PROJECT
geothermal Far left. The central-operations room houses controls, pumps, piping, and the Multistack condenser water-loop system. Left. The Multistack units allow extensive variation in temperature management by shifting heating and cooling according to demand, with or without feed from the bore field.
welcome feature walking in the front doors on a cold winter day. While all of the spaces have piped heating and chilled water available for simultaneous operation (useful for effective dehumidification on muggy summer days) of variable-air-volume fan-coils (VAVs), the wide-open spaces employ chilled-beam technology. The increase in overall comfort provided by chilled beams results from decreases in noise, draft conditions, and temperature inconsistencies. Typical air-distribution systems may produce sound levels in the range of NC 35 to 40, while chilled-beam systems operate with sound levels less than 20 NC. Some of the other features in the facility include rainwater storage, automatic window shades, a green (planted) roof and, of course, photovoltaic modules covering most of the building. A walk along the rooftop reveals openings in the PV panels in strategic positions to allow natural daytion and workforce development.
cooling most of the winter while some of the other spaces
light into the building through strategically placed sky-
In New York’s capital of Albany, the Empire State Plaza
that don’t have natural solar and internal heat gains will
lights. Mayor Bloomberg wanted a forum to implement his
uses a geothermal surface-water exchange system that was
need heating. The “waste heat” from cooling the southern
“Applied Sciences NYC Initiative,” designed to transform
constructed more than 50 years ago. The Hudson River
exposures is piped to spaces that need heat, dramatically
New York’s innovation economy and Cornell’s Bloomberg
serves as a geothermal heat sink for the massive chillers in
increasing overall system efficiency. This is called ther-
Center is helping to make that a reality. CA
that city’s central-energy plant, dramatically increasing the
mal-advantage load sharing.
exchange efficiency with the cool river water, and eliminat-
In this symbiotic operation, the Center’s condenser wa-
Jay Egg is a geothermal consultant, writer, and owner of
ing the need for cooling towers and the related mainte-
ter loop may operate at a stated capacity, such that there is
EggGeothermal, Kissimmee, FL. Egg has co-authored two
nance, noise, and replacement costs.
no need to extract or reject heat to/from the 55 F earth.
textbooks on geothermal HVAC systems published by Mc-
Because of the decoupled design, the loop pumps may re-
Graw-Hill Professional. He can be reached at jayegg.geo@
ROOM FOR GROWTH
main idle for extended periods of time. During this type of
gmail.com
The Bloomberg Center’s geothermal exchange design pro-
operation, heat-pump efficiency, normally at a 4 or 5 COP
vides considerable room for growth as occupancy at the
(coefficient of performance) is dynamically increased.
Center grows to its maximum load of 3,000 students. For
It’s important to remember that geothermal HVAC sys-
example, while the vertical loops have plenty of exchange
tems are fundamentally hydronic, meaning that the heat-
capacity as designed, there is an annulus pumping system
ing (and cooling) energy is distributed within pipes filled
that can be engaged, increasing capacity by encouraging
with water. This provides a level of thermal-energy control
increased flow through the annulus of the boreholes. (The
and energy efficiency that is not available with air-sourced
annulus is the space between the borehole wall and the
and forced-air distribution systems. Chilled-beam systems
exchange piping, usually filled with bentonite grout. Since
handle return air and sensible loads inside the conditioned
no grout was used in this design, it naturally fills with cool
space, reducing the volume of supply air, resulting in a sig-
ground water.) Intuitively, separate pumps are engaged by
nificant decrease in the amount of distribution materials
controls that monitor the borehole temperatures. When
(ductwork) and installation labor requirements. Reducing
called for, ground water is pumped from the annulus of
space required for ductwork can yield construction savings
boreholes, promoting greater advective heat transfer.
and allow greater ceiling heights and/or reducing overall
This article and accompanying podcast are part of our multi-month coverage of geothermal technology in commercial facilities in collaboration with the International Ground Source Heat Pump Association, Stillwater, OK, (igshpa.org). Visit commercialarchitecturemagazine. com/geothermal for more information.
The ground-loop system is decoupled from the con-
building height. A dedicated outdoor air system (DOAS)
denser water loop inside the building, allowing separate
handles the remaining ventilation and latent-load needs of
Visit the online version of this article at
operation of the condenser-water pumps for the chillers.
the building and occupants.
commercialarchitecturemagazine.com/geothermal to hear a podcast in which Jay Egg and editorial
Unlike air-sourced air conditioners and heat pumps, wateror geothermal-sourced systems have the ability to exchange
CREATURE COMFORTS
director Gary L. Parr provide more detail about the
rejected energy from one area and/or process it to another.
The creature comforts in Cornell’s Bloomberg Center
Cornell Bloomberg Center geothermal system.
For example, south-facing building spaces will need
are impressive. Radiant heating on the ground floor is a
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COMMERCI A L A RCHI T EC T URE
JANUARY 2018
commercialarchitecturemagazine.com
