Commercial Architecture January 2018 - 24

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

COMMERCI A L A RCHI T EC T URE

JANUARY 2018

commercialarchitecturemagazine.com

http://www.igshpa.org http://www.commercialarchitecturemagazine.com/geothermal http://www.commercialarchitecturemagazine.com

Table of Contents for the Digital Edition of Commercial Architecture January 2018