A. Mumma, Ph.D., P.E. Professor Emeritus of Architectural
Engineering, Penn State University
ASHRAE DOAS Webcast
alone, direct ducted HRV's
and ERV's are simple examples of dedicated outdoor air systems.
for DOAS lies within the body's own system where respiratory
systems and indoor air quality are separate from the thermal
sensing and endocrine systems controlling thermal comfort.
ASHRAE 62.1 and
ASHRAE 62.2 Ventilation / Indoor Air Quality are very
explicit in their scope which does not include thermal comfort
and refers user to ASHRAE Standard 55.
ASHRAE 55 Thermal Environmental Conditions for Human Occupancy
is explicit stating it does not address air quality
referring users to ASHRAE Standard 62.
ASHRAE Guideline 10, Interactions Affecting the Achievement of
Acceptable Indoor Environments should also be considered
when evaluating systems.
DOAS with a parallel radiant system reflects the body's own systems and
follows the principles of separate environmental standards for
thermal comfort and indoor air quality.
Dedicated Outside Air Systems (DOAS) and the
hybrid HVAC system
Text source credit:
Institute of Building Sciences /
The Whole Building Design Guide
of wisdom on DOAS
"The DOAS approach effectively eliminates
biological contaminants and inadequate
ventilation. It also avoids building-wide distribution of indoor
chemical contaminants" Stanley A. Mumma, Ph.D., P.E., Fellow
ASHRAE, Professor Emeritus of Architectural Engineering, Penn
the thermal conditioning of a building is decoupled from the
ventilation with thermally active surfaces by using water in the
mass of the building itself as the thermal system, rather than
air, this method of heat transfer reinvests the fabric of the
building with a more poignant role: the structure is the primary
mechanical system. The efficiencies of thermally active surfaces
emerge by responding more directly to the physiological and
thermodynamic behavior of the body as a context for design
decisions. These thermodynamic and physiological principles have
significant implications for energy consumption, design,
construction, and practice."
Kiel Moe, Assistant
Professor, Architectural Technology,