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Large Building Envelope Airtightness.

Are large buildings airtight?
Why should they be airtight?
Who is working on this problem?
How can airtightness be tested?

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Recent research has shown that U.S. commercial and institutional buildings are not as airtight as assumed, and that envelope air leakage has a significant impact on energy consumption and indoor air quality in these buildings. This applies to all building ages, sizes, and constructions.

ONLINE TECHNICAL INFORMATION AND RESEARCH:

ASSOCIATIONS AND MEETINGS

EXAMPLES OF LARGE BUILDING TESTS

TEST METHODS AND SOFTWARE:

AIRTIGHTNESS RECOMMENDATIONS:

The U.S. has not made any significant changes in building envelope construction recommendations based on the latest airtightness research results. The UK is now more advanced in their recommendations.

*5/14/02*
UK RECOMMENDED AIR LEAKAGE INDEX FROM CIBSE-T23
Building Type: Good
Practice:
m3/(h*m2)
@ 50 Pa
Best
Practice:
m3/(h*m2)
@ 50 Pa
Good*
Practice:
cfm/sf
@ 0.2 "wc
Best*
Practice:
cfm/sf
@ 0.2 "wc
Good*
Practice:
ACH @
50 Pa
Best*
Practice:
ACH @
50 Pa
Good*
Practice:
Hole sq in/
100 sq ft
Best*
Practice:
Hole sq in/
100 sq ft
Dwellings (naturally ventilated) 15.0 8.0 0.83 0.44 11.4 6.1 10.8 5.8
Dwellings (mechanical ventilation) 8.0 4.0 0.44 0.22 6.1 3.0 5.8 2.9
Offices (naturally ventilated) 10.0 5.0 0.55 0.28 3.6 1.8 7.2 3.6
Offices (mechanical ventilation) 5.0 2.5 0.28 0.14 1.8 0.9 3.6 1.8
Supermarkets 5.0 2.0 0.28 0.11 1.8 0.7 3.6 1.4
Industrial 15.0 2.0 0.83 0.11 3.0 0.4 10.8 1.4
Controlled (cold storage, labs, etc.) 1.0 under 1.0 0.055 under 0.055 0.4 under 0.4 0.7 under 0.7
* indicates an Infiltec calculation based on CIBSE-T23 building tightness specifications
To convert these leakage indexes to 0.30 "wc or 75 Pa, multiply flow (not area) values by 1.30.
ACH and hole size calculations assume 30'x50'x8' house, 300'x500'x10' other buildings (industrial assumes 20' height).
Hole size calculations assume orifice flow. Multiply (square inches/100 square feet) by 0.69 to get (square cm/square m).

FAN PRESSURIZATION TEST EQUIPMENT FOR TESTING LARGE BUILDINGS:

Several large fan pressurization test systems have been built by research organizations in Canada and the UK. Recently Infiltec and Building Sciences Limited developed the next generation of fan pressurization test equipment for large buildings:

For further assistance, call Infiltec toll free at (888) 349-7236 Or Email Infiltec Factory .
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This page copyright © 1996-2015 by Infiltec Inc., all rights reserved. It was last updated February 19, 2009.

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