Leaking Money

Since 2001, states around the country have been implementing regulatory energy codes that require buildings to be built airtight. More recently, the U.S. Army Corps of Engineers (USACE) has been a leading agency in requiring that all new and remodeled, conditioned buildings not only be built with a required air tightness, but be field-tested to ensure that a sufficient air tightness was achieved. It has been shown that reducing air leakage from a building can result in up to 35 percent heat energy cost savings, according to the National Institute of Standards and Technology.

For this reason, a correctly installed air barrier and subsequent whole building air leakage test is an important tool in creating energy efficient buildings with lower energy costs. The air barrier is a continuous membrane that covers the entirety of the exterior portions of the building, controlling any unintended movement of air into and out of the building, as defined by the Air Barrier Association of America.

Why Should You Test

The USACE, The International Energy Conservation Code and multiple state agencies require testing to quantitatively measure the air tightness of building envelopes. An improperly installed air barrier is a leading source of moisture and condensation, mold spores, odors, sound and energy losses due to uncontrolled air leakage.

The whole building air leakage test is useful in determining whether the air barrier was applied properly to ensure building tightness. Additionally, the air leakage test will allow an accurate estimate of the total energy savings or losses over a given time period. This test also is beneficial before a renovation or retrofit to determine whether an air barrier is a cost-effective addition.

How To Test

The standard for a building air leakage test is specified by the American Society for Testing and Materials to measure air leakage rates through building envelopes under controlled negative (de-pressurization) or positive (pressurization) pressures. Pressurization or de-pressurization of the building is achieved by using orifice blower doors capable of generating a constant airflow at incremental pressure differences. The resulting airflows through the blower door fans and the induced pressure difference between inside and outside demonstrate the air leakage rate of the building envelope and how effective the air barrier installation is.

In coordination with the air leakage test, Infrared Thermography Testing is used as a useful tool in locating potential air leakage locations. It is important that a certified thermography technician identify areas of energy difference, as apparent temperature differences can be caused by changes in materials and other factors that may seem like air tightness and temperature issues, but are just variations in the camera reading. Other methods such as smoke testing can be used to identify air leakage locations.

Calculating Energy Costs

The air leakage test of a building will provide the data necessary to determine the total area of potential openings in the air barrier. The factors to determine the air leakage rate through those openings include: the temperature and pressure differences between inside and outside the building, wind pressure caused by the wind velocity, variations in building height – which causes thermal buoyancy of the air – and other factors.

Once the air leakage rate through the air barrier is determined, the actual costs of energy loss can be calculated based on the amount of energy needed to heat and cool the leaked air and the prevailing gas and electricity costs. Many building owners, including the USACE, require that if a building does not pass the air tightness requirements, the contractor could be made to pay up to 30 years worth of energy costs, due to the uncontrolled air leakage.

In addition to the benefits seen from optimizing energy savings and reduced energy use, a project can earn up to three to five additional LEED points, with LEED’s Energy and Atmosphere credit towards earning a preferred LEED status. These benefits can save money and create revenue in a variety of ways that affect one thing – the bottom line.

With the advancement of green technology and incentives for its use, such as tax deductions and utility credits, the cost-to-benefit ratio to implement energy saving processes and behaviors is much more attractive. In addition, the marketing benefits to customers and shareholders that are created from being recognized as “green” or environmentally friendly is becoming more and more important in the global economy.

Air leakage in buildings also is a major contributor to increased energy costs to condition buildings. Air leakage also can carry mold spores, odors, sound and other “sick building” components. Based on the energy costs alone, a well-constructed air barrier is an economical way to increase the energy efficiency of buildings. The state and national building standards are moving towards requiring that all new and retrofitted buildings be quantitatively tested for air tightness.

An air leakage test of a newly constructed or renovated building will enable contractors and property owners to determine the effectiveness of their building’s air barrier. From this, an accurate estimate of energy losses from an incorrectly installed air barrier can be determined, or a building owner can determine if it is cost effective to install an air barrier prior to a renovation or retrofit.

Joshua Haar, EIT; Adam Haroz, EIT; and Karen Haroz, LEED AP are with Conversion Technology Inc. They can be reached at 770-263-6330, or jhaar@conversiontechnology.com, aharoz@conversiontechnology.com, and kharoz@conversiontechnology.com. For more information, visit http://www.airleakagetest.net.

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