Gabion:  Galvanized wire box filled with stones used to form retaining walls along a stream or bridge.

Gable: The triangular section of an end wall formed by the pitch of the roof.

Gable End: An end wall having a gable.

Gable Roof: A type of roof with sloping planes of the same pitch on each side of the ridge. Has a gable at each end.

GACT (Generally Available Control Technology): Methods, practices and techniques which are commercially available and appropriate considering economic impacts and the technical capabilities of the firms to operate and maintain the emissions control systems. Under Title III of the CAAA, EPA will establish either GACT or MACT standards for each source of HAPs.

Gage:  An instrument for measuring pressure.

Gage Pressure:  Pressure measured with respect to atmospheric pressure.

Galling:  A form of wear in which seizing or tearing of the gear or bearing surface occurs.

Gallon:  A unit of volume. A US gallon has 231 cubic inches or 3,785 liters.

Gallons per Minute (gpm):  This is a measurement of the quantity of water flowing through a pipe. The design specifications of water spray and sprinkler systems are based on the quantity of water flowing through the pipes and out of the nozzles.

Galvanic Action:  The corroding action of  two unlike metals due to elec­trical current passing between them.

Galvanic Corrosion:  Corrosion that occurs when two different metals that are in contact with moisture (especially salt water) form an electric circuit.

Galvanize: To coat a metal with zinc by dipping it in molten zinc after cleaning.

Galvanized Steel:  Steel that is treated with zinc to protect it from corrosion.

GAMA:  Gas Appliance Manufacturers Association.

Gamma Ray:  High-energy, short-wavelength, electromagnetic radiation emitted from the nucleus of an atom, frequently accompanying the emission of alpha or beta particles.

Gamma-rays:  Gamma-rays are electromagnetic waves produced by spontaneous decay of radioactive elements during de-excitation of an atomic nucleus. Sunlight also consists of electromagnetic waves but gamma-rays have a shorter wavelength and much higher energy. High-energy gamma-rays such as those produced by decay of cesium-137 may penetrate deeply into the body and affect cells. Gamma-rays from a cobalt-60 source are often used for cancer radiotherapy.

Gambrel Roof: A type of roof which has its slope broken by an obtuse angle, so that the lower slope is steeper than the upper slope. A double sloped roof having two pitches.

Gang Nail Plate: A steel plate attached to both sides at each joint of a truss. Sometimes called a Fishplate or Gusset.

Garbage In Garbage Out (GIGO):  This term refers to the fact that computers will process nonsensical, faulty or incomplete input data and produce nonsensical, faulty or incomplete output.

Garments:  Special cleanroom apparel made of synthetic fiber, such as nylon, Tyvek or Dacron that are lint-free and limit contamination from personnel.

Gas: A fuel burned in boilers and by internal combustion engines for electric generation. These include natural, manufactured, and waste gas.

Gas Bearings:  Are load carrying machine elements permitting some degree of motion in which the lubricant is air or some other gas.

Gas Bypass:  A portion of the discharge gas is redirected through a heat exchanger and then expanded back to suction pressure, where it is mixed with normal suction gas stream and commonly used to compensate for process flow demands.

Gas Chromatograph:  An analytical instrument used for quantitative analysis of extremely small quantities of organic compounds whose operation is based upon the absorption and partitioning of a gaseous phase within a column of granular material.

Gas Chromatography:  Analytical process by which chemical mixtures are separated into individual components for quantitative and perhaps qualitative analysis.

Gas Compressor:  A machine that compresses gases. Divided into two groups; process gas compressors and oil and gas field compressors.

Gas Drying:  The drying of compressed gases other than air. Equipment size, choice of materials and other specifications may be decidedly different for drying gases other than air because of the specific properties of the gases. Properties include specific gravity, specific heat, viscosity, thermal conductivity, explosive characteristics, toxicity, corrosion and others.

Gas Furnace:  A forced air system that burns gaseous fuel, such as natural gas and propane, in a heat exchanger.

Gas Furnace Heat Exchanger:  Located in the furnace, the heat exchanger transfers heat to the surrounding air, which is then pumped throughout your home.

Gas Heating System: A heating system that uses natural gas or bottled liquid propane gas as fuel.

Gas Lateral: The trench or area in the yard where the gas line service is located, or the work of installing the gas service to a home.

Gas Laws:  The behavior of perfect gases, or mixtures thereof, follows a set of laws. Boyle’ law, Charle’s law, Amonton’s law, Dalton’s law, Amagat’s law, Avogadro’s law, Poisson’s law.

Gas, Non-Condensable:  Gas that will not form into a liquid under the operating pressure-temperature conditions.

Gas Residence Time:  The calculated time that a contaminant or test agent theoretically remains in contact with an adsorbent, based on active volume of adsorbent and air or gas velocity through the adsorber bed.

Gas Sorption: Devices used to reduce levels of airborne gaseous compounds by passing the air through materials that extract the gases. The performance of solid sorbents is dependent on the airflow rate, concentration of the pollutants, presence of other gases or vapors, and other factors.

Gas Turbine: An engine that uses a compressor to draw air into the engine and compress it. Fuel is added to the air and combusted in a combustor. Hot combustion gases exiting the engine turn a turbine which also turns the compressor. The engine’s power output can be delivered from the compressor or turbine side of the engine.

Gas Turbine Plant: A plant in which the prime mover is a gas turbine. A gas turbine consists typically of an axial-flow air compressor, one or more combustion chambers, where liquid or gaseous fuel is burned and the hot gases are passed to the turbine and where the hot gases expand to drive the generator and are then used to run the compressor.

Gas-fired Absorption Chiller: A natural-gas powered mechanical appliance that supplies chilled water for air-conditioning or for process cooling, as well as hot water for space heating.

Gas-Phase Adsorber Cell:  A gas-phase adsorption filter for single-pass or recirculating air-cleaning systems where removal of gaseous contaminants is required. Also known as Molecular filters.

Gaseous State: One of three states of matter characterized by the greatest freedom of molecules and lack of any inherent fixed shape or volume.

Gases: Normally formless fluids which occupy the space of its enclosure and which can be changed to a liquid or solid state only by the combined effect of increased pressure and decreased temperature. Gasses diffuse.

Gasket: Elastic strip that seals a joint between two materials.

Gasket (Filter):  Material used to prevent air leakage between the filter frame and its holding device.

Gasket, Foam:  Joint sealing material made of rubber or plastic foam strips.

Gasoline Volatility: The evaporative properties of gasoline. Gasoline vapor is a volatile organic compound. (See also Reid Vapor Pressure.)

Gasses:  Individual atoms of molecules spread evenly through the air. They cannot be trapped by ordinary filters. See adsorption.

Gastroenteritis:  An inflammation of the stomach and intestine resulting in diarrhea, with vomiting and cramps when irritation is excessive. When caused by an infectious agent, it is often associated with fever.

Gate Valve:  A type of valve in which the closing element (the gate) is a disc that moves across the stream in a groove or slot for support against pressure. A gate valve has relatively large full ports and a straight line flow pattern. Very little pressure drop however subject to leakage if sealing surfaces are scored or marred or if debris becomes lodged in grove.

Gauge:  An instrument for measuring, testing, or registering.

Gauge Board (Spot Board): Board used to carry grout needed to patch small jobs.

Gauge, High Pressure:  Used for pressure ranges from 0 psig to 500 psig 1101.3 kPa to 3 600 kPa.

Gauge, Low Pressure:  Used for pressure ranges from 0 psia to 50 psia 10 kPa to 350 kPa.

Gauge Manifold:  A Chambered device constructed to hold both compound and high-pressure gauges. Valves control flow of fluids through it.

Gauge Port:  A connection in a system to provided for a service technician to install a gauge.

Gauge Pressure:  Is pressure as determined by most instruments and gauges.

Gauge Vacuum:  An Instrument used to measure pressures below at­mospheric pressure.

Gauntlets:  Gauntlets are similar to safety cuffs but extend further down the arm to provide protection to the lower forearm.

GC:  Gas Chromatography; similar to HPLC except that mobile phase is an inert gas such as helium.

Gelatinous:  Used to describe suspended solids that are slimy and deformable, causing rapid filter plugging.

GEN. SET:  Generator Set. Refers to one or more generators used to provide emergency power to the computer system in the event of a blackout. Generators are usually diesel powered and must be used in conjunction with a UPS. The UPS provides backup power while the generator is starting, rotating up to speed and getting synchronized.

General Contractor: A contractor responsible for all facets of construction of a building or renovation.

General Contractor (Prime Contractor): A contractor responsible for all facets of construction of a building or renovation.

Generating Unit: Any combination of physically connected generator(s), reactor(s), boiler(s), combustion turbine(s), or other prime mover(s) operated together to produce electric power.

Generation (Electricity): The process of producing electric energy by transforming other forms of energy; also, the amount of electric energy produced, expressed in watt-hours (Wh).

Generator: A machine that converts mechanical energy into electrical energy.

Generator Nameplate Capacity: The full-load continuous rating of a generator, prime mover, or other electric power production equipment under specific conditions as designated by the manufacturer. Installed generator nameplate rating is usually indicated on a nameplate physically attached to the generator.

Genuine:  There are many items such as bags, belts, parts and supplies that are used with vacuum cleaners and other appliances. The term “genuine” indicates that the same company that manufactured the original product also manufactured these items. Genuine items may also be referred to as “original” or OEM (Original Equipment Manufacturer) produced. This is opposed to “replacement” bags, belts, parts and supplies that are made by third-party companies. When you choose genuine items you are assured that they meet the same specifications as the original equipment.

Genus:  A grouping of similar species according to taxonomic criteria, for example, humans (Homo sapiens) belong to the genus ‘Homo’ and the species ‘sapiens.’

Geophysical Logging:  A general term for techniques used to infer physical or chemical properties of subsurface strata (e.g. porosity or permeability).  These techniques typically involve lowering a sensing device into a borehole to measure the properties of the strata.

Geoseismic Surveying: Geoseismic (sound) surveying and imaging is a more common and effective method of locating oil and gas reserves. Intense sound waves are sent into the earth from a series of points using dynamite, vibrator trucks, and air guns in water. These sound waves travel through the earth and are reflected back to the surface in different ways depending on the composition of the soils and how deep the rock deposits are located. Monitoring devices record the reflected sounds in terms of their movement patterns and how fast they travel through the earth. Computers can take this information and create multi-dimensional images of the subsurface landscape in order to reveal hidden reservoirs of oil and gas.

Geothermal:  Energy (heat) originating from deep within the Earth.

Geothermal Energy:   Heat energy stored in the earth’s crust by the absorption of solar energy and by conduction with the earth's hot interior.

Geothermal Equipment:  Heat pumps that uses the ground to transfer heat to and from the refrigerant in the unit. The unit circulates water through a heat exchanger into the a closed loop buried in the ground or by pumping water from a well through the unit.

Geothermal Heat:  A technology that utilizes the warmth from subsurface water to heat buildings, and it also extracts this heat to put back into the ground for cooling.

Geothermal Heat Exchange Technology:  In winter, geothermal heat exchange technology utilizes heat from subsurface water and soils to heat buildings; in summer, this technology extracts heat from the building into subsurface water and soils for cooling.

Geothermal System:  A heat pump that uses the ground or water as a heat source or sink. Efficiency is improved over air source heat pumps as the temperature of the ground or water is more constant and moderate than that of the air. Geothermal systems typically incorporate some method to contribute heat to the domestic hot water system.

GERD (Gastroesophageal Reflux Disease): GERD is a chronic disorder in which some of the acid and enzymes that belong in the stomach come up into the esophagus. This leads to the sensation of heartburn and sometimes also an unpleasant sour taste in the mouth. GERD and asthma can make a vicious circle: GERD is more common among people with asthma, and it also seems to make asthma worse in people who have it. Treatment of GERD can lead to an improvement in asthma symptoms.

GFI or GFCI (Ground Fault Circuit Interrupters): Special devices capable of opening a circuit when even a small amount of current is flowing through the grounding system.

GFRC (Glass Fiber Reinforced Concrete): Material used in wall systems that resembles but generally does not perform as well as concrete. Usually a thin cementitious material laminated to plywood or other lightweight backing.

Gigatonne (Gt): One Gigatonne is equivalent to a billion tonnes.

Gigawatt (GW): One billion watts.

Gigawatthour (GWh): One billion watt-hours.

Girder: A main beam upon which floor joists rest. Used to support concentrated loads at isolated points along its length, usually made of steel or wood.

Girdle: A large principal beam made of steel, reinforced concrete, wood or combination of these, used to support other structural members at isolated points along its length.

Glare: Condition of vision in which there is discomfort or a reduction in the ability to see details or objects, caused by an unsuitable distribution or range of luminance, or to extreme contrast.

Glare, Disability: Glare that impairs the vision of objects without necessarily causing discomfort.

Glare, Discomfort: Glare that causes discomfort without necessarily impairing the vision of objects.

Glass: A hard, brittle substance, usually transparent, made by fusing silicates under high temperatures with soda, lime, etc.

Glass-Base: Roll roofing product built on a fiberglass base sheet constructed with a heavyweight TAMKO fiberglass mat, coated with weathering-grade asphalt. Used as a base sheet in select TAMKO modified asphalt and fiberglass roofing systems and as an alternate for TAMKO Type 43 Coated Base Sheet in any TAMKO specification. Hot-asphalt applied or mechanically fastened.

Glass Load Factor: A number combining glass's solar heat transmission and its heat conduction. Used for cooling load calculations.

Glass-Seal: 3-tab self-sealing fiberglass shingles with a traditional square-tab design. A thick layer of weathering-grade asphalt gives them extra waterproofing protection. They are U.L. Class A fire rated and backed by a 20-year limited warranty. Algae-resistant granules optional.

Glaze Coat: In roofing, a light uniform mopping of bitumen on exposed felts to protect them from the weather, pending completion of the job.

Glazing: A generic term used to describe an infill material such as glass, panels, etc. Also the process of installing an infill material into a prepared opening in windows, door panels, partitions, etc.

Glazing Bead: In glazing, a strip surrounding the edge of the glass in a window or door which holds the glass in place.

Glazing Channel: In glazing, a three-sided, U-shaped sash detail into which a glass product is installed and retained.

GLC:  Gas Liquid Chromatography.

Glide:  The temperature difference between the starting and ending temperatures of a phase change within a system, exclusive of any subcooling or superheating.

Global Climate Change: Global climate change could result in sea level rises, changes to patterns of precipitation, increased variability in the weather, and a variety of other consequences. These changes threaten our health, agriculture, water resources, forests, wildlife, and coastal areas. For more information on the science and impacts of global climate change, visit EPA's Global Warming Web site.

Global Economy:  The emerging international economy characterized by free trade in goods and services, unrestricted capital flows and weakened national powers to control domestic economies.

Global Illuminance (g): illuminance [W/m2] produced by daylight on a surface.

Global Radiation: The total solar radiation projected on a surface, (i.e. the sum of the direct and diffuse radiation) [W/m2].

Global Warming: An increase in the near surface temperature of the Earth. Global warming has occurred in the distant past as the result of natural influences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases. Scientists generally agree that the Earth's surface has warmed by about 1 degree Fahrenheit in the past 140 years. The Intergovernmental Panel on Climate Change (IPCC) recently concluded that increased concentrations of greenhouse gases are causing an increase in the Earth's surface temperature and that increased concentrations of sulfate aerosols have led to relative cooling in some regions, generally over and downwind of heavily industrialized areas. (See climate change)

Globe Valve: A valve that lets you adjust the flow of water to any rate between fully on and fully off. Also see Gate Valve.

Gloss (Paint or Enamel): A paint or enamel that contains a relatively low proportion of pigment and dries to a sheen or luster.

Gloss Enamel: A finishing material made of varnish and sufficient pigments to provide opacity and color, but little or no pigment of low opacity. Such an enamel forms a hard coating with maximum smoothness of surface and a high degree of gloss.

Glovebag:  A manufactured impervious bag-like enclosure constructed of at least six (6) mil transparent plastic, seamless at the bottom, with inward-projecting long sleeve glove(s), which may also contain an inward-projecting water-wand sleeve, an internal tool pouch, and an attached, labeled receptacle or portion for asbestos waste. The glovebag is constructed and installed to surround the object or area to be decontaminated and contain all asbestos fibers released during the abatement process.

Glovebag Technique:  A method for removing asbestos material from heating, ventilating, and air conditioning (HVAC) ducts, piping runs, valves, joints and elbows,
and other non-planar surfaces, by use of a glovebag.

Glovebox:  An enclosure, fitted with sealed gloves that allows external manual manipulations in controlled or hazardous environments. Applications include nuclear, biomedical, semiconductor, chemical industries; and research laboratories - where isolation of the controlled zone is required.

Glued Laminated Beam (Glulam): A structural beam composed of wood laminations or lams. The lams are pressure bonded with adhesives to attain a typical thickness of 1 ½” . (It looks like 5 or more 2x4s are glued together).

Glycerol:  Is a lubricant but has found little because of its tendency to rapidly absorb moisture.

Glycol-Cooled System:  A type of air conditioning system that uses Freon as a refrigerant and a water/glycol solution as a condensing medium. Typically, the glycol-cooled condenser is located inside the air conditioner with the rest of the refrigeration components. Water/glycol is piped to the unit from a dry cooler or other suitable source. The glycol keeps the solution from freezing during winter operation.

Glycol Dehydration:  A method of drying natural gas.

GMP’s: Good Manufacturing Practices. Food and Drug Administration regulations governing the manufacture of drugs. Sometimes referred to as CGMP’s.

Gnotobiotic:  A gnotobiotic system is a completely closed biological environment in which all organisms are known. For example, a gnotobiotic mouse could be a mouse that has only one species of bacteria in its intestine.

GPF (Gallons Per Flush): The unit of measurement by which flow rate of toilets are measured and regulated. Current U.S. regulations for toilets require a maximum of 1.6 GPF.

GPH:  Gallons per hour.

GPM (Gallons Per Minute): The unit of measurement by which the flow rate of faucets and showerheads is measured and regulated.

Grab Sample:  A sample which is taken within a very short time period. The sample is taken to determine the constituents at a specific time.

Grade D Breathable Compressed Air:  ANSI specification for a Compressed air supply source that meets OSHA specification # 1910.134(i)(1)(ii)requirements for breathing air.

Grade MW: Moderate Weather grade of brick for moderate resistance to freezing used, for example, in planters.

Grade NW: No Weather brick intended for use as a back-up or interior masonry.

Grade SW: Severe Weather grade of brick intended for use where high resistance to freezing is desired.

Gradient:  The rate of change of a physical quantity with distance.

Gradient Density:  A stratified cross-section. Used to describe a filter medium where larger pores are at the upstream side of the medium with finer pores downstream. The configuration increases dirt-holding capacity and improved filter life. The medium may be inverted when a surface filter effect is desired resulting in lower differential pressure across the medium than if the medium has a single density throughout.

Graduated Payment Mortgage (GPM): A fixed-rate, fixed-schedule loan. It starts with lower payments than a level payment loan; payments rise annually, with the entire increase being used to reduce the outstanding balance. The increase in payments may enable the borrower to pay off a 30-year loan in 15 to 20 years, or less.

Grain: The direction, size, arrangement, appearance, or quality of the fibers in wood.

Grain Loading: The rate at which particles are emitted from a pollution source (i.e., number of grains per cubic foot of gas emitted).

Grains of Moisture:  The unit of measurement of actual moisture contained in a sample of air. (7000 grains = one pound of water).

Gram (g):  Standard metric measure of weight approximately equal to 0.035 ounce.

Gram-Negative Bacteria:  Bacteria that do not retain the crystal violet stain in their cells, when stained by the procedure described by Christian Gram, and thus appear pink or red when viewed under the light microscope.

Gram-Positive Bacteria:  Bacteria that retain the crystal violet stain in their cells when stained by the procedure described by Christian Gram, and thus appear blue or purple when viewed under the light microscope.

Granules: The mineral particles of a graded size which are embedded in the asphalt coating of shingles and roofing.

Gravel: Loose fragments of rock used for surfacing built-up roofs, in sizes varying from 1/8” to 1¾.”

Gravimetric Efficiency:  The efficiency of the filter in removing some portion of a specified test contaminant under a specific set of laboratory conditions. It determines the mass of the contaminant the filter removes from a known sample introduced to the filter.

Gravity Cooling:  Evaporator does not have a fan to distribute the air.

Gravity Filter:  Filter in which the driving force for filtration is provided solely by the head of liquor above the filter medium.

Gravity Furnace: A central heating system that uses natural gravity to distribute heat throughout the dwelling unit as opposed to forced circulation, pumps, or circulation blowers.

Gravity Heating:  Heat is distributed by gravity this king of unit has no fan.

Gravity Separation:  Separation of immiscible phases resulting from a difference in specific gravity by coalescing.

Gray (Gy):  SI unit of measure for absorbed dose; the quantity of energy imparted by ionizing radiation to a unit mass of matter, such as tissue. 1 gray = 100 rads, or 1 joule per kilogram.

Gray Water:  Untreated or partially treated waste-water that is used for such purposes as watering lawns or flushing toilets (rather than using cleaner water of drinkable quality).

Graywater: Wastewater that does not contain animal, human or food waste and can be reused for irrigation after simple filtration.

Green: Sustainable building design and construction that reduces the impact of development on the environment through energy and resource efficiency.

Green Accounting:  An informal term referring to management accounting systems that specifically delineate the environmental costs of business activities rather than including those costs in overhead accounts.

Green Buildings:  The building industry is increasingly focused on making its buildings greener, which includes using healthier, less polluting and more resource-efficient practices. Indoor environmental quality (IEQ) refers to the quality of the air and environment inside buildings, based on pollutant concentrations and conditions that can affect the health, comfort and performance of occupants — including temperature, relative humidity, light, sound and other factors.  Good IEQ is an essential component of any building, especially a green building.
                                                                                                                                               
Green Cleaning:  U.S. government’s executive order 13101 defines “environmentally preferable" products or services as having a “lesser or reduced effect on human health and the environment when compared with competing products or services that serve the same purpose.”  Tennant recognizes green cleaning definitions established by several independent organizations, including NSF International, CRI, Green Seal, NFSI, and LEED.

Green Design:  A design, usually architectural, conforming to environmentally sound principles of building, material and energy use. A green building, for example, might make use of solar panels, skylights and recycled building materials.

Green Development:  A development approach that integrates environmental responsiveness (benefiting the surrounding environment), resource efficiency (using resources in the construction, development, and operations of buildings and/or communities in ways that are not wasteful), and sensitivity to existing culture and community (fostering community in design, construction, and operations).

Green Electricity Provider:  A utility or company that generates, purchases, and/or invests in electricity from renewable sources, such as wind or solar power, and sells it to customers for a small premium over standard electricity costs.

Green Power: Electricity that is generated from renewable energy sources is often referred to as “green power.” Green power products can include electricity generated exclusively from renewable resources or, more frequently, electricity produced from a combination of fossil and renewable resources. Also known as “blended” products, these products typically have lower prices than 100 percent renewable products. Customers who take advantage of these options usually pay a premium for having some or all of their electricity produced from renewable resources. To find out more about green power, visit EPA’s Green Power Partnership Web site.

Green Power Marketers: Due to increased customer awareness of the environmental implications associated with power generation, a growing number of utilities and other types of energy service providers have begun offering green power products. The term “green power marketers” usually refers to energy providers operating in states that permit retail competition in the electricity markets. In states that do not allow this retail competition, many utilities have begun offering green power options under what are typically referred to as green pricing programs.

Green Power Purchasing: Green power can be purchased nationwide from several sources. Green power marketers offer green power products to consumers in deregulated markets-such as New Jersey, Pennsylvania, and New England. In states that do not allow retail competition in the electricity markets, many utilities offer renewable energy products through green pricing programs. In addition, all customers nationwide have the opportunity to buy renewable energy and stimulate the development of renewable generation sources through renewable energy certificates. Finally, customers can choose to install on-site renewable generation, such as solar panels..


Green Pricing: Green pricing refers to an optional utility service that allows customers of traditional utilities support a greater level of utility investment in renewable energy by paying a premium on their electric bill to cover any above-market costs of acquiring renewable energy resources.

Green Roof:  A garden roof with lightweight medium to support low growing plants. It provides evaporative cooling, converts carbon dioxide to oxygen and reduces stormwater runoff. Green roofs can also include reflective roofs (cool roofs).

Green Seal:  An independent nonprofit organization that aims to safeguard the environment and transform the marketplace by promoting the manufacture, purchase, and use of environmentally responsible products and services.

Green Technologies:  Environmentally friendly technologies including technologies that promote sustainability via efficiency improvements, reuse/recycling, and substitution.

Green Zone: A measurement on the peak flow meter that indicates that asthma is under control. You can reach the green zone when your peak flow is 80-100% of your personal best. When you are in the green zone, you have no symptoms of an asthma episode.

Greenfield:  Semirural real property that is undeveloped, except for possible agricultural use, which is being considered as a site for development

Greenfield Site:  Land on which no urban development has previously taken place; usually understood to be on the periphery of an existing built-up area.

Greenhouse Effect: The warming of the Earth's atmosphere attributed to a buildup of carbon dioxide or other gases. Some scientists think that this build-up allows the sun's rays to heat the Earth, while making the infra-red radiation atmosphere opaque to infra-red radiation, thereby preventing a counterbalancing loss of heat.

Greenhouse Gas: A gas, such as carbon dioxide or methane, which contributes to potential climate change.

Greenmail:  When companies threaten to close or relocate (often to another country) if they are forced to comply with environmental laws.

Greenwash:  Disinformation disseminated by an organization so as to present an environmentally responsible public image.

Greywater:  Wastewater that doesn’t contain contaminates and can then be reused for irrigation after filtration.

Grid: The completed assembly of main and cross tees in a suspended ceiling system before the ceiling panels are installed. Also the decorative slats (munton) installed between glass panels.

Grille: Mechanical device that usually removes exhaust or return air from a room. Grilles
are usually on the ceiling but can be on the wall or floor. If a grille is on a ceiling or
floor or low on a wall, it is usually for exhaust or return air. However, if a grille is high
on a wall, it can be exhaust, return, or supply.

Grommet:  Plastic, metal, or rubber doughnut-shaped protectors which line holes where wires or tubing pass through panels.

Ground-level Ozone: A colorless and highly irritating gas that forms just above the earth's surface. It is called a secondary pollutant because it is produced when two primary pollutants react in sunlight and stagnant air. These two primary pollutants are nitrogen oxides (NOx) and volatile organic compounds (VOC). NOx and VOC come from natural sources as well as human activities. When ozone is combined with particulate matter it forms smog.

Ground: Refers to electricity’s habit of seeking the shortest route to earth. Neutral wires carry it there in all circuits. An additional grounding wire or the sheathing of the metal-clad cable or conduit protects against shock if the neutral leg is interrupted.

Ground Coil:  Heat exchanger buried in the ground. May be used either as an evaporator or as a condenser.

Ground Iron: The plumbing drain and waste lines that are installed beneath the basement floor. Cast iron was once used, but black plastic pipe (ABS) is now widely used.

Ground Loop:  A series of heat exchange pipes  which are buried either vertically or horizontally in the earth.

Ground, Short Circuit:  A fault in an electrical circuit allowing elec­tricity to flow to ground.

Ground Source:  A refrigeration system which utilizes the earth as it’s source of energy.

Ground System: The connection of current-carrying neutral wire to the grounding terminal in the main switch which in turn is connected to a water pipe. The neutral wire is called the ground wire.

Ground Water:  The water below the land surface.

Ground Water Recharge:  Refers to the addition to the water within the earth that occurs naturally from infiltration of rainfall and from water flowing over the earth materials that allow water to infiltrate below the land surface.

Ground Water-Source:  Water from an underground well is being used as the heat source or heat sink for a heat pump.

Grounding Rod: Rod used to ground an electrical panel.

Grounds: Guides used around openings and at the floorline to strike off plaster. They can consist of narrow strips of wood or of wide sub-jambs at interior doorways. They provide a level plaster line for installation of casing and other trim.

Groundwater: Water from an aquifer or subsurface water source.

Grout: A hydrous mortar whose consistency allows it to be placed or pumped into small joints or cavities, as between pieces of ceramic clay, slate, or tile. Also, various mortar mixes used in foundation work to fell voids in soils, usually injected through drilled holes.

Grout or Grouting: A cement mortar mixture made of such consistency (by adding water) that it will flow into joints and cavities of masonry work to fill them solid.

Growth Management Plan: A plan for a given geographical region containing demographic projections (i.e., housing units, employment, and population) through some specified point in time, and which provides recommendations for local governments to better manage growth and reduce projected environmental impacts.

GS-37:  The “green” standard for industrial and institutional cleaners as certified by Green Seal, an independent, non-profit organization that strives to achieve a healthier and cleaner environment by identifying and promoting products and services that cause less toxic pollution and waste, conserves resources and habitats, and minimizes global warming and ozone depletion. (www.greenseal.org)

Guide:  The portion of a valve used to guide the disc.

Guide Vane:  A stationary element that may be adjustable and which directs the flow medium to the inlet of an impeller.

Guided Self-Management: Providing patients and their families with suitable information and training so that the patient is able to stay healthy and adjust treatment according to a medication plan developed with assistance of a health care professional.

Gun Consistency: Sealant formulated in a degree of viscosity suitable for application through the nozzle of a caulking gun.

Gunite: A construction material composed of cement, sand or crushed slag and water mixed together and forced through a cement gun by pneumatic pressure, used in the construction of swimming pools.

Gurley Test:  Measure of time required to expel 100 cc’s of air though a filter medium placed within an apparatus that can be fitted with a selection of office sizes and weights. Historically used for paper products and more recently for microporous membranes. (ASTM: D-726).

Gusset: A metal or wood plate added to the surface of a joint to strengthen the connection.

Gutter: Metal or wood trough at the eaves of a roof to carry rain water from the roof to the downspout.

Gutter Strap: Metal bands used to support the gutter.

Guy Wire: A strong steel wire or cable strung from an anchor on the roof to any tall slender projection for the purpose of support.

Gypsum Board: A common interior sheeting material for walls and ceilings made of gypsum rock powder packaged between two sheets of heavy building paper. Also called sheetrock, gyprock, or gypboard.

Gypsum Keene Cement: Material used to obtain a smooth finish coat of plaster, for use over gypsum plastic base coats only and in areas not subject to moisture. It is the hardest plaster.

Gypsum Plaster: Gypsum formulated to be used with the addition of sand and water for base-coat plaster.