ASHRAE Terminology

A Comprehensive Glossary of Terms for the Built Environment
ashrae.org/ashraeterms

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dedicated outdoor air system (DOAS)

1. A dedicated outdoor air system (DOAS) uses separate equipment to condition all of the outdoor air brought into a building for ventilation and delivers it to each occupied space, either directly or in conjunction with local or central HVAC units serving those same spaces. The local or central HVAC units are used to maintain space temperature. 2. Primary Air System

dedicated outdoor air system unit (DOASu)

Outdoor air unit that provides ventilation directly to a space or sensible heating/cooling units. If equipped with an exhaust fan it can control building pressure. Can have an air-to-air recovery device to save energy . Other options include custom air cleaning, enhanced dehumidification devices, compressors, condensors. 2. Make up air unit.

integrated seasonal coefficient of performance (ISCOP)

a seasonal efficiency number that is a combined value based on the formula listed in AHRI Standard 920 of the two COP values for the heating season of a direct expansion dedicated outdoor air system (DX-DOAS) unit water or air source heat pump, expressed in W/W.