ASHRAE Journal - August 2021 - 71

HONORABLE MENTION | 2021 ASHRAE TECHNOLOGY AWARD CASE STUDIES
credit's potential at seven points. Each building in the
complex has its own dedicated HVAC system complete
with a smart, gas-phase air scrubber system, which
earned an additional two points toward energy savings
by reducing the volume of outdoor air required for
compliance with Standard 62.1-2010 while providing
enhanced air quality.
Energy Effi ciency
Dedicated Outdoor Air System (DOAS)
DOAS units supply outdoor air directly to the interior
spaces, resulting in higher zone air distribution effectiveness.
Delivering outdoor air directly to the breathing
zone eliminates ineffi ciencies inherent to mixed air systems
and allows cycling of space conditioning systems.
During heating mode the supplied ventilation air temperature
is less than 15°F (8.3°C) higher than the space
heating design temperature.
IAQP, LEED and Energy Use/Cost Savings Results
One of the three calculation procedures to show
compliance with Standard 62.1-2010 is the Indoor Air
Quality Procedure (IAQP), a method to provide performance-based
compliance with minimum zone outdoor
airfl ow values as an alternative to the Ventilation Rate
Procedure (VRP) and the geometry-prescriptive path
of the Natural Ventilation Procedure. Since the IAQP is
based on contaminant concentrations and a subjective
evaluation of perceived IAQ, it allowed the design team
to take credit gas-phase air cleaning to supplement conventional
ventilation.
Using gas-phase air cleaning units allows the required
ventilation to be calculated using the mass balance
equations for Standard 62.1-2010's IAQP, based on the
concentration of chemicals, particulates, etc., that
would likely accumulate in this type of space rather
than the prescriptive amount from the VRP. Ultimately,
this optimized the outdoor air volume in the proposed
design. This resulted in rates below the minimum
required for Standard 62.1-2010's VRP (which sets the
Standard 90.1-2010 Appendix G baseline building ventilation
rate), allowing for a reduction in peak cooling load
and energy consumption.
Using effective indoor air cleaning technologies,
tested for effi ciency using ASHRAE Standard 145.2-2011,
that address all contaminants of concern, including
CO2, results in reduced outdoor airfl ow requirements,
FIGURE 1 The average CO2 concentration for the event space addition stays below
ASHRAE/IES Standard 62.1-2010 design concentrations even during higher-occupancy
events as a result of the gas-phase air scrubber and ventilation design.
1,200
1,000
800
600
400
200
15
16
17
Metered
Concentration
Standard 62.1-2010
VRP Design
Concentration
Average Ambient
Concentration
18
FIGURE 2 Modeled and metered energy use.
120,000
100,000
80,000
60,000
40,000
20,000
Electricity
Metered
PV Generated
Modeled
|
19
Sep 2019
20
21
22
23
Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
2018
2019
producing signifi cant energy savings and keeping
contaminants below VRP design thresholds. Using the
IAQP to reduce ventilation rates without also removing
CO2 will result in higher than VRP design CO2
concentrations.
In addition, LEED allows the use of the IAQP to determine
outdoor air requirements under Pilot Credit 124:
Performance-Based Indoor Air Quality Design and
Assessment. Following the IAQP, dilution is substituted
partially by air cleaning. Air cleaning using high effi -
ciency sorbents (tested according to Standard 145.2-2011
and ASHRAE Standard 55.2-2012) results in fresh air
that can be cleaner than the ambient outdoor air.
Energy Effi ciency Performance Documentation
The analysis for creating a high performance design
includes comprehensive energy modeling to compare
strategies in the proposed design against the Standard
90.1-2010 Appendix G Baseline. The project was also
designed to comply with the more stringent Standard
90.1-2013 for state energy code compliance. Two HVAC
A U G U S T 2 0 2 1 ashrae.org ASHRAE JOURNAL
a s h r a e . o r g A S H R A E J O U R N A L
7 1
Energy Use and Production (kBtu)
CO2 Concentration (ppm)
http://www.ashrae.org
ASHRAE Journal - August 2021

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