Step 6. Construct the Building to Meet Plans and Specifications
Once the building is designed, it is the role of the construction team to assemble the building.
The building must comply with the building energy code, not just on paper but in practice. It is critical that each person involved in the construction of the building be aware of the requirements and the importance of not deviating from the approved plans and specifications.
DOE's Commercial Buildings for Architects Resource Guide (Resource 1) points out that "all current model codes and standards include a provision for installing materials and products per the manufacturers' instructions. In this case, energy code compliance is not ensured through plans and specifications, but by making sure that materials and products are properly installed. Designers can reinforce this by specifying that construction must meet manufacturers' installation instructions and applicable quality assurance criteria, and by having the client retain them during construction to verify that their design and specifications are properly implemented." These statements, while written for commercial architects, are equally appropriate for residential designers.
Issues in this step typically revolve around quality of the workmanship and the subcontractors being aware of the energy code requirements and how to handle them properly.
Installation issues seem to be problematic according to information from the enforcement community. Air leakage is another specific issue that is closely related to installation issues.
Areas to pay particular attention include the installation of insulation, air barriers, and ducts. Helpful resources addressing these specific areas are referenced below.
The recommended amount of insulation depends on the building design, climate zone, price of energy, and the cost of materials and labor. There are many insulation options that will meet the requirements of the energy codes. Regardless of the type of insulation chosen, it is critical that the insulation be properly installed in order for the full effectiveness to be realized. Even small gaps and compressed areas can reduce insulating levels significantly. For example, compressing fiberglass insulation reduces its effectiveness and does not achieve the full R-value.
RESNET has set an industry standard for insulation installation. Although this standard is not required specifically in the energy codes, it is good practice and is referenced in "ENERGY STAR for Homes Version 3" (Resource 2). RESNET assigns insulation grades based on gaps and compression or incompletely filled areas. Grade I allows for "occasional very small gaps and up to 2% of the insulated area can have compression or incomplete fill." For more information, visit RESNET (Resource 3).
DOE's Building Technologies Office (BTO) and Building America Program have several resources related to the proper installation of insulation in residential buildings. These resources do not cover the code requirements specifically but offer best-practice suggestions:
- BTO's "Wall Insulation, Provide Moisture Control and Insulation in Wall Systems" fact sheet describes effective wall insulation and the various insulation types (Resource 4).
- DOE's Office of Energy Efficiency and Renewable Energy offers an insulation fact sheet focused on homes and discusses why homes should be insulated and how insulation works (Resource 5).
- A Building America Partner, Building Science Corporation, has an information sheet, "Installation of Cavity Insulation for All Climates," which covers the installation techniques important to achieving the effective performance of cavity insulation (Resource 6).
- Another Building Science Corporation information sheet, "Slab Edge Insulation for All Climates," covers slab-edge insulation (Resource 7).
- An article in Home Energy, "Insulation Inspections for Home Energy Ratings: Assessing insulation gaps, compression, and incomplete fill provides a way to measure installation effectiveness," provides additional information in quality insulation installation (Resource 8).
- Southface Energy Institute's energy technical bulletins may also be of interest, which cover topics such as wall insulation, ceiling and attic insulation and ventilation, and insulating foundations and floors (Resource 9).
The IECC defines an air barrier as "material(s) assembled and joined together to provide a barrier to air leakage through the building envelope. An air barrier may be a single material or a combination of materials." DOE's Building America Program has several resources related to the proper installation of air barriers. These resources do not cover the code requirements specifically but offer best-practice suggestions.
- Building Science Corporation has several valuable information sheets such as "Air Barriers—Airtight Drywall Approach for All Climates," "Sealing Air Barrier Penetrations for All Climates," and "Air Barriers—Tub, Shower and Fireplace Enclosures for All Climates" (Resource 10).
- Another Building America Partner, Consortium for Advanced Residential Buildings, offers details on the garage band joist air barrier (Resource 11).
- The Air Barrier Association of America develops specifications that provide guidance on air barriers to design professionals (Resource 12).
The 2009 and 2012 IECC both require leakage testing of ducts in residential buildings that have any ducts that pass outside of the conditioned space (e.g., has ducts in unconditioned attics, basements, or crawlspaces). The leakage rate cannot exceed a specified limit. Southface has videos on topics including blower door testing and duct leakage testing (Resource 13). Southface also offers energy fact sheets, including "Blower Door and Duct Blaster Testing" and "Blower Door and Duct Blaster Testing for Duct & Envelope Tightness Verification" (Resource 14).
The 2012 IECC requires testing of air leakage through the building envelope. The leakage rate cannot exceed a specified limit. DOE's Meeting the Air Leakage Requirements of the 2012 IECC Resource Guide was prepared primarily for use by residential builders and contractors. The air leakage requirements in residential codes are more detailed than those found in commercial codes because residential buildings tend to be smaller in size, simpler and easier to air seal, and easier to test than commercial buildings.
- Commercial Buildings for Architects Resource Guide
- ENERGY STAR for Homes Version 3
- BTO's Wall Insulation, Provide Moisture Control and Insulation in Wall Systems Fact Sheet
- DOE's Insulation Fact Sheet
- Building Science Corporation's Installation of Cavity Insulation for All Climates Information Sheet
- Building Science Corporation Slab Edge Insulation for All Climates Information Sheet
- Insulation Inspections for Home Energy Ratings: Assessing insulation gaps, compression, and incomplete fill provides a way to measure installation effectiveness (Article in Home Energy)
- Southface Energy Institute's Energy Technical Bulletins:
- Building Science Corporation's Information Sheets:
- Consortium for Advanced Residential Buildings High Performance Building Details: Garage Band Joist Air Barrier
- Air Barrier Association of America specifications
- Southface Videos:
- Southface Fact Sheets:
- DOE's Air Leakage Resource Guide
- Southface Energy Technical Bulletin: Airsealing (residential)
- Northwest Energy Technical Bulletin: Airsealing (Residential)