AC, HVAC, Air Filter Related Terms A-C

Glossary
Air Filter Related TERMS A-C

A
Abatement: The reduction or elimination of pollution.
Absolute Humidity - Air moisture content expressed in grains (or pounds) of water vapor per pound of dry air.
Absolute pressure: pressure referred to a perfect vacuum. It is the sum of gauge pressure and atmospheric pressure.
Absolute viscosity : the force per unit area required to produce unit relative velocity between two parallel areas of fluid distance apart; also called coefficient of viscosity .
Absolute zero temperature : the zero point on the Kelvin temperature scale, (= -273.16oC)
Absorbent: a material which extracts one or more substances form a liquid or gaseous medium which it contacts and charges physically or chemically, or both (e.g. soled absorbent: Calcium chloride, liquid absorbent: solutions of lithium chloride, lithium bromide, and ethylene glycols).
Absorber: an object absorbing another object or radiation (e.g. the blackened surface within a solar collector, which absorbs the solar radiation converting it to heat. These surfaces usually absorb solar radiation but do emit a limmited amount of radiative heat because of the so-called spectral selective coatings applied to the surface).
Absorptance: the ratio absorbed objects or radiation. (For solar energy the ratio of absorbed to incident solar radiation on a surface).
Absorptance of a glazing material: in this context the absorption of solar energy in the glazing material occurring throughout the thickness of a glazing material. The absorptence is the fraction absorbed related to the incident overall radiation (invoIving multiple reflections). The absorptence is different for different wavelengths (coloured glazing) and angles of incidence. The transmittance + absorptance + reflectance = 1.
Absorptance of an opaque surface: the ratio of the radiation absorbed at a surface relative to the incident radiation on that surface. The absorptance is different for different radiation waveIengths and angles of incidence. The absorptance of normally incident radiation however is always numerically equal to the emittance of the surface for the same wavelength. 'bIack body' is a theoretical perfect absorber with an absorptance of 1 for all wavelengths: a typical matt black paint has an absorptance of 0.97 for normal soIar radiation and 0.95 for long-wave (thermal) radiation. For any wavelength and angle of incidence, for an opaque surface, absorptance + reflectance = 1.
Absorption: a process where an object absorbs another object or radiation for example a process whereby a material extracts one or more substances present in an atmospheric or mixture of gases or liquids accompanied by the material's physical and/or
Absorption Factor: For solar radiation the fraction of solar radiation, transmitted through a glazing system that is absorbed inside the building.
Absorption and Adsorption: In addition to differences in boiling points, each type of hydrocarbon and impurity may have a preferred attraction to another substance or chemical. Two processes, adsorption and absorption, take advantage of this attraction and are used to separate the various parts of fossil fuels and in particular natural gas. Adsorption is the sticking or adhesion of liquids or gases to the surface of a solid or another liquid, similar to gum on a wall; where absorption is the taking up or surrounding of a substance by another substance, similar to how a sponge soaks up liquids and holds it within little pockets.
Accent Lighting: Accent lighting illuminates walls, reduces brightness and contrast between walls and ceilings or windows.

Acceptable Daily Intake (ADI): The highest daily amount of a substance that may consumed ver a lifetime without adverse effects.
ACID AEROSOL: Acidic liquid or solid particles that are small enough to become airborne. High concentrations of acid aerosols can be irritating to the lungs and have been associated with some respiratory diseases, such as asthma.
Acid Deposition - A complex chemical and atmospheric phenomenon that occurs when emissions of sulfur and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere, often far from the original sources, and then deposited on earth in either wet or dry form. The wet forms, popularly called "acid rain," can fall to earth as rain, snow, or fog. The dry forms are acidic gases or particulates.
Acid rain is a term used to describe several ways that acidic compounds fall out of the atmosphere, causing a variety of ground-level environmental effects. These effects include damage to forests and soils, fish and other living things, and human health. Acid rain also reduces how clearly we can see through the air, an effect called visibility reduction.
Sulfur dioxide and nitrogen oxides are the primary causes of acid rain. In the United States, about two-thirds of all sulfur dioxide and one-quarter of all nitrogen oxides come from electric power generation that relies on burning fossil fuels like coal. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. These acidic compounds fall to the earth as acidic rain, fog, and snow, or as dry deposited gases and particles that can be blown to the ground by the wind. In fact, prevailing winds can blow the compounds that cause acid rain across state and national borders, and sometimes over hundreds of miles.
Activated Carbon
Activated Carbon is a specially treated carbon that has been exposed to heat around 800-900 degrees Celsius. The great thing about activated carbon is that it has a large internal surface area and can trap a lot of impurities inside it. Activated carbon is most commonly seen in simple tap water filters and fish tank filters, but is also used in some small air filters and has even been used in cigarette butts.
ACTION LEVEL: A term used to identify the level of indoor radon at which remedial action is recommended. (EPA's current action level is 4 pCi/L.)
ACTION PACKET: In reference to the IAQ Tools for Schools Action Kit - contains numerous products to assist school personnel to implement an effective yet simple IAQ program in their school.
Acute Exposure: One or a series of short-term exposures generally lasting less than 24 hours.
Acute Health Effect: A health effect that occurs over a relatively short period of time (e.g., minutes or hours). The term is used to describe brief exposures and effects which appear promptly after exposure.
Adaptive model (adaptive approach): For thermal comfort this is an approach to the study thermal comfort starting from the observation that there are a range of actions which occupants can take to achieve thermal comfort, and that discomfort is caused by constraints imposed on the range of actions by social, physical or other factors (see also Adaptive Principle). Over time this means that people are comfortable at the 'usual' or 'average' temperature which they experience.
Adaptive opportunity: For thermal comfort: the ability of a building to allow adaptation to broaden the band of temperatures at which the person could be comfortable. Actions might include adding or removing a layer of clothing, changing posture, or adjusting the metabolic rate. Spatial variation of temperature across the room, availability of a desk fan, and the presence of sun shading or openable windows would make the adaptive opportunities still greater. These actions either alter the temperature which is required for comfort, or alter the room temperature towards that which the occupants will find comfortable
Adaptive Principle: A principle which can be stated as: If a change occurs (in the thermal environment) such as to produce discomfort, people react in ways which tend to restore their comfort.
Adaptive processes: The range of actions that man takes to achieve thermal comfort.
Add-On Control Device: An air pollution control device such as carbon absorber or incinerator that reduces the pollution in exhaust gas. The control device usually does not affect the process being controlled and thus is "add-on" technology, as opposed to a scheme to control pollution through altering the basic process itself. See also pollution prevention.
Adsorber: An emissions control device that removes VOCs from a gas stream as a result of the gas attaching (adsorbing) onto a solid matrix such as activated carbon.

Adverse Health Effect: A health effect from exposure to air contaminants that may range from relatively mild temporary conditions, such as eye or throat rritation, shortness of breath, or headaches to permanent and serious conditions, such as birth defects, cancer or damage to lungs, nerves, liver, heart, or other organs.
Aerosol - 1. Small droplets or particles suspended in the atmosphere, typically containing sulfur. They are usually emitted naturally (e.g. in volcanic eruptions) and as the result of anthropogenic (human) activities such as burning fossil fuels. 2. The pressurized gas used to propel substances out of a container
Akylation: input definition
Afterburner - In incinerator technology, a burner located so that the combustion gases are made to pass through its flame in order to remove smoke and odors. It may be attached to or be separated from the incinerator proper.
Agricultural Residue - Plant parts, primarily stalks and leaves, not removed from the fields with the primary food or fiber product. Examples include corn stover (stalks, leaves, husks, and cobs); wheat straw; and rice straw.
Air: So called "pure" air is a mixture of gases containing about 78 percent nitrogen; 21 percent oxygen; less than 1 percent of carbon dioxide, argon, and other gases; and varying amounts of water vapor. See also ambient air.
Air barrier: for buildings a material carefully installed within a building envelope assembly to minimise the uncontrolled passage of air into and out of a dwelling.
Air Basin: A land area with generally similar meteorological and geographic conditions throughout. To the extent possible, air basin boundaries are defined along political boundary lines and include both the source and receptor areas. California is currently divided into 15 air basin.

Air Borne
The term Air Borne is used to describe any particles or substances that float in the air. Air borne particles are the reason that air filters are used to clean air in a given area. In a home or office setting, the bulk of air borne particles are made up of tiny bits of human skin.

Airborne Toxic Control Measure (ATCM): A control measure adopted by the ARB (Health and Safety Code Section 39666 et seq.), which reduces emissions of toxic air contaminants.
Air change: One air change is an exchange of one volume of air equal to internal volume of a room or building (see also Air Change Per Hour).
Air changes Per hour (ach): ventilation unit denoting the number of times a room exchanges its own total air volume with outside air per hour. For the calculation of the air permeability of a room or building this is determined (1) under natural conditions and (2) under a 50 Pascal pressure difference. (The R-2000 Home Program requires a house with 1.5 ach at 50 Pascal).
AIR CLEANING: An IAQ control strategy to remove various airborne particulates and/or gases from the air. The three types of air cleaning most commonly used are particulate filtration, electrostatic precipitation, and gas sorption.
Air conditioning: Control of the indoor environment by controlling the thermal characteristics (cleaning, changing the water content but mainly heating and cooling) the air supplied to the room.
Air District: A political body responsible for managing air quality on a regional or county basis. California is currently divided into 35 air districts. (See also air pollution control district and air quality management district).
Air Exchange Rate: The rate at which outside air replaces indoor air in a space. Expressed in one of two ways: the number of changes of outside air per unit of time air changes per hour (ACH); or the rate at which a volume of outside air enters per unit of time - cubic feet per minute (cfm).
Air Handler A steel cabinet containing a blower with cooling and/or heating coils connected to ducts that transports indoor air to and from the air handler.

Air Infiltration Barrier A woven plastic sheet that stops almost all air traveling through a building cavity, while allowing moisture to pass through the cavity.

Air leakage: the uncontrolled flow of air for instance through a component of the building envelope, or the building envelope itself, when a pressure difference is applied across the component. Infiltration refers to inward flowing air leakage and exfiltration refers to outward flowing air leakage
Air Monitoring: Sampling for and measuring of pollutants present in the atmosphere.
Air movement: the movement of the air past a point, generally represented as the speed or velocity of the air measured with an anemometer.
AIR PASSAGES: Openings through or within walls, through floors and ceilings, and around chimney flues and plumbing chases, that permit air to move out of the conditioned spaces of the building.
Air permeability: the property of a building component to let air pass when it is subjected to a differential pressure.
Air Pollutant - Any substance in air that could, in high enough concentration, harm man, other animals, vegetation, or material. Pollutants may include almost any natural or artificial composition of airborne matter capable of being airborne. They may be in the form of solid particles, liquid droplets, gases, or in combination thereof. Generally, they fall into two main groups (1) those emitted directly from identifiable sources and (2) those produced in the air by interaction between two or more primary pollutants, or by reaction with normal atmospheric constituents, with or without photo activation. Exclusive of pollen, fog, and dust, which are of natural origin, about 100 contaminants have been identified. Air pollutants are often grouped in categories for ease in classification; some of he categories are solids, sulfur compounds, volatile organic chemicals, particulate matter, nitrogen compounds, oxygen compounds, halogen compounds, radioactive compound, and odors.
Air Pollutants: Amounts of foreign and/or natural substances occurring in the atmosphere that may result in adverse effects to humans, animals, vegetation, and/or materials. (See also air pollution.)
Air Pollution - The presence of contaminants or pollutant substances in the air that interfere with human health or welfare, or produce other harmful environmental effects.
Air Pollution Control Device - Mechanism or equipment that cleans emissions generated by a source (e.g. an incinerator, industrial smokestack, or an automobile exhaust system) by removing pollutants that would otherwise be released to the atmosphere.
Air Pollution Control District (APCD): A county agency with authority to regulate stationary, indirect, and area sources of air pollution (e.g., power plants, highway construction, and housing developments) within a given county, and governed by a district air pollution control board composed of the elected county supervisors. (See also air quality management district). For more information, click here.
Air pressure: the pressure exerted by the air. This may refer to static (atmospheric) pressure, or dynamic components of pressure arising from air flow, or both acting together.
Air Sealing Also known as "house doctoring," air sealing is a systematic approach to "tightening" a dwelling unit's heated envelope (building shell) to reduce uncontrolled heat loss through air leakage points present in the shell. The prevalent technique is to perform this tightening from the interior of the home. Trained workers seal the air leakage points using a variety of materials, such as insulation, caulk, foam, vapor barriers, and weather-strip. Air leakage identification is usually aided by using diagnostic equipment like blower doors and infrared scanners, since many leakage point are not obvious to the naked eye. Part of the air sealing protocol includes testing to ensure that the building envelope is not sealed too tightly. Over-tightening can result in health and safety problems for the occupants, including back drafting of combustion equipment (furnaces, hot water heaters) and moisture condensation causing mold and mildew on surfaces.

Air Quality Index (AQI): A numerical index used for reporting severity of air pollution levels to the public. It replaces the formerly used Pollutant Standards Index (PSI). Like the PSI, the AQI incorporates five criteria pollutants -- ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide -- into a single index. The new index also incorporates the 8-hour ozone standard and the 24-hour PM2.5 standard into the index calculation. AQI levels range from 0 (Good air quality) to 500 (Hazardous air quality). The higher the index, the higher the level of pollutants and the greater the likelihood of health effects. The AQI incorporates an additional index category -- unhealthy for sensitive groups -- that ranges from 101 to 150. In addition, the AQI comes with more detailed cautions.

Air Quality Management District (AQMD): A group of counties or portions of counties, or an individual county specified in law with authority to regulate stationary, indirect, and area sources of air pollution within the region and governed by a regional air pollution control board comprised mostly of elected officials from within the region. (See also air pollution control district).
Air Quality Management Plan (AQMP): A plan prepared by an APCD / AQMD, for a county or region designated as a nonattainment area, for the purpose of bringing the area into compliance with the requirements of the national and / or California ambient air quality standards. AQMPs are incorporated into the State Implementation Plan (SIP).
Air Quality Manager: An individual employed by the local, state, or federal government to manage air quality.
Air Quality Simulation Model: A mathematical relationship between emissions and air quality which simulates on a computer the transport, dispersion, and transformation of compounds emitted into the air.
Air Quality Standard (AQS): The prescribed level of a pollutant in the outsideair that should not be exceeded during a specific time period to protect public health. Established by both federal and state governments. (See also ambient air quality standards
Air sealing: the practice of sealing unintentional gaps in the building envelope (from the interior) in order to reduce uncontrolled air leakage.
Air Quality Standards - The level of pollutants prescribed by regulations that are not being exceeded during a given time in a defined area.
Air Quality Working Groups (AQWG): Advisory groups that provide forums for communication, cooperation, and coordination in the development and implementation of air quality control measures. They may be comprised of representatives from the ARB, citizen groups, environmental groups, industry, local air districts, and the U.S. EPA.
Air Resources Board: (See California Air Resources Board.)
Airshed: A subset of air basin, the term denotes a geographical area that shares the same air because of topography, meteorology, and climate.
Air tightness: the degree to which unintentional openings have been avoided in a building's structure.

Air Toxics: A generic term referring to a harmful chemical or group of chemicals in the air. Substances that are especially harmful to health, such as those considered under U.S. EPA's hazardous air pollutant program or California's AB 1807 and / or AB 2588 air toxics programs, are considered to be air toxics. Technically, any compound that is in the air and has the potential to produce adverse health effects is an air toxic.
Airborne Particulates - Total suspended particulate matter found in the atmosphere as solid particles or liquid droplets. Chemical composition of particulates varies widely, depending on location and time of year. Sources of airborne particulates include dust, emissions from industrial processes, combustion products from the burning of wood and coal, combustion products associated with motor vehicle or non-road engine exhausts, and reactions to gases in the atmosphere.
Allergen
An allergen is a normal substance that causes an acute defensive reaction in a person's immune system. Common allergens are pet dander, smoke, and pollen, although the list of possible allergens is long and varied. When a person has a reaction to an allergen that person is said to be allergic to it.
Allergic respiratory disease. Allergy resulting from inhaled substances affecting the respiratory system.
Allergy. A state of immunologically mediated hypersensitivity to a foreign material that is inhaled, ingested, or touched.
Alternative Fuels - Fuels that can replace ordinary gasoline, such as compressed natural gas (CNG), alcohols, liquefied petroleum gas (LPG), and electricity. Alternative fuels may have particularly desirable energy efficiency and pollution reduction features. The 1990 Clean Air Act encourages development and sale of alternative fuels.
Ambient Lighting Lighting spread throughout the lighted space for safety, security, and aesthetics.
Ampere A unit of measure for the flow of electric current
ANIMAL DANDER: Tiny scales of dead animal skin.
ALLERGEN: A substance capable of causing an allergic reaction because of an individual's sensitivity to that substance.
ALLERGIC RHINITIS: Inflammation of the mucous membranes in the nose that is caused by an allergic reaction.
ANTIMICROBIAL: Agent that kills microbial growth. See "disinfectant," "sanitizer," and "sterilizer."
Annual Fuel Utilization Efficiency (AFUE) A laboratory-derived efficiency for heating appliances that accounts for chimney losses, jacket losses, and cycling losses, but not distribution losses or fan/pump energy.
Annual Return The yearly savings divided by the initial cost needed to achieve the savings, expressed as a percent.
Asbestos A material made of sharp mineral fibers that damage lung and other bodily tissues.
ASHRAE - American Society of Heating, Refrigeration, and Air Conditioning Engineers
ASTM - American Society for Testing and Materials A nonprofit organization that provides a forum for producers, consumers, and representatives of government and industry, to write laboratory test standards for materials, products, systems, and services. ASTM publishes standard test methods, specifications, practices, guides, classifications, and terminology
Atopic asthma. Asthma characterized by atopy.
Atopy. The state of having one or more of a defined group of diseases-allergic rhinoconjunctivitis, allergic asthma, and atopic dermatitis-that are caused by a genetic propensity to produce immunoglobulin E (IgE) antibodies to environmental allergens encountered through inhalation, ingestion, and possibly, skin contact. A broader definition, sometimes used for epidemiologic studies, requires only the presence of IgE antibody, regardless of allergic disease.
Ambient Air - Any unconfined portion of the atmosphere open air, surrounding air.
Air Toxics: A generic term referring to a harmful chemical or group of chemicals in the air. Substances that are especially harmful to health, such as those considered under U.S. EPA's hazardous air pollutant program or California's AB 1807 and / or AB 2588 air toxics programs, are considered to be air toxics. Technically, any compound that is in the air and has the potential to produce adverse health effects is an air toxic. For more information, click here.
Albedo: The proportion of the global solar radiation that is reflected by the surface of the Earth. Will clearly vary with materials and topography.
Altitude angle: the angular height of above the horizon, i.e. the solar altitude is the angle between the centre of the sun and the horizon.
Ambient air: Generally, the air surrounding an object or building.
Ambient temperature: See: Air Ambient
Ammonia (NH3): A pungent colorless gaseous compound of nitrogen and hydrogen that is very soluble in water and can easily be condensed into a liquid by cold and pressure. Ammonia reacts with NOx to form ammonium nitrate -- a major PM2.5 component in the Western United States.
Anaerobic Decomposition - Decomposition of cellulose and proteins occurring in the absence of oxygen, such as in landfill waste, producing methane and carbon dioxide. Anaerobic bioreactors increase the rate of methane generation, which can then be collected and used for energy recovery.
Anemometer: Instrument to measure the air speed; Common electrical types are hot wire or and the hot-body anemometers. The principle used is to apply a fixed electrical current to a wire and the voltage over the wire is measured. The current heats the wire. Moving air cools the wire, decreasing the electrical resistance. This change is measured through the voltage across the wire.
Annual Consumption
Annual consumption refers to the amount of electricity used by a consumer in one year and is typically measured in kilowatt-hours (kWh). This information can be acquired from your electricity bill or by contacting your energy provider.
ANSI: American National Standards Institute
Area Sources: Those sources for which a methodology is used to estimate emissions. This can include area-wide, mobile and natural sources, and also groups of stationary sources (such as dry cleaners and gas stations). The California Clean Air Act requires air districts to include area sources in the development and implementation of the AQMP. In the California emission inventory all sources which are not reported as individual point sources are included as area sources. The federal air toxics program defines a source that emits less than 10 tons per year of a single hazardous air pollutant (HAP) or 25 tons per year of all HAPs as an area source.
Area-Wide Sources: Sources of pollution where the emissions are spread over a wide area, such as consumer products, fireplaces, road dust and farming operations. Area-wide sources do not include mobile sources or stationary sources
Anthracite: A hard, black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and low percentage of volatile matter.

Arsenic is a highly poisonous semi-metallic element. According to a 1999 study by the National Academy of Sciences, arsenic can cause bladder, lung, and skin cancer and may cause kidney and liver cancer. The study also found that arsenic harms the central and peripheral nervous systems, as well as heart and blood vessels, and causes serious skin problems. It also may cause birth defects and reproductive problems. These health impacts are caused when arsenic contaminates drinking water supplies. It enters water supplies either from natural deposits in the earth or from industrial and agricultural pollution.
Aromatic: A type of hydrocarbon, such as benzene or toluene. Some aromatics are toxic.
Asbestos: A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. The U.S. EPA has banned or severely restricted its use in manufacturing and construction and the ARB has imposed limits on the amount of asbestos in serpentine rock that is used for surfacing applications.
ASHRAE: The American Society of Heating Ventilating and Air-conditioning Engineers, based in Atlanta Georgia, USA.
"ASHRAE scale: a set of seven descriptors of subjective warmth. Usual wording is: Cold (-3), cool (-2), slightly cool (-1), neutral (0), slightly warm (+1), warm (+2), and hot (+3).
"ASHRAE/ANSI Standard 55: A temperature standard proposed by the American Society of Heating, Refrigeration and Air-conditioning Engineers formerly based on the Gagge's Standard Effective Temperature, but due to come in line with ISO7730 (see below) in using Fanger's PMV/PPD.
Ash: Impurities consisting of silica, iron, alumina, and other noncombustible matter that are contained in coal. Ash increases the weight of coal, adds to the cost of handling, and can affect its burning characteristics. Ash content is measured as a percent by weight of coal on an "as received" or a "dry" (moisture-free, usually part of a laboratory analysis) basis.
Asthma. A usually chronic inflammatory disorder of the airways characterized by intermittent episodes of wheezing, coughing, and difficulty in breathing, sometimes caused by an allergy to inhaled substances.
Attic Insulation
The installation of approved insulation products (rockwool, fiberglass, and cellulose) evenly across the unconditioned attic area to achieve desired levels of thermal resistance. Insulation products have manufacturer rated "R" levels (resistance to heat loss measurements). The more inches of insulation installed the higher the resistance level. The recommended "R" values vary by climatic regions of the country. It is common for weatherization programs to install a minimum of R-19 or as much as R-38 in colder regions. The cost-effective level of insulation to be added, if any, depends on the existing level of insulation in the attic. Auditors determined the amount of insulation to be added through prescriptive lists or energy audit programs that calculate the saving to investment ratio from increasing insulation levels.
Attic Preparation
This refers to the protocol for inspecting and preparing an attic area for the installation of insulation. The preparatory work is directed primarily to air infiltration and safety issues. Some of the protocols include placing barriers around heat-producing sources in the attic (electrical junction boxes, recessed lights, etc.); placing chutes by the eaves to prevent the insulation from blocking needed air ventilation paths; and sealing bypasses and other penetrations between the heated space and the unconditioned attic area.
Atmosphere: The gaseous mass or envelope of air surrounding the Earth. From ground-level up, the atmosphere is further subdivided into the troposphere, stratosphere, mesosphere, and the thermosphere.
Attached sunspace: solar collector that doubles as useful building space also attached greenhouse, solarium. The term 'attached' specifically implies a space that shares one common wall with the associated building, such as a conservatory.
Attainment Area: A geographical area identified to have air quality as good as, or better than, the national and / or California ambient air quality standards (NAAQS / CAAQS). An area may be an attainment area for one pollutant and a nonattainment area for others.
Audit
The process of identifying energy conservation opportunities in buildings.
AWG - American Wire Gauge
Authority to Construct (A/C): A pre-construction permit issued by an air district.
Atmospheric dispersion: the atmosphere's capacity to dilute the concentration of pollutants in the air.
Auxiliary heating: the conventional (i.e. non-solar) contribution to the total load (e.g. gas boiler etc.).
Awning: an exterior, movable and usually flexible sun shading device. Protects by deflecting or diffusing solar radiation at certain angles.
Azimuth angle: The horizontal angle (in degrees) from the North point measured clockwise. Thus North = 0o, East = 90o, South = 180o etc.

B
Back-drafting: Continuous spillage of combustion gases from a combustion appliances
Back-draft Damper: A damper, installed near a fan, that allows air to flow in only one direction.
Backer Rod: Polyethylene foam rope used as a backer for caulking.
Bacteria: Bacteria are microscopic, single-celled organisms that have a cell wall and a specific shape depending on the type of bacteria. Bacteria have no easily identifiable nucleus. There are many types of bacteria, and although many are harmful to humans there are some that actually help.
Baffle: A plate or strip designed to retard or redirect the flow of flue gases.Balance point - The outdoor temperature at which no heating is needed.
Baghouse Filter:- Large fabric bag, usually made of glass fibers, used to eliminate intermediate and large (greater than PM20 in diameter) particles. This device operates like the bag of an electric vacuum cleaner, passing the air and smaller particles while entrapping the la
Balance Heating: This is the result of balancing the airflow of the central heating distribution system so that intake and output air exists at levels to maximize efficiency. The balancing of the distribution system assures that all areas of the home being served by the same heating or cooling system or any zone within the system receive approximately equal heated or cooled air.
Ballast: A coil of wire or electronic device that provides a high starting voltage for a lamp and limits the current flowing through it
Band Joist See: Rim Joist
Base temperature: a fixed temperature in the definition of degree-days.
Banking: A provision in air district permit regulations that allows a facility to accumulate credits for reducing emissions beyond regulatory limits (emission reduction credits) and then use or sell those credits at a later date.
Batt: A narrow blanket of fiberglass insulation, generally 14.5" or 22.5" wide.
Beam or direct radiation: the solar radiation directly from the sun without changed angle or diffusion. Instruments for measuring direct radiation require for practical reasons a wider aperture so the measured radiation also contains radiation from the immediate region of the sky around the sun (called circum solar; see also diffuse radiation).
Bedford scale: A set of seven descriptors of subjective thermal response from Much Too Warm (7), Too Warm (6), Comfortably Warm (5), Comfortable, neither warm nor cool (4), Comfortably Cool (3), Too Cool (2), Much Too Cool (1). This differs from the ASHRAE scale in defining the central three categories as Comfortable.
Best Available Control Measure (BACM): A term used to describe the "best" measures (according to U.S. EPA guidance) for controlling small or dispersed sources of particulate matter and other emissions from sources such as roadway dust, woodstoves, and open burning
Best Available Control Technology (BACT) - An emission limitation based on the maximum degree of emission reduction (considering energy, environmental, and economic impacts) achievable through application of production processes and available methods, systems, and techniques. BACT does not permit emissions in excess of those allowed under any applicable Clean Air Act provisions. Use of the BACT concept is allowable on a case-by-case basis for major new or modified emissions sources in attainment areas and applies to each regulated pollutant.
Best Available Retrofit Technology (BART) - Under NAAQS, EPA requires states to make a BART analysis to predict the effect of forcing all plants to install scrubbers. States must then either carry out the forced scrubbing program, or create a state cap and trade system.
BHR: Bronchial hyper-responsiveness. Describes airways that narrow too easily or too much in response to a provoking stimulus.
Bimetal Element: A metal spring, lever, or disc made of two dissimilar metals that expand and contract at different rates as the temperature around them changes. This movement operates a switch in the control circuit of a heating or cooling device.
BIOLOGICAL CONTAMINANTS: Agents derived from, or that are, living organisms (e.g., viruses, bacteria, fungi, and mammal and bird antigens) that can be inhaled and can cause many types of health effects including allergic reactions, respiratory disorders, hypersensitivity diseases, and infectious diseases. Also referred to as "microbiologicals" or "microbials."
Bioaccumulants - Substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted.
Bioactivation enzymes: are produced in cells and are capable of speeding up chemical reactions necessary for life. When affected by toxins these enzymes can malfunction and produce reactive metabolites.
Biogenic Source: Biological sources such as plants and animals that emit air pollutants such as volatile organic compounds. Examples of biogenic sources include animal management operations, and oak and pine tree forests. (See also natural sources.) For more information, click here.
Biohazard
The term "Biohazard" is used to describe any time of biological waste. Often, this biological waste is pathogenic in nature or contaminated in some way.
Bitumun: input definition
Bituminous Coal: The most common coal. It is dense and black (often with well-defined bands of bright and full material). Its moisture content usually is less than 20 percent. It is used for generating electricity, making coke, and space heating. Comprises five groups classified according to the following ASTM Specification D388-84.
LV = Low volatile bituminous coal
= Medium volatile bituminous coal
A = High volatile A bituminous coal
B = High volatile B bituminous coal
C = High volatile C bituminous coal
Black Wall
The Black Wall is an occurrence common with ionizing air purifiers. The "Black Wall Effect" happens when the air around an ionizer becomes negatively charged. This negatively charged area causes air borne particles to stick to surrounding surfaces (often the wall behind the device) and cause a build up of dirt and bacteria. Black Wall can be a breeding ground for microscopic organisms.
Boiler: A device for generating steam for power, processing, or heating purposes or for producing hot water for heating purposes or hot water supply. Heat from an external combustion source is transmitted to a fluid contained within the tubes in the boiler shell. This fluid is delivered to an end-use at a desired pressure, temperature, and quality.
Boiling Points of Hydrocarbons: Differences in the size, shape and weight of hydrocarbons mean that they have different reaction properties, including the temperature at which they boil or the "boiling point." Generally, the larger the hydrocarbon, the heavier it is and the more energy it will take to boil. Using these differences in boiling points and weights, fossil fuel can be separated into their various parts within distillation towers. (also see absorption and adsorption)
Biogenic Source: Biological sources such as plants and animals that emit air pollutants such as volatile organic compounds. Examples of biogenic sources include animal management operations, and oak and pine tree forests. (See also natural sources.) For more information, click here.
Black body: a perfect absorber and emitter of electromagnetic radiation (light, heat etc). A black body absorbs all radiation without any reflection (see also absorption). A cavity is a perfect black body. Lampblack is close to a black body , while aluminium (polished) is a poor absorber and eminer of radiation.
Blower Door
A blower door is a diagnostic tool used to locate the points of infiltration in the building envelope and help prioritize the air sealing protocols. This device can be mounted in an exterior door or window opening. The blower door uses a calibrated, powerful, variable speed fan to pressurize or depressurize the dwelling. Its adjustable frame allows the fan assembly to fit snugly in most frames. Air movement and pressure differentials are measured using a set of gauges attached to the frame and fan. These calculations of air movement allow technician to quantify the level of leakage. Such leakage measurements are usually expressed in terms of equivalent leakage area (ELA), air changes per hour (ACH), and cubic feet per minute of airflow (CFM). Any one or more of these measurements can help determine levels of air leakage, indoor air quality, and amount of sealing work to be performed. In addition to measuring air movement, the blower door will exaggerate the leakage points in the building shell for easy identification. This diagnostic tool, when used in conjunction with an infrared scanner, produces even more accurate results.

Blow-Down: The act of removing water from a boiler to remove sediment and suspended particles.
Blower Fan: The squirrel-cage fan in a furnace or air handler.
Boiler: A fossil fuel appliance used for producing hot water or steam as the medium to distribute heat to the dwelling unit.
Boot: A duct section that connects between a duct and a register or between round and square ducts
Branch Circuit: An electrical circuit used to power outlets and lights within a home.
BREATHING ZONE: Area of a room in which occupants breathe as they stand, sit, or lie down.
Brightness: The intensity of the sensation derived from viewing a lit surface. Measured in footlamberts, it is also called luminance or luminous intensity.
Bright sunshine: sunshine above a certain level sufficient to be registered on a Campbell-Stokes sunshine recorder .The threshold is imprecisely defined and varies according to the type of recorder, but generally refers to sunshine bright enough to cast a shadow. Burning typically starts when the beam intensity is 200W /m2.g
British Thermal Unit (Btu): The quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit.
Brownian motion. The random motion of microscopic particles suspended in a liquid or gas, caused by collision with molecules of the surrounding medium. Also called "Brownian movement."
BSI: British Standards Institute
Building Cavities
The spaces inside walls, floors, and ceilings between the interior and exterior sheeting
Building Envelope
The area of the building that encloses conditioned space. Only the exterior four walls to the ceiling under the attic and the floor above the unheated basement area are considered part of the building envelope. The floor of a unit that is built on stilts or is above an unheated crawl space is considered a part of the building envelope. The roof of a building that has no ceilings (or that is part of the ceiling) is considered part of the building envelope.
Building orientation: Orientation of tihe building, generally used to refer to solar orientation which is the siting of building with respect to solar access. Although any building will have different orientations for its different sides, the orientation can refer to a particular room, or to the most important facade of the building.
BUILDING-RELATED ILLNESS (BRI): Diagnosable illness whose symptoms can be identified and whose cause can be directly attributed to airborne building pollutants (e.g., Legionnaire's disease, hypersensitivity pneumonitis). Also: A discrete, identifiable disease or illness that can be traced to a specific pollutant or source within a building.
Building Science: Branch of science dealing with construction, maintenance, safety, and energy efficiency of buildings.
Burner: A device that facilitates the burning of a fossil fuel, like gas or oil.
C
Calorific value: the energy content per unit mass, per unit volume or released if reacting with usualy oxigen (burned).
Candela (cd) : SI (Standard International) unit of luminous intensity: the candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and has a radiant intensity in that direction of 1/683 watt per steradian. (16th General Conference of Weights and Measures, 1979)
Candela per square metre (cd/m2): SI unit of luminance. (Note: this unit was sometimes called the nit [nt] (name discouraged). Other units of luminance: 10-4 metric, non-SI: Lambert (L)
Coronal Discharge
A type of air purifier that uses ozone to clean the air, a Coronal Discharge device is sometimes referred to as a "thunderstorm in a box". The air inside a coronal discharge device is charged with between 5,000 and 10,000 volts of electricity. The massive shock causes unstable bonds to form between single atoms of oxygen (O) and Oxygen molecules (O2). Ozone then attacks any air borne particles in the surrounding area (O3).
Capture Efficiency: The fraction of organic vapors generated by a process that are directed to an abatement or recovery device.
Carbon Canister Vapor Capture: An automotive filter in which activated carbon has been placed so that gas tank fuel vapors, which have accumulated when the vehicle is not running, are trapped in the filter. When the engine is running, hot air is forced into the filter and pushes out the vapors into the engine. In this way pollution is reduced and fuel conservation is maintained.
Carbon dioxide (CO2): an odorless and colorless gas that's found in the atmosphere, used by plants and expelled by animals. CO2is produced by burning fossil fuels (coal, oil and natural gas) and as a result of deforestation. CO2 is also the primary greenhouse gas (GHG) released by combustion
Carbon Monoxide (CO) - A colorless, odorless, poisonous gas, produced by incomplete burning of carbon-based fuels, including gasoline, oil and wood. Carbon monoxide is also produced from incomplete combustion of many natural and synthetic products. For instance, cigarette smoke contains carbon monoxide. When carbon monoxide gets into the body, the carbon monoxide combines with chemicals in the blood and prevents the blood from bringing oxygen to cells, tissues and organs. The body's parts need oxygen for energy, so high-level exposures to carbon monoxide can cause serious health effects, with death possible from massive exposures. Symptoms of exposure to carbon monoxide can include vision problems, reduced alertness, and general reduction in mental and physical functions. Carbon monoxide exposures are especially harmful to people with heart, lung and circulatory system diseases.
Cardiovascular Diseases - A group of diseases of the blood vessels that includes coronary heart disease, stroke, and hypertension.
Casing: Exposed molding or trim around a window or door.
Casual gain: see internal gains
Catalytic Converter - An air pollution abatement device that removes pollutants from motor vehicle exhaust, either by oxidizing them into carbon dioxide and water or reducing them to nitrogen.
Catalytic Incinerator - A control device that oxidizes volatile organic compounds (VOCs) by using a catalyst to promote the combustion process. Catalytic incinerators require lower temperatures than conventional thermal incinerators, thus saving fuel and other costs.
CEILING PLENUM: Space below the flooring and above the suspended ceiling that accommodates the mechanical and electrical equipment and that is used as part of the air distribution system. The space is kept under negative pressure.
Centrifugal Collector - A mechanical system using centrifugal force to remove aerosols from a gas stream or to remove water from sludge.
Catalyst: a substance or condition that is necessary or enhances a chemical reaction process but is not chemically involved or altered by the reaction.
CCME - Canadian Council of Ministers of the Environment
Cellulose Insulation: Insulation, packaged in bags for blowing, made from newspaper or wood waste and treated with a fire retardant
CEN: The European Standards Institution
Centigrade: A temperature scale on which water freezes at 0 degrees and boils at 100 degrees
Central Heating System: This refers to the primary heating system of the dwelling unit including the heat producing appliance, the return and supply system for heat distribution, and ducts or pipes for flue gas ventilation. Central heating systems usually do not include wood stoves, kerosene heaters, space heaters, and electric baseboard heating units.
CEPA 1999: Canadian Environmental Protection Act, 1999. An Act that respects the prevention of pollution and the protection of the environment and human health in an effort to contribute to sustainable development.
CFCs (chlorofluorocarbons): Chemicals used in industry for refrigeration and air conditioning, and in consumer products. CFCs and their relatives, when released into the air, rise into the stratosphere, a layer of the atmosphere high above the Earth. In the stratosphere, CFCs and their relatives take part in chemical reactions which result in reduction of the stratospheric ozone layer, which protects the Earth's surface from harmful effects of radiation from the sun. The 1990 Clean Air Act includes provisions for reducing releases (emissions) and eliminating production and use of these ozone-destroying chemicals.
Chemical mediators: are a group of chemical compounds (proteins, mostly) that help to cause inflammation.
CFM50: This term means the amount of cubic feet per minute of air moving through a structure and measured at 50-pascal pressure.
CFMn: The cubic feet of air flowing through a house from indoors to outdoors during typical, natural conditions. This figure can be roughly estimated using a blower door.
CFM Per Person or Per Room: An estimate of the cubic feet per minute of fresh air available or required per occupant or per room.
CFM - Cubic Feet per Minute
Usually seen as CFM 50, cubic feet per minute of air movement due to 50 pascal house/outdoor pressure differential.
Chemisorption. The assimilation of gas, vapor, or dissolved matter by the surface of another substance resulting from electron transfer and a bond-forming chemical reaction between the surface and the gas, vapor, or dissolved matter.
CHEMICAL SENSITIZATION: Evidence suggests that some people may develop health problems characterized by effects such as dizziness, eye and throat irritation, chest tightness, and nasal congestion that appear whenever they are exposed to certain chemicals. People may react to even trace amounts of chemicals to which they have become "sensitized."
Chimney effect: see stack effect
Chronic bronchitis: is inflammation of the smaller airways in the lung usually caused by bacterial or viral infection.
Chronic obstructive pulmonary disease (COPD): is a disease with shortness of breath, cough and sputum production most commonly caused by chronic bronchitis and emphysema. Bronchitis is inflammation of the smaller airways in the lung usually caused by bacterial or viral infection. Emphysema is characterized by disabling breathlessness caused by loss of the thin walls dividing the air spaces (alveoli), which reduces the area available for the exchange of oxygen and carbon dioxide.
CIBSE: The Chartered Institution of Building Services Engineers.
CIE Standard Overcast Sky: completely overcast sky for which the ratio of its luminance Ly in the direction at an angle X above the horizon to its luminance Lz at the zenith is given by the relation Ly=Lz(1+2sinX)/3
CIE standard sources: artificial sources specified by the CIE, whose radiations approximate CIE standard illuminants A, B and C, (see CIE Publication N015).
Circuit Breaker: A device found in a Circuit Panel Box that completes an electric circuit. This breaker disconnects the circuit from electricity when it senses an overload of current.
Class I Area - Under the Clean Air Act, an area in which visibility is protected more stringently than under the national ambient air quality standards; includes national parks, wilderness areas, monuments, and other areas of special national and cultural significance.
Clean Air Act - Originally passed in 1963, although the 1970 version of the law is the basis of today's U.S. national air pollution program. The 1990 Clean Air Act Amendments are the most far-reaching revisions of the 1970 law, and are usually referred to as the 1990 Clean Air Act.
Clean Fuels - Low-pollution fuels that can replace ordinary gasoline. These are alternative fuels, including gasohol (gasoline-alcohol mixtures), natural gas and LPG (liquefied petroleum gas).
Clear sky (Standard): cloudless sky for which the relative luminance distribution is described in CIE Publication N022 (1973).
Clear Sky: Cloudless Sky - clear sky in this context has two separate meanings. In the radiation Tables clear sky refers to days producing the mean maximum monthly daily global radiation on a horizontal surface. These days on average contain some cloud but the precise cloud amount is not known. In the temperature Tables, the term clear skies refers to summaries of measured temperature data for days when the mean total amount of cloud during hours of daylight was less then 2/8.Night-time temperature data for such days are related to the same 'clear' days i.e. night-time cloud cover was not taken into account.
Clerestory: a window that is placed vertically (or near vertical) in a wall above one's line of vision to provide natural light in a building.
Climate chamber: A chamber usually in a laboratory in which the environmental conditions can be changed by the experimenter, used to investigate the effects of the thermal environment on subjects.
Clean and Tune (C&T): A procedure performed on a heating system by a licensed furnace service technician to maximize the appliance efficiency using existing hardware. The C&T is usually preceded by a combustion efficiency test to assess whether other conditions exist requiring extensive furnace work. The C&T can involve a variety of activities to upgrade the efficiency and safe operation of the heating system. These can include pilot and burner adjustment, adjustment of ventilation and combustion, check and reset controls, inspect filters, lubricate motors, flush low water cut-off, check operation of steam and water relief valves, check thermostat, check safety valve, and check thermocouple. Climate Change (also referred to as 'global climate change') - Sometimes used to refer to all forms of climatic inconsistency, but because the Earth's climate is never static, the term is more properly used to imply a significant change from one climatic condition to another. In some cases, 'climate change' has been used synonymously with the term, 'global warming'; scientists however, tend to use the term in the wider sense to also include natural changes in climate.
Climate control : The control of the indoor climate.
Clo unit: a unit for the insulating effect of clothing on a person. 1 clo = 0.155 (K.m2)/W.
Clothing insulation: The effective insulation of clothing worn characterized as a single layer covering the whole body surface; measured in Clo Units or K.m2/W
Clothing surface temperature: Average temperature of the surface of the clothes for use in heat
CO: Carbon monoxide is an odorless, colorless and toxic gas. Because it is impossible to see, taste or smell the toxic fumes, CO can kill you before you are aware it is in your home. At lower levels of exposure, CO causes mild effects that are often mistaken for the flu. These symptoms include headaches, dizziness, disorientation, nausea and fatigue. The effects of CO exposure can vary greatly from person to person depending on age, overall health and the concentration and length of exposure.exchange calculations.
CO2: Carbon dioxide.
Coal: A black or brownish-black solid combustible substance formed by the partial decomposition of vegetable matter without access to air. The rank of coal, which includes anthracite, bituminous coal, subbituminous coal, and lignite, is based on fixed carbon, volatile matter, and heating value. Coal rank indicates the progressive alteration from lignite to anthracite. Lignite contains approximately 9 to 17 million Btu per ton. The contents of subbituminous and bituminous coal range from 16 to 24 million Btu per ton and from 19 to 30 million Btu per ton, respectively. Anthracite contains approximately 22 to 28 million Btu per ton.
Coalbed Methane: Most coal deposits contain natural gas adsorbed onto the coal. This gas is known as coalbed methane.
Co-efficient of Performance (COP): A heat pump or air conditioner's output in watt-hours of heat moved divided by watt-hours of electrical input.
Coil : A snake-like piece of copper tubing surrounded by rows of aluminum fins that clamp tightly to the tubing and aid in heat transfer.
Coking: input definition
Cogeneration: also known as Combined Heat and Power (CHP)
Colour rendering: Effect of (not nescessarily white) light on the colour appearance of objects compared to their colour appearance under a reference illuminant.
Colour Rendering Index (R): measure of the degree to which the psychophysical colour of an object illuminated by the test illumihant conforms to that of the same object illuminated by the reference illuminant, suitable allowance having been made for the state of chromatic adaptation.
Color Temperature: A measurement of the warmness or coolness of a light source in the Kelvin temperature scale.
Column: A vertical building support usually made of wood or steel.
COMBINATION FOUNDATIONS: Buildings constructed with more than one foundation type; e.g., basement/crawlspace or basement/slab-on-grade.
Combined Heat and Power: Combined heat and power (CHP), also known as cogeneration, is an efficient, clean, and reliable approach to generating power and thermal energy from a single fuel source. CHP is not a specific technology but an application of technologies to meet an energy user's needs. CHP systems achieve typical effective electric efficiencies of 50 to 80 percent - a dramatic improvement over the average efficiency of separate heat and power. Since CHP is highly efficient, it reduces traditional air pollutants and carbon dioxide, the leading greenhouse gas associated with climate change.
Combustion - Burning of fuels such as coal, oil, gas, and wood. Many important pollutants, such as sulfur dioxide, nitrogen oxides, and particulates (PM-10) are combustion products.
Combustible: Means something will burn, although not necessarily readily.
Combustion Air: Air that chemically combines with a fuel during the combustion process to produce heat and flue gases, mainly carbon dioxide and water vapor.
Combustion Analyzer: A device used to measure steady-state efficiency of combustion heating units.
Combustion Chamber: The area inside the heat exchanger where the flame burns
Combustion Test: This test is performed to determine the efficiency at which a heating appliance is operating at steady state. The actual tests or sequence of tests may vary in conjunction with the type of testing equipment used or the type of heating appliance being tested. Persons performing these tests must be extremely familiar with the testing equipment being used and must be trained in conducting the tests. In some states, a license is required to perform such tests.
Comfort chart: a chart showing effective temperatures with dry-bulb temperatures and humidities (and sometimes air movement), by which the effects of various thermal conditions on human comfort may be compared.
Comfort line: a line on the comfort chart showing relation between the effective temperature and the percentage of adults feeling comfortable.
Comfort temperature (neutral temperature): 1)The temperature (or environment) judged by a population to be neutral on the ASHRAE scale, or Comfortable, Neither Warm Nor Cool on the Bedford scale: assumed by most workers in the field to be the desired temperature or 2) the temperature at which the greatest number of people feel comfortable
Comfort vote: The subjective response given by a subject on a comfort scale such as the ASHRAE or Bedford scales (see above).
Comfort zone: The range of temperature within which a subject will feel comfortable, though not necessarily neutral.
Commercial Energy Customer: A commercial energy customer refers to non-industrial customers occupying retail space or office buildings.
COMMISSIONING: Start-up of a building that includes testing and adjusting HVAC, electrical, plumbing, and other systems to assure proper functioning and adherence to design criteria. Commissioning also includes the instruction of building representatives in the use of the building systems.
Competitive Markets: Until recently, most consumers received generation, transmission, and distribution services from one local utility company. As a regulated monopoly, the utility was given an exclusive franchise to provide electricity to consumers in any particular community. Rates were set, and consumers had little choice but to pay that rate. In recent years, however, many states have restructured their electricity industry and are now allowing consumers to choose from among competing electricity suppliers.
In these states with retail competition, sellers of electricity obtain power by contracting with various generation sources and setting their own price. Consumers in these states have the opportunity to choose their energy provider and purchase products based on the price or type of power supplied to their home or business. Some consumers are exercising this choice and switching to accredited "green power" resources. In states that have not restructured their electricity markets, consumers interested in purchasing renewable energy now have the option to participate in green pricing programs offered by their local utility.
Compressor: A motorized pump that compresses the gaseous refrigerant and sends it to the condenser where heat is released.
Computer Controlled Air/Fuel Management System: Maintains the air/fuel ratio in the correct operating range needed for complete combustion without an excess of either air or fuel, resulting in low engine-out emissions and maximized catalyst performance.
Concentration - The relative amount of a substance mixed with another substance. Examples are 5 ppm of carbon monoxide in air and 1 mg/l of iron in water.
Condense: When a gas turns into a liquid as it cools, it condenses. Condensation is the opposite of evaporation. When a gas condenses into a liquid it releases heat.
Condenser: The coil in an air conditioning system where the refrigerant condenses and releases heat, that is carried away by air moving through the coil.
Condensate: Vapor condensed back to a liquid.
Condensate Receiver: A tank for catching returning condensate water from a steam heating system.
Condensation: condensed liquid - in this context beads, drops or a film of water (or frost) that accumulates on the inside of facade elements, roofs or floors (usually on windows) when warm, moisture air from the interior reaches a point where the temperature (the 'dew point') no longer permits the air to sustain the moisture it holds.
Conditioned: Intentionally heated or cooled areas of a building
CONDITIONED AIR: Air that has been heated, cooled, humidified, or dehumidified to maintain an interior space within the "comfort zone." (Sometimes referred to as "tempered" air.)
Conductance: The property of a material to conduct some energy form like heat or electricity.
Conduction: the heat moving from a warmer to a colder region in the same substance without mass transfer, this type of heat transfer depends on the thermal conductivity of the material [measured in W/m2.K].
Conductive heat transfer : Process of conduction through a material. Materials like copper or silver are good conductors.
CONSTANT AIR VOLUME SYSTEMS: Air handling system that provides a constant air flow while varying the temperature to meet heating and cooling needs.
Constraints: factors in the physical or social environment which prevent people from taking actions to achieve thermal comfort.
Contaminant - Any physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil
Continuous Emission Monitoring Systems (CEMS) - Machines that measure, on a continuous basis, pollutants released by a source. The 1990 Clean Air Act requires continuous emission monitoring systems for certain large sources.
Contrast: Difference in brightness measured by the relationship between an object's brightness and the brightness of its background.
Control Circuit: A circuit whose work is switching a power circuit or opening an automatic valve.
Control Technology; Control Measures - Equipment, processes or actions used to reduce air pollution. The extent of pollution reduction varies among technologies and measures. In general, control technologies and measures that do the best job of reducing pollution will be required in the areas with the worst pollution. For example, Best Available Control Technology/Best Available Control Measures (BACT/ BACM) are required in serious nonattainment areas for particulates, a criteria air pollutant. A similar high level of pollution reduction will be achieved with maximum achievable control technology (MACT) that will be required for sources releasing hazardous air pollutants.
Controlled ventilation: ventilation brought about by mechanical means through pressure differentials induced by the operation of a fan.
Convection: heat transfer between a surface and adjacent fluid (usually air or water) and by the flow of fluid from one place to another. See also Forced convection, Natural convection.
Convective heat transfer : Process of heat transport by convective flow. With free convection the flow is caused by temperature differences is the liquid or gas. For example the air inside double glazing transports heat due to natural convection: the glazing layer on the inside is warmer than the one on the outside; the air inside the cavity moves because of this temperature difference and transports the heat. With forced convection energy is transferred due to a mechanically driven gas flow or liquid flow.
Convector: an agency of convection. In heat transfer, a surface designed to transfer its heat to a surrounding fluid largely or wholly by convection. The heated fluid may be removed mechanically or by natural convection (gravity convector). Such a surface may or may not be enclosed or concealed. Apparatus for heating, in which the heat is passed on to the room by convection, due to natural air movement sometimes helped by a fan.
Cooling: The process of active heat extraction for the benefit of climate control. see also direct cooling, evaporative cooling, indirect cooling, regenerastive cooling, surface cooling.
Cooling effect, sensible: difference between the total cooling effect and the dehumidifying effect, usually in watts.
Cooling effect, total: difference between the total enthalpy of the dry air and water vapour mixture entering the cooler per hour and the total enthalpy of the dry air and water vapour mixture leaving the cooler per hour , expressed in watts.
Cooling element: heat transfer surface containing refrigeration f1uid where refrigerating effect is desired.
Cooling load: The thermal energy extracted from a building to maintain a pre-determined indoor setpoint temperature.
Cooling medium: any substance whose temperature is such that it is used, with or without a change of state, to lower the temperature of other bodies or substances.
Cooling range: in a water cooling device, the difference between the average temperatures of water entering or leaving the device.
Cooling water: water for condensation of refrigerant; condenser water
COPD. Chronic Obstructive Pulmonary Disease.
Core temperature (deep body temperature): The temperature of the internal organs of the body, especially the brain, on the basis of which the thermoregulatory system of the body is controlled.
Correlation:: An indication of the strength of the relationship between two variables characterised by the correlation coefficient (r). The value of r varies between zero (no relationship) and one (linear or exact relationship).
Corresponding values: values of parameters corresponding to other parameters.
Counterflow: flow in the opposite direction in heat exchange between two fluids; the coldest portion of one meeting the coldest portion of the other.
Cracking: input definition
Creosote: a highly flammable tar-like oily deposit that is produced by slow-burning fires.
Criteria Air Pollutants - The 1970 amendments to the Clean Air Act required EPA to set National Ambient Air Quality Standards for certain pollutants known to be hazardous to human health. EPA has identified and set standards to protect human health and welfare for six pollutants ozone, carbon monoxide, total suspended particulates, sulfur dioxide, lead, and nitrogen oxide. The term, "criteria pollutants" derives from the requirement that EPA must describe the characteristics and potential health and welfare effects of these pollutants. It is on the basis of these criteria that standards are set or revised.
Critical temperature: the saturation temperature corresponding to the critical state of the substance at which the properties of the liquid and vapour are identical
Cross Section: A view of a building component drawn or imagined by cutting through the component.
Cross ventilation: flow of air through a building caused by wind-generated pressure drop across it.
Crude Oil: A naturally occurring mixture of hydrocarbons trapped in underground rock formations. Crude oil can be refined into many products such as transportation fuels (gasoline and diesel), heating oil, asphalt, petrochemicals and plastics.
Crude Bitumen: A mixture of hydrocarbons that is semi-solid. Alberta's oil sands are rich in bitumen, and are the world's largest source.
Curtailment Programs - Restrictions on operation of fireplaces and woodstoves in areas where these home heat sources make major contributions to pollution
CSA: the Canadian Standards Association. A not-for-profit association that develops standards to enhance public safety and health and preserve the environment.
CSBG - Community Services Block Grant: The Community Services Block Grant (CSBG) is federal, anti-poverty block grant which funds the operations of a state-administered network of local agencies. This CSBG network consists of more than 1,100 agencies that create, coordinate and deliver programs and services to low-income Americans in 96% of the nation's counties.
Most agencies in the CSBG network are Community Action Agencies (CAAs), created through the Economic Opportunity Act, a predecessor of the CSBG. Community representation and accountability are hallmarks of the CSBG network, where agencies are governed by a tri-partite board. This structure consists of elected public officials, representatives of the low-income communtiy, and appointed leaders from the private sector. Because the CSBG funds the central management and core activities of these agencies, the CSBG network is able to mobilize additional resources to combat the central causes of poverty.
Cubic Foot Per Minute (CFM): A measurement of air movement past a certain point or through a certain structure
Curtain Wall: A wall between columns and beams that supports no weight but its own
Customer Certification: A final determination concerning program eligibility based on income and ownership, resulting in the customer's receipt or denial of WAP benefits.
CWS: Canada Wide Standards. Standards for environmental contaminants or issues developed with the participation of industry, municipal, environmental, health and aboriginal groups after the Environment Ministers have jointly agreed on priorities for these standards.
Cyclone Collector - A device that uses centrifugal force to remove large particles from polluted air