Namesort descending Definition
BPM

abbr. brushless permanent magnet

A type of motor with electronic speed and torque controls built in. BPM motors are used to drive fans in heating and cooling systems. They are speed controlled to ensure optimal airflow, and are quieter and more energy-efficient than conventional motors as long as the duct system is not overly restrictive. BPM motor fans are especially useful in situations that require continuous air circulation. Historically, BPM motors have often been referred to as electronically commutated motors (ECMs). However, this term is more properly used as the trade name for the BPM motor originally produced by GE/Regal Beloit. Other common variants are listed below.

Variants: Electronically Commutated Motor (ECM), Integrated Circuit Motor (ICM), Brushless Direct Current (BLDC).

Brushless Direct Current

See Brushless Permanent Magnet (BPM).

Brushless Permanent Magnet

A type of motor with electronic speed and torque controls built in. BPM motors are used to drive fans in heating and cooling systems. They are speed controlled to ensure optimal airflow, and are quieter and more energy-efficient than conventional motors as long as the duct system is not overly restrictive. BPM motor fans are especially useful in situations that require continuous air circulation. Historically, BPM motors have often been referred to as electronically commutated motors (ECMs). However, this term is more properly used as the trade name for the BPM motor originally produced by GE/Regal Beloit. Other common variants are listed below.

Variants: Electronically Commutated Motor (ECM), Integrated Circuit Motor (ICM), Brushless Direct Current (BLDC)

Building Enclosure

The system or assembly of components that provides environmental separation between the conditioned space and the exterior environment.

Note: The enclosure is a special type of environmental separator. Environmental separators also exist within buildings as dividers between spaces with different environmental conditions.

Building Envelope

See Building Enclosure.

CAD

abbr. computer-aided design

The use of computer systems to create, modify, or analyze a design. CAD software packages vary in their capabilities and are sometimes specialized for particular fields or project types.

Cap Flashing

A flashing overlapping the vertical leg of base flashing to prevent water from migrating behind the base flashing.

Capillary Action

The movement of water within the confined spaces of a porous material or between two adjoining hydrophilic materials due to the attractive force of surface tension. Only significant in gaps of less than about 1/8” (3 mm).

 

Capillary Break

A hydrophobic material or non porous material (such as glass, plastic, or metal) or gap between parallel layers of material (often less than 1/16” or 1.5 mm) sufficient to stop capillary action.

Caulking

See Sealant.

ccSPF

abbr. closed-cell spray polyurethane foam

A type of spray polyurethane foam expanded with non-reactive blowing agents to yield a rigid cellular structure. It has a density between 1.5 and 2.5 lb. per cubic foot and a nominal thermal resistance of R-6.5 per inch (this will vary from manufacturer-to-manufacturer).

CDCU

abbr. Community Development Corporation of Utah

A non-profit, 501(c)(3) organization, originally created by the Salt Lake City Council in 1990 to relieve blighted downtown neighborhoods.

CEC

abbr. California Energy Commission

The primary energy policy and planning agency of the state of California.

Cement Board

A rigid sheathing made of cement-bonded, fiber-reinforced composites. Typically glass or wood fibers are used for reinforcing. Cement board is moisture resistant and non-combustible.

Center-of-Cavity R-value

The R-value at a line through an assembly that contains the most insulation, and the least framing, typically the middle of a stud-bay in framed construction.

CFL

abbr. compact fluorescent light

A fluorescent lightbulb in which the tube is folded or twisted into a spiral to concentrate the light output. In terms of producing light, CFLs are significantly more energy efficient than traditional incandescent lightbulbs. Because incandescent bulbs also produce a significant amount of heat, whereas CFLs do not, the total energy savings of switching to CFLs will vary based on whether and how a space is heated.

CFM

abbr. cubic feet per minute

A unit of volumetric flow rate, often used as a metric of ventilation, airflow, or air leakage.

Cladding

A material or assembly that forms the exterior face of a wall. Examples of cladding include stucco, EIFS, metal panels, brick/stone veneer, wood siding, and vinyl siding.

Clear-Wall R-value

R-value of an assembly containing only insulation and minimum necessary framing materials at a clear section with no windows, corners, columns, architectural details, or interfaces with roofs, foundations or other walls.

Climate

The exterior environmental conditions that will impose a load on the building enclosure, including temperature, humidity, rainfall, wind, and solar radiation. Dividing a map into climate zones allows designers, code bodies, and others to make recommendations based on expected regional loads.

Closed-Cell SPF

See ccSPF.

Coating

A thin surface treatment applied to achieve special properties. For example, waterproof coatings, low-e coatings, paint coatings.

Cold Joint

A visible junction between two liquid-applied materials, such as concrete or EIFS coating, caused by allowing one side to cure before the application of the second side.

Commissioning

A quality assurance process during and following building construction, prior to occupancy. Tests and inspections should note any problems to be fixed immediately (“fix and tune”). Tests should be conducted for duct leakage, building enclosure leakage, air pressure relationships under all operating conditions, proper venting of all combustion appliances under all operating conditions, carbon monoxide output of all combustion appliances, and confirmation of airflow and refrigerant charge in the HVAC systems. Additionally, the building occupants should be educated about the correct operation and maintenance of the building and equipment.

Concealed Barrier

An approach to enclosure rain control that employs a single waterproof barrier to rain penetration. The barrier is not on the exposed face of the assembly but concealed behind the cladding and other material layers, which reduces the amount of rainwater reaching the barrier. Drainage is by definition not required for good performance in this approach. A subset of perfect barrier approaches.

Condensation

The change of state from vapor to liquid.  A common factor in moisture damage. Occurs on surfaces, which must be cooler than the air containing vapor next to it. Vapor supply to the condensation surface is usually by airflow but can be by diffusion.

Conditioned Space

The part of the building that is designed to be thermally conditioned (heated or cooled), either for the comfort of occupants or for other reasons such as preserving temperature-sensitive goods.

Control Joint

A formed, sawed, or assembled joint acting to regulate the location of cracking, separation, and distress resulting from dimensional or positional change.

Cooling Degree Days

Heating degree days and cooling degree days are climatological metrics used to express the magnitude of the heating or cooling load in a given location. These metrics are expressed in terms of a "base temperature" (e.g., "Cooling Degree Days Base 65 F"). Cooling degree days are calculated by taking the daily average temperature; if it is hotter than the "base temperature," the difference is calculated. This difference is summed for the period (week, month, year) in question. Note that cooling season data are often presented in terms of “cooling degree hours” (due to diurnal temperature swings), which are not directly translatable to cooling degree days.

Corrosion

The deterioration of metal by chemical or electrochemical reaction resulting from exposure to weathering, moisture, chemicals or other agents or media.

Crack

The result of tensile or shear forces that exceed the strength of a material at a particular location resulting in a discontinuity with a high aspect ratio (length:width).

CRI

abbr. color rendering index

A metric of the ability of a lighting source to render colors correctly relative to an ideal light source. A CRI of 100 is the maximum value. For reference, incandescent lights are in the 95-100 CRI range, and current compact fluorescents are reaching the 80s.

CT

abbr. color temperature

A specification of the apparent color of a light source relative to the color appearance of an ideal incandescent source held at a particular temperature and measured on the Kelvin (K) scale.

Cure

To develop the ultimate properties of a wet state material by a chemical process. Different than drying, which is not a chemical process, although drying is often a necessary part of a chemical process.

Dehumidification

Removal of water vapor from air (from Gatley, Understanding Psychrometrics).

Delamination

A separation along a plane parallel to the surface.

Dew Point

The temperature at which the relative humidity of a sample of air with constant water vapor reaches 100%. The air is saturated with water when it reaches the dew point and condensation will occur on a surface.

DHW

abbr. domestic hot water

Diffusion

The movement of individual molecules through a material. The movement occurs because of concentration gradients and (to a much lesser degree) thermal gradients, independent of airflow. A mode of water vapor transport in building enclosures that is much slower than airflow.

Drainage Plane

Drainage planes are water repellent materials (building paper, housewrap, foam insulation, etc.) which are designed and constructed to drain water. They are interconnected with flashings, window and door openings, and other penetrations of the building enclosure to provide drainage of water to the exterior of the building. The materials that form the drainage plane overlap each other shingle fashion or are sealed so that water flow is downward and outward.

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