Backdraughting

The reversed flow of polluted air (or flue gases) in a chimney, flue or other air outlet, back into the room or building.

Backfill

The gravel or earth replaced in the space around a building wall after the foundation is in place.

Backup

The cheaper material in a masonry wall that is covered by more expensive, ornamental material, e.g., face brick, stone, marble, metal panels.

Bacteria

A form of unicellular microorganisms.

Baffle

Plate or vane used to direct or control movement of fluid or air within confined area.

Balance

A mechanical device (normally spring-loaded) used in single- and double-hung windows as a means of counterbalancing the weight of the sash during opening and closing.

Balance Point

An outdoor temperature - usually between 30°F to 45°F - at which a heat pump's output exactly equals the heating needs of the house. Below the balance point, supplementary electric resistance heat is needed to maintain indoor comfort.

Barometer

Instrument for measuring atmospheric pressure. May be calibrated in pounds per square inch or in inches of mercury in column.

Base

In building construction, the lowest part of a wall, pier, pedestal or column.

Base Flashing

That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering.

Base Plate

The horizontal member at the bottom of a column or post which transmits the column loads to its foundation.

Baseboard Heating

A system of perimeter heating with radiators, convectors or air outlets located at the base of the wall where the baseboard would be may be hot water, forced air or electric. Also called panel heating.

Baseline Data

Baseline (or historical) data is compiling past chiller logs for review.

Basement

Any area of a building having its floor subgrade (below ground level) on all sides.

Basement Floor

Concrete floors with interior drain tile only can result in moisture and radon movement into the home. Concrete is a permeable product, so moisture moves through it. To prevent this from occurring, it is recommended that a polyethylene product be installed under the basement slab. Also, select a sealed sump pit that is vented to the outside. This will vent any buildup of moisture or radon directly to the exterior if pressure differences occur between the home's indoor environment and the earth.

Basin

Cold water reservoir in the cooling tower system.

Basin Temperature

The actual temperature of the cold water basin in the cooling tower system.

Bathroom

A room containing a toilet, a lavatory and a bathtub or shower.

Batten

A narrow strip of wood used to cover a joint between boards or to simulate a covered joint for architectural purposes.

Bay

An opening in a wall.

Bay Window

A window that forms a bay in a room and projects outwardly from the wall it is supported by its own foundation, as distinguished from an oriel or box bay window, which lacks foundation support.

Bay Window

An arrangement of three or more individual window units, attached so as to project from the building at various angles. In a three-unit bay, the center section is normally fixed, with the end panels operable as single-hung or casement windows.

Bead

A wood strip against which a swinging sash closes, as in a casement window. Also, a finishing trim at the sides and top of the frame to hold the sash, as in a fixed sash or a double-hung window. Also referred to as bead stop.

Beam

A principal load-supporting member of a building, may be made of wood, steel or concrete. The lumber in a rectangular cross section of a building, five or more inches thick and eight or more inches wide.

Beamed Ceiling

A ceiling with beams exposed. A false beamed ceiling has ornamental boards or timbers which are not load-bearing.

Bearing

A support or guide by means of which a moving part such as a shaft or axle is positioned with respect to the other parts of a mechanism.

Bearing Oil Reservoir

Excess oil used in the lubrication of the bearing system located in the compressor system.

Bedroom

A room containing bed and other furniture whose primary use is to sleep. This room must contain a built-in closet, heating and ventilation and at least one electrical outlet.

Bel

A bel is a decibel divided by 10.

Bevel

To angle an edge on a piece of wood or other material.

Beveled Siding

Clapboard

Bi-Level

A house built on two levels a split-level house.

Black Top (Bituminous Concrete)

Bituminous or asphalt material used in hard surface paving.

Blackbody

The ideal, perfect emitter and absorber of thermal radiation. It emits radiant energy at each wavelength at the maximum rate possible as a consequence of its temperature, and absorbs all incident radiance.