The deposition of dissolved salts I the material (such as concrete or brick) being transported within water (usually by capillary action) on a visible surface after evaporation of water.


The ability of a material to emit radiant energy from its surface. Also called emittance.


Energy is power used over a specified time (energy = power x time) A 3 ton 13 SEER unit draws nearly 3,500 watts (power) while running on full capacity. If it runs for 3 hours a day at full capacity, how much energy does it consume in the 3 hours? (Answer: 10.5 kWh)


thermodynamic quantity equal to the sum of the internal energy of a system plus the product of the pressure-volume work done on the system; enthalpy cannot be directly measured; however, enthalpy differences between the initial and final statepoints of a process can be measured. (from Gatley, "Understanding Psychrometrics")


abbr. equivalent leakage area; typically expressed as the size of opening of a building enclosure at a 10Pa pressure diffference

Equivalent Leakage Area of a Building

Of a building. Quantitative expression of the airtightness of a building enclosure. EqLA is the method set by the Canadian General Standards Board in which a blower door depressurizes the building enclosure to 10 Pascals and the leakiness of the enclosure is expressed as a summary hole in square inches.


Or Energy/Enthalpy-Recovery Ventilator – a ventilator that recovers latent and sensible energy from the exhaust airstream and imparts it to the incoming airstream. The main difference between an ERV & HRV, is that in an ERV the heat exchanger transfers a certain amount of water vapor along with heat energy, while a HRV only transfers heat.


EXTERNAL STATIC PRESSURE - The sum of the static and velocity pressures of a moving air system at the point of measurement.


Water changing from liquid into vapor.


The heat transfer coil of an air conditioner or heat pump that cools the surrounding air as the refrigerant.


Room air lost from a space through cracks due to positive pressure.

Exhaust Air

The air flow leaving the conditioned space and discharged to the outdoors.

Expanded Polystyrene Insulation

A rigid cellular foamed plastic insulation material manufactured by expansion of polystyrene beads within a mold. This mold creates an open cell structure filled with air. EPS Type I is the most widely used insulation. Type I has a density of 1 lb/ft3 (16 kg/m3) ), Type II is a denser, more durable insulation of 1.5 lb/ft3 (24 kg/m3) density.

Extruded Polystyrene Insulation

A rigid cellular foamed-plastic insulation material manufactured by extrusion of polystyrene in the presence of a blowing agent. The blowing agent dissipates out of the closed cell structure over time, creating a structure that resists liquid water penetration and vapor diffusion. The manufacturing process for XPS insulation results in a smooth surface skin. Typical density of 2 lb/ft3 and R-value of 5 per inch (0.029 W/mK).