Air-to-Air Heat Exchangers for Greenhouse Ventilation Heat Recovery
Air-to-Air Heat Exchangers for Greenhouse Ventilation Heat Recovery
Greenhouses ventilate constantly to dump heat and humidity, but in cool seasons that vented air is warm and carries energy the grower just paid to produce. Recovering that heat with an air-to-air heat exchanger pre-warms the incoming fresh air, cutting heating cost without raising humidity — a key point for crop health.
Why Greenhouses Lose So Much Heat
A single air change can dump the entire sensible heat buffer of a greenhouse in minutes. In winter, continuous ventilation against cold outdoor air means the boiler runs almost without pause. A sensible plate core placed in the ventilation path transfers the warmth from exhaust to supply, so the boiler only tops up the remaining gap. Our efficiency reference shows how effectiveness translates directly into fuel saved.
Why a Plate Core (Not a Wheel) for Greenhouses
Greenhouse exhaust is warm and humid; the goal is to keep the incoming air warm but not to carry that moisture back inside, because elevated indoor humidity drives fungal disease. A fixed plate exchanger recovers sensible heat only — temperature rises, absolute humidity stays at the (low) outdoor level. A rotary wheel would also carry moisture back in, raising indoor humidity and disease risk. The same logic appears in our agriculture piece on plate vs rotary for livestock houses and the wheels-banned guide. Where a wheel is unsuitable, plate or heat-pipe wins — see also sensible vs latent recovery.
Sizing Example
A 2,000 m² greenhouse venting at 20,000 m³/h, indoor 22°C, outdoor 0°C, with an 80% effective counter-flow plate core: recovered heat ≈ 20,000 × 1.2 × 22 × 0.8 / 3600 ≈ 117 kW returned to the supply air each hour the ventilation runs. That is 117 kW the heater no longer must supply. Our sizing guide walks the full calculation including the frost-risk note below.
Frost and Cold-Climate Operation
In hard freezes, the exhaust-side plate can ice up. Manage it with a bypass, a pre-heater on the supply, or alternating airflow — details in frost prevention for plate exchangers. Because the core is sensible-only, there is no indoor moisture swing to complicate the strategy.
Integration Checklist
- Place the core in the active ventilation path, exhaust and supply separated (no leak).
- Specify a counter-flow plate for highest effectiveness.
- Add frost protection for sub-zero design days.
- Keep humidity down — do not use a wheel that returns moisture.
Related
See our application library and how an air-to-air exchanger works for fundamentals.
Get a Greenhouse Core
We build corrosion-resistant plate cores for greenhouse and agriculture ventilation, sized to your air change rate and climate. For a quotation, contact +86 15753355505.