BEDES Dictionary

Version 2.6

You can explore the BEDES dictionary in several ways: use the search box to search for a particular term; filter the list of terms by category using the checkboxes below; click on each term for more details. You can also download all the terms and list options in CSV or XML format using the buttons below.

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Termsort descending Term Definition Lists Unit of Measure
Quantity Intensity

The number of entities per unit area. This can be used to represent load densities (e.g., People/ft2, Watts/ft2)

Quantity Of Units Per System

Number of units in each system. For instance, a photovoltaic system will have a number of modules per array. In an office, there might be a number of displays per workstation.

R Value

The R-value, also known as thermal insulance, is the temperature difference per unit heat flux, at steady state, between two defined surfaces of a material or construction that induces one unit of heat flux between the surfaces. The R-value is used for comparing insulating values of different materials, for the specific thickness of the material. The higher the R-value, the greater a material's insulating properties and the slower heat flows through it. The R-value does not include the interior and exterior air film coefficients. The R-value is the reciprocal of the U-factor.

R Value Per Unit Dimension

The R-value of a material, per inch of thickness.

Rated Lifetime

Rated life time of operation in number of years.

Ratio of Melanopic to Standard Illuminance (M/P ratio)

M/P ratio - The melanopic ratio is the ratio of the melanopic response (of the cells in the eye that help control the circadian rhythms) to the visual response

Sector Classification

The sector classification appropriate for the premises. Also, the sector-appropriate sizing for equipment.

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Serial Number

A unique code assigned for identification of a single unit.

Solar Absorptance

The fraction of incident radiation in the solar spectrum that is absorbed by the material or surface. Value range: 0-1


Dimension of the distance between two components. Examples include: Framing spacin--the dimension from centerline to centerline of a surface framing material; Window spacing--the dimension between windows in a discrete window layout.

Specific Heat

Ratio of the quantity of heat required to raise the temperature of a given mass of any substance one degree to the quantity required to raise the temperature of an equal mass of a standard substance one degree (usually water at 59¡F (15¡C)

Surface Roughness

A description of the roughness of the exposed surface of a material. This property is used to approximate the effect of the surface condition on the convection of air across the surface. In energy simulation models, it is used to help determine the convection coefficients for a surface.

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Thermal Absorptance

The fraction of incident long wavelength infrared radiation that is absorbed by the material or surface. For opaque materials the thermal absorptance value will equal the value of thermal emittance. Value range: 0-1

Thermal Conductance

A measure of a material's ability to conduct heat, defined as the heat flux through the material induced by a unit temperature difference between the surfaces of the material.

Thermal Conductivity

A measure of a material's ability to conduct heat, defined as the amount of heat transferred per unit time, given a unit area of the material and a unit temperature gradient through the thickness of the material.

Thermal Zone Layout

Type of zoning used for space conditioning

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Dimension of the thickness of a component. Can be used to define overhang thickness, in addition to overhang depth and width.

Tilt Angle

The angle from a horizontal surface; can be applied to an opaque surface, a fenestration unit, a solar panel, etc.

Tilt Description

A descriptive value for tilt, when an exact numeric angle is not known.

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U Factor

The U-factor, also known as thermal transmittance, is the overall heat transfer coefficient through a particular body or assembly, including its boundary films. Note that the U-factor for a construction assembly, including fenestration, includes the interior and exterior film coefficients (the boundary films referenced above). For characterization of fenestration products, the U-factor is calculated for the whole product, including the effect of the frame (center of glass, edge of glass, frame). The U-factor is the reciprocal of the R-value.

Useful Life

The expected remaining service life of a component.


Generic holder for numeric value characterized by atomic qualifiers

Visible Absorptance

The fraction of incident visible wavelength radiation that is absorbed by the material or surface. Value range: 0-1


The space inside the boundary of a 3 dimensional shape

Warranty Duration

The time duration of a warranty for the component