Installation of Central Air-Conditioning

In modern buildings the design, installation, and control systems of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally capacity engineer and select HVAC systems and equipment. For larger buildings, building services designers and engineers, such as mechanical, architectural, or building services engineers analyze, design, and specify the HVAC systems, and specialty mechanical contractors fabricate and commission them. Building permits and code-compliance inspections of the installations are normally required for all sizes of buildings.

Although HVAC is executed in individual buildings or other enclosed spaces (e.g. think NORAD's underground headquarters), the equipment involved is in some cases an extension of a larger district heating (DH) or district cooling (DC) network, or a combined DHC network. In such cases, the operating and maintenance aspects are simplified and metering is necessary to bill for the energy that is consumed, and in some cases energy that is returned to the larger system. (For example, in a DHC network at a given time a building may be utilizing chilled water for air conditioning, but the warm water it returns may be utilized by another building for heating or the overall DH portion of the DHC network, likely with energy added to boost the temperature.)