Here are some common abbreviations and terms found in the pages of Engineered Systems.

A

a/c: air conditioning
AE: architectural and engineering
afd: adjustable-frequency drive
AHU: air-handling unit
asd: adjustable-speed drive
ASHRAE: American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
B
bas: building automation system
bhp: boiler horsepower; also, brake horsepower
bms: building management system
C
CAD: computer-aided design
cfm: cubic feet per minute
chw: chilled water
CMMS: computerized maintenance management system
D
D-B: design-build
db: drybulb
ddc: direct digital controls
DOAS: dedicated outdoor air system
DOE: The U.S. Department of Energy
DX: direct expansion
E
EMS: energy management system
EPA: U.S. Environmental Protection Agency
G
gpm: gallons per minute
I
IAQ: indoor air quality
M
MEP: mechanical, electrical, plumbing
O
O&M: operations and maintenance
R
rh: relative humidity
RFP: request for proposal
RFS: request for submittal
ROI: return on investment
RO: reverse osmosis
RTD: resistance temperature detector
S
scfm: standard cubic feet per minute
T
TES: thermal energy storage
V
vav: variable-air volume
vfd: variable-frequency drive
vsd: variable-speed drive
W
wc: water column