A cathedral, a school and a water utility show how heat pumps can work on tight sites.
Let's face it, we are creatures of habit. When we get used to paying a certain amount for utilities and replacing the same kind of air conditioner, why mess with the status quo? Digging or drilling for heating and cooling can sound like a lot of trouble. But two Manhattan projects show how different the answer can look when there’s barely any room to work.
New York City studied where geothermal could fit and in 2016 adopted Local Law 6, which established geothermal evaluation requirements for certain city capital projects. The city’s geothermal screening tool explains the factors engineers look at, from the ground beneath the lot to the building’s heating and cooling needs.
Take a look at the Trevor Day School. Geothermal loops were installed in many of the building’s foundation piles. The piles already had a job holding up the building. Putting loops inside them gave those same piles another job exchanging heat with the ground.
At Trevor Day School, some foundation piles double as heat exchangers.
At St. Patrick’s Cathedral, the retrofit team used standing-column wells to serve an existing landmark. The two projects show how different the answer can be for a new building with a foundation under design and a historic building with tight access.
The original illustration shows wells beneath St. Patrick’s Cathedral. Well design depends on site geology and building loads.
A third approach was tested at William L. Buck Elementary School. American Water’s pilot in Valley Stream used a heat exchanger to transfer heat between the utility water and a separate building loop. That took coordination with the water utility and project regulators.
American Water’s pilot used a heat exchanger to connect two separate water circuits thermally. Diagram credit: American Water, as shown.
There are benefits beyond the energy bill. A ground-source heat pump can move heat without a conventional outdoor condenser. When the indoor heat pump eventually needs replacing, a serviceable loop can often stay in place, much like the plumbing stays when you replace a clothes washer. For a small lot, ask what can be drilled, what equipment can reach the site, and how the loop will be sized before comparing bids.
Jay's passion for geothermal air-conditioning and heating started during a repair to his own home air-conditioning system 1989. Frustrated by the extreme tropical climate which had added to the premature failure of his air-conditioning system, he modified his home air conditioner to become a ground water-cooled system. Jay founded EggGeothermal in 1990 to provide geothermal HVAC systems. As a result of the American Recovery and Reinvestment Act of 2009, EggGeothermal entered into a new age of acceptance. Jay currently focuses his professional efforts on geothermal consulting, writing, and speaking engagements. Among his clients are federal, state and local governments, developers, associations, and private entities.
How New York City Makes Room for Geothermal
A cathedral, a school and a water utility show how heat pumps can work on tight sites.
Let's face it, we are creatures of habit. When we get used to paying a certain amount for utilities and replacing the same kind of air conditioner, why mess with the status quo? Digging or drilling for heating and cooling can sound like a lot of trouble. But two Manhattan projects show how different the answer can look when there’s barely any room to work.
New York City studied where geothermal could fit and in 2016 adopted Local Law 6, which established geothermal evaluation requirements for certain city capital projects. The city’s geothermal screening tool explains the factors engineers look at, from the ground beneath the lot to the building’s heating and cooling needs.
Take a look at the Trevor Day School. Geothermal loops were installed in many of the building’s foundation piles. The piles already had a job holding up the building. Putting loops inside them gave those same piles another job exchanging heat with the ground.
At Trevor Day School, some foundation piles double as heat exchangers.
At St. Patrick’s Cathedral, the retrofit team used standing-column wells to serve an existing landmark. The two projects show how different the answer can be for a new building with a foundation under design and a historic building with tight access.
The original illustration shows wells beneath St. Patrick’s Cathedral. Well design depends on site geology and building loads.
A third approach was tested at William L. Buck Elementary School. American Water’s pilot in Valley Stream used a heat exchanger to transfer heat between the utility water and a separate building loop. That took coordination with the water utility and project regulators.
American Water’s pilot used a heat exchanger to connect two separate water circuits thermally. Diagram credit: American Water, as shown.
There are benefits beyond the energy bill. A ground-source heat pump can move heat without a conventional outdoor condenser. When the indoor heat pump eventually needs replacing, a serviceable loop can often stay in place, much like the plumbing stays when you replace a clothes washer. For a small lot, ask what can be drilled, what equipment can reach the site, and how the loop will be sized before comparing bids.
Updated content · November 13, 2026
By Jay Egg, Guest Columnist
Jay's passion for geothermal air-conditioning and heating started during a repair to his own home air-conditioning system 1989. Frustrated by the extreme tropical climate which had added to the premature failure of his air-conditioning system, he modified his home air conditioner to become a ground water-cooled system. Jay founded EggGeothermal in 1990 to provide geothermal HVAC systems. As a result of the American Recovery and Reinvestment Act of 2009, EggGeothermal entered into a new age of acceptance. Jay currently focuses his professional efforts on geothermal consulting, writing, and speaking engagements. Among his clients are federal, state and local governments, developers, associations, and private entities.Also Read