How do I specify greenhouse climate control so quotes are comparable?
Specify the climate outcome and the design conditions, then let bidders propose the system. State the target internal conditions for the crop, the external design extremes, the acceptable number of hours outside target, the covered area and volume, and the energy source available. Ask each bidder to state the assumed ventilation rate, cooling or heating capacity, control strategy and expected energy consumption under those conditions. Without shared design conditions, a pad-and-fan quote and a mechanical cooling quote describe different projects.
What actually drives the answer
Design conditions must be shared with every bidder in writing: design dry-bulb and wet-bulb temperatures, radiation, humidity and wind data with their source.
Ask for capacity and assumptions, not just equipment lists: airflow, evaporative efficiency assumptions, screen properties, heating capacity and the control set-points used in the calculation.
Energy consumption estimates should be stated with the tariff and hours assumed, so the operating cost comparison is transparent.
Controls and sensors deserve their own line: number of climate zones, sensor count and placement, alarm handling and remote access.
Redundancy is a specification decision: state which failures the crop cannot survive and require the bidder to explain how the design handles them.
Variables that change the answer
- Crop target conditions and tolerance
- External design extremes
- Covered area, volume and gutter height
- Water availability for evaporative cooling
- Energy source and tariff
Evidence a supplier needs before quoting
- Local climate dataset for the site
- Crop and target market assumption
- Water availability and quality
- Energy supply and tariff structure
What this answer does not settle
- This standardises the enquiry. Final climate design, capacity calculations and equipment selection belong to the supplier's engineers and the project's agronomist.
Responsibility
- Professional review:
- Greenhouse climate engineer and independent agronomist
- Delivered by:
- Climate system supplier or integrator
- Feeds RFQ section:
- Climate control and energy
Sources
- Greenhouse Horticulture research programmeWageningen University & Research · Secondary source · accessed 2026-08-21
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