How it Works

In year-round hot climates and temperate-zone summers, Sunarc’s liquid foam is infused into the cavity formed by the two layers of polyethylene membrane covering double-poly greenhouses. During the day, the foam mimics clouds in lessening and diffusing energy penetration when solar radiation levels are high.

At dusk, the remaining liquid from collapsed foam is drained back into the surfactant reservoirs and recycled to be used again the next day. Sensors ensure automatic production by regulating the operation of foam generators and sprinklers as conditions demand. Software is programmable to local needs and may be monitored and operated by remote computer control.

Sunarc’s On-Demand Shade System maintains the thermal equilibrium in a controlled environment. As a result, optimal temperature conditions during each 24-hour cycle can be maintained year-round.

The foam’s insulation protects crops from damaging heat stress that can cause production loss. Energy savings result as the liquid foam shading reduces the need to over-ventilate or cool the interior.

The Sunarc On-Demand Shade System currently offers variable shade levels of 20%-45%. The advantage of using this type of shade is that it can be deployed on demand when maximum sunlight is present. On cloud covered days, when shade is not needed, the system remains on standby.

Compared to Shading Screens

Commercial greenhouse operations use forced air ventilation and shade screens to reduce exposure to sun. Ventilation introduces pollen and pests, which corrupt the growing process. In southern drier climates like Texas, California and Mexico, forced air ventilation is often used with cooling pads to reduce heat in the greenhouse. The cost of forced cooling rises with rising electricity prices, cutting into profit margins.

The combination of Sunarc’s variable shading and natural ventilation substantially improves crop management, including far more beneficial use of CO2 and reduced plant stress – while lowering energy costs. Sunarc’s On-Demand Shade System reduces temperature extremes and works well with naturally ventilated gutter opening greenhouse structures. The more beneficial use of CO2 increases crop yield.

CO2 is essential to photosynthesis, the process by which plants use sunlight to produce carbohydrates – the material comprising their roots and body. Increasing CO2 levels speeds the time in which plants mature and improves their growth efficiency and water use. Commercial greenhouse growers often pump CO2 into greenhouses.

“Sunarc technology is powerful because it allows for natural ventilation versus shade thermal curtains which create a pocket of warm air above the screen. Sunarc’s System with open double-poly allows for natural ventilation.”
Research Scientist, Environmental Physiology and Energy Conservation
Greenhouse and Processing Crops Research Centre

The Sunarc System replaces the need for shade screens that require a great deal of mechanical control and which reduce the quantity and quality of light in the growing space. When used instead of screens, the cloud effect of liquid foam filters and diffuses sunlight without depriving growing plants of the natural light they require. As a result, ventilation needs are reduced, the inside environment is less contaminated by outside air, is richer in CO2 and plants are healthier; resulting in significant improvement in crop growth, yield and performance.

Agronomic Benefits

Light is the energy source that powers photosynthesis. For each plant species there is an optimal light level. Beyond the optimal level, the photosynthetic level becomes static. In fact, further increases in light levels may cause plant damage and reduce total yield. Providing suitable shading to reduce excess sunlight and/or heat is a problem for greenhouse operators everywhere in the world.

During periods of high solar radiation, levels must be lowered for most plants. From both a technical and economic point of view, shade on-demand is essential. The goal of greenhouse crop production is to optimize light levels to achieve the appropriate equilibrium of light and shade for maximal plant health. Sunarc liquid foam does not reduce the proportion of PAR light (portion of spectral band that is best for photosynthesis) in the greenhouse. Based on data obtained in research done at Université Laval, 20%-25% shading during the early morning and late afternoon periods and up to a maximum of 30%-35% during the mid-day hours will be sufficient for most crops.

Plant leaf temperature is an important indication of crop performance. The flexibility and shading capability of Sunarc On-Demand liquid foam enable growers to vary the amount of shade, depending on need. The Sunarc System lowers inside temperatures by absorbing some of the infra-red radiation that accounts for up to 50% of heating by sunlight. Sunarc has achieved lower leaf temperatures of as much as 5 degrees Celsius growing tomatoes. Fruit temperatures will also be lower by 2 to 3 degrees Celsius. By holding leaf temperatures below harmful levels, vegetable crop output increases by 10% or more, increasing bottom line results. The benefits of lower leaf temperatures are even more significant for lettuce production.

Fluorescence measurement is an indication for plant stress caused by excessive sunlight. Crops in greenhouses equipped with the Sunarc On-Demand Shade System register lower stress levels during the period of highest daily sunlight (11 a.m. to 1 p.m.) compared to greenhouses without the system. When stress levels become too high, plant photosynthesis activity shuts down. However, plants will continue in photosynthesis mode for up to 15 hours/day when using the On-Demand Shade System.

Sunarc’s On-Demand Shade System enhances photosynthetic activity for commercial greenhouse growers leading to increased crop yield.

How to Calculate your Cost/Savings

Calculating the savings on heating costs is simple. Simply divide your heating bills in half; the savings will be at least 50%.

Several key elements go into calculating the payback of the Sunarc System.

1. What type of fuel is being used to heat the greenhouses?
   What is your current cost?
2. Do you cease operations for a limited period during cold weather?
   If you continued to operate 12 months of the year with 50% reduced heating costs, how much additional revenue/profit might be generated?
3. For vegetable growers: factor possible crop yield increases of 10%-20% as a result of the agronomic benefits that the Sunarc System delivers.
4. For vegetable growers: greater control of your micro-environment enables quality to be maintained or improved despite the scorching summer sun. Maintaining AAA quality = revenue and earnings expectations are met or possibly exceeded.

These are just some of the factors; Sunarc will assist growers to determine their payback period. Generally the payback is about 24 months; however, it is possible to achieve payback in as little as 12 months depending on grower-specific factors. Contact us and we will help you determine your payback period.

Installations

Existing Installations

1. Université Laval, Faculty of Agriculture and Food Sciences – Tomatoes
2. Agriculture Canada's Greenhouse and Processing Crops Research Centre, Harrow, Ontario – Tomatoes, Cucumbers
3. Les Jardiniers du Chef, Site #1 – Herbs grown in Blainville, Quebec. Ground-to-ground greenhouse structure
4. Les Jardiniers du Chef, Site #2 – Herbs grown in Blainville, Quebec. Gutter-connected greenhouse structure
5. Sunarc Research and Development Centre – St-Sauveur, Quebec
6. Sunarc Product Development & Distribution Centre – Laval, Quebec
7. Cedarline Greenhouses – Bell Peppers grown in Dresden, Ontario
8. Pyramid Farms – Tomatoes grown in Leamington, Ontario