06-06
2.
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.
3.
Insulating glass with lower "U" value might be necessary
to prevent condensation while maintaining the required
30% Relative Humidity (RH) in perimeter spaces with -4
C (25 F) outdoor design temperature and below.
The "U" values are expressed as W/m2/C (BTU/Hr/Ft2/F).
4.
5.
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.
2.
Overall "U" Value: The above recommended
values should be used to establish the overall "U" factor
(Uo) for the building gross wall area. Designer A/E shall
compute these values and demonstrate that they do not exceed
the limiting values listed below in Table 6.2.
Table 6 - 2 Overall "U" Value
Degree-Days
Uo (Overall
3000 & Below
.73 (0.36)
3001 to 5000
.63 (0.31)
5001 & Above
.57 (0.28)
Uo
=
Uw x Aw + Ug + Ag + Ud x Ad
Ao
Uo
=
Overall Transmission Factor
Ao
=
Overall Gross Wall Area
Uw
=
Wall "U" Factor
Aw
=
Wall Area
Ug
=
Glass "U" Factor
Ag
=
Glass Area
Ud
=
Door "U" Factor
Ad
=
Door Area
Notes:
1.
The roof or floor "U" factors and areas do not enter
into computation.
2.
There are no specific requirements for the door "U"
values. Insulated doors are recommended.
3.
Perimeter Insulation: For heated occupied spaces, the
slabs-on-grade shall be thermally isolated by providing
22
Previous Page
