TABLE 7-1 NOTES CONTINUED:
(3) Wall (UW) value is the thermal transmittance of all elements
of the opaque wall area. UW values shall be used for upgrade of existing
facilities where the alteration of the wall cavity and resizing of window
glazing to meet gross wall values (UO) are not cost effective. There may be
situations where upgrading all the perimeter walls in low, medium, and high
internal loaded spaces to the specified transmission value may not be
life-cycle cost effective. The designer will recommend appropriate
alternatives when such situations occur, providing supporting life-cycle cost
data based on appropriate hour-by-hour computer simulations. This
requirement to assess the above-mentioned situation may necessitate a
variation from the values set forth in this table.
(4) Ceiling/roof (UR) values are for ceiling/roof areas where
adequate space exists for insulation to be applied above ceiling and/or below
roof structure. Built-up roof assemblies and ceiling assemblies in which the
finish interior surface is essentially the underside of the roof deck will
have a maximum Ur value of 0.284 (0.05) for any Heating Degree-Day area.
(5) Floor, space (UFS) values are for floors of heated space over
unheated areas such as garages, crawl space, and basements without a positive
heat supply to maintain a minimum of 10 oC (50 oF).
(6) Floor, grade (UFG) values are for slab-on-grade insulation
around the perimeter of the foundation.