06-06
Manual, the A/E shall provide definite recommendations to do so after
a careful review of the Standards and VA Manual.
6.2 BUILDING THERMAL ENVELOPE
A. NEW CONSTRUCTION: The building thermal envelope for the new VA animal
research facilities shall be energy efficient to minimize the heat
gain and loss due to conduction and solar radiation. The building
envelope shall minimize the air leakage to and from the occupied
spaces and shall also ensure condensation control.
1. Recommend "U" Values: The following represents the recommended "U"
values of walls, roof, and glass, and the Shading Coefficients
(SCs) of glass for new construction. These values should be used
to meet the overall Uo factor, for the building gross wall area,
defined under the next paragraph.
Table 6.1
Wall
Glass
Roof
Floor
"U"
"U"/SC
"U"
"U"
Degree-Days
3000 & Below
0.13
1.13/0.6
.05
0.12
3001 to 5000
0.10
0.5/0.5
.05
0.10
5001 & Above
0.07
0.5/0.33
.03
0.08
Notes:
a. The degrees days are based on heating season below
65oF outdoor temperature in accordance with the
ASHRAE Handbooks of Fundamental and Systems.
b. The SCs of the glass windows are based on the
intrinsic property of the glass material only, that
is, without any assistance from the external shading
devices, such as, venetian blinds and/or curtains.
c. Insulating glass with lower "U" value might be
necessary to prevent condensation while maintaining
the required 30% Relative Humidity (RH) in perimeter
spaces with 25oF outdoor design temperature and
below.
d. The "U" values are expressed as BTUH/Hr/Ft2/oF.
e. The "U" values for floors, are for floors of heated
spaces over unheated areas, such as, sub-basements
(pipe basements), garages, crawl spaces, etc. The
requirements of insulation for the slabs-on-grade for
the heated spaces are shown under perimeter
insulation.
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