ASHRAE Journal - June 2021 - 62

ASHRAE TECHNOLOGY AWARD CASE STUDIES
FIGURE 2 2019 metered and modeled electric (a) and natural gas (b) use.
Metered (2019) Electric
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Modeled Electric
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purposefully chose to use higher load assumptions to
give the building greater tenant fl exibility throughout
its useful life. Metered natural gas (Figure 2b) is higher
than predictions because ventilation is operated continuously
during the cold nights of ASHRAE Climate
Zone 6A to support the untraditional business hours of
entrepreneurs, who are among the building's tenants.
Indoor Air Quality and Thermal Comfort
Exceptional indoor air quality (IAQ) and ventilation
was a project minimum requirement. All occupied
spaces are served with a 100% exhausted, dedicated
outdoor air system (DOAS) that inherently reduces
indoor air pollution from cross-contaminating other
spaces. Ventilation zone air distribution effectiveness
(Ez) was 0.8 (ceiling supply of warm air 15°F [8.3°C] or
more above space temperature and ceiling return) per
ASHRAE Standard 62.1-2013 Table 6.2.2.2. The ventilation
system was sized to meet the greater of the latent
load and the ventilation load. Ventilation requirements
are exceeded by more than 5%. Operating the DOAS continuously
with zone-level controls ensures optimum IAQ
is always achieved.
Thermal comfort was designed to meet ASHRAE
Standard 55-2013. Seasonal thermal comfort parameters
and setpoint ranges were considered. Clo values were
estimated per ASHRAE Standard 55-2013 Table 5.2.2.2A
to be 0.61 (trousers, long sleeve shirt, long-sleeve
sweater) in summer and 1.01 (trousers, long sleeve shirt)
in winter. An average met value of 1.1 was used (per
ASHRAE Standard 55-2013 Table 5.2.2.2A, averaging
reading and writing 46% of time, typing 50% of time and
walking about 7% of time). Air speeds were considered
when diffusers were selected: 20 fpm (0.1 m/s) was used
in the analysis. Radiant temperature is assumed to be
equal to space temperature away from the curtainwall
systems.
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Metered (2019) Gas
Modeled Gas
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Radiant heating panels were located adjacent to curtainwall
systems, and triple-pane glass was specifi ed to
improve radiant temperature and reduce drafts near
curtainwall systems. Envelope commissioning was conducted
to ensure the curtainwall systems were functioning
as designed.
The Spark promotes indoor environmental awareness
with real-time displays of CO2, ozone, temperature and
humidity accessible to building occupants near core
bathrooms and elevators on a per-fl oor basis. These
sensors verify CO2 does not exceed 800 ppm, dry-bulb
temperatures are within the range of 70°F to 76°F (21°C
to 24°C), relative humidity is above 35% and ozone is less
than 5 ppb.
The building design promotes occupant productivity
and cognitive function through incorporation of numerous
additional IAQ and thermal comfort components,
including:
* Occupant-controlled thermostats in all occupied areas
of the building. Occupants can adjust temperatures
within the range of 70°F to 76°F (21°C to 24°C);
* MERV 13 media fi lters;
* Pure water atomizing humidifi cation systems;
* Rack space for future carbon fi lters if desirable;
* Materials selected with the goal to minimize VOCs
and a preoccupancy air fl ush;
* Outdoor air monitoring devices on the DOAS;
* Air infi ltration management through design and
envelope commissioning; and
* Negative pressure bathrooms, showers, copy/print
rooms, janitor closets and café area to manage moisture
and odors, verifi ed through building commissioning.
Most temperature-related maintenance calls were due
to occupants not knowing they could adjust thermostats.
The company has not observed drafts or cold spots near
the curtainwall during the coldest winter days. There
have been no maintenance calls related to air quality.
2021
Electric (MMBtu)
Natural Gas (MMBtu)
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ASHRAE Journal - June 2021

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