Retrotec USACE - Manual (Page 297)

Appendix F F3
louvers such as at elevator shafts. Damper and control to close all ventilation or
make-up air intakes and exhausts, atrium smoke exhausts and intakes, etc when
leakage can occur during inactive periods. Compartmentalize garages under
buildings by providing air-tight vestibules at building access points. Provide
air-tight vestibules at building entrances with high traffi c
Compartmentalize spaces under negative pressure such as boiler rooms
and provide make-up air for combustion.
Discontinuities in the air barrier will cause air to fl ow right around or
through the insulation, rendering it ineffective or worse allowing interior air to
contact exterior surfaces without insulation, causing condensation within the
walls.
F.5 Balancing Energy and Air Quality
Everyone has heard of the building that was “too tight”. This is a myth because
it is not possible to get a building too tight but it is certain that these buildings
were not properly ventilated. Build tight and ventilate right gives the best of
energy conservation and air quality.
F.6 Air Leakage Reduction in New and Existing Buildings
For existing buildings, air leakage reduction starts with interviews to fi nd out
what comfort or energy complaints there are to be followed up by an inspec-
tion of the envelope and mechanical systems. The envelope can then be door
fan tested to measure the existing air leakage. If the entire building is not avail-
able, sections of the building or even one apartment can be tested to quantify
the existing air leakage levels. Interior walls may be neutralized with additional
door fans to isolate one section of envelope for analysis. An estimation of the
air leakage reduction can then be made along with an analysis of the effects
that reduction may have on ventilation rates.
Air leakage in a new building starts with a good design. Leakage rates of
wall sections, windows and doors are important but most problems occur where
walls or fl oors meet. This detailing is most important. When the air leakage
target is set, the ventilation system can be designed to match the load. Con-
sider that the envelope may not supply much accidental ventilation or exhaust
and if possible, specify a balanced ventilation system for each unit. Unless the
building is fi tted with windows that cannot be opened, assume the windows
will be open and place more emphasis on the internal barriers to airfl ow; the
partition walls, hallway walls, fl oor slabs, elevator shafts, elevator hoist rooms,
elevator lobbies, stairwells, chases, and garbage chutes. Many of these features
can be separately door fan tested to discover what parts of the building are
responsible for the largest portions of air leakage.