Geothermal Heat Pumps
The thermal storage capacity of soil, rock, and water near the surface is a vast, highly accessible geothermal resource. Though it may not be hot, the nearly constant year-round temperature within about 10 meters of the surface can provide a heat-exchange medium for efficient, low-cost heating and cooling of residential and commercial buildings.
Geothermal heat pumps (GHPs, also commonly referred to as "ground-source heat pumps") take advantage of consistent shallow-earth temperatures. A GHP system includes a group of buried or submerged pipes to provide heat exchange, a forced-air and/or radiant delivery system, and a heat pump to move thermal energy between the system and the ground. These systems can be installed almost anywhere and can provide hot water, heating, and cooling.
RESPEC has widespread experience designing and overseeing the construction of both vertical and horizontal loop fields and their accompanying heat pump system infrastructure. RESPEC has provided closed-loop ground coupled heat pump systems for schools, office buildings, aquatic centers, airports, and more.
PROJECT SPOTLIGHT
University of Albany Geothermal Ground Loop
University of Albany // Albany, NY, USA // 2010
RESPEC provided construction observation for a geothermal ground loop to heat and cool a new 500-bed dormitory at the University of Albany and was responsible for observing and documenting the performance of the geothermal contractor according to the design specifications for drilling, looping, grouting, excavation, horizontal piping, and tie-ins to the building. The multistory dormitory was approximately 184,000 square feet with an estimated peak heating and cooling load of 355 and 315 tons, respectively.
The wellfield included drilling 150 boreholes, 450 feet deep, for a total of 67,500 feet of vertical bore. Thick overburden deposits beneath the site were deposited in Glacial Lake Albany. The typical stratigraphic sequence for the site included a surficial layer of sand underlain by varved silt and clay to a depth of approximately 92 feet below ground surface (bgs). Glacial till was present from 92 to 200 feet bgs and underlain by bedrock assigned to the Hudson River valley mélange.
Three rigs completed the drilling. Overburden casings were installed to the top of the rock using mud rotary techniques, and the bedrock was drilled with an air rotary. Each loop was installed with thermally enhanced grout and individually pressure tested. Circuits were constructed with 3-inch supply and return piping with 15 loops per circuit, in a step-up, step-down, and reverse return configuration. Each circuit was individually tested before burial and tied into a central vault. At completion, the system was purged and flushed, and pressure and flow tested with 20 percent ethanol added for freeze protection.
PROJECT SPOTLIGHT
MEndenhall Valley Public Library
City and Borough of Juneau // Juneau, AK, USA // 2015
RESPEC staff provided the mechanical engineering design and construction services for a new 21,000-square-foot library building in the Juneau Mendenhall Valley. Mechanical systems include geothermal heating and cooling, central air handling unit with displacement ventilation and exhaust air, exhaust air heat recovery systems, outside air demand control ventilation, variable speed hydronic pumping, radiant floor heating, plumbing, wet sprinkler, and direct digital controls. The geothermal system features 18 vertical boreholes.
The Mendenhall Valley Library received LEED GOLD Certification.
PROJECT SPOTLIGHT
Geothermal Heating at the Juneau International Airport
Juneau International Airport // Juneau, AK, USA // 2010 - 2023
RESPEC has been a primary contributor to several major projects at the Juneau International Airport over the past 15+ years, overseeing the modernization of building systems, including the design and construction of geothermal systems to aid in heating, cooling, and snow removal.
A renovation completed in 2011 used 108 vertical boreholes to provide heating and cooling for the entire facility, including a 2023 terminal expansion. Savings from decreased oil consumption paid for the loop field in 8 years.
The Snow Removal Equipment Building, which houses the major equipment for runway and airport maintenance, is now served by a horizontal loop system covering 4 acres. The system provides heating and cooling to the building, and exterior snow melting via in-ground radiant tubing.
