Chadds Ford, Pennsylvania, USA, January 10th, 2022 – Bridgestone Associates, Ltd. (www.brdgstn.com) today signed an agreement with District Farms LLC to evaluate and design an earth/air heat exchanger (EAHX) system for the District Farms controlled environment greenhouse in Frederick, Maryland. This EAHX system will use the relatively constant subsurface ground temperature under the greenhouse to provide cooling of greenhouse air in summer and heating of greenhouse air in winter.
Under the agreement Bridgestone Associates will conduct a detailed analysis of the greenhouse heating and cooling requirements, the subsurface ground thermal characteristics and properties, and the seasonal variations in subsurface temperatures. Based on this analysis Bridgestone will develop a detailed design, layout, drawings, capital cost estimate, operating cost estimate, and proforma financial analysis to determine the viability of this novel heating and cooling approach.
“The use of the subsurface ground as a heat sink for cooling or as a source of heat for heating is relatively common with Ground Source Heat Pumps (GSHP) in commercial and residential applications,” said Frank Miller, Senior Project Manager, Bridgestone Associates, Ltd. “In typical GSHP applications, a thermal fluid is circulated through wells or buried piping to transfer heat to or from the surrounding ground and then that fluid is circulated through a building heat exchanger to provide heating or cooling replacing traditional HVAC equipment,” continued Mr. Miller. “In our design for the greenhouse we will circulate greenhouse air through an extensive network of large pipes buried below the greenhouse. As the air passes through ribbed underground pipes, it will transfer heat to the surrounding ground in summer and absorb heat from the surrounding ground in winter. The air will then be returned to the surface and distributed throughout the greenhouse. As part of the detailed analysis, we will evaluate how much heating and cooling can actually be obtained in this way, the energy required to circulate the air, and the overall capital and operating costs. We will also study the subsurface ground temperatures, the ground’s thermal characteristics, and the ability of the ground under the greenhouse to dissipate thermal energy when the greenhouse above is insulating it from outside ambient cooling.”
About Bridgestone Associates, Ltd.
Bridgestone Associates, Ltd. is a 30-year-old Chadds Ford, Pennsylvania, USA based energy consulting and development company focused on the evaluation, development, financing, design, construction, and operations of Renewable, Combined Heat and Power (CHP) and Independent Power (IPP) energy production facilities, and on the efficient use and utilization of energy. The Company provides these services to developers and owners of power generating and other energy related projects worldwide, as well as commercial and industrial energy users.
About District Farms, LLC
District Farms owns and operates a large hydroponic greenhouse approximately six miles south of downtown Frederick, Maryland. The controlled environment greenhouse uses a state-of-the art design to ensure the highest level of consistency and quality produce with the lowest impact on the environment. Unlike traditional farming that depends on the climate and weather patterns for harvesting, the closed-loop indoor facility maintains the best climate for maximum growth and nutrient absorption when compared to most indoor and outdoor farms. The greenhouse produces a wide variety of greens, from green and red butterhead, to baby leaf mixed varieties. These are grown without the use of harmful pesticides or herbicides, and the growing techniques qualify as non-GMO and organic. Unlike most greens available at retailers, District Farms greens have not traveled thousands of miles, and are usually available to the consumers the same day as they were harvested.