75 terms

Energy Management Glossary English definitions

Energy Management Principles and Practice: Vilnis Vesma, BSi
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adsorption chiller
cooling apparatus driven by heat alone
accuracy
degree to which a measurement reflects reality
AHU
air handling unit: assembly of fan, filters, etc for supplying air to or extracting air from a ducted distribution system
ammeter
instrument for measuring electric current
AMR
automatic meter reading
anemometer
device to measure air velocity
ballast
component of electrical control gear in a fluorescent light fitting
BEMS
building energy management system: computerized control and monitoring equipment for regulating time and temperature schedules, etc
blowdown
removal of a fraction of boiler water to enable removal of sludge and dilution of dissolved solids
calorific value
energy content of fuel per unit mass or volume
capacity charge
rental paid for an electrical supply connection capable of caring a certain current
CFL
compact fluorescent lamp: plug-in substitute for a light bulb
code 5
in UK context, a meter for registering half-hourly electricity consumption for loads above 100kW
compensator
control device to regulate circulating water temperature in a heating system, reducing temperature when heat demand is low and vice versa
condensate
water resulting from the cooling of steam
condenser
in a refrigeration circuit, the component through which heat is rejected
conduction losses
heat losses through the walls, roof, floors, doors, windows and other solid elements of the building envelope
convection losses
heat lost in air leaving the building through draughts and deliberate ventilation
convector, fan assisted
heat emitter on a central heating system in which a fan blows room air across a heat exchanger
convector, natural
heat emitter on a central heating system, usually enclosed in a cabinet with inlet and outlet vents, which warms room air without the assistance of a fan
cooling tower
device in which water used for cooling something gives up some of its heat to the air, enabling it to be recirculated in a closed loop. May be 'dry', employing a sealed heat exchanger, or 'wet' in which case evaporation of the water increased the cooling effect
correction factor
in the context of natural gas, the factor by which its metered volume must be multiplied to account for its pressure and temperature being other than that assumed as standard
current
rate of flow of electrical energy
current transformer
device placed around one conductor of an electrical supply cable to convert the current flowing in it into a safely-measurable signal for input to a meter
damper
flap used to control air flow in a duct
degree days
measure of how hot or cold the weather was over a given interval typically a week or month, in a given location or region. Used in an analogous fashion to production output as the driving factor for heating or air-contdiioning energy consumption
delta
connection method for three-phase devices where the load is connected from phase to phase without a neutral (cf star)
dichroic
attribute of a filament spot lamp whereby the reflector allows heat to escape through the back
direct-fired heater
heater in which fuel is used directly, as distinct from a heat emitter on a hot-water or steam circuit with centralized combustion
discounted cash flow
method of accounting for future expenditure and receipts which explicitly recognizes that postponing a cash flow diminished its value in present terms
driving factor
recurrent and measurable determinant of energy consumption, such a production output or degree-day value
efficiency
the ratio of useful output to energy input
energy
electricity, gas, oil, steam, compressed air or other like medium
energy audit
review of emery-using systems with a view to identifying opportunities for energy saving
energy factor
obsolete term used in BS EN 16001:2009 (see 'Driving factor')
evaporator
in a refrigeration circuit, the component through which heat is absorbed
flash steam
steam resulting when hot 'condensate' is dropped to a lower pressure
frost protection
automatic application of heat to prevent freezing damage out of hours
heat
thermal energy which can raise something's temperature, or melt or boil it.
heat pump
refrigeration unit operated in reverse, providing heat at moderate temperature by cooling either the outside air or the ground nearby
historical baseline performance characteristic
'performance characteristic' which applied at the onset of the energy management campaign
hygroscopic
tending too absorb water vapour
incidental gains
heat gains in a building arising from lights, equipment, uninsulated hot surfaced, occupants, sunshine, etc
kelvin
(K) unit of temperature difference
latent heat
heat required to melt or vaporize a substance; or heat released when a vapour condenses or a liquid solidifies. Notwithstanding the release or absorption of heat, the change of state between liquid and solid or vapour occurs without a change of temperature
load factor
ratio between actual output or input and the maximum theoretically possible with continuous operation at full output or input
lux
measure of the light incident on a surface per unit area
maximum demand
in UK context, the peak electrical power drawn over any half-hour period in a month
monitoring and targeting
systematic assessment of actual against expected consumption by means of weekly (usually) 'overspend league table' augmented by analysis tools to assist in target-setting and diagnosis of abnormal performance
night blind
insulating blind on chilled display cabinet to reduce cooling requirement out of hours
optimum start
time-control regime which postpones star-up, usually of heating boilers, to the latest possible time commensurate with achieving desired internal conditions at the required time
overspend league table
weekly (usually) or monthly report in which deviation from expected consumption are ranked in descending order of excess cost
performance characteristic
mathematical relationship between energy consumption and one or more 'driving factors'
phase
alternating-current electrical supplies are either singe-phase (delivered through one pair of wires) or three-phase (delivered through three wires, the current waveform in each being one-third of a cycle behind or ahead of the others)
power
rate of flow of energy
power factor
in alternating-current electrical supplies, the ratio of useful power delivered to the theoretical maximum possible for the given current and voltage
precision
degree of resolution in a measurement
relative humidity
the ratio between the amount of water vapour present in the air and the theoretical maximum at the prevailing temperature
repeatability
degree to which measurements vary consistently irrespective of accuracy
SCADA
supervisory, control and data acquisition: computerized control and monitoring equipment for industrial process plant
sequencing
usually of boilers but also applicable to chillers, compressors, and other gauged utility equipment: a control regime which regulates how many units are enabled so as to match the load
smoke pump
device to measure the level of soot present in the flue gases when testing oil and cola-fired appliances
standing loss
incidental heat loss from equipment incurred regardless of demand
star
connection method for three-phase devices where the load is connected between each phase and neutral (cf delta)
sun pipe
internally-reflective tube used to conduct daylight into an internal space where conventional roof lights cannot be used
survey, energy
review of energy-using systems with a view to identifying opportunities for energy saving
target performance characteristic
'performance characteristic' representing the best achievable
temperature
measure of how hot something is
thermocouple
temperature-measuring device exploiting the small voltage developed when a junction between dissimilar metals is heated
transformer
device for converting alternating-current electricity from one voltage to another
U-value
property of an element of the building envelope expressing how easily heat flows through it per square metre of surface area
vapour-compression chiller
cooling apparatus driven by mechanical power
variable-speed drive
electronic device which alters the mains frequency fed to an electric motor, causing it to rotate at a different speed
venting
removal of air from, for example, steam circuits
viscosity
property of a fluid which determines its resistance to flow