The efficiency of air conditioners is often rated by the Seasonal Energy Efficiency Ratio (SEER) which is defined by the Air Conditioning, Heating, and Refrigeration Institute in its 2008 standard AHRI 210/240, Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump Equipment.

Asbestos refers to a set of six naturally occurring fibrous minerals: chrysotile, crocidolite, amosite, anthophyllite, tremolite, and actinolite. Among these, chrysotile and amosite asbestos are most common.

Ducts are used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. The needed airflows include, for example, supply air, return air, and exhaust air. Ducts commonly also deliver ventilation air as part of the supply air. As such, air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort.

A duct system is also called ductwork. Planning (laying out), sizing, optimizing, detailing, and finding the pressure losses through a duct system is called duct design.

A register is a grill with moving parts, capable of being opened and closed and the air flow directed, which is part of a building’s heating, ventilation, and air conditioning (HVAC) system. The placement and size of registers is critical to HVAC efficiency.

The evaporator coil is the primary contact point for warm air in a central air conditioning system. The purpose of the evaporator coil is to remove the heat and humidity from the air that is passing over it.

An air handler, or air handling unit (often abbreviated to AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system.

A package unit is the all-in-one heating and cooling system for homes that don’t have a lot of room indoors for either a furnace and coil, or an air handler. Package units will contain all of their parts in one outdoor unit that sits on either the roof or to the side of a building.