The Energy Challenge
Greenhouses and indoor farms maintain warm, humid conditions around the clock. Heating can be 30 to 50 percent of operating cost, while transpiration loads create enormous latent heat in the exhaust air.
Recovering Heat from Exhaust and Condensation
Air-to-air plate exchangers recover sensible heat from ventilation exhaust; condensing heat-recovery units capture latent heat as vapour condenses on cold surfaces, returning both warmth and distilled water to the crop.
Geothermal Pre-Heat
Ground-source pre-heating of incoming air using stable earth temperatures reduces peak boiler load. 26YC corrosion-resistant cores suit the high-humidity horticulture environment.
Payback
With continuous operation, greenhouse heat recovery often pays back within one to three seasons, especially where gas prices are high or carbon limits apply.
Design detail determines the result. Plate exchangers handle the sensible load well, but in very humid exhaust a condensing unit captures additional latent heat and can yield distilled water useful for irrigation. Frost risk in cold climates calls for a bypass or recirculation strategy so the core does not ice at the inlet. Corrosion-resistant coatings or polymer cores extend life where the air carries fertilizer salts or pesticides. Sizing should match the ventilation rate that the crop’s transpiration and CO2 strategy demand, not just the heating load, because over-recovery can depress humidity below the optimum for growth. Integrating recovery with a ground-source pre-heat smooths the coldest spells. For commercial growers facing carbon limits or high fuel cost, the combined sensible and latent recovery often justifies the equipment within a few growing seasons.
Frequently Asked Questions
How does heat recovery work in a greenhouse?
Air-to-air plate exchangers recover sensible heat from ventilation exhaust, while condensing units also capture latent heat as vapor condenses, returning warmth and sometimes distilled water to the crop.
What type of exchanger suits horticulture exhaust?
Corrosion-resistant plate or polymer cores suit the high-humidity fertilizer-laden air, and ground-source pre-heating of incoming air reduces peak boiler load.
Does greenhouse heat recovery pay back quickly?
With continuous operation, recovery often pays back within one to three seasons, especially where gas prices are high or carbon limits apply.
How should a greenhouse recovery system be sized?
Size to the ventilation rate the crop’s transpiration and CO2 strategy demand, not just the heating load, and add frost protection so the core does not ice in cold climates.