Ontario’s greenhouse industry is expanding. Ontario has traditionally been a hotspot for cultivating products, from vegetables to flowers. Many Ontario growers are now using greenhouses to increase the amount of produce they can produce, partly in response to consumer demand for more locally-grown goods. In fact, during the last six years, the number of vegetables and fruit grown in Ontario has increased by 30%. In a greenhouse, the energy used to operate lighting, heat pumps, and ventilation increases. The good news is that growers have control over how much energy they consume. Greenhouses are most effective when designed and sited for energy efficiency and optimum light transmission. Greenhouses must allow sunlight during the day, retain as much heat as possible during cold weather, and provide adequate ventilation to avoid excessive interior temperature and humidity.
What Is Greenhouse Efficiency?
It is the process of capturing and storing heat from sunlight. The sun’s energy passes through windows, walls, or other transparent surfaces into a building’s interior spaces. This solar radiation then heats the interior air, which warms up the indoor environment. Greenhouse efficiency measures how much of the sun’s energy is retained by a structure and how well heat is distributed throughout the space. The higher the efficiency, the fewer heat escapes and the more evenly distributed.
Greenhouse building materials with the highest insulation ratings should be utilized whenever possible. Glazing material appropriate for the job reduces energy loss while still letting the natural spectrum of light inside aid in the healthy growth of the plants. Some fuels have a higher heat value than others, and some heating units are more efficient than others when heating greenhouses.
What Are the Factors that affect Greenhouse Efficiency?
Several factors affect greenhouse efficiency, including:
- -The type of material used for the transparent surfaces: Single pane glass has lower efficiency than double-pane or insulated glass.
- -The thickness of the walls: Thicker walls help reduce heat loss.
- -The color of the walls: Darker colors absorb more heat than lighter colors.
- -The type of roofing material: A metal roof will reflect more heat than a shingled roof.
- -How well the structure is sealed: Gaps and cracks around doors and windows can let heat escape.
- The structure’s orientation: A south-facing building will receive more direct sunlight than a north-facing building.
How to Reduce Heat Loss in your Greenhouse?
The top tactics for saving energy while preserving the best possible growing conditions in your greenhouse include reducing air leaks, insulating the edges, employing thermal curtains, and adding in-ground heating.
- Eliminate leaks: Install door closers and weather-strip doors. Examine vents for obstructions or leaks, and lubricate fan shutters. Install one-inch-thick polystyrene or polyurethane insulation board at the greenhouse’s edge to a depth of 18″ – 24″ below grade for insulation.
- Thermal curtains: Install thermal curtains to prevent thermal heat loss at night or use them for shading to reduce cooling loads during the summer months. Curtains should be in good working order, sealed around the edges, free of rips and holes, and ideally connected to a controller to be most effective. Payback can take anything from six months to five years.
- Heating beneath the ground: To direct heat where it’s most valuable, install radiant hot water beneath or at ground level. Root zone temperature is more critical than leaf temperature to have optimum plant growth. If the optimal root zone temperature is maintained, the greenhouse air temperature can be reduced by 5 to 10 degrees.
- Replace your covers: Replacing your polyethylene or polycarbonate coverings can help you save up to 50% on heat loss.
- Replace your coverings: For a 12 to 15% reduction in heat loss, apply an infrared inhibitor (IR) and anti-condensation film to the inner layer of your greenhouse walls and ceilings.
The Lighting Opportunity
We all know that plants require light to survive, so it’s no surprise that lighting presents the greatest chance for greenhouses to conserve energy regardless of what’s growing inside. Depending on the time of year and the availability of sunlight, vegetable growers often keep their lights on for eight to sixteen hours every day. Greenhouse operators have traditionally used high-pressure sodium lights to assist in replicating sunlight and keep plants growing even when the weather turns gloomy and cold. On the other hand, LED lighting is far more energy-efficient than high-pressure sodium lighting, using up to 50% less electricity.
LED lighting also outlasts high-pressure sodium lighting five to ten times, lowering maintenance expenses. Greenhouse operators that invest in energy-efficient LED lighting often see a return in two to three years.
For example, Suntec Greenhouses in Manotick, Ont. saved 3,271,680 kWh by switching to LED lights in its 180,000 square foot greenhouse, which grows tomatoes, eggplant, cucumbers, and other produce. LEDs also enable more precise illumination control, resulting in improved yields. Growers can adjust the light spectrum to fit the crop or stage of development. For example, a grower may discover that more blue light than red light increases quality at a given time. It is possible thanks to LEDs.
They also operate cooler than other lighting sources, allowing producers to put them closer to plants, perhaps increasing agricultural yield. Vertical racks, with plants that require less light further down, can also help reduce energy loss, depending on the plants in the greenhouse. Finally, adopting natural light controls can help improve growing conditions while also reducing electricity consumption. Retractable curtains are a terrific way to get the most out of natural light and heat while protecting your plants on sweltering days.
Make the Most of Your HVAC System
Reduced lighting heat may also help producers better manage humidity levels and minimize the burden on their heating, ventilation, and air conditioning (HVAC) systems, thus saving even more energy. Dehumidification, which necessitates mechanical cooling, is necessary for certain crops to avoid mold and mildew, but it, like lighting, can increase energy use.
Variable frequency drives (VFDs) on exhaust fans, heat buffering systems, zone pumps, and mixing valves can help greenhouse operators improve efficiency. VFDs help control the speed of motor-driven equipment like fans and pumps so that they don’t waste energy. Consider how you may obtain more control over heating and cooling in your greenhouse, just as you did with lighting. Growers may benefit from electronic sensors and automated thermostats, which can help them maintain more correct temperatures and save energy. Consider taking it a step further and integrating environmental controls as well. Thermal curtains, VFDs, heat buffering systems, HVAC systems, and irrigation equipment all use these controls instead of stand-alone control systems.
A well-maintained building envelope, just like homes, workplaces, or any other structure, benefits greenhouses by allowing heating and cooling technologies to perform more efficiently. Air leakage can be prevented by polycarbonate sheets on the side and end walls, insulating board around the perimeter base, and weather stripping around doors and windows. Make it a routine to check for (and repair) leaks or holes in your greenhouse, which will increase energy efficiency and assist in preventing pests. As more farmers enter the market, keep in mind that conserving energy is a competitive advantage. Take the effort to optimize your greenhouse’s lighting and HVAC efficiency, seeing some spectacular results.
What Is the Most Energy-Efficient Greenhouse?
The most energy-efficient greenhouse is appropriately insulated and has a sound ventilation system. A well-designed greenhouse will have a much higher chance of being energy efficient than one that is not. There are many factors to consider when designing a greenhouse, but if you keep the following in mind, you will be well on your way to creating an energy-efficient space.
- Make sure your greenhouse is adequately insulated, and this will help keep the heat in during the winter and cool it during the summer.
- Consider using double-paned windows; these are specially designed to help with insulation and can make a big difference in the overall efficiency of your greenhouse.
- Make sure your ventilation system is up to par. A sound ventilation system will help regulate the temperature inside your greenhouse and keep the air fresh.
- Keep an eye on your lighting. Using energy-efficient lighting can help to reduce the amount of energy you use in your greenhouse.
By following these tips, you can create a more energy-efficient greenhouse that will help you save money and be more environmentally friendly.
How Much Energy do Greenhouses Use?
Heat in a typical greenhouse takes about two liters of oil per day, and the average person uses about four liters of oil a day, so a greenhouse uses about half as much energy as the average person. But there are a lot of variables that affect how much energy a greenhouse uses. For example, the size of the greenhouse, the type of heating system, the type of insulation, and the climate all play a role in how much energy a greenhouse uses.
A more miniature greenhouse will use less energy than a larger one, and a greenhouse with a more efficient heating system will use less energy than one with an older, less efficient system. And a greenhouse located in a colder climate will use more energy than one located in a warmer climate.
How Can I Heat my Greenhouse at Night without Electricity?
There are a few ways to heat your greenhouse at night without electricity. One way is to use a wood stove or pellet stove. You can also use candles, oil lamps, or even a campfire to provide warmth. Another option is to insulate your greenhouse well so that the heat generated during the day will be trapped inside at night. Finally, you can consider using a greenhouse heater on alternative energy sources such as solar power or wind power.
Can you Put Solar Panels in a Greenhouse?
The answer to this question is yes; you can put solar panels in a greenhouse. It can be a great way to generate renewable energy and offset your carbon footprint. There are a few things to consider before installing solar panels on your greenhouses, such as the type of panels you want to use and the sun’s angle. You will also need to ensure that the panels are correctly installed and maintained to avoid damage.
To Wrap it all up
Greenhouse energy efficiency is an essential factor in the overall sustainability of our planet. In this guide, we’ve outlined some simple ways to make your greenhouse more energy-efficient and reduce your environmental impact. From using thermal curtains to regulating humidity levels, there are many easy steps you can take to improve the efficiency of your greenhouse. We hope you find this guide helpful in your efforts to be more sustainable!