Glossary of HVAC Regulation Terminology

Industry regulations can be complicated, but we’ve developed a list of terms from A to Z that will help contractors and facility managers better familiarize themselves.

AFUE
Annual Fuel Utilization Efficiency rating. A rating system for furnaces that compares energy input and energy output.

AHRI
Air Conditioning, Heating, and Refrigeration Institute.  A North American trade association of air conditioning, heating, and commercial refrigeration equipment manufacturers.

Air conditioner
A system or an assembly comprised of certain system components that are designed for the control of air temperature, relative humidity and air flow in a living or working space.

ANSI
American National Standards Institute.  An organization that develops standards for a variety of industry sectors including HVAC.

ANSI/AHRI Standard 340/360
This is the standard for performance rating of unitary air conditioning and heat pump systems from 65,000 to 250,000 Btu/hr.

AHRI Standard 540-91
A method of rating compressor performance, published by AHRI and used widely by the industry.

ASHRAE
American Society of Heating, Refrigeration and Air Conditioning Engineers. An organization focused on building systems, energy efficiency and indoor air quality in the heating, ventilation, air conditioning and refrigeration industry.

ASHRAE Standard 55
Provides Thermal Environmental Conditions which help define a Human Occupancy Standard. ASHRAE 55 is intended to provide a design standard which considers both the comfort needs of a majority of the occupants and the overall environmental sustainability of the building.

ASHRAE Standard 62.1
Ventilation for Acceptable Indoor Air Quality Standard. Compliance with ASHRAE 62.1 indicates that the building meets the minimum ventilation requirements set forth by ASHRAE Standard 62.1.

ASHRAE Standard 90.1
Energy standard for buildings, except low-rise residential buildings. ASHRAE 90.1 has been a benchmark of U.S. Commercial building energy codes.

ASTM
American Society for Testing and Materials.  An international standards organization that develops and publishes voluntary consensus technical standards.

BTU
British Thermal Unit.  The quantity of heat required to raise the temperature of one pound of water by one Fahrenheit degree.

CAE ratio
Combined Annual Efficiency ratio. A rating system used for combined heating systems, which heat both air and water.

CFC
Chlorofluorocarbon refrigerants are composed of chlorine, fluorine, and carbon. CFCs have been shown to deplete the ozone layer. Common examples include R-11, R-12, and R-13.

COP
Coefficient Of Performance.  The ratio of the work performed to the energy used by an air conditioning or refrigeration system.

Defrost
A part of the refrigeration cycle in which evaporator frost and ice accumulation is melted.

DOE
U.S. Department of Energy.  A federal agency that, among other objectives, is responsible for setting HVAC minimum equipment efficiency standards.

Economizer
Used to reduce the mechanical cooling load, an economizer allows the use of outside ventilation air for supply air when the enthalpy or temperature of the outdoor air is lower than required supply air during the cooling cycle.

EER
Energy Efficiency Ratio. A ratio of cooling capacity (in Btu/hr) to energy consumed (in Watts) used to determine the energy efficiency of an air conditioner the higher the EER rating, the more efficient the unit.  EER ratings are generally lower than Seasonal Energy Efficiency Ratio (SEER) ratings because SEER ratings are seasonally adjusted while EER ratings are calculated against a fixed ambient temperature.

Efficiency
A measure of how much energy is used to accomplish a cycle, measured by ratios such as SEER, EER, IEER, IPLV, or HSPF.  The higher the rating, the more efficient a system is and the lower your energy consumption will be.

Energy Audit
The process of accurately determining the current energy consumption for a given area of a refrigeration or air conditioning system.

Energy Star® Applied to unitary equipment 20 tons or less, Energy Star® labeled equipment exceeds Environmental Protection Agency (EPA) guidelines for energy efficiency.

Enthalpy
Total amount of heat in one pound of refrigerant calculated from an accepted temperature base.

EPA
Environmental Protection Agency.   A governmental agency empowered to protect the environment.

EUI
Energy Utilization Index. A number used to compare energy usage for different areas. It is calculated by dividing the energy consumption by the square footage of the conditioned space.

F-Gas
Generally refers to Fluorinated gases (e.g. hydrofluorocarbons) which are often used as refrigerants.  Studies have shown that these chemicals can contribute to a global greenhouse effect, global warming, global climate change, etc.

F-Gas Regulations
Generally refers to a series of European Union refrigerant regulations dealing with Flourinated gases.  The F-Gas regulatory approach is based on containment and recovery of Flourinated gases as well as restrictions on the use of Flourinated gases in HVAC equipment and other applications.

Flooded system
A type of air conditioning or refrigeration system in which the liquid refrigerant fills most of the evaporator at all times.

Geothermal
An underground or underwater temperature source used for the operation of a heating and cooling system.

Glide
The temperature difference in a refrigerant that occurs between the vapor state and liquid state during evaporation or condensation at constant pressure.

GWP
Global Warming Potential. A relative measure of how much heat a greenhouse gas traps in the atmosphere.  CO2 is given a GWP of 1, and all other gases are measured relative to this.

HCFC
Hydrochlorofluorocarbon refrigerants are composed of hydrogen, chlorine, fluorine, and carbon.  Damaging to the ozone layer, but to a lesser degree than CFCs. R-22 and R-123 are examples of hydrochlorofuorocarbon refrigerants.

Heat pump
Compression cycle system used to supply heat to a temperature-controlled space. A reversible heat pump system can also remove heat from the same space i.e. air conditioning cooling in the summer and heating in the winter.

Heat transfer coefficient
A measure of the amount of heat that a material or combination of materials will allow through; also known as the U-value.

HFC
Hydrofluorocarbon refrigerants are composed of hydrogen, fluorine, and carbon. HFC refrigerants do not contain any ozone depleting chlorine. Common examples include R-134A, R-404A, R-407C, R-410A, R-422A/B/D, and R-507.

HVAC
Heating, Ventilation, and Air Condition. The term HVAC is used to describe the industry and technology of indoor environmental comfort. Refrigeration is sometimes added to the field’s abbreviation as HVACR.

HFO
Hydrofluoroolefins.  A new class of low GWP refrigerants with lower global warming potential than HFCs. Examples of HFO refrigerants include HFO-1234yf and HFO-1234ze.

Hot gas bypass
Piping system used to reduce system capacity by moving hot refrigerant gas from the condenser into the low pressure side.

HSPF
Heating Seasonal Performance Factor.  It is a measure of efficiency for air source heat pumps. A higher number represents higher efficiency.

IAQ
Indoor Air Quality.  The status of indoor air as measured by numerous factors.

IECC
International Energy Conservation Code. IECC is a code that establishes minimum design and construction requirements for energy efficiency.

IEER
Integrated Energy Efficiency Ratio. This ratio expresses cooling and weighted part load EER for commercial unitary air conditioning and heat pump equipment at different loads.

IPLV
Integrated Part Load Value.  This value defines the efficiency performance factor at part load cooling, and is commonly used on chiller systems. It is weighted toward operating hours at part load.

Latent load
Load due to moisture introduced into a building. Latent loads may come from ventilation air, people, equipment and infiltration. Latent loads are a concern for cooling and humidifying applications.

LCCP
Life-Cycle Climate Performance.  A method of calculating the global warming impact of any product which includes both the direct impact (from refrigerant leaks) and the indirect impact (from the energy consumption), which comprise TEWI and the energy associated with refrigerant production and the impact of end-of-like decommissioning of the equipment.

LEED
Leadership in Energy and Environmental Design. Sponsored by the U.S. Green Building Council (USGBC), LEED is a certification program that guides the design, construction, operation and maintenance of buildings and homes.

MERV
Developed by ASHRAE as a rating system for filters, Minimum Efficiency Reporting Value rates filter performance on a scale of 1 to 16. The higher the MERV value, the more efficient the filter is at trapping airborne particles.

Natural refrigerant
These occur in nature’s biological and chemical cycles without human intervention.  Examples include ammonia, carbon dioxide, natural hydrocarbons, water and air.

ODP
Ozone Depletion Potential.  A relative amount value indicating the potential of a substance to destroy ozone gas as compared to CFC-11.

PSC motor
Permanent-Split Capacitor motor (also known as a capacitor start and run motor).  Frequently used in air handlers, blowers, and fans and other cases where variable speeds are desired.

Rating point
A specific operating condition in which the performance of a system is evaluated and published.

R-value
A measure of the resistance of an insulating or building material to heat flow. The higher the number, the greater the resistance to heat flow.

SEER
Seasonal Energy Efficiency Ratio. The SEER rating is the cooling output divided by the total electric energy input during a typical cooling season. The higher the rating, the more energy efficient a system is.

Shaded-pole motor
A small AC motor designed to start under light loads.

Split-phase motor
A motor with two stator windings. Both windings are in use while starting. One is disconnected by centrifugal switch after the motor attains speed. The motor then operates on the other winding only.

Squirrel cage
A fan that has blades parallel to the fan axis and moves air at right angles, or perpendicular to the fan axis.

Subcooling
The amount of heat removed from of liquid refrigerant below its condensing temperature at a given pressure.

Superheat
The amount of heat added to vapor refrigerant above its boiling temperature at a given pressure.

Swamp cooler
An evaporative-type cooler in which air is drawn through porous mats soaked with water.

TEWI
Total Equivalent Warming Impact. The sum of the direct global warming impact (from refrigerant leakage) and indirect global warming impact (from energy consumption and the indirect emissions from the energy used to operate the system) measured over the service life of a system.

Thermal Resistance
A measure of a material’s resistance to heat flow. Measured as the R-value.

Total Energy Management
A conservation concept where a building is analyzed in terms of its total energy usage, rather than its individual systems.

U-value
A measure of the flow of heat through an insulating or building material. The lower the U-value, the better the insulating ability.

VAV
Variable Air Volume.  A type of HVAC system where variable air flow rates are used to distribute conditioned air to meet the changing load conditions of the space or spaces being served.

Wet bulb temperature
A measure of the degree of moisture in the air. It is the temperature of evaporation for an air sample.

Zeotropic
A refrigerant blend, comprised of various refrigerants, that changes in volumetric composition and saturation temperature when used.

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2 thoughts on “Glossary of HVAC Regulation Terminology

  1. Good day,
    Could you kindly assist me with the following.
    In order to calculate the heat load that an air conditioning plant needs to handle in a production environment I need to determinate the connected KW of all equipment on the floor to be cooled. I assume that the connected load is not the heat load as the greater portion of the connected load is transferred into rotational movement (3 phase motors driving machinery). My question is this. Is there an industrial accepted norm to say that a certain percentage of the electrical connected load is converted into heat which needs to be handled by the air conditioning plant. As an example.
    I have a liquid filler which has a connected KW of 5KW. Of this 5KW one KW is dissipated heat and the 4KW is transferred into rotational movement which does not contribute towards the air conditioning heat load. in addition you have the lighting heat load and the operating people that generate and dissipate heat.
    Your solution is greatly appreciated.
    Kind regards,
    Manfred

    • Manfred,

      There are a number of factors which could effect the total heat of rejection from a compressor. But as a general “rule of thumb” I would suggest using: Watts * 3.42 * 10% = total heat rejected.

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