Architectural and Engineering Glossary


Heat Transmission Coefficient

Any one of several coefficients used in the calculation of  heat transmission by conduction,convection,and radiation,through various materials and structures.Also see thermal conductance,thermal conductivity,thermal resistance,thermal resistivity,thermal transmittance.

Heat Transmittance

Same as thermal transmittance.

Heat Treatment

Heating and cooling a solid metal or alloy in order to produce changes in its physical and mechanical properties.

Heat-absorbing Glass

A faintly blue-green plate or float glass,which absorbs 40% of the sun’s infrared (heat) rays and approximately 25% of the visible rays that pass through it;must be exposed uniformly to sunlight (without irregular shadows) to avoid cracking due to nonuniform heating.

Heat-activated Adhesive

A dry adhesive film that is rendered tacky or fluid by application of heat or of heat and pressure.

Heat-fusion Joint

A joint in which heat is used to melt the end of a plastic pipe and the socket of a plastic fitting into which the pipe is inserted.When cooled,a solid joint is formed; can be used only with plain end plastic pipe and with fittings manufactured specifically for this purpose.

Heat-insulating Glass

See insulating glass.

Heat-reflective Glass

See reflective glass.

Heat-release Link

See fusible link.

Heat-resistant Concrete

Any concrete which does not disintegrate when exposed to constant or cyclic heating at any temperature below which a ceramic bond is formed.

Heat-resistant Glass

Glass able to withstand higher temperatures than usual because of its low expansion coefficient.

Heat-resistant Paint,heat-resistant Enamel

A special paint (or enamel) for use in the temperature range between about 250F and 750F (approx. 120C and 400C).


A method of joining plastic sheets or films by the simultaneous application of heat and pressure to the areas in contact.

Heat-strengthened Glass

Annealed glass:(a) that has been cut to size,(b) heated to near its softening point, and (c) then cooled faster than normal to place the outside surfaces and edges in compression and the interior in tension;is about twice as strong as annealed glass.

Heat-treated Glass

Same as tempered glass.

Heated Space

The space within a building with a positive heat supply.

Heating Cable

See strip heater.

Heating Capacity,recovery Capacity

The capacity of a water heater to raise a given number of gallons per hour (liters per hour) by a specified number of degrees,for example,from 40 to 140F (4.4 to 60C);usually expressed in Btu per hour (kilowatts per hour);does not include the heat losses in the system which the water heater serves.

Heating Degree Day

Same as degree day. 

Heating Load

See heat load.

Heating Medium

Any solid or fluid (such as water,steam,air,or flue gas) which is used to convey heat from a heat source (such as a boiler furnace),either directly or through a suitable heating device,to a substance or space being heated.

Heating Plant

A system for heating a building or group of buildings;usually includes a boiler and a piping system with radiators,or a furnace,ducts, and air outlets.

Heating Rate

The rate at which temperature is raised,as for example in an autoclave or kiln;usually expressed in degrees per hour.

Heating System

See forced-air heating system,hot-water heating system,one-pipe system,radiant heating system,sealed hot-water system,solar heating system,steam heating system,warm air heating system.

Heating Unit

See electric heating element.

Heating,ventilating,and Air-conditioning

Types of systems differ,but a basic system often includes an outside-air intake,chiller,preheater,dehumidifier,heating coil,humidifier,fans,duct work,air outlets,and air terminalsmechanical energy in the process;used in an air conditioner whose cooling cycle can be reversed so that it can function as a heater.


The upward movement of soil caused by expansion or displacement resulting from phenomena such as moisture absorption,the removal of overburden,the driving of piles,and the action of frost.

Heave-off Hinge

See loose-joint hinge.

Heavy Concrete

See high-density concrete.

Heavy Grading

The moving of large masses of earth by deep cuts and fills.

Heavy Joist

A timber usually at least 4 in.(10 cm) thick and 8 in.(20 cm) or more in width.

Heavy Soil

A fine-grained soil composed largely of silt or clay.

Heavy-bodied Paint

A paint having a high viscosity.

Heavy-duty Scaffold

According to OSHA:a scaffold designed and  constructed to  carry a working load not to exceed 75 lb per sq ft (367.5 kg per sq m).

Heavy-timber Construction

Construction in which fire resistance is obtained by using wood structural members of specified minimum size and wood floors and roofs of specified minimum thickness and composition;by using bearing walls and nonbearing exterior walls of noncombustible construction;by avoiding concealed spaces under floors and roofs;and by using approved fastenings,construction details,and adhesives for structural members.

Heavyweight Aggregate

Aggregate of high specific gravity such as barite,magnetite,limonite,ilmenite,iron,or steel;used to produce high density concrete.

Heavyweight Concrete

See high-density concrete.


A building 100 ft (30.5 m) in length or width;esp.the cella of the great temple of Athena,the Parthenon,at Athens.


A building having a hundred columns.


1.A door having its upper part hinged independently of its lower part,or one with an open or latticework panel.2.A latticed gate.


A metric unit of area equal to 10,000 square meters;approximately 21⁄2 acres.


Same as hexastyle.


1.A barrier or fence formed by bushes or small trees growing close together;2.A closely grown row of any kind of shrubbery.


Trees and shrubs in a row forming a fence which encloses or separates fields.


1.The lower end of an upright timber, resting on a support.2.The lower end of the hanging stile of a door.3.The floor brace for timbers that brace a wall.4.The trailing edge of the blade of a bulldozer,or the like.

Heel Cut

Same as seat cut.

Heel Stone

A stone at the bottom of a gate pier;used to mount the bottom hinge pin for the gate. 

Heel Strap

A steel fastener used to join a rafter to its tie beam.


1.A post or stanchion at the free end of the partition of a stall.2.A post to receive the hinges of a gate (either part of the gate or the stationary support).


1.The distance between two points aligned vertically.2.In buildings,the distance vertically from the average grade at front sides and/or rear of a building (or the average elevation of the curb or curbs of the streets faced by the building) to the average level of the roof.