Novel approaches to improve energy efficiency in northern New England greenhouses

Final Report for LNE10-299

Project Type: Research and Education
Funds awarded in 2010: $195,781.00
Projected End Date: 12/31/2014
Region: Northeast
State: Vermont
Project Leader:
Dr. Bruce L. Parker
University of Vermont
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Project Information

Summary:

A novel system for insulating double-poly greenhouses during the winter was compared to a commercially-available energy curtain and an unimproved greenhouse. The novel system involved the production of soap bubbles to fill the void between the two plastic layers covering the greenhouse. The energy curtain closes at night over the plants, confining heat in the greenhouse to the plant-growing area and reflects the heat downwards onto the plants. This work resulted in development of significant improvements to the bubble system design. The systems were operated for three winters generating the first ever data comparing energy conservation resulting from insulating with bubbles vs. an energy curtain. Energy savings from the bubble system were substantial compared to the control, ranging from 27 to 43% with the highest savings seen during the coldest periods of winter. Savings using the energy curtain ranged from 25 to 31% compared to the control. Results from the study have been presented to many Northeastern growers, including a day-long conference (Energy Extravaganza) held at a commercial greenhouse facility in Colchester, VT. A video was produced highlighting the project results. It was uploaded for viewing by the public to our Greenhouse Energy Conservation webpage at: http://www.uvm.edu/~entlab/Bubble%20Greenhouse%202010/BubbleGreenhouse.html.

Nine commercial greenhouse operators participated in comprehensive energy audits at their operations, six in Vermont, and three in New Hampshire. The growers indicated that the audit information was very useful and they have begun implementing energy saving practices. One of the growers even hosted a workshop to encourage other growers to arrange for audits. Another grower developed a 5-year plan for carrying out recommended improvements, including replacing the boilers in six greenhouses, installing digital thermostats, and installing an energy curtain.

A grower in southern Vermont indicated in a questionnaire of ours that there were no limits for his improving energy conservation in his greenhouse operation.  With government assistance he would install an energy curtain, a geothermal heating system and solar panels. He stated that the energy audits gave him many ideas that were easy to implement. Eight additional growers in Vermont and New Hampshire expressed interest in applying to the USDA NRCS for an energy audit.  The total number of applications for USDA NRCS assisted funding for energy audits or other conservation measures is not known, although NRCS personnel gave presentations at the 2014 Energy Extravaganza in Colchester VT, and the 2015 Green Works conference in Burlington, VT providing application materials and guidance to approximately 100 growers.

The outreach performed resulted in 5 growers expressing interest in implementing a soap bubble insulation system in their greenhouses.  The publications prepared, the video made and currently showing on You Tube, and the many grower contact events indicated about 29,000 growers and people in the industry were exposed to this SARE project and its goal of energy conservation in Northern New England Greenhouses.

Introduction:

Sustainable agriculture integrates three basic goals, “environmental stewardship, farm profitability and prosperous communities”. This concept will survive only through innovation and implementation of strategies that increase production and reduce negative environmental impacts. Unfavorable weather is a bane to farmers leading to financial instability. Growers are turning to greenhouse production to reduce loss due to poor weather and increase the length of the growing season. Though plastic hoop houses are inexpensive to erect, they demand large amounts of energy, especially in northern climates. As dairy profits decline, farmers are diversifying their operations with high-value greenhouse crops, which nationally generate >$14 billion in wholesale revenues annually. This project built on our greenhouse network in Maine, New Hampshire and Vermont, partnering with growers to increase their sustainability through improved energy conservation in hoop houses. Two energy conservation systems, a soap bubble insulation system developed in Canada, and a thermal curtain, were retrofitted into separate gable-style 88 ft. long greenhouses at the largest Vermont greenhouse ornamentals operation. A third house without additional insulating improvements was used as a control. The bubble insulation system injects soap bubbles between the two layers of plastic covering the greenhouse. This system was reported to increase the R value from the 1-2 of an un-insulated house to 30-40. In 2001, a grower constructed one of the first hoop greenhouses with bubble insulation in Ontario where winter temperatures commonly reach -30ºC. He reduced propane heating costs from $1,137 to $146/year (http://organic.yukonfood.com/bubblehouse/htm) and extended greenhouse production from 6 to 10-12 months per year. Bubbles as a form of insulation for greenhouses has been considered for many years, and a few houses demonstrating its potential have been constructed, but other prevailing conditions have never been right to lead to its adoption by commercial growers. Times have changed. Now was an ideal time to reconsider this promising conservation system as fuel costs have increased and tax incentives for energy conservation have become available. The concept behind the system was that bubbles produced from a liquid soap solution would provide significantly more insulation value than air alone, and because the bubbles dissipate over time, they offer unique low maintenance flexibility, reducing energy loss at night or on cloudy days, and disappearing on sunny days when growers seek to maximize on solar radiation. They also serve as a shading system to reduce energy consumption in late spring and summer when overheating rather than cold is an issue. 

The second energy conserving system tested was an energy/shade curtain to capture and retain available energy from the sun to supplement conventional heating equipment. Both of these systems are not “new”, but their value in plastic hoop greenhouses had not been fully evaluated and compared in northern New England nor are they often currently used by commercial growers. Monitoring equipment was installed to quantify energy savings relative to ambient temperature. 

In addition to conducting research on the energy use of different energy conserving systems, a greenhouse grower survey was conducted on energy use in the tri-state region (ME, NH and VT). Most responding growers spent less than $10,000 annually on electricity and over half spent less than $10,000 on propane or oil for heating. Twenty-four percent of the respondents used $10,000-25,000 on fuel. The expense of implementing energy saving measures was identified as the most limiting factor, and providing tax incentives for energy conservation was cited as the most helpful to encourage adoption of conservation practices. 

As part of this project energy audits were completed at six Vermont commercial greenhouse operations and three in New Hampshire to demonstrate the benefits of this service. Feedback from growers having the audits indicated that the information they received from was very useful. One of the growers was so enthusiastic about what he learned that he hosted a workshop to encourage other growers to arrange for audits. Another grower receiving an audit has replaced the boilers in six of his greenhouses because he recognizes the savings he will ultimately realize from these improvements. He also has installed digital thermostats to enhance his energy savings. He is considering installing an energy curtain in one of his greenhouses because of the energy benefits he observed in the test greenhouses at his operation.

The project also had an outreach component which included presentations at several events for growers. An Energy Extravaganza was held at the research site to showcase the two energy systems tested, and present other information on energy conservation for growers. This was the culmination of the project bringing all of the different aspects together to share with growers. Attendees came from Maine, New Hampshire, Vermont and New York. Based on the participant evaluations, the event was very useful, and all of the attendees learned new techniques they intend to use in the future to conserve energy or promote energy conservation.

Performance Target:

  1. Assess two innovative energy-saving devices retrofitted into a greenhouse: a bubble insulation system and an energy/shade curtain system.
  2. Conduct comprehensive energy audits before and after retrofitting the greenhouses to quantify the benefits of both devices.
  3. Determine cost of greenhouse retrofitting, energy savings and potential tax incentives from which to assess the costs and benefits of both systems compared to an unimproved greenhouse.
  4. Conduct a survey to generate baseline data on current energy consumption and conservation used by greenhouse growers in the tri-state region.
  5. Conduct energy audits at 9 greenhouse operations to provide quantitative information about trends in current energy consumption and identify the most significant measures that would improve conservation.
  6. Conduct workshops in each state to present information on energy conservation and federal and state incentive opportunities, and host an open house to demonstrate the innovative energy conservation systems tested.
  7. Produce a grower-friendly guide entitled How to Retrofit a Greenhouse for Energy Conservation. Cost of retrofitting, energy savings and potential tax incentives will be determined from the data, from which an accurate assessment of the benefits of these systems will be made.
  8. Develop a web-based program enabling growers to calculate cost savings from energy conservation activities.

Performance Target

Over 1,650 growers will receive information about energy conservation in greenhouses. Of the total growers receiving information, 5% (~80 growers) will implement at least one recommended tactic in one 2,000 sq ft greenhouse (total 160,000 sq ft), resulting in an annual reduction of energy cost of $500 per greenhouse grower operation. One grower per state (3 growers) will retrofit at least one greenhouse with either a bubble or thermal blanket insulation system, resulting in a yearly cost savings in fuel use of $1,000.

Cooperators

Click linked name(s) to expand
  • Dr. John Bartok, Jr.
  • Chris Conant
  • Judith Doerner
  • Christopher Jones
  • Dr. Brian Krug
  • Craig Metz
  • Rachael Phillips-Tibbetts
  • Peter Skinner
  • Dr. Margaret Skinner
  • Joey Villeneuve

Research

Materials and methods:

The research was performed in three side-by-side gable style greenhouses, each ~4,000 sq ft, located at Claussen’s Greenhouses, the largest commercial grower of greenhouse ornamentals in Vermont. One house was retrofitted with a bubble insulation system, one with the energy/shade curtain system, and the other remained unimproved to serve as a control. These greenhouses are for commercial bedding and ornamental plant production. Similar plants requiring comparable growing conditions were produced in each house. Temperature and humidity data were collected in the houses, and a comprehensive audit was conducted to generate information on energy usage among the three greenhouses. Data were collected for three winters which generally spanned from late October until early April, with a short period of non-use from late December through January.

Bubble Insulation System.

A dismantled prototype bubble system was acquired from Sunarc of Canada. This system had been installed in a 200 ft long greenhouse. It required major modifications to be used in our gable-style, 88-ft long greenhouse. The system components are composed of tanks to hold the soap solution, a Jet-pump to transfer the soap solution from the tanks to the foam generators along the peak of the gable, an air pump to force outside air up and into the foam generators, a filtering system to remove particulates out of the soap solution, a tubing system that runs along the peak with both air and soap solution lines, individual foam generators which produce the soap bubbles, a separate rinse system with valves, tubing, and nozzles, and PVC and polyethylene tubing to connect it all. A schematic of the system can be found in Document 1. Other control components consisted of an electrical panel, over-pressurization shut-off switch, outside air damper system to vent the system and prevent over pressurization, a solar sensor, and a timer to shut the system on and off at predetermined intervals. The entire system was automated with temperature and light sensors to facilitate operation.

 The soap solution was produced using a proprietary recipe provided by Sunarc of Canada. The ingredients were obtained from US vendors. The original solution recipe did not include an antifreeze so polyethylene glycol (PEG) was added to ensure the soap solution didn’t freeze in the system. This addition did not appear to hinder the foaming action of the solution.

Energy/shade curtain system.

A commercial energy/shade curtain system was installed by a nationally recognized vendor. It was installed in a slope-flat-slope design so it would be suitable inside the gable-style greenhouse. The initial installation included manual controls. In year two a Shade-Stat controller was installed which automatically opened and closed the curtain at predetermined times. The system is composed of several sections of reflective curtain which open and retract on cables driven by a single motor drive unit. 

Energy Data Collection and Analysis.

Each of the three greenhouses had its own meter to measure natural gas usage. When the greenhouses were being used, gas-usage data were collected daily. Notes were taken describing any problems discovered or remedied and any other observations such as plant health and/or quality. EnSave, a local agriculture energy conservation company, conducted a comprehensive energy audit before and after retrofitting the greenhouses. Humidity, temperature, solar radiation sensors monitored these conditions both inside and outside of the greenhouses. Interior sensors monitored total electricity use in each greenhouse. The monitoring equipment sent data electronically to EnSave for their monthly reports. These data facilitated a quantitative analysis of the benefits of the systems.

Research results and discussion:

Obj. 1. Assess two innovative energy-saving devices retrofitted into a greenhouse: a bubble insulation system and an energy/shade curtain system.

Options for installing an energy curtain were investigated, and J.C. van der Spek Greenhouse Services, Berlin, CT specializing in retrofitting curtains for double-poly greenhouses was identified. The energy curtain, Model Ener-Shade, using XLS 15 Firebreak – heat retention and shading cloth was installed. The cost was $10,800. The curtain as installed limited the placement of potted plants towards the outer edges of the benches. To correct this, the installer shortened the curtain and relocated weights to hold it down. This redesign made room for about 200 potted plants on the outside edges of the benches.

Installing the bubble insulation system was more complicated than anticipated. The system was not available “off-the-shelf”. We purchased a prototype system from a grower in Canada. The system as purchased was designed by Sunarc Canada and was installed in a 220 ft. gutter connected greenhouse. It required significant modifications to retrofit it into the 88 ft long greenhouse at Claussen’s Florist & Greenhouses, Colchester, VT.

Assessment. Although the bubble insulation system had continual problems that required adjustment, redesign and repair, significant data were accumulated that clearly demonstrated energy savings in the greenhouses fitted with the curtain and the soap bubble insulation systems (Table 1). Data from the winters of 2012, 2013, 2014 when averaged showed a 40% less natural gas usage in the soap bubble insulated greenhouse when compared to the unimproved greenhouse. This represented an average savings of $636 per year. This dollar savings surpasses the $500 per year savings as projected in our performance target. Data from the 2012, 2013, 2014 winters when averaged showed a 26% less natural gas usage in the thermal curtain insulated greenhouse when compared to the unimproved greenhouse. This represented an average savings of $426 per year. Using data of dollar savings and comparing the soap bubble insulated greenhouse to the thermal curtain greenhouse one saves an additional $210 by installing a soap bubble insulated system.

The 2013 winter was unusually mild, which reduced the impact of energy savings from the two energy conservation systems compared to the control house. This was true when comparing energy use the fall 2013 to the winter 2014 growing season. Energy savings increased as the outside temperatures decreased. Energy usage and savings is presented in Table 2 and Fig. 1. Data are based on the amount of natural gas used and its cost (which in 2014 averaged $1.30/ccf).

The greenhouses used for this study were heated with natural gas which is a relatively inexpensive fuel. Propane users would see about four times the savings as those stated above and fuel oil users would see twice the savings stated above.  One slight issue we’ve experienced is that the grower needed to run the three test houses at different temperatures to meet the needs of the plants in each one. This makes it harder to compare the gas use in the three greenhouses. We consulted with a greenhouse energy conservation specialist, Mr. John Bartok, and were given a formula to use to pro-rate the usage of the houses to make the data equitable for comparison. An example of the pro-rated gas usage data comparing the three greenhouses for fall 2013 and winter 2014 heating periods is shown in Fig. 2 and 3.

Key components and beneficiary actions. The following were some early problems needing constant attention in the greenhouse retrofitted with the soap bubble insulation system: a) foam generators were frequently knocked off the main aluminum tube going down the length of the greenhouse by the flapping plastic covering and b) leaks in the system, especially along the gutters that carry the solution back to the tanks, resulted in significant loss of the soap solution. We developed improvements to eliminate these problems such as: a) rubber grommets that held the foam generators on the air supply pipe were replaced with rigid brass tubes that passed through the aluminum pipe and securely held each foam generator in place, b) plastic forms were designed and manufactured which once installed along the ridgeline, held the outer layer of plastic above the foam generators to prevent them from pushing on the generators, and c) bolted unions connecting the sections of gutter were welded together to minimize expansion and contraction and prevent leakage of the soap solution from these areas. 

While it was encouraging to have corrected these earlier problems, additional problems developed: a) recurring leaks of the soap solution because of small tears in the plastic coverings; b) an O-ring in a critical valve failed due to high temperatures in the greenhouse during the summer; c) soap bubbles were of inferior quality due to dilution of the soap solution, and d) spray nozzles in the foam generators frequently clogged with debris. The following adjustments were made to correct these problems: a) the plastic covering the greenhouse was replaced and care was taken to make it tighter than in previous years to reduce flapping; b) broken valve was replaced with a heavy-duty manual one and care was taken to ensure that the greenhouse exhaust fan operated during the summer to keep internal greenhouse temperatures below damaging levels; c) special tubes were installed between the two layers of plastic to permit the unrestricted flow of the solution to the collecting tanks; d) a laboratory-based foam generator device was designed to allow for precise testing of the soap solution to determine the best soap:polyethylene glycol (carbowax, an antifreeze) ratio to maximize freeze protection while maintaining bubble quality, and e) the Hayward in-line soap solution filter was replaced with a 43-micron stainless steel element to increase its ability to filter out particulates which could clog the nozzles.

Many redesigns to the original system were made to correct flaws in the system. For example, because of cracking of the bubble generators, a new schedule 80 PVC reducer was sourced and a new sturdier generator assembly developed. A new approach would locate all of the air and solution piping, tubing, and generator assemblies under both layers of plastic rather than up and in between them. This will allow for servicing the generator nozzles and all of the piping/tubing unions without having to remove the inner plastic layer.

Objective 2. Conduct comprehensive energy audits before and after retrofitting the greenhouses to quantify the benefits of both devices.

Energy consumption, interior greenhouse conditions, and weather data were collected by EnSave, Richmond, VT, a local energy analysis company. We also recorded natural gas usage daily during the period of operation of the systems. An energy audit was conducted by EnSave in 2010, at Claussen’s Florist and Greenhouses, Colchester, VT which provided baseline data on energy consumption for this SARE project. We determined that recording daily gas usage was a simpler and more effective means of assessing the benefits of both insulation devices. Therefore, an audit after retrofitting the greenhouses was not conducted, as it would not have contributed significantly to the overall assessment of energy conservation for this project.

In 2012 digital thermostats (Model G-Stat 4, Griffin Greenhouse Supply Co.) were installed in the three greenhouses and an automatic opener and closer for the thermal curtain. These new devices provided accurate comparable control of temperatures in each greenhouse and ensured that the curtain opening and closing coincided with operation of the soap bubble system.

Objective 3. Determine cost of greenhouse retrofitting, energy savings and potential tax incentives from which to assess the costs and benefits of both systems compared to an unimproved greenhouse.

The 2010 cost of retrofitting one 88 ft. long greenhouse with a thermal curtain by J.S. van der Spek Greenhouse Services was $10,800. The Model was an Ener-Shade with a XLS 15 Firebreak heat retention and shade cloth. It took two men two days to install it. The cost would have been less if the installation occurred at the time the greenhouse was constructed. It is not possible to present a cost for retrofitting a greenhouse with a soap bubble insulation system because (a) the entire system based on 3 years of testing requires significant improvements in design and (b) it is not commercially available.

 Although the bubble insulation system had continual problems that required adjustment, redesign and repair, significant data were accumulated that clearly demonstrated energy savings in the greenhouses fitted with the curtain and the soap bubble insulation systems (Table 2). Data from the winters of 2012, 2013, 2014 when averaged showed a 40% less natural gas usage in the soap bubble insulated greenhouse when compared to the unimproved greenhouse. This represented an average savings of $636 per year. This dollar savings surpasses the $500 per year savings as projected in our performance target. Data from the 2012, 2013, 2014 winters when averaged showed a 26% less natural gas usage in the thermal curtain insulated greenhouse when compared to the unimproved greenhouse. This represented an average savings of $426 per year. Using data of dollar savings and comparing the soap bubble insulated greenhouse to the thermal curtain greenhouse one saves $210 by installing a soap bubble insulated system.

 Energy savings are also presented in Objective 1 above. In general information on potential tax incentives was not determined because the Federal Government’s time limits on availability are often short and frequently change yearly or monthly. However, information on tax incentives for energy audits can be found in Objective 5 below.

Objective 4. Conduct a survey to generate baseline data on current energy consumption and conservation used by greenhouse growers in the tri-state region.

A survey was developed to collect information from growers on their greenhouse energy usage and conservation measures and sent to over 2000 growers in the Tri-state region. It was also placed on our Entomology Research Laboratory website (http:/www.uvm.edu/~entlab/). Additional copies of the survey were handed out to growers at several greenhouse grower workshops to encourage participation. The purpose of the survey was to learn what growers are doing currently for energy conservation in their greenhouses. Based on responses from 53 greenhouse growers 91% spent less than $10,000 per year on electricity, and 62% spent less than $10,000 on heating fuel. Twenty-four percent used $10,000-25,000 on heating fuel. When asked what actions they take to save energy, three measures were identified by over 50% of the respondents: adjusting their planting dates, sealing gaps around doors and vents, and checking the furnaces annually. Cost was identified as the most significant factor limiting implementation of energy saving measures and providing tax incentives for energy conservation was cited as the most helpful for encouraging them to adopt energy conservation practices.

 Key outcomes:

Responses differed significantly in the three states. Following is a summary of the most important findings:

  • 56.6% of the growers surveyed were retail vegetable growers, 66% were retail ornamental growers and 52.8% were co/owners of a horticultural business
  • 34.0% had 1-2 full time employees, 26.4% had over 6, 13.2% had 3-4 and 17% had none.
  • Bedding plants accounted for 28.5% of revenue for the growers surveyed, 11.8% were vegetables, 11.7 were flowering potted plants, 11.3 were perennials and 9.5 were vegetable starter plants.
  • About 50% of the operations had less than 10,000 ft2 of greenhouse space; 26.4% had 10,000-25,000 ft2.
  • Across all three states, the percentage of greenhouse space used increases from January to May. Usage peaks in May to 95.3% and gradually decreases over the rest of the year
  • 49.1% of the growers surveyed use oil to heat their greenhouses, 47.2% used propane gas, and 22.6% used wood fired heaters.
  • 62.3% of those surveyed spent less than $10,000 on fuel annually; 5.7% used $25,000-50,000.
  • To save energy 58.49% of the growers surveyed adjust their planting dates, 56.6% seal gaps around doors and vents, 51% get their boiler or furnace checked annually, 45% insulate the endwalls, 28% use bottom heat, 23% use energy efficient light bulbs. 47.2% use electronic thermostats and horizontal air flow systems, The most popular energy saving measure for all states surveyed was adjusting planting dates (of total)
  • When asked what limits them from improving energy conservation, 37.7% said it was too expensive, 17% said they didn’t have time or didn’t know the cost benefits, 15% didn’t know if they qualified for tax incentives and 11% didn’t know what to do.
  • When asked what would help them adopt more energy conservation measures, 51% said providing tax incentives would be the most helpful; 43% said providing free energy audits, 40% felt they needed assistance with learning what programs were available to help them.
  • When asked what research information would help them adopt more energy conservation, 39.6% said cost benefit analyses would be the most helpful, 34% said learning what benefits they would receive from making changes would help, and 21% felt guidelines on what to do to reduce energy use was needed.

A complete summary of survey results and data can be found in Appendix A.

Objective 5. Conduct energy audits at 9 greenhouse operations to provide quantitative information about trends in current energy consumption and identify the most significant measures that would improve conservation.

Growers attending the annual Tri-state Greenhouse workshops were notified about opportunities to receive energy audits to assist them with improving their energy conservation. The project PIs interacted with several growers in the region, particularly in Vermont and New Hampshire, to assist them with linking with USDA Natural Resource Conservation Service (NRCS) offices to arrange for a federally-funded energy audit. NRCS has a program that partially funds energy audits for growers, and our goal was to assist growers with signing up for this service. Growers who have had an energy audit completed by a federally-registered technical service provider are eligible to apply for funds to implement improvements. Several issues were identified that hinder growers from taking advantage of these federal opportunities. Specifically, the application process is complicated and time-consuming; it is difficult in some states to determine what services NRCS will support (it isn’t consistent across all states); there are deadlines for submitting applications and receiving NRCS support; and lastly the services provided by the auditors vary widely (some auditors produce audits in a format that are more useful than others). Despite these barriers, energy audits were completed in nine commercial greenhouse operations, six in Vermont, and three in New Hampshire. We felt it was important to identify growers in these states who had sufficient greenhouse space and would benefit most from such an audit. All of these audits were conducted by Mr. John Bartok, Greenhouse Agricultural Engineer and Extension Professor Emeritus from the University of Connecticut. He has over 40 years of experience working on greenhouse energy conservation, and is highly respected in the greenhouse industry. We found that the growers with whom we were working specifically requested his services because of his expertise and ability to present information to them in a way they could clearly understand.

The growers receiving these audits indicated that the information was very useful. One of the growers was so enthusiastic about what he learned that he hosted a workshop to encourage other growers to arrange for audits. Another of the growers receiving an audit owns the largest greenhouse operation in Vermont. He spends over $275,000 on heating fuel and $50,000 on electricity. His experience vividly demonstrates the value of audits. He recently gave a presentation on the energy conservation from the grower’s perspective (see his complete presentation in Appendix F). As a result of the audit, he developed a 5-year plan for carrying out recommended improvements. This included replacing the boilers in six of his greenhouses because he recognizes the savings he will ultimately realize from these improvements. He also has installed digital thermostats to enhance his energy savings. He is considering installing an energy curtain in one of his greenhouses because of the energy benefits he observed in the test greenhouses at his operation.  This is what he had to say after the audit, “this program is essential to our understanding, implementation, and capital expenditures spent on energy conservation.  The Energy Audit that was conducted by John Bartok will become a “bible” for our company in the future to not only save on energy expenses, but aim to guide/improve all of our company’s production profitability projections during the planning stages of the future. We will continue to implement energy saving measures throughout the operation in the coming years to not only to work on existing equipment/projects, but determine our need for future capital improvements for energy conservation because of this energy audit conducted.  Thank you for this opportunity.”

We facilitated linkages between growers, energy audit providers, and the Federal agency providing the funding (NRCS) for the audits. Through our involvement growers received energy conservation information in a format enabling them to take positive action to implement the recommendations provided by the audits. The project PIs assisted numerous other growers with completion of applications for the NRCS EQUIP program, which will allow them to receive the audit and support for implementing energy saving measures in the future.

Objective 6. Conduct workshops in each state to present information on energy conservation and federal and state incentive opportunities, and host an open house to demonstrate the innovative energy conservation systems tested.

Day-long workshops were held in ME, NH and VT in January 2012, 2013, 2014, and 2015. Growers received handouts on energy conservation and presentations on the scope of this project with results and discussion. A video of the bubble insulation system in operation was shown. Growers were very interested in the option. In the workshop evaluation, energy conservation was listed as a topic that growers wanted to learn more about in the future. Several opportunities occurred to demonstrate the bubble and curtain systems for growers and regional specialists. For example, a tour of the site 10 members of the Northeast Horticulture Inspection Society was held in mid-April 2012. People were very intrigued by it. A University of Vermont undergraduate student prepared a video describing the system for Vermont Independence Day (http://www.youtube.com/watch?v=W9lOxF_jOZE)

During 2013 we had two other opportunities to present information about energy conservation, and specifically these systems. In July, 2013 the Board of Directors of the American Floral Endowment, a leading national greenhouse/floriculture industry association received a tour of the SARE funded research site. This group of 20 leaders in the industry was fascinated with the project and impressed by the grower involvement in the project. Additionally, a presentation to 50 greenhouse growers from New Hampshire at the annual meeting of the New Hampshire Horticulture Association was given. The growers were interested in the technology, and requested an on-site demonstration in the coming year.

The “Vermont Greenhouse Energy Extravaganza” was held on Thursday, September 4th 2014 at Claussens Florist and Greenhouse, Colchester, Vermont (see Fig. 4-6). It was a day-long conference with sessions on energy conservation and demonstrations of the soap bubble insulation system and energy curtain. Mr. John Bartok, Professor Emeritus, University of Connecticut and Mr. Chris Callahan, University of Vermont Extension gave presentations and tours of the greenhouses discussing important areas for conservation improvements. Mr. Bob Kort, USDA NRCS, presented information on government funding for energy conservation. Forty-five attendees came from throughout the Northeast. Breakout sessions and demonstrations of the soap bubble insulation and energy curtain equipped greenhouses were given. The entire program for the event can be seen in Appendix B.  In general, participants thought the workshop was very informative and stated that they learned a great deal about energy conservation in greenhouses and would likely pass on the information to other growers.  An executive summary of participant evaluations of this event is provided in Appendix B1.

Objective 7. Produce a grower-friendly guide entitled How to Retrofit a Greenhouse for Energy Conservation. Cost of retrofitting, energy savings and potential tax incentives will be determined from the data, from which an accurate assessment of the benefits of these systems will be made.

A seven-page guide titled “Retrofitting a Greenhouse for Energy Conservation” was produced in August, 2014. The guide was prepared for growers to assess deficiencies and make energy conservation improvements to their greenhouses. Areas addressed were: tightening up the greenhouse, insulating, windbreaks and air flow, electrical efficiency of cooling and heating systems, and lighting. At the end of the guide is a checklist for growers including all topics covered. Approximate energy cost savings are given. The guide was distributed at the September, 2014 Energy Extravaganza, at the January,2015 Tri-State Greenhouse IPM workshops in Maine, New Hampshire and Vermont, and at the Green Works Vermont Nursery and Landscape Association Winter Meeting on January 27, 2015. It is available on the UVM Entomology Research Laboratory web site (www.uvm.edu/~entlab/). The guide is also included in Appendix C.

Milestones

1.  At least 450 growers will learn new energy conservation concepts while attending workshops in ME, NH, VT (150 growers per year), of which 30% will implement one or more energy saving measures presented. The energy conservation measures presented will be based on results from quantitative energy audits performed in 9 commercial hoop houses (3 in each state [ME, VT & NH]); from which sources of energy loss will be identified and recommendations for energy conservation made.

Results. Approximately 750 growers were introduced to the soap bubble greenhouse insulation project while attending the Tri-State Greenhouse conferences in the years 2011 through 2015. The conferences were held in ME, NH and VT. Presentations were given and informational handouts distributed. The energy audits provided insight into what energy conservation practices were most lacking and helped guide the development of the “Retrofitting a Greenhouse for Energy Conservation” guide completed in August 2014. It was distributed at the September 4, 2014 Energy Extravaganza, the January 2015 Tri-State Greenhouse conferences, and at the Green Works Vermont Nursery and Landscape Association Winter Meeting on January 27, 2015. Several growers have implemented other conservation measures identified in the audits and outlined in the guide.

 2.  Over 200 growers will attend an open house demonstrating the bubble insulation system and energy/shade screen system in retrofitted hoop greenhouses, where a cost/benefit analysis will be presented comparing energy conservation in a retrofitted vs. a non-retrofitted greenhouse. At least 2-3 growers who attend will indicate their intention to investigate its use in their operation. The local press will be invited to attend.

 Results. The September 2014 Energy Extravaganza provided an opportunity for 40 growers attending the conference to see both the soap bubble insulated greenhouse and the greenhouse with the energy/thermal curtain. Both systems were demonstrated and explained and question and answer periods provided. Our personnel led the bubble greenhouse tour and questions while Hans van der Spek of J.C. van der Spek Greenhouse Services (who installed the energy curtain) led the demonstration and discussion of the energy/thermal curtain equipped greenhouse. A six-minute video of the greenhouse project was produced which clearly describes both the bubble and energy/thermal curtain greenhouses and the energy savings and costs/benefits associated with each. A link to this video can be found on the UVM Entomology Laboratory website (http://www.uvm.edu/~entlab/Bubble%20Greenhouse%202010/BubbleGreenhouse.html) or directly on YouTube (https://www.youtube.com/watch?v=yRAzv44cEJw&feature=youtu.be). This video has been shown at the 2015 Tri-State greenhouse conferences and at the January 27, 2015 Green Works conference (winter meeting) held at the University of Vermont. These showings of the video have reached 200 growers.

Five growers, two in Vermont, one in New York, and two in Quebec, Canada have expressed an interest and intention to install a soap bubble insulation system in their greenhouses.

 3.  At least 200 growers will complete a survey on energy conservation, and the results will lead to development of effective programs to encourage 30% of the growers attending the workshops to implement energy conservation measures.

Results. See Objective 4 above in Results and Discussion section. Over 700 growers received a manual entitled “Retrofitting a Greenhouse for Energy Conservation” written, peer-reviewed and published by scientists involved in this SARE project (Appendix C). It is projected that ~200 growers will adopt one or more of the energy saving measures described.

 See Objective 7 above in Results and Discussion section for additional information.

 

Participation Summary

Education

Educational approach:

See Objective 6 and Objective 7 in “Results and Discussion/Milestones” and “Impact of Results/Milestones” sections above. See appendices A through F.

Two important contributions to our outreach efforts were articles published in mainstream grower-related media outlets.  One was prepared for the Cornell Small Farmer Quarterly in October of 2011 introducing the soap bubble technology and our research to the grower community.  A pdf of the full article can be found in Appendix D.  Another article on our research project describing the bubble insulation technology was featured in the October 2013 issue of Greenhouse Management magazine both in print and online. This article can be found on the web at: http://www.greenhousemag.com/gm1013-greenhouse-energy-soap-bubbles.aspx or in the attached pdf file (Appendix E).

No milestones

Additional Project Outcomes

Project outcomes:

Impacts of Results/Outcomes

Performance Target

Over 1,650 growers will receive information about energy conservation in greenhouses. Of the total growers receiving information, 5% (~80 growers) will implement at least one recommended tactic in one 2,000 sq ft greenhouse (total 160,000 sq ft), resulting in an annual reduction of energy cost of $500 per greenhouse grower operation. One grower per state (3 growers) will retrofit at least one greenhouse with either a bubble or thermal blanket insulation system, resulting in a yearly cost savings in fuel use of $1,000.

Results. The “Tri-State Greenhouse IPM” workshops held in ME, NH and VT in 2012, 2013, 2014, and 2015 attracted ~50 growers per workshop for a total of 600 growers reached by these events. Several opportunities occurred to demonstrate the bubble and curtain systems for growers and regional specialists. We hosted a tour of the site for 10 members of the Northeast Horticulture Inspection Society in mid-April 2012. We collaborated with a Univ. of Vermont undergraduate student to prepare a video describing the system for Vermont Independence Day. The video can be viewed at http://www.youtube.com/watch?v=W9lOxF_jOZE To date it has been viewed by 2319 people.

In July, 2013 we hosted the Board of Directors of the American Floral Endowment, a leading national greenhouse/floriculture industry association, and gave a tour of the research site at Claussen’s. This group of 20 leaders in the industry was fascinated with the project and impressed by the grower involvement in the research. In addition we gave a presentation to ~45 greenhouse growers from New Hampshire for the annual meeting of the New Hampshire Horticulture Association. In 2014, the “Vermont Greenhouse Energy Extravaganza” was held at Claussens Florist & Greenhouses in Colchester Vermont. It was a day-long conference with sessions given by noted experts in the field of energy conservation and demonstrations given of the bubble insulation system and energy curtain. Forty participants from around New England had a chance to see demonstrations of the bubble insulation system and energy curtain in operation. A short article was prepared for the Small Farmer Quarterly in October, 2011 introducing the soap bubble technology and our research project to the grower community. Readership of this newsletter is several thousand. A pdf of this article can be found in Appendix D. Another article on our research project describing the bubble insulation technology was featured in the October, 2013 issue of Greenhouse Management magazine both in print and online. Readership of this magazine is approximately 17,000 print and 6,000 digital viewers per issue. This article can be found on the web at: http://www.greenhousemag.com/gm1013-greenhouse-energy-soap-bubbles.aspx or as a pdf in Appendix E.

These events and publications represent more than 29,000 growers and people in the industry that will have had the opportunity to hear about and learn more about the soap bubble insulation technology and energy/thermal curtains and energy conservation measures that can be done in their greenhouses. This information including the “Retrofitting a Greenhouse for Energy Conservation” guide is also available on the University of Vermont Entomology Research Laboratory website (http://www.uvm.edu/~entlab/ ) representing the exposure of this work to potentially many more industry professionals. It’s hard to know just how many of this large number of people in the industry have actually implemented any of these conservation measures or how many of them own greenhouses. Many of the local growers who we work with in the Northeast have implemented many of the energy conservation measures identified in energy audits and outlined in our “Retrofitting a Greenhouse for Energy Conservation” guide. Some have had energy/thermal curtains installed and many have expressed a desire to pursue the bubble insulation technology. Most of the energy conservation measures that can be done will save an estimated 5 to 10% in energy use with a combination of measures saving even higher percentages. Our study has shown that the readily available energy/thermal curtain alone will save an average of 25 to 30% in heating costs which represents hundreds of dollars per greenhouse in just a single season. Couple that with other measures such as properly insulating doors, sealing cracks and installing LED lighting and 35 to 40% reductions in energy costs can be realized. One of the growers was so impressed with the potential to save on energy costs, he arranged a workshop for growers at his facility with Dr. John Bartok, a greenhouse energy specialist, to demonstrate the improvements he had made to other growers. These improvements included upgrading his existing energy curtain, installing automatic thermostats and insulating the end walls. Another grower receiving an audit installed automatic thermostats in most of his range and replaced six aging boilers with high efficiency models, and put in a high efficiency water heater. This was in addition to earlier improvements he made by insulating the end and side walls of three greenhouses.

Economic Analysis

See Objective 1 and Objective 3 in “Results and Discussion/Milestones” section above.

Farmer Adoption

Farmer/Grower Adoption

Despite the additional cost and various problems associated with retrofitting the greenhouses, Chris Conant, Owner of Claussens Florist and Greenhouses (the cooperating grower) has already noticed a significant reduction in gas consumption in the greenhouses with the thermal curtain and bubble system compared with the unimproved greenhouse. He has assigned his personnel to assist us with various aspects of retrofitting the bubble system at no cost to us. He has been involved in all phases of the retrofitting process. He and his staff have provided critical expertise relevant to greenhouse construction that has contributed to developing an effective bubble system. He has shared information about the project with other growers and industry representatives.

The growers who received energy audits were highly satisfied with the information they received and several have already invested in the recommended changes. One grower at his personal initiative hosted a demonstration to show other growers the benefits of an audit.

Five growers, two in Vermont, one in New York, and two in Quebec, Canada have expressed an interest and intention to install a soap bubble insulation system in their greenhouses.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

It has been clearly demonstrated that significant energy saving will result if plastic covered greenhouses are furnished with a soap bubble insulation system or a thermal energy curtain. Three years of experience with the soap bubble insulation system showed that continual maintenance was required. During this SARE project the PI’s developed many major improvements to the soap bubble insulation system. These improvements are as follows:

  1. Raised the peak of the greenhouse so the plastic would not bang against the foam generators.
  2. Redesigned the attachment of the foam generators. They are now threaded onto brass tubing with slots on two sides to allow air to freely flow into them.
  3. Did away with use of rubber grommets attaching nozzles in soap solution delivery. They are now threaded into the polyethylene tubing.
  4. Reduced the number of soap solution lines to the foam generators by plugging one side and putting a Y in from the other side.
  5. Welded aluminum gutters and the large polyethylene pipe. They are now solid pieces. Problems with expansion and contraction minimized.
  6. Added a drain line to the far end of the aluminum gutters (welded in place) so solution goes more directly out of the gutters to the storage tanks. It is now a straight run out of the gutters instead of a 90 degree elbow as the exit hole. It is critical to get the liquid out of the gutter and into the storage tanks quickly because of freezing in the winter.
  7. Eliminated the rinse function as we found it unnecessary.
  8. Added a higher ridge to the large pressure vent (inside) to prevent soap bubbles escaping to the outside. Not 100% effective but better than before. The large vent tubing should be made of plastic because leaks can develop between sections of the flexible metal tubing and drip soap solution on plants below.
  9. Added a different filter (43 micron size) to the basket filter to screen out debris. The original basket filter was not of a fine enough mesh size. End result was that more nozzles in the foam generators became plugged.
  10. Converted the automatic shut off of one valve to manual shut off.
  11. Installed automatic timer for on-off of bubble generation.
  12. Installed digital thermostats to replace mercury ones. Accuracy increased.
  13. Used tie downs to secure the black polyethylene tubing in place – the black polyethylene pipes tended to expand and loop out of slots in the large aluminum carrier pipe during hot weather.
  14. Developed a way to install the large aluminum tube inside the greenhouse (suspended it) and not between the two layers of plastic.
  15. Redesigned the foam generators so that the nozzles could be easily removed, cleaned or replaced. The old generators broke apart following just two years of use. Structurally the new ones are much more rugged. Once the generators are on the inside of the greenhouse they can be more easily serviced.
  16. Developed a system so the nozzle inside the foam generators is aimed directly at the cloth filter i.e. directly in the center.
  17. Eliminated the need for a water pipe clamp to hold the cloth filter and screen on the end of the foam generator in place; i.e.we are now using a screw on cap. No rough edges to tear the plastic etc.
  18. Designed a system whereby the foam generators are located on the inside of the greenhouse and not between the two layers of plastic.
  19. Installed a two track system for holding double sheets of white or clear pvc to which the foam generators are attached. The possibility of generator leaks developing is greatly minimized. The action end of the foam generators is still between the two layers of plastic.
  20. Designed a system to keep the gutters on the inside of the greenhouse so they would come in contact with warm air to help keep the soap solution from freezing.
  21. Changed the position of the squirrel fans so warm air surrounds the gutters to prevent freezing.
  22. Installed squirrel fan in overhead pvc instead of into plastic sheeting where it tended to rip out. The result is a more solid fit and eliminates the typical screw-clamp style prone to failure.

The above improvements in design were developed to make the soap bubble insulations system ”grower friendly” by significantly reducing maintenance requirements. The improved system should be installed and tested for at least one additional winter season. The following improvements should also be addressed:

  1. An automatic on/off system that controls production of soap bubbles should be developed.
  2. Stronger squirrel fans to increase expansion of plastic sheeting should be installed. Consider using an anemometer on the outside that actually serves to increase squirrel fan output or switch on an additional squirrel fan during periods of high winds.
  3. Decide if it is more efficient to bury the soap solution storage tanks or have them under the benches.
  4. Consider placing the controls (the jet water pump and the air pump plus electrical controls) in a small shed outside the greenhouses and have them function to serve two greenhouses instead of just one? This becomes an economic matter and might serve as a greater attractant to potential buyers of the system.
  5. The entire electric control system could be greatly simplified.

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.