Reducing New England High Tunnel Heating Costs and Fossil Fuel Usage Utilizing an Earth Air Heat Exchanger

Project Overview

Project Type: Farmer
Funds awarded in 2020: $15,000.00
Projected End Date: 02/28/2023
Grant Recipient: Hip Peas Farm
Region: Northeast
State: New Hampshire
Project Leader:
Dan Lagueux
Hip Peas Farm

Project was terminated early and work ended as incomplete.


Not commodity specific


  • Crop Production: season extension
  • Energy: energy conservation/efficiency, renewable energy, solar energy
  • Farm Business Management: budgets/cost and returns, feasibility study
  • Sustainable Communities: infrastructure analysis

    Proposal summary:

    Winters in New England routinely reach temperatures below freezing for months at a time. For years, growers in New England have turned to high tunnels to shelter their crops from snow and frost, extending their growing seasons by up to six months. Crop selection for unheated high tunnels are limited, so supplemental heat can broaden crop options during winter months. While increasing the variety of crops grown, costs can quickly climb to thousands of dollars per month. Hip Peas Farm will measure the effectiveness of using an Earth Air Heat Exchanger (EAHE) to reduce heating costs. An EAHE draws warm ambient air heated by the sun through pipes buried in crushed stone during warm days, then draws heat from stone on cold nights to raise the greenhouse air temperature. A 50 degree minimum air temperature will be maintained in each of two separate high tunnels using an in ground radiant heating system in one, and an in ground radiant heating system plus the EAHE in the other. Hip Peas Farm already has these structures and does not require funding for their construction. The reduction in the amount of fossil fuel needed, and cost savings will be measured. The study will determine the financial efficacy of using an EAHE. Results will be shared at the 2022 New England Vegetable and Fruit Conference, through twilight meetings at the farm, a Reddit A.M.A., and working with UNH Extension’s Marketing and Communication department to create promotional educational materials for additional farmer outreach.

    Project objectives from proposal:

    This project seeks to determine the efficacy of an Earth Air Heat Exchanger (EAHA) in reducing fossil fuel-based heating costs in winter growing high tunnels in NH. We will compare the fuel used in a tunnel utilizing an EAHE and a radiant heating system to a tunnel utilizing just a radiant heating system. From there, an economic analysis can be performed to determine the cost savings of using this system on different common fuel types.


    If the system is effective, it could help growers reduce winter heating costs, allowing them to save on heating bills and reduce fossil fuel expenditure. If not, it can inform others how the system can be improved for future use. Suggestions from UNH Extension Agricultural Business Management Field Specialist, Seth Wilner, were made to observe yield and quality data of crops grown. While this is an intriguing aspect to study, Hip Peas Farm is a working farm, and will need to grow different crops at different successional timings in each tunnel, so having side by side comparisons would not be viable. Research could be performed by another party if the crops could be identical so comparisons could be made.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.