We’ve compiled this glossary to help you understand the different air conditioning/cooling/HVAC industry terms and acronyms used across our website and literature. Click on the alphabetical links below to jump to the appropriate section.

ACH50: (Air Changes per Hour at 50 Pascals) measures a building’s airtightness by how many times its total air volume is replaced in an hour under a 50 Pascal pressure difference

AFUE: a percentage rating for furnaces and boilers showing how much fuel is converted into usable heat

Air conditioner – An appliance, system, or mechanism designed to control temperature, humidity and air quality in a defined space.

Annual energy savings: the money and energy conserved by improving efficiency, often achieved through upgrades

Blower Door Test – a diagnostic tool that measures the overall air leakage of a building’s exterior shell

CMF50 – a simple measure of how leaky a house or building is

EER2 – a modern standard that measures how efficiently an air conditioner or heat pump cools your home

SEER2 – Seasonal Energy Efficiency Ratio 2) is a measurement of an air conditioning or heat pump system’s energy efficiency, similar to miles per gallon (MPG) for a car

Tenmat Cover – Recessed light cover is a fire-resistant, non-combustible enclosure, typically made from mineral wool, designed to fit over recessed (can) lights in an attic to create a safe barrier, allowing insulation to be piled over them without fire risk, while also sealing air leaks for energy efficiency. These covers are essential for non-IC (Insulation Contact) rated fixtures, stopping heat loss and preventing flames/heat from spreading through the ceiling assembly during a fire, with some offering 1- or 2-hour fire ratings.

UEF: Uniform Energy Factor for water heaters (a higher number means greater efficiency)