Greenhouse kept warm and dry on winter nights
How a 2,000 m² polyhouse growing cut flowers can be heated and dehumidified with heat pumps on winter nights, and what it saves against diesel hot-air generators.
▶Video: Space heating for buildings and farms
V13 · 2–2.5 minFloor heating, fan coils and air handlers, from homes to poultry sheds
Video coming soon01Problem statement
- Cold nights stop growth. Roses and gerberas slow down below 15 °C and flower quality drops. A single frost can damage a crop.
- Condensation brings disease. Warm, humid air meeting a cold roof drips onto leaves and flowers, causing botrytis and mildew.
- Diesel heaters add fumes. Direct-fired hot-air generators release combustion gases into the house unless flued properly, and fuel cost limits how much growers heat.
- Losses between fuel and process. Burning diesel in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference unit is a 2,000 m² naturally ventilated polyhouse in a hill state growing roses for export. Winter nights fall to 2–5 °C, and the crop needs at least 15 °C at night with low leaf wetness.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Night heating | Inside 15 °C, outside 5 °C | 2,600 m² cover × 4 W/m²K × 10 K × 10 h | 1,040 |
| Ventilation reheat for dehumidifying | Air 18 °C | 2,000 m² × 15 W/m² × 6 h early morning purge | 180 |
| Irrigation and nutrient water warming | 12 → 20 °C | 10,000 L/day, 12 → 20 °C | 93 |
| Storage and pipework standing losses | – | about 5% | 66 |
| Total useful heat | 1,379 | ||
Averaged over 14 running hours, the heat pumps need about 98 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 1 × SE-AH-100V (100 kW) (SE-AH air-source heat pump) delivering 50 °C, covering the day's 1,379 kWh in about 13.8 running hours.
- A 3,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The diesel-fired hot-air generators stays connected behind a normally closed valve as standby.
- Low-level pipe-rail or under-bench heating pipes warm the crop zone directly, where the plants are.
- Fan-assisted unit heaters circulate warm air to break up cold, humid pockets and dry leaf surfaces.
- In the early morning the vents open briefly while heating continues, purging humid air without chilling the crop.
- A small PHE warms irrigation water so roots are not chilled.
Selected equipment
| Model | SE-AH-100V × 1 |
|---|---|
| Heating capacity | 100 kW each, 100 kW total |
| COP | 4.2 at A20 °C / W50 °C (data sheet T1) |
| Power input | about 23.8 kW total at rated conditions |
| Rating | rated 55 °C, 60 °C maximum, R410A |
| Supply temperature | 50 °C |
| Storage | 3,000 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the top of the tank starts the heat pumps below 44 °C and stops them at 50 °C. TIC-201 holds night air temperature at 15 °C using the pipe-rail valve. A humidity sensor drives the unit heaters and vent purge when relative humidity exceeds 85%. Diesel heaters stay as frost standby.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Less fungal disease
Keeping leaves above dew point reduces botrytis and mildew, and with them spray costs.
Clean greenhouse air
No combustion gases near the crop.
Affordable night heating
Lower heating cost lets growers hold the right night temperature instead of rationing fuel.
Lower energy cost
Each kWh of electricity delivers about 4.2 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Greenhouse area, cover type and height
- Crop and night temperature target
- Lowest winter temperatures and number of cold nights
- Current heating fuel use
- Ventilation and screen details
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Thermal screens. A night energy screen can cut heat loss by 30–40%. Fit one before sizing the heat pumps.
- Defrost in cold climates. Air-source units in hill areas will defrost on cold, damp nights. Size the tank to carry heating through defrost.
- Pipe position. Place heating pipes low and spread evenly so warm air rises through the crop.
- Electrical. About 24 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Winter output. Air-source output falls in cold weather: about two-thirds of rated capacity at 5 °C ambient. Size on the coldest design day for northern sites.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.
Talk to us
Greenhouse kept warm and dry on winter nights
How a 2,000 m² polyhouse growing cut flowers can be heated and dehumidified with heat pumps on winter nights, and what it saves against diesel hot-air generators.
▶Video: Space heating for buildings and farms
V13 · 2–2.5 minFloor heating, fan coils and air handlers, from homes to poultry sheds
Video coming soon01Problem statement
- Cold nights stop growth. Roses and gerberas slow down below 15 °C and flower quality drops. A single frost can damage a crop.
- Condensation brings disease. Warm, humid air meeting a cold roof drips onto leaves and flowers, causing botrytis and mildew.
- Diesel heaters add fumes. Direct-fired hot-air generators release combustion gases into the house unless flued properly, and fuel cost limits how much growers heat.
- Losses between fuel and process. Burning diesel in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference unit is a 2,000 m² naturally ventilated polyhouse in a hill state growing roses for export. Winter nights fall to 2–5 °C, and the crop needs at least 15 °C at night with low leaf wetness.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Night heating | Inside 15 °C, outside 5 °C | 2,600 m² cover × 4 W/m²K × 10 K × 10 h | 1,040 |
| Ventilation reheat for dehumidifying | Air 18 °C | 2,000 m² × 15 W/m² × 6 h early morning purge | 180 |
| Irrigation and nutrient water warming | 12 → 20 °C | 10,000 L/day, 12 → 20 °C | 93 |
| Storage and pipework standing losses | – | about 5% | 66 |
| Total useful heat | 1,379 | ||
Averaged over 14 running hours, the heat pumps need about 98 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 1 × SE-AH-100V (100 kW) (SE-AH air-source heat pump) delivering 50 °C, covering the day's 1,379 kWh in about 13.8 running hours.
- A 3,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The diesel-fired hot-air generators stays connected behind a normally closed valve as standby.
- Low-level pipe-rail or under-bench heating pipes warm the crop zone directly, where the plants are.
- Fan-assisted unit heaters circulate warm air to break up cold, humid pockets and dry leaf surfaces.
- In the early morning the vents open briefly while heating continues, purging humid air without chilling the crop.
- A small PHE warms irrigation water so roots are not chilled.
Selected equipment
| Model | SE-AH-100V × 1 |
|---|---|
| Heating capacity | 100 kW each, 100 kW total |
| COP | 4.2 at A20 °C / W50 °C (data sheet T1) |
| Power input | about 23.8 kW total at rated conditions |
| Rating | rated 55 °C, 60 °C maximum, R410A |
| Supply temperature | 50 °C |
| Storage | 3,000 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the top of the tank starts the heat pumps below 44 °C and stops them at 50 °C. TIC-201 holds night air temperature at 15 °C using the pipe-rail valve. A humidity sensor drives the unit heaters and vent purge when relative humidity exceeds 85%. Diesel heaters stay as frost standby.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Less fungal disease
Keeping leaves above dew point reduces botrytis and mildew, and with them spray costs.
Clean greenhouse air
No combustion gases near the crop.
Affordable night heating
Lower heating cost lets growers hold the right night temperature instead of rationing fuel.
Lower energy cost
Each kWh of electricity delivers about 4.2 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Greenhouse area, cover type and height
- Crop and night temperature target
- Lowest winter temperatures and number of cold nights
- Current heating fuel use
- Ventilation and screen details
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Thermal screens. A night energy screen can cut heat loss by 30–40%. Fit one before sizing the heat pumps.
- Defrost in cold climates. Air-source units in hill areas will defrost on cold, damp nights. Size the tank to carry heating through defrost.
- Pipe position. Place heating pipes low and spread evenly so warm air rises through the crop.
- Electrical. About 24 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Winter output. Air-source output falls in cold weather: about two-thirds of rated capacity at 5 °C ambient. Size on the coldest design day for northern sites.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.