This site seeks to support the 6 points listed below:
1) It is almost impossible to verify that the ASHRAE ventilation standard
62.1 has been met with an all-air system. 2) Therefore a dedicated outdoor air system (DOAS) is required for verifiable ventilation air
distribution. 3) Once the use of DOAS is in place, it is one small step to decouple the space sensible and latent loads by supplying dry
Outdoor Air (OA) at a low (45-50 F) Dew Point Temperature (DPT).
This results in a significant improvement in the Indoor Air
Quality (IAQ), with a potential savings to US businesses
of $208 billion/year (in 1996 dollars when the Gross Domestic Product (GDP) was
$8,000 Billion) through reduced medical expenses and lost productivity. (source: LBL)
Note: The US GDP had grown to over
$16,660 Billion/yr by
the end of the 2nd quarter 2013. 4) That leaves sensible only cooling for the parallel system since all of the moisture is removed with the ventilation air, eliminating high humidity conditions.
5) There are many design choices for the parallel space sensible cooling system. At this site,
ceiling radiant cooling panels (CRCP)/chilled
ceiling or chilled beams
are favored. With the
DOAS-Radiant system, contaminants generated or released in one space are not
throughout the building by the HVAC sys. 6)
THE BENEFITS OF THIS APPROACH: This mechanical system design concept, when
to the conventional all air VAV system, resultsin
costs, provides superior IAQ and thermal & acoustical comfort, reduces the
a biological or chemical attack in the building, reduces the required plenum depth,
and is easier to
balance and maintain.
The challenge of conforming to ASHRAE Standard 62.1 in an energy efficient manner has led some HVAC practitioners to the conclusion that using
dedicated outdoor air systems (DOAS) in conjunction with sensible cooling at terminal units offers the best solution.
This section contains a first cost and operating cost analysis; for a 6 story office building; utilizing a dedicated outdoor air system (DOAS)-radiant system,
with a comparison to a conventional all air VAV system serving the same facility.
This section contains copies of archival technical papers ASHRAE published papers and
technical papers on dedicated outdoor air systems (DOAS) and radiant ceiling
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This section is intended to explore the potential rating points that the DOAS-radiant mechanical system design could contribute to the overall Green Building rating. The
DOAS-radiant system is significant for its energy and environmental benefits.