Development of Small-Scale Storage Facilities for Winter Storage of Fresh Produce

2014 Annual Report for LNC11-329

Project Type: Research and Education
Funds awarded in 2011: $108,829.00
Projected End Date: 12/31/2015
Region: North Central
State: Wisconsin
Project Coordinator:
Scott Sanford
University of Wisconsin-Madison

Development of Small-Scale Storage Facilities for Winter Storage of Fresh Produce


During 2014, work continued on the bulletin which is now in final review and should be published in late May or June 2015. The development of the publication has consumed the bulk of the project but I think the final product will be very valuable to growers. The reviewers have given it high marks. During January thru March 2014 presentations were made at the Wisconsin, Illinois, Missouri, Indiana, Iowa and MOSES Organic conference with about 800 people attending the 8 presentations at the seven conferences. A small low-cost humidifier and humidistat was testing in a cold storage over the winter in a grower’s storage unit and worked well. Work is progressing on a controller for using ambient air for cooling using off-the-self controllers, fans and duct zone damper. Some survey work was conducted to evaluate the cost, space requirements, income and income per cubic foot of storage from installing cold storage for extending the marketing season into winter.

Objectives/Performance Targets

  • Develop plans and construction details for 3 different basic storage facilities types that can be modified (enlarged or reduced in size) based on a grower’s needs and resources: These three basic types are: in-ground (earth contact on a minimum of 3 sides), new above ground construction, and storage rooms install into existing buildings (such as old dairy barns).


  • Develop plans for an effective low-cost environmental control using commercially available components to control temperature, humidity and take advantage of outside air for temperature modification.


  • Test different methods for humidifying small storage facilities and develop recommendations for small-scale winter storage facilities. Methods under consideration for testing include residential room humidifiers, small evaporative cooling pads, misting, and commercially-available humidifiers.


  • Develop extension publication(s) that will cover design and management of a cold storage facility. This will include full plans for sample structures that would be available as a free PDF download from the University of Wisconsin Extension Publication web site.


  • Develop and deliver workshops and webinar presentations to disseminate the information to educators and growers throughout the North Central region. Our goal would be to do 6 to 10 workshops and 4 to 8 webinars. Some of the workshops would be in cooperation with a grower that has built a facility or with a regional meeting such as the Midwest Organic Farming Conference. An average of thirty people per workshop or webinar is expected.


  • Develop a spreadsheet decision tool to aid growers in determining if winter storage crops will be economical for their operation. It will be posted on the national eXtension website.


  • Develop web pages on crop storage facilities for the national eXtension website. Links will be provided for publications, spreadsheet tools, educational presentations from workshops and webinars.


  • Work with grower/cooperators to test plans, designs and environmental controls. We hope to find growers to test all three designs. Because of the time between the writing of this grant, the start of funding and the availability of finished plans is about 2 years, it was premature to identify growers now. If a grower currently has an interest in building a storage facility, they are likely not going to wait 2 years for our project to develop plans. With the interest in locally supplied food, we don’t think we will have any trouble finding interested parties to test our plans.


  • Provide assistance to growers who are developing their own facilities. We will aid growers who have been through a workshop or webinar to develop a farmstead plan and modify plans to fit their individual needs.


The Project is rushing to the finish. The draft of the crop storage bulletin has grown to about 80 pages and is in final review. The bulk of the time this year has been spent on developing the publication. As part of the development of the bulletin, a model has been developed to estimate the energy use in coolers and a spreadsheet to estimate the material list for a conventionally framed small storage facility. An economic analysis tool has also been developed that allow growers to assess the amount of produce needed to cost justify a storage facility for fall harvested produce. These will be posted on a website shortly.

Outreach activities since January 2014 included presentation to the Wisconsin School for Beginning Market Growers (1/18 to 1/20/2014 – 40 people), Wisconsin Fresh Market Growers conference (1/21/2014 – 50), Illinois Specialty Crop Conference (1/9/2014 – 100), Great Plains Fruit and Vegetable Growers Conference (1/10/2014 – 50-60), Indiana Hort Congress(1/22-23/2014 – 115), Iowa Fruit and Vegetable Growers Conference(1/24/2014 -30), and the MOSES Organic Farming Conference(3/1/2014 – 270+ room couldn’t hold everyone). In all we had direct contact with about 800 people during 2013 and 2014.

Equipment testing is continuing. The cooling unit developed by as Senior Design Project is ready to test shortly. It uses ice water to provide cooling and humidification and has the advantage of not having to deal with evaporators freezing up as the refrigeration is supplied by ice cube makers located outside the cooler. There is also no risk of freezing crops that are to be stored close to 32F. A size appropriate humidification unit was purchased and tested in a cool storage during the winter at a grower’s facility and did an adequate job of maintaining the humidity level. We’ve also shown it off at presentations as an example of the technology. A programmable controller (PC) was purchase to use for providing control for an ambient air cooling system so cold ambient air could be used for cooling instead of using mechanical refrigeration. The PC unit is being programmed and tested. The program and equipment list will be available so growers can install their own system.

We have had only two contacts for consulting assistance during 2014. Once the very belated bulletin is published, I’m sure it will come with many questions.

Impacts and Contributions/Outcomes

Eight hundred growers and educators have learn about the types of structures for crop storage structures, refrigeration requirements, environmental controls, material handling, types of storage containers, estimating space requirements, crop storage requirements (temperature, humidity), types of humidification equipment, air flow patterns and requirements, planning traffic flow and selecting the cooler size and door placement to match the storage container size to maximize storage capacity.

Consultations resulted in a visit to a grower’s facility near Madison, WI and an email and phone exchange for the other grower in Minnesota. One grower is planning on building a cooler in an older barn and the other is building an additional facility because he can’t meet his market demand with his current facility.


John Hendrickson
Sr. Outreach Specialist
Agricultural Bulletin Building
1535 Observatory Dr
Madison, WI 53706
Office Phone: 6082653704
Scott Sanford
Sr. Outreach Specialist
U of Wisconsin-Madison
460 Henry Mall
Madison, WI 53706
Office Phone: 6082625062