Namesort ascending Definition

abbr. National Association of State Energy Officials

The National Association of State Energy Officials (NASEO) is the only national non-profit organization whose membership includes the governor-designated energy officials from each state and territory.


abbr. National Association of Home Builders

NAHB is a trade association that helps promote the policies that make housing a national priority. Since 1942, NAHB has been serving its members, the housing industry, and the public at large.


abbr. National Appliance Energy Conservation Act


A type of fungus that is different from plants, animals and bacteria. Molds are decomposers of dead organic material such as leaves, wood and plants. Molds sometimes can infect living plants and animals. The spores and hair-like bodies of individual mold colonies are too small for us to see without a microscope. When a lot of mold is growing on a surface, it often appears black or green. The color of mold is influenced by the nutrient source and the age of the colony. Mold growing on fabric is called mildew.

Variants: mould


A full-scale but limited extent demonstration of a finished assembly, such as a window in a wall, a roof parapet, or a washroom plumbing arrangement.


abbr. Minimum Efficiency Reporting Value

A metric of air filter efficiency, in terms of its ability to remove air particulates.


A thin pliable or flexible sheet forming a lining, covering, or layer.

Mechanical Ventilation

Controlled, purposeful introduction of outdoor air to the conditioned space using some mechanical contrivance such as a fan or bellows.


abbr. Model Energy Code


abbr. million cubic feet (typically used as a metric for natural gas)


Heavy-consistency compound that may remain adhesive and pliable with age. Typically an airtight, waterproof compound that is applied to exterior walls and roof surfaces or used to provide a robust and durable air seal to air duct distribution systems.


A regular process of inspection, cleaning and minor repairs of building elements and exterior systems. Cleaning removes dirt, impurities, or extraneous matter as required on a regular basis, such as removing leaves from gutters and drains in the fall or cleaning lint from dryer vents. Minor repairs encompass small projects that reinstate failed elements such as areas of cracked sealant or peeling paint.


Most often used in reference to a coating for high-performance windows. The "E" stands for "emissivity," which is the degree of efficiency. A thin metallic oxide coating increases the U-value and/or decreases the SHGC of the window by reducing heat flow from a warm(er) surface to a cold(er) glazing surface. The best location for the coating should be calculated but is often based on whether the primary heat flow control direction is from the inside out (heating climates) or the outside in (cooling climates).


See Header.


abbr. Leadership in Energy and Environmental Design

LEED is a set of rating systems intended to assess the design, construction and operation of high performance green buildings, homes and neighborhoods. LEED was developed by the U.S. Green Building Council (USGBC). In Canada, LEED is overseen by the Canadian Green Building Council (CaGBC).


1. A part of a door or shutter that is moveable.

2. Leaf may also refer to a single vertical layer of masonry.

Variant: Wythe (when referring to masonry)


Latent Heat

Change of enthalpy during a change of phase (from Gatley, Understanding Psychrometrics).


Composite layer in EIFS that is installed over the insulation and is comprised of the reinforcement, base coat and finish coat.

Kiln-Dried Lumber

Any lumber placed in a heated chamber or "shed" to reduce its moisture content to a specified range or average under controlled conditions. For softwood framing lumber, the moisture content of kiln-dried lumber is somewhat based on regional conventions but is most often an average of 12% by weight. In comparison, the moisture content of thoroughly air-dried softwood framing lumber is 15% to 20%.

KD Lumber

See Kiln-dried Lumber.

Jump Duct

A flexible, short, U-shaped duct (typically 10-inch diameter) that connects a room to a common space as a pressure balancing mechanism. Jump ducts serve the same function as transfer grilles. Used when return ducts are not located in every room.


An interface between elements. Joints may be needed to allow for movement of different parts of a building or assembly, or may be required to make construction sequences practical. In all cases, the functional requirements of the enclosure must be maintained the same as for the body of an enclosure element, although aesthetic requirements may be relaxed. A joint may pass through the entire enclosure assembly, in which case it is a building movement or assembly joint, often commonly (and imprecisely) referred to as an expansion joint. Control joints are surface cuts or intentional geometric features which control the location of shrinkage cracks. Construction joints are formed between successive building elements parts during construction work.


The vertical side or edge of a doorway, window, or other opening.


abbr. incremental overall source energy use

Integrated Circuit Motor

See Brushless Permanent Magnet (BPM).


(1) Thermal insulation: Any material which significantly slows down or retards the flow or transfer of heat. Building insulation types are classified according to form (e.g loose-fill, batt, flexible, rigid, reflective, and foamed-in-place) or material (mineral fiber, organic fiber, foam plastic). All types are rated according to their ability to resist heat flow (R-Value or RSI).

(2) Electrical insulation: A non-conductive wire covering, often rubber, thermoplastic, or asbestos. The thickness of insulation varies with wire size and type of material, application or other code limitations.

Insulating Sheathing

Non-structural insulating board products with varying R-values and a wide variation in vapor permeability and drainage characteristics. Materials include expanded polystyrene (EPS), extruded polystyrene (XPS), polyisocyanurate (most often foil-faced), rigid fiberglass, and mineral wool.

Variants: insulated sheathing

Installed R-value

A metric commonly referenced in building codes and used by industry. This is simply the R-value labeled on the product installed in the assembly.

Related resource: RR-0901: Thermal Metrics for High Performance Walls—The Limitations of R-Value, The Thermal Metric Project

Initial Set

A time-related set caused by the hydration process of cement-based mixtures.

Indoor Air

Air in a conditioned space.


abbr. indoor environmental quality


abbr. International Energy Conservation Code


abbr. integrated design process


abbr. indirect-direct evaporative cooler


abbr. integrated circuit motor

See Brushless Permanent Magnet (BPM).

Hygrothermal Region

See Climate.


Materials that interact with water vapor by adsorbing water vapor into their pore structure as a function of the relative humidity of the surrounding air.


A term used to describe pressures developed by a non-moving fluid (typically water, in our cases), such as the buildup of subsurface water against a foundation wall.


Materials that do not attract liquid water; they will force liquid water to form beads on their surface, act as capillary breaks and are non-hygroscopic.


A term used to describe a surface or material that attracts and holds water, transiently bonding with it via hydrogen bonds.  Liquid water on a hydrophilic surface will tend to absorb into the material—i.e., the material is "wettable."

Related terms: Hydrophobic, Hygroscopic