Meeting Stricter Air-Infiltration Standards in Your Commercial Building
As the search for greater energy efficiency in construction processes continues, industry standards change and evolve to reflect this increased attention on boosting efficiency and trimming energy loss wherever possible. With the publication of the 2012 International Energy Conservation Code (IECC), standards for energy conservation in commercial buildings have been tightened. In particular, the new IECC code provides stricter air-infiltration standards that require construction professionals to determine the amount of air infiltration in the commercial facilities they design, build and maintain.
What Is Air Infiltration?
Air infiltration occurs when outside air enters a building through openings in the building’s seal or envelope. These openings can include normal doors and windows, but more often are smaller, difficult-to-locate gaps, cracks or other openings in the building’s structure. They can include openings around door and window frames, cracks in the building frame, and gaps between foundation and floor. At the same time, conditioned air can leak out of these same openings. Air infiltration causes significant loss of energy, increases stress on building HVAC systems, and drives utility expenses much higher than necessary.
Testing Required by Air-Infiltration Standards
The most common testing method for determining air infiltration is an infiltrometer test, often called a blower door test. This test is usually conducted as part of an overall commercial energy audit that helps locate areas where building energy efficiency can be improved. In smaller commercial buildings and residences, this testing is accomplished using one or more large, powerful fans mounted in a door leading to the outside of the building. When the fan is activated, it reduces the pressure level inside the structure. When this happens, outside air is pulled into the building through any holes, gaps, cracks or other openings.
Airflow in and out of the building can then be measured using a manometer. Subtle or hidden air leaks can be located using other equipment, such as a smoke pencil that produces a thin stream of smoke that moves in the presence of an air leak. In larger commercial structures or multi-story buildings, a high-capacity testing apparatus or more than one fan may be needed to conduct an effective infiltrometer test. When a test is successfully completed and the locations of air infiltration and loss have been identified, air-infiltration standards can be met by sealing those areas where air leaks occur.
Methods of Compliance With IECC Air-Infiltration Standards
The IECC standard creates a new requirement for architects, engineers and other construction professionals to know and respond to the amount of air infiltration in their buildings. It provides for two effective methods of compliance.
ASTM Standard E779-10: This standard, titled Standard Test Method for Determining Air Leakage Rate by Fan Pressurization, sets out the requirements for infiltrometer testing and test interpretation. It requires that buildings meet strict air-infiltration standards of no more than 0.4 cubic feet per minute (cfm) of air infiltration per square foot of floor space at 0.3 in wc (75 Pa).
U.S. Army Corps of Engineers Standard: The USACE standard has even stricter requirements, permitting only 0.25 cfm of air infiltration per square foot at the same pressure difference of 0.3 in. wc (75 Pa). Of the two standards, the USACE standard will produce a much more energy-efficient building that loses less energy and costs less to heat and cool.
Compliance with the USACE air-infiltration standard may be more expensive and time-consuming initially, but the long-term savings in energy costs can more than make up for the initial investment. For example, the ASTM standard can provide for ongoing energy savings of 30 percent or more. Applying the USACE standard can increase savings by as much as an additional 15 percent.
Our goal is to help educate our customers about Plumbing, HVACR, Fire Protection, and Alarm Systems in Mechanical, Commercial and Residential settings. For more information about new air-infiltration standards and what can be done to meet them, as well as to view projects we’ve worked on, visit our website!