USDA – Definitions

COMMUNITY SYSTEM. A state-regulated central utility system owned, operated, and maintained by a private corporation or a nonprofit property owner’s association.

CONDUCTANCE, THERMAL. The time rate of heat flow through a unit area of a material of a given thickness, per unit of temperature difference. Value is expressed in Btu/(hr x sq ft x F) or w/(m sq x k). Symbol C

CONDUCTIVITY, THERMAL. The time rate of heat flow through a unit area of a homogenous material under the influence of a unit temperature gradient. Value is expressed in (Btu x in)/(hr x sq ft x F) or w/(m x k). Symbol k

HABITABLE ROOM. A room designed and used for living, sleeping, eating, or cooking, or any combination thereof. Bathrooms, toilet compartments, closets, halls, storage spaces, laundry and utility rooms, basement recreation rooms, and similar areas are not considered habitable rooms.

INDEPENDENT INSPECTION AGENCY. Where the term “independent inspection agency” is used in the standards, the reference is to an agency which maintains a program of continuous control, testing, and inspection over the quality of the product. Such an agency must conform to procedures set forth in ANSI Z34.1-87, and shall be acceptable to HUD.

LISTED AND LISTING. Terms referring to materials, equipment, or products which have been tested to and comply with an applicable standard and which are shown in a list published by a recognized certifying agency.

LIVING UNIT. A single residential unit providing complete, independent living facilities for one or more persons which includes permanent facilities for living, sleeping, eating, cooking, and sanitation.

PERM. The unit of measurement of the water vapor permeability of a material. Value of one perm is equal to one grain of water vapor per square foot per hour per inch of mercury vapor pressure difference.

PROPERTY. An area of ground under the ownership of a single person or entity including all buildings and improvements thereon.

PUBLIC SPACE. An open space on the premises accessible to a public way or street, such as a yard, court, or open space dedicated to public use and abutting the premises.

PUBLIC SYSTEM. A central utility owned, operated, and maintained by a municipality, county, or other unit of local government having power to tax or levy assessments.

R THERMAL RESISTANCE. A measure of ability to retard head flow. The reciprocal of thermal conductance: R=1/C=(hr x sq ft x F)/Btu or (m sq x k)/w.

REQUIRED. Mandatory.

SHALL. Indicates that which is required.

TOILET ROOM. (Half bath). Enclosed space, containing a watercloset and a lavatory.

U OVERALL COEFFICIENT OF HEAT TRANSMISSION. The combined thermal value of all the materials in a building section, air spaces, and surface air films. U is expressed in Btu/(hr x sq ft x F) or w/(M sq ft x k).