Part 2 DEFINITIONS

 

 

 

The following definitions are stipulated for the purposes of this document:

 

ABMA                  American Boiler Manufacturers Association

ANSI                  American National Standards Institute

 

ARI                   Air - Conditioning and Refrigeration Institute (U.S.)

 

ASHRAE                American Society of Heating Refrigerating and Air -Conditioning Engineers

 

ASME                  American Society of Mechanical Engineers

 

Air changes per hour (ACE).    Number of complete changes of interior air by outdoor air per hour.

 

Air Infiltration.     The uncontrolled air exchange in a building due to air leakage through cracks and interstices in any building element and around windows and doors of a building, caused by the pressured effects of wind and/or the effect of differences in the indoor and outdoor air density.

 

Air transport factor. The ratio of the rate of useful sensible heat removal from the conditioned space to the energy input to the supply and return fan motor (s) , expressed in consistent units and under the designated operating conditions.

 

Automatic.             Self - acting, operating by its own mechanism when actuated by some impersonal influence, as for example, a change in current strength, pressure, temperature or mechanical configuration.

 

Boiler capacity.       The rate of heat output in W(Btu/h) measured at the boiler outlet, at the design inlet and outlet conditions and rated fuel/energy input.

 

British thermal unit (Btu). Approximately the amount of heat required to raise the temperature of one pound of water by one Fahrenheit degree, at 60 F. International Steam Table Btu x 1.055 = kJ.

 

Building envelope.    The elements, of a building which enclose conditioned spaces through which thermal energy may, be transferred to or from the exterior or to or from unconditioned spaces exempted by the provisions (See Section 3.)

 

 

 Building project.    A building or group of buildings, including on‑site energy conversion or electric generating facilities which utilize a single submittal for a construction permit or are within the boundary of a continuous area under one ownership.

 

C = thermal conductance. The thermal transmission in unit time through unit area of a particular body or assembly having defined surfaces, when unit average temperature is established between the surfaces:  W/m .C (Btu/ft . h. F) .

 

Coefficient of performance (COP) ‑ cooling. As defined in the following paragraphs:

 

 

Coefficient of performance (COP), heat pump ‑ heating Mode. As defined in para 4.3.4.

 

Comfort envelope.     The area on a psychometric chart enclosing all those conditions described in ANSI/ASHRAM Standard 55‑74, Fig. l, as being comfortable.

 

Conditioned floor area. The horizontal projection of that portion of interior space which is contained within exterior walls and which is conditioned directly or indirectly by an energy‑using system.

 

Conditioned space.    Space within a building which is provided with heated and/or cooled air or surfaces and, where required, with humidification or dehumidification means so as to maintain a space condition falling within the comfort zone set forth in ANSI/ASHRAE Standard 55‑74 "Thermal Environmental Conditions for Human Occupancy.,,

 

Cooled space.         Space within a building which is provided with a positive cooling supply.

                       

D.O.E.                  Department of Energy (U.S.)

 

Dwelling unit.         A single housekeeping unit comprised of one or more rooms providing complete, independent living facilities for one or more persons including permanent provisions for living, sleeping, eating, cooking and sanitation.

 

Economiser cycle.     A control sequence of an air supply system that modulates the quantity of outdoor air supplied for the purpose of space conditioning in order to reduce or eliminate the use of refrigeration energy for cooling.

 

Efficiency, HVAC system. The ratio of the useful energy output (at the point of use) to the energy input for a designated time period, expressed in percent.

 

Energy.               The capacity for doing work; taking a number of forms which may be transformed from one into another, such as thermal (heat), mechanical (work), electrical, and chemical; in SI units, measured in joules (J), where 1 joule = 1 watt‑second; in customary units, measured in kilowatt hours (kWh) or British thermal units (Btu).

 

Energy efficiency ratio (EER). The ratio of net equipment cooling capacity in Btu/h to total rate of electric input in watts under designated operating conditions. When SI units are used this ratio becomes equal to COP. (See coefficient of performance.)

 

Enthalpy.              A thermodynamic property of a substance defined as the sum of its internal energy plus the quantity Pv/J:  where P = pressure of the substance, v = its volume, and J = the mechanical equivalent of heat; formerly called total heat and heat content.

 

Exterior envelope.    (See building envelope.)

 

Fenestration.          Any light‑transmitting opening in a building wall or roof.

 

Gross floor area.     The sum of the areas of one or more floors of the building, including basements, mezzanine and intermediate‑floored tiers and penthouses of headroom height, measured from the exterior faces of exterior walls or from the centerline of walls separating buildings, but excluding:

 

·        Covered walkways, open roofed‑over areas, porches and similar spaces.

 

·        Pipe trenches, exterior terraces or steps, chimneys, roof overhangs, and similar features.

 

Gross wall area.       See section 3.2 for definition.

 

HVAC.                 Heating, ventilating and air conditioning.

 

 

HVAC system.           A system that provides either collectively or individually the processes of comfort heating, ventilating, and/or air conditioning within or associated with a building.

 

HVAC system equipment. The word "equipment" used without modifying adjective, may, in accordance with common industry usage, apply either to HVAC system equipment or HVAC system components.

 

HVAC system efficiency. (See efficiency, HVAC system.)

 

Heated space          Space, within a building, which is provided with a positive heat supply. Finished living space within a basement, or in the presence of registers or heating devices designed to supply heat to a basement space, shall automatically define that space as heated space.

 

Humidistat.            A regulatory device, actuated by changes in humidity, used for automatic control of relative humidity.

 

Illumination.          The density of the luminous flux incident on a surface; it is the quotient of the luminous flux by the area of the surface when the latter is uniformly illuminated.

 

Luminaire.             A complete lighting unit consisting of a lamp or lamps together with the parts designed to distribute the light, to position and protect the lamps, and to connect the lamps to the power supply.

 

MCF.                    Customary term for one thousand cubic feet.

 

Manual.                Capable of being operated by personal intervention (adjective). (See automatic).

 

Marked rating.         The design load operating conditions of a device as shown by the manufacturer on the nameplate or otherwise marked on the device.

 

OTTV.                   Overall thermal transfer value. The maximum thermal transfer permissible into the building through its walls or roof, due to solar heat gain and outdoor-in‑door temperature difference, as determined by the equation appearing in Section 3.3.1.

 

Opaque areas.          All exposed areas of a building envelope which enclose conditioned space, except openings for windows, skylights, doors and building service systems.

 

 

Outdoor air.           Air taken purposely from the outdoors and, therefore not previously circulated through the system.

 

Packaged terminal air‑conditioner (PTAC). A factory selected combination of heating and/or cooling components, assemblies or sections, intended to serve a room or zone.

 

Packaged terminal heat pump. A factory‑selected combination of heating and cooling components, assemblies or sections, intended for application in an individual room or zone.

 

Positive cooling supply. Cooling deliberately supplied to a space, such as through a supply register. Also, cooling indirectly supplied to a space through uninsulated surface of space cooling components, such as evaporator coil and cooling distribution systems.

 

Positive heat supply. Heat deliberately supplied to a space such as through a supply register, radiator or heating element. Also, heat indirectly supplied to a space through uninsulated surface of service water heaters and space heating components such as furnaces, boilers, and heating and cooling distribution systems.

 

Power.                  In connection with machines, power is the time rate of doing work. In connection with the transmission of energy of all types, power refers to the rate at which energy is transmitted. In SI Units it is measured in joules per second (J/s) or in watts (W); in customary units, it is measured in watts (W) or British thermal units per hour (Btu/h).

 

R = Thermal resistance.    The reciprocal of thermal conductance; (m C)/W or (hr.ft² . F)/Btu.

 

Recommend.             Suggest as appropriate; not required.

 

Recooling.             The removal of heat by sensible cooling of the supply air (directly or indirectly) that has been previously heated above the temperature to which the air is to be supplied to the conditioned space for proper control of the temperature of that space.

 

Recovered energy.     Energy utilized which would otherwise be wasted (i.e., not contribute to a desired end use) from an energy utilization system.

 

 

Reheat.                The application of sensible heat to supply air that has been previously cooled below the temperature of the conditioned space by either mechanical/ absorption refrigeration or the introduction of outdoor air to provide cooling.

 

Residential building. Living units of one story, two stories, or other low‑rise or high‑rise multi‑family dwellings.

 

Room air conditioner. An encased assembly designed as a unit primarily for mounting in a window or through a wall, or as a console. It is designed primarily to provide free delivery of conditioned air to an enclosed space, room or zone. It includes a prime source of refrigeration for cooling and dehumidification and means for circulating and cleaning air, and may also include means for ventilating and heating.

 

Short Ton.             Customary term for two thousand pounds mass.

 

Service systems.       All energy - using systems in a building that are operated to provide services for the occupants or processes housed therein, including HVAC, service water heating, illumination, transportation, cooking or food preparation, laundering or similar functions.

 

Shading coefficient (SC).

 

Note:  To be compared under the same conditions.

 

Shall.                  Term used to indicate provisions that are mandatory within the code.

 

Should.                Term used to indicate provisions which are not mandatory but which are desirable as good practice.

 

Solar energy source.  Source of natural day lighting and of thermal, chemical or electrical energy derived directly from conversion of incident solar radiation.

 

System.                A combination of equipment and/or controls, accessories, interconnecting means, and terminal elements by which energy is transformed so as to perform a specific function, such as HVAC, service water heating or illumination.

 

 

Terminal element.     The means by which the transformed energy from a system is finally delivered:  i.e., registers, diffusers, lighting fixtures, faucets, etc.

 

Thermostat.            An automatic control device actuated by temperature and designed to be responsive to temperature.

 

U_o value or thermal transmittance. The coefficient of heat transmission (air to air). It is the time rate of heat flow per unit area and unit temperature difference between the warm side and cold side air films W/m² C (Btu/ft² h.F). The U value applies to combinations of different materials used in series along the heat flow path, single materials and materials that comprise a building section, cavity air spaces, and surface air films on both sides of a building element.

 

U_o value or thermal transmittance, overall. The overall (average) heat transmission Ff a gross area of the exterior building envelope W/m² .C (Btu/ft² h.F). The U_o value applies to the combined effect of the time rate of heat flows through the various parallel paths, such as windows, doors, and opaque construction areas, comprising the gross area of one or more exterior building components, such as walls, floor, or roof/ceiling.

 

Unitary cooling and heating equipment. One or more factory‑made assemblies which normally include an evaporator or cooling coil, a compressor and condenser combination, and may include a heating function as well. Where such equipment is provided in more than one assembly, the separate assemblies shall be designed to be used together.

 

Unitary heat pump.    One or more factory‑made assemblies which normally include an indoor conditioning coil, compressor(s) and outdoor coil or refrigerant‑to‑water heat exchanger, including means to provide both heating and cooling functions. When such equipment is provided in more than one assembly, the separate assemblies shall be designed to be used together.

 

Ventilation.           The process of supplying or removing air by natural or mechanical means to or from any space. such air may or may not have been conditioned.

 

Ventilation air.       That portion of supply air which comes from outside (outdoors) plus any recirculated air that has been treated to maintain the desired quality of air within a designated space.

 

 

 Water-chilling package, absorption. A factory designed and prefabricated assembly (not necessarily shipped as a single package) of one or more condensers; evaporators (water coolers):  absorbers; and generators; with interconnections and accessories, used for chilling water.

 

Water-chilling package, centrifugal or rotary. A factory‑designed and prefabricated assembly (not necessarily shipped as one package) of one or more centrifugal or rotary compressors; condensers; and water‑coolers (evaporators), with interconnections and accessories, used for chilling water.

 

Water-chilling package, reciprocating. A factory designed and prefabricated assembly, self‑contained or condenserless, of one or more reciprocating compressors:  condensers (self‑contained only); water coolers (evaporator):  and interconnections and accessories:  used for chilling water. The condenser may be air‑evaporatively, or water‑cooled.

 

Watt (W).              SI unit of power equal to one joule per second (J/s) . Also, the power delivered by one volt with one ampere flowing (unity power factor). (See power.)

 

Whole House Fan.       A mechanical fan system used to exhaust air from the interior of a building to the exterior and which can transfer the air with little or no resistance.

 

Zone.                   A space or group of spaces within a building with heating and/or cooling requirements sufficiently similar so that comfort conditions can be maintained through‑out by a single controlling device.