this analysis allows the rater to identify the most effective upgrades to meet Energy Star performance guidelines. The Builder Option package The builder and rater use a set of climate-specific construction specifications that result in homes consistently meeting ENERGY STAR guidelines. II. The Thermal Bypass Inspection Checklist must be completed for homes to earn the ENERGY STAR label. The checklist requires visual inspection of framing areas where air barriers are commonly missed and inspection of insulation to ensure proper alignment with air barriers (air and thermal barriers must be continuous and complete). III. Completion of Field Verification. In addition to the Thermal Bypass Inspection Checklist, the Home Energy Rater must conduct on-site pressure testing of the home. The rater will check for proper equipment size, air sealing, insulation and air distribution and will pressure test the duct system if not located within conditioned space. The final inspection will be after the HVAC system start-up, with permanent electrical power, and with the home totally enclosed. The rater will perform a blower door test to verify the home s airtightness.
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I.0 THERMAL BYPASS GsUIDE general tips and best practices 1.1 Overall air barrier and thermal alignment Fiberglass batts shall be face-stapled to the studs. Fibrous batt insulation should not be cut short or cut long and forced/compressed into small areas. To minimize compression, fibrous batts shall be cut around electrical boxes and split around plumbing and wiring. Wet spray cellulose shall be cropped smoothly to prevent convective channels and void cavities between the insulation and sheetrock. 1.2 Gap between garage and conditioned space due to incomplete blocking Creating air barriers to close gaps between the garage and the conditioned space can become increasingly difficult to construct as the joists become more irregular at their cross section. This is particularly true for I-joists and web-trusses. A simple solution is to plan ahead and align the end of joists with the wall adjoining the conditioned space to allow for end blocking. Filler blocking much Filler simpler blocking shape with much simpler dimensional shape lumber. with dimensional lumber Filler blocking much Filler harder blocking shape with much harder Engineered shape lumber. with Engineered lumber
1.3 Attic eave baffles Wind intrusion can occur at roof eaves through soffit vents. If the attic insulation is left exposed, the wind blowing through the soffit can flow through the insulation and in some cases blow it away from the edge. As a result, wind intrusion can undermine the effectiveness of the insulation and create opportunities for moisture problems. Blown insulation Energy Truss Soffit dam use batt or rigid foam board Rafter baffle Batt insulation Raised Top Plate Additional top plate Rafter baffle Sheathing Soffit vent Soffit vent 1.4 Slab edge insulation There are two basic ways to insulate a slab. First, rigid insulation can be installed directly against the exterior of the slab, as shown in the detail at left. Note that in areas with high termite populations, builders should be careful to avoid installing foam insulation in contact with the ground. A second option is a floating slab, which can be constructed using interior insulation, as shown in the detail at right. In both cases, insulation should be continuously aligned with the air barrier. R i g i d i n s u l a t i o n e n c a p s u l a t e d o r c o v e r e d w i t h m e m b r a n e t o p r o t e c t f r o m t e r m i t e s a n d e x t e r i o r d a m a g e. Metal termite flashing Sill gasket 1.5 Critical rim / band joist closure areas Perforated drainage pipe is embedded in gravel, covered with filter fabric, and located at lower perimeter of foundation footing to provide drainage. Gravel base 10-mil poly vapor diffusion retarder is extented under footing. Metal termite flashing Sill gasket Rigid insulation Perforated drainage pipe is embedded in gravel, covered with filter fabric, and located at lower perimeter of foundation footing to provide drainage. 10-mil poly vapor diffusion retarder Fiberglass insulation alone is not enough to stop air from leaking through the rim / band joist. Foam or foam board fixed tightly and sealed at the edges will stop air leakage. Gravel base Caulk bottom plate to subfloor Caulk band joist to subfloor and plates and insulate Caulk bottom plate to subfloor Sill gasket or double-bead of caulk 12 13
1.6 Minimize thermal bridging The intersecting corner of two insulated walls shall be framed such that insulation is continuous in the external wall (corners with unnecessary 2x4 s are not permitted). A California corner or two-stud corner with drywall clips are methods of achieving this. Advanced corner Advanced corner Advanced aldder T-wall framing Advanced ladder T-wall framing Drywall and interior walls are attached to Drywall clip to hold "ladder," which spans drywall in place between studs. 2.0 Walls Adjoining Exterior Walls or Unconditioned Spaces 2.1 Wall behind shower / tub 2.2 Wall behind fireplace Insulate and air seal behind tub with sealed polyethylene plastic or sheet material. All exterior walls of fireplaces shall be sealed with proper sealant and, where permissible, a proper sealant shall be used at the junction between sheathing and flue pipe and comply with the fire code and the manufacturer s specification. Seal Exterior wall Seal Seal Seal tub penetration.
2.3 Insulated attic slopes / walls 2.4 Attic knee walls - 19 R-value Attic living space Seal Hardboard Knee wall Attic ventilation Rigid board insulation seals and adds R-value ; extend to bottom of joists, ; caulk and tape to form air seal. Knee wall Seal Desired ventilation Attic space Attic Living Space Seal outlet box to drywall. Seal all edges of rigid foam insulation. Seal outlet box to drywall Loose-fill or batt insulation Attic ventilation Roof Unwanted air leakage Attic ventilation Soffit vent 2.5 Skylight shaft walls - 19 R-value Skylight shafts protruding through the ceiling and an unconditioned space need to be insulated since the shaft s walls are effectively attic knee walls adjoining an unconditioned space. Skylight shaft walls shall be insulated to the same level as attic knee walls and shall include a sealed air-barrier aligned with the insulation on both interior and exterior sides of the walls Air Barrier Skylight Attic Air Barrier Insulation 14 15
2.6 Wall adjoining porch roof To complete an air barrier at porch roofs, install blocking or another solid, sealed air barrier between the porch roof and conditioned space of the home. DO NOT HAVE PHOTO TO INSERT Eyebrow roofs and porches, if built wrong (left), can allow cold air to penetrate exterior walls. 2.7 Staircase walls An air barrier is needed at staircases where they come in contact with the exterior wall or attic above and below the stairs. This involves sealing any gaps with caulk or foam, and providing a complete air barrier assembly. Tape & joint compound seal Structural sheathing extend above & below stringer to allow taping with joint compound
2.8 Double walls Double walls are becoming common in some markets to provide a more dimensional architectural appearance. The insulation must be aligned with and enclosed by air barriers on all sides. Interior air barrier Interior wall with insulation Exterior boundary The interior wall with exterior air barrier Interior air barrier Exterior air barrier Double wall area filled with insulation 3.0 Floors Between Conditioned and Unconditioned Spaces An air barrier is installed at any exposed insulated edges. Insulation is installed to maintain permanent contact with sub-floor above including necessary supports (e.g., staves for blankets, netting for blown-in). Blanket insulation is verified to have no gaps, voids, or compression. Blown-in insulation is verified to have proper density with firm packing. 3.1 Insulated floor above garage Floors constructed of dimensional lumber can be easier to block, insulate and seal than those constructed with engineered framing members. With dimensional lumber, only the two open ends of the joist cavities need to be blocked and air sealed. Floor assemblies constructed with open web trusses can be very difficult to effectively block, insulate, and air seal. In particular, open web areas are labor-intensive to fill with batt or rigid insulation but can easily be filled with blown or spray insulation. All four edges of an open-web truss floor assembly require the installation of a sheathing material to enclose the entire floor cavity and then all joints and penetrations need to be air sealed. Subfloor The installation of sheathing material on all four edges to enclose the floor assembly. Air seal All joints in the sheathing material must be air sealed. The sheathing must be air sealed to the subfloor and also to the drywall on the bottom. Drywall ceiling Diagram courtesy of McGrann Associates, Inc. 16 17
3.2 Cantilevered floor 4.0 Shafts Openings to unconditioned space must be fully sealed with solid blocking or flashing. 4.1, 4.2 Duct shaft & pipe penetrations 4.3 Flue shaft Seal and insulate dropped soffit Seal chases Caulk electrical boxes and fixtures to drywall Seal HVAC penetrations Seal electrical penetrations Seal bottom plate Seal plumbing penetrations Seal HVAC penetrations
5.0 Attic / Ceiling Interface - 19 R-Value 5.1 Attic access panel 5.2 Attic drop-down stair (with full gasket and insulated) (with full gasket and insulated) Insulation dams prevent loose-fill insulation from falling through access Hatch lid pushes up and out of the way for access.. Cover Raised box frame pushes provides up and insulation out of blocking the way. for access Rigid insulation box forms lid for pull-down attic staircase ; Lid swings up firmly attach insulation. Build up staircase frame and hinge rigid top and attach insulation Air seal. gasket Air seal gasket Scuttle hole cover Air seal gasket Weatherstripping Panel Pull-down attic Panel staircase Pull-down attic staircase ; Seal stairs frame gap with caulk or foam Seal stairs frame. gap with caulk or foam 5.3 Dropped ceiling / soffit (full air barrier aligned with insulation when soffit adjoins exterior walls) DO NOT HAVE DIAGRAM TO INSERT 5.4 Recessed lighting fixtures (icat labeled and sealed to drywall) Fixture tested for air leakage Tight housing Label Some have gaskets.. 18 19
5.5 Whole-house fan (insulated cover with gasket) Whole house fan Whole house 6.0 Common Walls Between Dwelling Units A solution to thermal bypass at common walls is to air seal the gaps between the drywall and framed common walls using expanding foam (if allowed by code) or fire rated blocking or caulk. A i r s e a l h e r e F r a m e d w a l l D r y w a l l Air seal here
ENERGY STAR PERFORMANCE REQUIREMENTS Cooling equipment shall be sized according to the latest editions of ACCA Manuals J and S, ASHRAE 2001 Handbook of Fundamentals, or an equivalent procedure. Maximum over-sizing limit for air conditioners and heat pumps is 15%. Duct seams and air handler sealed with mastic All transverse seams in supply and return ducts, including supply and return plenums and leakage sites in the air handler, shall be sealed with duct mastic and fibrous reinforcing mesh according to SMACNA specifications. Duct tape is not a suitable sealant for ducts but may be used for sealing leakage sites at the air handler s removable access panels and at filter access panels. All supply duct take-offs spaced 6 inches apart All supply duct take-offs shall be spaced at least 6 inches apart from each other with no duct take-offs originating from the cap of the supply plenum. Junction boxes with 4 take-offs or less are excluded. Allow 6" clearance on all sides and between duct take-offs from plenum Seal all joints and seams in air handler and ductwork with mastic or mastic tape Seal collars to plenum with mastic or mastic tape Use removeable tape for filter door Flex duct properly installed Correctly supported flex duct 5' maximum Sag ½" per foot of support spacing Sag ½" per foot of support spacing Smooth turns no sharp angles Correct: Correctly supported flex flex duct duct installed with enough material, to create Correct: smooth turns with proper angles flex duct installed with enough material, to create smooth turns with proper angles 5' maximum Mastic or mastic tape Mastic or mastic tape Incorrectly supported flex duct Incorrectly Incorrect: supported flex duct installed with extra material, creating Incorrect: bunched flex duct turns with pinched angles flex duct installed with extra material, creating bunched turns with pinched angles Always seal with mastic or mastic tape. Always seal with mastic or mastic tape 20 21
Ceiling boot air sealing Floor boot air sealing SCANNED BUT NOT DROPPED Sealing return plenum All air handlers shall be installed with a ducted return plenum sealed to the unit and any associated ducts with mastic or mastic tape. No supply or return ducts,boots or registers shall be located in exterior walls..
ENERGY STAR MANUAL J Load Calculation Requirements ENERGY STAR standards require that a load calculation be performed on every home in accordance with the latest version of ACCA Manual J (currently version 8). ENERGY STAR requires that the following inputs be used for the Manual J: Maximum allowable duct leakage is 6 cfm to outdoors / 100 sq. ft.(6%) of conditioned floor area if certified by Performance Path (HERS Rating) or 4 cfm to outdoors / 100 sq. ft.(4%) of conditioned floor area if certified by Builder Option Package (BOP). If software allows for grades of duct tightness, choose tight or the equivalent term. Outdoor temperatures shall be the 99.0% design temperatures as published in the ASHRAE Handbook of Fundamentals for the home s location or most representative city for which design temperature data are available. House infiltration shall be based on (0.5 CFM50/SFBE) or shall use the software choice of tight or the equivalent term. Must use actual house orientation and location. Must use actual window, insulation and door specifications. Indoor temperatures shall be 75 F for cooling and 70 F for heating. The results of the Manual J must be used when sizing and installing equipment. ENERGY STAR requires the following sizing guidelines: Maximum over sizing limit for air conditioners and heat pumps is 15%. In specifying equipment, the next available size may be used. The indoor and outdoor coils shall be matched in accordance with ARI standards. Provide the ARI Certificate of ARI-Certified Performance (from www.aridirectory.org) or manufacturer s performance data to the Home Energy Rater. Builders must submit the completed Manual J documentation to Rappahannock Electric Cooperative. Documentation must show that all above requirements have been met. Resources Air Conditioning Contractors of America Insulation Contractors Assoc. of America 2800 Shirlington Rd, Suite 300 (ICAA) Arlington, VA 22206 1321 Duke St, Suite 303 Ph (703) 575-4977 Alexandria, VA 22314 Ph (703) 739-0356 Alliance to Save Energy National Rural Electric Cooperative Association (NRECA) 1850 M. Street, NW, Suite 600 4301 Wilson Boulevard Washington, DC 20036 Arlington, VA 22203 Ph (202) 857-0666 Ph (703) 907-5699 Earth Craft Virginia Residential Energy Services Network (RESNE) 1840 W. Braod St., Suite 200 PO Box 4561 Richmond, VA. 23220 Oceanside, CA 92052 Ph (804) 225-9843 Ph (760) 806-3448 Energy Efficient Building Association U.S. Environmental Protection Agency 10740 Lyndale Ave., South, 10W 1200 Pennsylvania Ave., NW Bloomington, MN 55420 Washington, DC 24060 Ph (952) 881-1098 Ph (202) 564-2300 22 23
REC s ENERGY STAR NEW HOME PROGRAM This panel to be dropped in from existing files. A service of: P.O. Box 7388 Fredericksburg, VA 22404 540.898.8500 800.851.3275