ASHRAE-90.1-2022- - Page 034
Extracted Content
floor spandrels, peripheral edges of floors, and foundation walls . For the purposes of determining building envelope requirements, the classifications are defined as follows:
above-grade wall: a wall that is not a below-grade wall . below-grade wall: that portion of a wall in the building envelope that is entirely below the finish grade and in contact with the ground. mass wall: a wall with a heat capacity exceeding (a) 7 Btu/ft [2] ·°F or (b) 5 Btu/ft [2] ·°F, provided that the wall has a material unit weight not greater than 120 lb/ft [3] . metal building wall: a wall whose structure consists of metal spanning members supported by steel structural members (i.e., does not include spandrel glass or metal panels in curtain wall systems). steel-framed wall: a wall with a cavity (insulated or otherwise) whose exterior surfaces are separated by steel framing members (i.e., typical steel stud walls and curtain wall systems). wood-framed and other walls: all other wall types, including wood stud walls .
wall area, gross: the area of the wall measured on the exterior face from the top of the floor to the bottom of the roof .
warm-up: increase in space temperature to occupied set point after a period of shutdown or setback .
water heater: vessel in which water is heated and is withdrawn for use external to the system .
west-oriented: facing within 45 degrees of true west to the south and within less than 22.5 degrees of true west to the north in the northern hemisphere; facing within 45 degrees of true west to the north and within less than 22.5 degrees of true west to the south in the southern hemisphere.
wood-framed and other floors: see floor .
wood-framed and other walls: see wall .
3.3 Abbreviations and Acronyms
χ chi-factor, thermal transmittance of a point thermal bridge
Ψ psi-factor, thermal transmittance per unit length of a linear thermal bridge
ac alternating current
ach air changes per hour
AFUE annual fuel utilization efficiency
AHAM Association of Home Appliance Manufacturers
ANSI American National Standards Institute
AHRI Air-Conditioning, Heating and Refrigeration Institute
AMCA Air Movement Control Association
ASTM ASTM International
BEP best efficiency point
( fan ) bhp ( fan) brake horsepower
BSR Board of Standards Review
Btu British thermal unit
Btu/h British thermal unit per hour
Btu/ft [2] ·°F British thermal unit per square foot per degree Fahrenheit
Btu/h·ft [2] British thermal unit per hour per square foot
Btu/h·ft·°F British thermal unit per hour per linear foot per degree Fahrenheit
Btu/h·ft [2] ·°F British thermal unit per hour per square foot per degree Fahrenheit
CDD cooling degree-day
CDD 50 cooling degree-days base 50°F
CEER combined energy efficiency ratio
CFEI ceiling fan energy index
32 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)