Commercial greenhouses are both organic and mechanical ecosystems. Greenhouses are also a part of an external ecosystem. To maximize their sustainability, greenhouses need to be sustainable inside and out. Sustainable development, as the United Nation (UN) views it, means “an integrated approach that takes into consideration environmental concerns along with economic development.” The UN argues that to embrace sustainability is to mitigate “the hazardous man-made effects of climate change.” ¹ There are 17 UN Sustainable Development Goals (SDGs). SDG 7 focuses on “access to affordable, reliable, sustainable, and modern energy.” Sustainable energy and energy-saving devices in greenhouses help a greenhouse’s internal ecosystem function cost effectively. 

Ventilation considerations

Proper ventilation maintains temperature and humidity at optimal levels in greenhouses while ensuring plant health by reducing stress, moisture, fungal issues, and disease.” Properly placed vents allow for natural air flow while fans help the flow of air when a greenhouse’s design is “complex.” Automated thermostats and hygrometers add precision. Sustainable ventilation systems include passive vent systems, energy-efficient fans, solar powered fans, and “advanced systems” that adjust to external weather conditions. ²

Ventilation “becomes less effective and less efficient” in cool and cold months. A buildup of humidity creates negative effects for crops in the form of, for example, mildew, reduced growth, poor fruit creation, and “overall low output and low quality,”³ as well as condensation coating surfaces and plants.⁴ Dehumidification helps control humidity without relying on external air. These devices work best when they are “compatible with other equipment or systems”; located in optimal locations; calibrated; and when their data is interpreted by appropriate software or an expert.⁵

A 2023 study compared the effects and costs of a mechanical refrigeration dehumidifier (MRD), a liquid desiccant dehumidifier (LDD), a heat recovery ventilation system (HRV), and an “energy recovery ventilator” (ERV). The results indicated a system’s effectiveness depends on time of year, external air temperatures, and materials a greenhouse’s interior ceiling is made from. Ensuring a new system is properly integrated into an existing system was also concluded to be important as was the cost of energy (electricity vs. natural gas).⁶

A study of potential dehumidification methods in a southern Ontario greenhouse examined three types of dehumidification.

It found, in the greenhouse studied, that: Liquid desiccant dehumidification (LDD) is most effective in fall; highest energy savings would occur when using mechanical refrigeration dehumidifier (MRD) in fall; heat recovery ventilation saved lowest energy overall; LDD had robust energy savings compared with “baseline” of dehumidification by exhaust fan ventilation; carbon emission decreases up to 35.8 per cent would be possible with MRD and LDD; changing to LED lamps can save up to $7,000 in fall, with up to $24,300/year; space heating loads increase in each season using LEDs instead of high-pressure sodium; changing to LED lights from HPS lamps saved energy in spring and summer.⁷

The study’s conclusions, based on the test case, draw attention to the considerations needed for effective use of energy saving technology, the combined interactions, and the season.  

Thermal screens
Thermal screens add protection between crops and a greenhouse’s glass or poly cover. They retain heat and reduce heat while controlling humidity and condensation. Screens can reduce heating costs from 20 per cent to 75 per cent based on a greenhouse’s “design, curtain material, and local climate.” Automated screens can be integrated with a greenhouse’s other systems such as lighting and ventilation and respond to weather conditions. ⁸  

Heating

Alternative Fuels: Biomass
Alternative fuels are another route to sustainability. In choosing alternative fuels, such as biomass as an example, the following should be considered: current and future costs; ROI; managing the chosen fuel onsite; the ‘combustion chamber’ and its ‘characteristics’; government approvals; waste disposal; environmental effects; future availability as well as legislation, regulation, and official approvals.⁹ 

Sources for biomass fuel include wood; agricultural, organic, construction, demolition, and municipal waste products^10,11. Biomass fuel is a local, renewable, easily sourced resource, that is sustainable. In wood pellet form it is a very efficient fuel with 85 per cent of its energy being “converted to usable heat.” Biomass emits much less GHG compared to other fuels. The systems used in biomass fuel can be appropriately sized to heat a greenhouse and the water heated during the day and stored can be circulated at night.

Passive Solar
Fresh Pal’s passive solar greenhouses, near Olds, Alberta, grow vegetables and flowers year-round. Passive solar captures and stores solar energy allowing the company’s two 10,000 sq.-ft. greenhouses to function year round. On each greenhouse’s north wall, there is a half-metre of clay amounting to hundreds of tonnes of clay.

Sunlight heats these walls to about 30°C. At night, this heats the greenhouses with the help of a 1/3-inch thick insulated blanket lowered at night. The greenhouses are kept at 25°C to 32°C¹² and can produce two growing cycles a year for tomatoes equalling 30,000 lbs. The motor to move the blankets costs the company $1 per day with almost no environmental effects.¹³ 

Heat pumps
“Geothermal can be reasonably efficient,” said W.D. Lubitz, associate professor in the School of Engineering, at the University of Guelph, in a recent interview with Greenhouse Canada. Heat pumps, Lubitz notes, can use electricity to make geothermal heat accessible to greenhouses. 

Lubitz, who specializes in renewable energy technologies and agricultural energy systems, said that existing greenhouses with natural gas boilers and newer larger greenhouses have hot water boilers that can be retrofitted and can also be used to store and circulate heat and water. Heat pumps for greenhouses can be closed or open loop or direct exchange using ground, water, refrigerants, respectivel (GoC, 2025).¹⁴ 

Deep geothermal
When generating electricity from geothermal energy, three ingredients are needed: the correct temperature and porosity in rocks and water pressure. ‘Deep thermal’ geothermal energy has low GHG, is always available, has a small carbon footprint, and costs US $56–$93 MWh that makes it “competitive with coal, nuclear, and some solar applications.”¹⁶  

A new geothermal project underway involves Oppy, a specialist in fresh produce marketing and distribution, and DEEP Earth Energy Production, a company that uses geothermal energy for commercial power production.

The companies are working on a 20-acre greenhouse project that will have a “geothermal heating system, which takes advantage of the earth’s stable underground temperature to heat the facility,” notes Kevin Batt, Oppy’s category director of greenhouse. 

“We’ll use deep geothermal drilling to access naturally heated 120°C brine from the reservoir [and] use natural gas with carbon capture to produce power [that will] be reused in our greenhouse, making the system more efficient and sustainable,” Batt adds.

Commercial greenhouses are ecosystems that have multiple interconnected routes to sustainability. They are an ideal environment to apply both traditional sustainable approaches in combination with technology as well as traditional resources with tomorrow’s innovations to reduce GHG, pollution, reduce resource depletion, and fight climate change.  

More on greenhouse climate control from Greenhouse Canada can be found here.

Sources

1. United Nations, n.d.
2. Dakota Storage Buildings, 2024 
3. Meir, R., 2024 
4. Eddy, R., 2025 
5. NiuBoL, n.d. 
6. Agricultural Adaptation Council, 2023 
7. Nauta, A., Han, J., Tasnim, S. H., Lubitz, W. D., 2023 
8. Farmonaut Technologies, 2025 
9. Ontario.ca, 2008 
10. The Pembina Institute, 2011 
11. Froese, H., 2021 
12. Moyles, T., n.d.
13. VergePermaculture, n.d. 
14. Government of Canada, 2025 
15. Buck, N., 2022 
16. Canada Energy Regulator, 2023