ASHRAE Journal - August 2022 - 37

TECHNICAL FEATURE
PHOTO 1 Lower Manhattan at night. (Photo Credit: Andre Benz on Unsplash)
FIGURE 1 Map of New York City and Westchester.
building information. The tool covers nearly 900,000
lots and is available at https://www1.nyc.gov/assets/ddc/
geothermal/index.html.
Overall, three different geothermal systems (closed
loop, standing column well and open loop) were analyzed
for potential implementation in comparison to
installing a conventional HVAC system. Buildings were
categorized into 25 different types based on vintage, size
and occupancy to establish a baseline for thermal load
and conventional energy consumption. Potential ground
thermal capacity was determined by calculating the
amount of thermal capacity accessible by wells or loops
installed within the available outdoor area on each lot.
The Westchester County screening tool- " Westchester
GeoPossibilities " -demonstrates that the New York City
tool can be adapted for use by individual counties and,
therefore, used nationwide. In this case, the county
is suburban, but Westchester GeoPossibilities, whose
development was funded by the New York State Energy
Research and Development Authority (NYSERDA),
could in turn be adapted for rural counties as well. The
Westchester tool is available at https://geopossibilities.
ny.gov.
Results
The greatest application of geothermal energy lies in
properties covering larger areas with less intense density.
These include lower-rise offi ce and housing developments,
university and college campuses and medical
centers. Manhattan's narrowly sited offi ce towers are,
therefore, less suitable than an offi ce park or housing
complex in Westchester.
In New York City, positive cost-effective results were
less likely in Manhattan and the Bronx, where building
loads often exceed the potential thermal capacity
within the available outdoor area. Staten Island, Queens
and Brooklyn demonstrated better results as outdoor
space for installing piping or drilling is more plentiful,
and building loads are generally less intense. Most commercial
buildings were deemed not feasible due to the
large cooling load they require, given the limited area
they occupy. However, many less intensive building sites
could be feasible, particularly if using a hybrid system
using a cooling tower to offset excess heat. Of the feasible
full geothermal lots in New York City, the majority were
small multifamily buildings or single-family homes with
suffi cient outdoor space available to meet the heating
and cooling requirements for those buildings.
While generic installation costs suggest these locations
may be feasible, site-specifi c review may result
in additional costs that negatively impact a project's
payback period. All decisions must ultimately be
made after completing an in-depth feasibility study
for the site and taking accounting of any technological
improvements over time.
Table 1 shows the variation across New York City's fi ve
boroughs in the percentage of lots that can expect a
given payback period. In Manhattan, for instance, only
20% of lots would have a payback in under 12 years,
while in Staten Island 90% would.
Project Overview
The overall purpose of screening tools is to provide
a threshold assessment of the potential for the use of
ground source heat pumps for buildings within the
jurisdiction. This assessment is based on key known
variables, including but not limited to building thermal
demand, land area availability for drilling and geology at
the borough-block-lot (BBL) level. The results provided
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https://www1.nyc.gov/assets/ddc/geothermal/index.html https://www1.nyc.gov/assets/ddc/geothermal/index.html https://geopossibilities.ny.gov https://geopossibilities.ny.gov http://ashrae.org
ASHRAE Journal - August 2022

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