WHOLE BUILDING AIR LEAKAGE TESTING
CODE COMPLIANCE AND ENERGY SAVINGS
Recent editions of the International Energy Conservation Code that are referenced and adopted by local jurisdictions, now require whole building air leakage testing as outlined below:
C402.5 Air Leakage - Thermal Envelope
The building thermal envelope shall comply with Sections C402.5.1 through Section C402.5.11.1, or the building thermal envelope shall be tested in accordance with Section C402.5.2 or C402.5.3.
However, both compliance paths contain Sections C402.5.2 and C402.5.3. As such, one of the following testing protocols must be performed.
C402.5.3 Building Thermal Envelope Testing
The building thermal envelope shall be tested in accordance with ASTM E779, ANSI/RESNET/ICC 380, ASTM E3158 or ASTM E1827 or an equivalent method approved by the code official. The measured air leakage shall not exceed 0.40 cfm/sq.ft. of the building thermal envelope area at a pressure differential of 0.3-inch water gauge (75 Pa). Alternatively, portions of the building shall be tested, and the measured air leakages shall be area-weighted by the surface areas of the building envelope in each portion. The weighted average test results shall not exceed the whole building leakage limit. In the alternative approach, the following portions of the building shall be tested:
1. The entire envelope area of all stories that have any spaces directly under a roof.
2. The entire envelope area of all stories that have a building entrance, exposed floor, or loading dock, or are below grade.
3. Representative above-grade sections of the building totaling at least 25 percent of the wall area enclosing the remaining conditioned space.
Exception: Where the measured air leakage rate exceeds 0.40 cfm/sq.ft. but does not exceed 0.60 cfm/sq.ft., a diagnostic evaluation using smoke tracer or infrared imaging shall be conducted while the building is pressurized along with a visual inspection of the air barrier. Any leaks noted shall be sealed where such sealing can be made without destruction of existing building components. An additional report identifying the corrective actions taken to seal leaks shall be submitted to the code official and the building owner and shall be deemed to comply with the requirements of this section
For multi-family and hotel construction, the code will also allow the following testing:
C402.5.2 Dwelling and Sleeping Unit Enclosure Testing
The building thermal envelope shall be tested in accordance with ASTM E779, ANSI/RESNET/ICC 380, ASTM E1827 or an equivalent method approved by the code official. The measured air leakage shall not exceed 0.30 cfm/sq.ft. of the testing unit enclosure area at a pressure differential of 0.2-inch water gauge (50 Pa). Where multiple dwelling units or sleeping units or other occupiable conditioned spaces are contained within one building thermal envelope, each unit shall be considered an individual testing unit, and the building air leakage shall be the weighted average of all testing unit results, weighted by each testing unit's enclosure area. Units shall be tested separately with an unguarded blower door test as follows:
Where buildings have fewer than eight testing units, each testing unit shall be tested.
For buildings with eight or more testing units, the greater of seven units or 20 percent of the testing units in the building shall be tested, including a top floor unit, a ground floor unit, and a unit with the largest testing unit enclosure area. For each tested unit that exceeds the maximum air leakage rate, an additional two units shall be tested, including a mixture of testing unit types and locations.
What is Whole Building Air Leakage Testing?
Now that whole building air leakage, or blower door, testing is mandated per the building code, what exactly is it? In order for air to flow, a pressure differential is necessary to move air from a higher, or positive, air pressure to a lower, or negative, air pressure. Therefore, this test produces both pressurization and depressurization using a fan, or blower, that is sealed within a building enclosure penetration, such as a door or window. Once the requisite pressure with regards to the exterior is maintained across the building enclosure, an air flow meter is used to calculate the amount of air flow, or leakage, through the building enclosure. The air leakage rate across a building enclosure is critical to performance, as higher air leakage rates can result in interstitial condensation and microbial growth, drafts that affect thermal comfort, significant increases in energy costs, and can tax the HVAC equipment of the home due to increased demand.
Why Blower Door Testing?
- Reduce Condensation Issues: Condensation development is typically associated with air leakage. Reducing the flow of exterior air into conditioned space and/or interior conditioned air out to the environment can significantly reduce the risk for condensation.
- Increase Thermal Comfort: Ever felt a chill from a drafty window? Northern climates have experienced wind chill! Air flow can dramatically change the felt temperature even if the ambient temperature is adequate.
- Increase Indoor Air Quality: Unexpected or unwanted air leakage that creates a high humidity environment can produce conditions that will proliferate certain molds. Some of which can impact the health of occupants.
- Reduce Energy Use: Want to lower your energy bill and extend the life of your HVAC equipment? Insulation can only get you so far (see graph). Choking off air leakage is more substantial for reducing energy use than adding insulation!
Our Approach -The How!
Document Review: Prior to the testing, FCG needs to review the construction documents to plan out the location of the blower doors to provide the most efficient means of testing. Further, the mechanical drawings need to be reviewed to determine which inlets and outlets need masked off from the testing protocol.
Pre-Test Meeting: FCG requires a virtual or in-person meeting with the construction team. The purpose of the meeting is to discuss the scope of the testing and the requirements from the construction team ahead of the testing. If Whole Building Air Leakage Testing (WBALT) will be a known part of the project, it is recommended that this meeting is held during pre-construction meetings. This is especially important for multi-family residential and hotel properties as the units slated for testing should be selected ahead of time.
Items of note outlined during these discussions include, but are not limited to, electrical power availability, coordination of trades and closure of the facility during testing, test preparation, and expectations from the construction team pre- and post-testing.
Testing: FCG will provide blower doors and air flow measuring devices to determine the air leakage rate of each building based on ASTM E779 Standard Test Method for Determining Air Leakage Rate by Fan Pressurization. This test will require operable doors within the exterior wall of each building as well as electrical power. FCG will need complete access to the building with no entry or exit from others during the testing.
The testing assumes that the results will meet the Exception of Section C402.5.3 Building Thermal Envelope Testing. As such, FCG will utilize infrared thermography and/or tracer smoke to assist in locating air leakage paths for repair. If repairs require revisiting the test site to retest, additional costs will be incurred and a separate proposal for the retesting will be submitted.
Reporting: FCG will analyze the findings of the testing and provide a written report summarizing pertinent information as well as our recommendations for reducing air leakage, if necessary. The written report may include photographs, figures, excerpted drawings, and other information as necessary to convey the findings.
