ASHRAE Journal - November 2020 - 42

systems, their arrangement,
and performance. The design
conforms to the requirements
of ANSI/ASHRAE Standard 55,
ANSI/ASHRAE Standard 62.1,
ANSI/ASHRAE/IES Standard
90.1 (2010 editions), and the
ASHRAE Laboratory Design Guide.

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2020

ASHRAE TECHNOLOGY AWARD CASE STUDIES

Typical general laboratory suite.

Energy Efﬁciency

Designing heating, ventilating, and air-conditioning
(HVAC) systems in Fairbanks, Alaska, where winter temperatures can dip down to -60°F (-51°C) and summer
temperatures reach 90°F (32°C), is challenging at best.
Add to that a laboratory facility with a potential exhaust
air/makeup air rate of 60,000 cfm (102,000 m3/h), and
things get interesting. Ending up with a facility that
averaged just 113 kBtu/ft2·yr (1283 MJ/m2·yr) of energy
use during its ﬁrst year of occupied operation is worth
talking about.
The ELIF's high-performance design begins with its
building envelope, which uses a special unitized curtainwall with thermal breaks, custom designed for this speciﬁc arctic location. The architect's attention to detail at
each and every panel connection was critical to the overall
success of this project. The building receives low-pressure
steam (15 psig [103 kPa]) and chilled water/waste heat
from the central UAF campus power plant through an
underground utilidor network. The Owner's Performance
Requirements allocated a maximum of 500 gpm (0.032
m3/s) of 42°F (5.6°C) chilled water (30% ethylene glycol
[30% EG] solution) to cool the building. During the heating season, this system is switched over to provide an
unlimited supply of 90°F-100°F (32°C-38°C) central plant
"waste heat." The building HVAC system is speciﬁcally
designed to work within these parameters and to use as
much low-quality unlimited waste heat as possible. This
is primarily achieved through detailed radiant ﬂoor tubing sizing, placement and spacing, and greatly oversized
outside air intake preheat coils at each of the ﬁve central
air-handling units (AHUs).
During the summer, the sun is up almost 24 hours a
day and at a very low azimuth. As a result, the building
receives almost continuous direct solar heat gain. The
radiant ﬂoor system is designed to operate in heating or
cooling mode on a zone-by-zone basis (32 zones) to keep
solar heat gain in check, while maintaining comfortable
42

ASHRAE JOURNAL

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N OVEM BER 2020

summer zone set-point temperatures.
The three 100% outside-air AHUs, which serve the
laboratory suites, high bay structural testing lab, and
machine shops, each include air-to-air heat recovery,
dual variable-speed drive supply and exhaust fans and
circulation pumps. Occupancy sensors and precise
indoor pressure control greatly reduce this facility's
energy use. The facility's mechanical systems are strictly
designed in accordance with the latest ASHRAE laboratory design standards.
The ventilation system is designed to provide the necessary percentage of fresh outside air in accordance with
ASHRAE IAQ standards whenever the building is occupied. All ventilation air is ﬁltered through MERV 8/14
ﬁlter banks. Due to frequent forest ﬁres, often accompanied by heavy smoke, the AHUs are designed to accept
special activated carbon ﬁlter media whenever the need
arises.
To provide proper IAQ, while keeping energy use
in check, classrooms and other building areas with
short-term, high-density occupancies implement
both occupancy and carbon dioxide (CO2) sensing to
reduce ventilation rates to match actual zone occupancy level.
Building zones ventilated with 100% outside air are
designed to provide up to 12 ach of exhaust ventilation.
Zone variable-air-volume terminal units are slightly
undersized such that background noise level noticeably increases at 12 ach. This ensures occupants that the
ventilation system is operating properly if emergency
exhaust evacuation is implemented from wall-mounted,
emergency exhaust push buttons. Slightly undersizing the terminal units also allows for greater turndown
when the labs are not occupied (limited by terminal unit
inlet airﬂow station accuracy). In some cases, a turndown as low as 2-3 ach can be achieved, greatly saving
energy. Under normal occupied operation at 6-8 ach,
background noise levels remain well within the guidance in Chapter 48 of the 2015 ASHRAE Handbook-HVAC
Applications.

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ASHRAE Journal - November 2020

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