Greenhouse Energy Conservation Strategies and Alternative Fuels

Project Overview

Project Type: Professional Development Program
Funds awarded in 2007: $33,432.00
Projected End Date: 12/31/2010
Region: North Central
State: Wisconsin
Project Coordinator:
Scott Sanford
University of Wisconsin-Madison

Annual Reports


Not commodity specific


  • Education and Training: extension
  • Energy: bioenergy and biofuels, energy conservation/efficiency, energy use

    Proposal abstract:

    Greenhouse heating expenses have increased by 30% to 50% since 2003 while retail prices for plants have remained flat, putting a squeeze on profits. Energy is the third largest cost in most greenhouse facilities behind plant materials and labor. Many agricultural educators are well versed in greenhouse plant production issues, but lack knowledge about energy conservation strategies and alternative energy sources for greenhouse growers. Many growers are looking for options to reduce their energy costs but they don’t always understand which options will provide the greatest return on investment. Curriculum materials, extension bulletins, resource lists and a spreadsheet model will be developed with the intention that educators can use the materials in full or part to deliver programming on energy management and conservation for greenhouse production. All of the curriculum materials will be placed on the Wisconsin Energy Efficiency and Renewable Energy web site for easy access to educators and the public. Two one-day workshops will be held to present the curriculum materials and provide in-service training for extension agents, vocational agriculture teachers and other educators. Program outcomes include increasing the knowledge based of educator, increase the number of educators providing workshops or including content on greenhouse energy efficiency in programming. The long-term goal is for growers to increase the use of energy efficient equipment and structures and to adopt energy efficient growing practices. A survey of workshop participants and growers at the end of the year 3 will be used to evaluate the impact of the program.

    Project objectives from proposal:

    A survey of extension agents in Wisconsin indicated that extension bulletins are still a preferred vehicle for providing information to clients, but they would like them to be available on-line so they are easy to find and they can access the latest reversion. PowerPoint presentations were also ranked highly by extension agents as a media for information transfer.

    A series of at least four PowerPoint presentations will be developed to cover equipment, management practices and plant production strategies for reducing energy use in greenhouses.

    The first presentation will focus on equipment and structures covering types of structures, glazing systems, types of heating systems, night curtains, side wall insulation, infiltration heat loss, heating system maintenance, exhaust fan efficiency, space utilization and environmental control systems. The presentation will include examples of how the type size and shape of the greenhouse can affect energy use, provide a case study on the energy consumption if different types of unit heaters are used and illustration of how under bench heating system can be incorporated into an existing greenhouse.

    Presentation 2 will cover thermal/ shade curtain installations in detail. The types of curtain systems, system components, curtain materials, drive system to open and close curtains, controls and control strategies will be covered. The presentation will also include how a manually operated system can be installed in stand-alone quonset or Gothic type greenhouse.

    Presentation 3 will focus on plant production methods to reduce energy use. This will include the use of supplemental lighting to reduce growing times, selection of plants and greenhouse temperature management based on research and publications done by Erik Runkle (Michigan State U), AJ Both (Rutgers University), Paul Fisher (U of Florida) and others. The fourth presentation will cover alternative energy sources including waste heat sources, core wood, pellet fuels (wood, paper, and biomass), corn, coal, biodiesel, waste oil, solar and wind. Some of these energy sources are considered low cost or “free” but everything has costs. The advantages and disadvantages of each fuel will be highlighted and true costs will be estimated.

    Peer reviewed extension bulletins will be developed to compliment the PowerPoint presentations. The first bulletin (“Energy Efficient Greenhouse Production Strategies”) will focus on the use of supplemental lighting and temperature control so crops can be started later and still be ready for the consumer on time. The bulletin will cover the use of daylight integral to determine how much supplemental lighting to provide plants and how DIF can be used to reduce heating costs without slowing plant growth. The second bulletin (“Greenhouse Energy Conservation”) will focus on the top 10 strategies for reducing energy use, such as glazing types, heater selection and maintenance, thermal curtains, ventilation efficiency, and infiltration losses.

    About 80% of greenhouse heating occurs at night. A thermal, retractable curtain can cut heat loss by up to 50% in the winter and can also be used as a shade curtain in the summer to reduce cooling costs or extend the use of the greenhouse. A bulletin will describe the types of curtain system installations, including what materials are required and how to install a manual opening and closing system. The primary target for this bulletin is stand-alone greenhouses, but applies to all greenhouses. Commercially available thermal curtains are often too expensive for small growers.

    As growers try to reduce their heating cost, they are often lured to alternative fuels. The true cost of alternate fuels is often overlooked; core wood is often look at as being low cost or free. A separate bulletin will discuss the pros and cons of different alternative fuels such as core wood, corn, pelleted fuels, waste oils, biodiesel and waste heat sources, as well as the burners or furnaces and other equipment required to use the energy sources. This bulletin will provide reference lists for those who want more in-depth information.

    A greenhouse energy model, that is an MS Excel application, will be modified from previous work for use by educators to help estimated the energy used for different equipment and management parameters. The application allows modeling a greenhouse with different heating systems, glazing types, thermal curtains, temperature set-points, insulation of walls and foundation, and infiltration heat losses. The program requires input data about the size of the greenhouse, types of glazing used, greenhouse location, heater types, day and night time temperature settings, and the estimated infiltration loss of the greenhouse. The program uses monthly average temperatures and calculated the estimated energy consumption. The user can look at the affects of changing the glazing type, temperature settings, heater efficiencies, adding thermal curtain and reducing infiltration losses on the average yearly energy consumption.

    As pointed out previously, busy educators prefer web based information to paper copies for organizational purposes and it allow them to always have access to the most up-to-date information. Therefore, all materials developed will be available on-line at the Wisconsin Energy Efficiency and Renewable Energy Resource web site ( for free access by educators and the public. Registration will be required before downloading materials so users can be notified of any updates and we have some demographic information on who is using the materials.

    A reference list will be developed with bibliography of supporting documents, helpful web sites, equipment vendors that offer energy conserving equipment and a list of extension specialist that may be able to aid educators with local programs or with greenhouse grower questions.

    A workshop will be developed to provide in-service training for extension agents, and vocational agriculture teachers as its main focus but energy auditors for state and utility energy grant programs would also benefit from the workshops. The one-day workshop will present the materials developed to provide knowledge and understanding about greenhouse energy conservation options and strategies. Speakers with expertise in the topic areas will be invited to make presentations on the information provided in the presentation materials and extension bulletins. Workshop participants will be provided with a CD containing PowerPoint presentations, extension bulletins, spreadsheet greenhouse energy model and other reference resources. Two workshops are planned with tentative locations in northwestern Wisconsin or St. Paul, MN area and southern Wisconsin, possible in Madison.

    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.