Handbook of air conditioning and refrigeration / Shan K

Mandatory Provisions
W/m 2 ). Compliance includes mandatory provisions, the prescriptive building envelope option, and
the building envelope trade-off option.
The standard mandates that insulation materials shall be installed in accordance with the manufacturer’s
recommendation to achieve rated R value of insulation. Rated R value of insulation is the
thermal resistance of the insulation alone in units of h�ft 2 �°F/Btu (m 2 �°C/W) at a mean temperature
of 75°F (23.9°C). Rated R value refers to the thermal resistance of the added insulation in
framing cavities or insulated sheathing only and does not include the thermal resistance of other
building materials or air films.
Insulation shall be installed in a permanent manner in substantial contact with the inside surface.
The roof insulation shall not be installed on a suspended ceiling with removable ceiling panels. Insulation
outdoors shall be covered with a protective material to prevent damage from sunlight,
moisture, landscaping operations, equipment maintenance, and wind. Insulation materials contacts
with the ground shall have a water absoption rate no greater than 0.3 percent.
Fenestration performance shall be determined from production line units or representative units purchased.
U factors shall be determined in accordance with National Fenestration Rating Council (NFRC)
100. Solar heat gain coefficient (SHGC) for the overall fenestration area shall be determined in accordance
with NFRC 200. Visible light transmittance shall be determined in accordance with NFRC 300.
The following areas of building envelope shall be sealed, caulked, gasketed, or weather-stripped
until air leakage is minimal:
● Joints around fenestration and door frames
● Junctions between walls and foundations, between wall corners, between walls and roofs, wall
and floors, or walls and panels
● Openings because of penetrations of utility services through roofs, walls, and floors
● Fenestrations and doors built at site
● Building assemblies used as ducts and plenums
● Joints, seams, and penetrations due to vapor retarders
● Other openings in the building envelope
Air leakage of fenestration and doors shall be determined in accordance with NFRC 400. Air
leakage shall not exceed 1.0 cfm/ft2 (5.0 L/s�m 2 ) for glazed swinging entrance doors and revolving
doors and also 0.4 cfm/ft2 (2.0 L/s�m 2 ) for all other products. A door that separates conditioned
space from the exterior shall be protected with an enclosed vestibule with all doors into and out of
the vestibule installed with self-closing devices.
All mandatory provisions in Standard 90.1-1999 will be presented in the form “standard mandates
that”, whereas for nonmandatory provisions, only “standard specifics that” will be used.
Prescriptive Building Envelope Option
HEAT AND MOISTURE TRANSFER THROUGH BUILDING ENVELOPE 3.49
The exterior building envelope shall comply with the requirements for the appropriate conditioned
space in Table 5.3 for various climate (located in Normative Appendix B of Standard 90.1-1999). In
Table B1 to B26 of I-P edition:
● There are 26 tables, each of them has a number of heating degree days of 65°F (HDD65), and a
number of cooling degree days of 50°F (CDD 50). Select a table with number of HDD 65 and
CDD 50 equal to or most nearly equal to the values where the proposed building locates.
● There are three kinds of conditioned space: nonresidential, residential, semiheated.
● Total vertical fenestration area, including both fixed and operable fenestration shall be less than
50 percent of the gross wall area. The total skylight area, including glass and plastic skylights
with or without a curb, shall be less than 5 percent of the roof area.