Optimizing greenhouse energy efficiency in Québec

Thermal screens: A barrier against heat loss

The first measure is also undoubtedly the best known: thermal screens are used to reduce the volume of air to be heated and radiation losses.¹ They also help limit light pollution and create shade, depending on the specific needs of the crops.

These screens, which are fixed under the greenhouse gables and deployed at night, are used mainly to intercept infrared radiation from the plants and thermosiphon system² to the night sky during heating periods, but also to reduce heat loss through convection.

Testing by Wageningen UR Greenhouse Horticulture and Delphy in the United States shows that thermal screens can reduce energy consumption by 15.5% annually;³ however, empirical evidence shows that this reduction could be as high as 35% in Quebec due to its harsher climate.

How an insulating wall can reduce heat loss

For new greenhouses, building a concrete insulating wall approximately one metre high around the perimeter of the greenhouse reduces natural gas consumption while improving the greenhouse climate, particularly in winter. This eliminates the risk of snow buildup around the glass walls and reduces the risk of breakage at the bottom of the walls. In addition, it makes it easier to install greenhouse walls by optimizing the working height and providing a solid foundation for the glass walls.

Automated climate management: Data intelligence for productivity

Automated climate management systems use a computer connected to a network of sensors and probes to adjust humidity, ventilation, air flow and irrigation levels in real time based on the needs in different areas of the greenhouse. They also provide accurate and practical data for production-related decisions. By automatically managing energy, the system also eliminates the risk of oversights or errors that could lead to energy or production losses. It is estimated that this type of system can increase crop yields by 20% to more than 30%.^4,5

Automation to increase greenhouse production density

Automating cultivation using commercially available technologies makes it possible to significantly increase greenhouse production density while reducing human intervention. For example, the amount of lettuce produced on one acre with this type of system is equivalent to that produced on over 50 acres of open field farming and is several times higher than the yield of a traditional greenhouse system.⁶ In addition, an automated system can compensate for labour shortages and optimize space and energy use.

Heat recovery + CO₂ injection: Nothing is lost, everything is transformed

Heat recovery from boiler stacks using thermal storage and CO₂ injection presents multiple advantages. For a greenhouse heated with hot water, capturing heat from boiler flue gases using a heating water return exchanger makes it possible to recover thermal energy by condensing the moisture contained in the combustion products. This system not only increases the thermal efficiency of gas boilers by 10%, but also recovers CO₂ (the other combustion product) to stimulate plant growth. For hot water systems, in the middle of the season, a buffer water reserve is used to heat the greenhouse at a lower cost at night, while during the day, CO₂ is injected at the plant roots to promote growth and vigour.

For example, in most greenhouse crops, the photosynthetic yield increases by 50% when the CO₂ concentration rises from 340 ppm to 1,000 ppm.⁷

Heat pumps and energy loops

Heat pumps reduce natural gas consumption by harnessing heat from outside air, a free and renewable energy. They can increase thermal efficiency by 200% to 250%. However, these appliances are mainly suitable for greenhouses heated with hot air. This is because their heating temperature is relatively low (50° to 60°C), while hot water systems often reach around 80°C, and the supply of high-temperature heat pumps is still limited on the market.

On the other hand, the proximity of industrial sites with significant potential for heat recovery is a determining factor for a growing number of greenhouse projects. By setting up near data centres or factories, greenhouses can recover and reuse some of the heat generated by these facilities to reduce their own heating costs.

Vegpro: Cutting-edge technology for freshness and productivity

Vegpro’s new “ecofriendly greenhouse,” commissioned in April 2025 in Sherrington, Quebec, uses state-of-the-art greenhouse technology, including an automated growing system, residual heat recovery, heat pumps and computerized climate control. Thanks to these innovations, the company should be able to produce 68 tonnes (150,000 lb.) of lettuce per week under controlled conditions, without pesticides or GMOs.

In addition, they will enable the company to save considerably on natural gas and significantly reduce its GHG emissions,⁸ as shown in the table below.

Measures implemented	Natural gas savings (m³)	GHG reduction⁹ (tonnes)
Permanent insulation around greenhouse perimeter	230,708	443
Thermal screens	1,138,644	2,188
Greenhouse climate control	235,648	453
Energy savings through heat recovery from chimney flue gases with thermal storage and cogeneration heat exchanger recovery	676,294	1,300
Low-temperature heat pump and thermal reserve	718,976	1,382
Savings in greenhouses not built due to the use of an automated growing system	1,868,649	3,592
Total	4,868,919	9,358

As part of this project, Vegpro will receive a grant from Énergir totalling $2,225,000.

Grants that make your job easier

To make it easier to implement energy efficiency measures and accelerate their return on investment, Énergir offers a number of financial incentives for greenhouse farming under its energy efficiency grants program. For program conditions and eligibility criteria, click the links below:

Up to $4,500 for the purchase of a condensing unit heater
Up to $50,000 for a feasibility study on implementing energy efficiency measures
Up to $1,000,000 for the implementation of energy efficiency measures ($1 per m³ of gas saved)

We are here to advise and support you

Do you currently or are you planning to operate a greenhouse and want to learn more about energy efficiency measures that could reduce your energy bill and improve crop productivity? Contact our experts at DATECH, a team dedicated to the success of your projects.