James Elston

James Elston

Published July 10, 2025

Last Updated on July 10, 2025

Last Updated on July 10, 2025

Air source heat pumps (ASHPs) have become a widely adopted renewable heating solution in the UK, but can they be used to heat a greenhouse efficiently and cost-effectively?

In this in-depth guide, we’ll explore whether it’s viable to install an air source heat pump in a greenhouse, the potential benefits and challenges, and how this decision could affect both homeowners and commercial growers.

Is It Possible to Use an Air Source Heat Pump in a Greenhouse?

Yes, you can put an air source heat pump in a greenhouse, and in many cases, it can be an ideal heating solution. Air source heat pumps extract heat from the outside air and transfer it indoors, even at temperatures as low as -15°C making them suitable for the UK’s relatively mild winters. 

This technology can be adapted to heat greenhouses efficiently, maintaining consistent growing conditions year-round.

Greenhouses typically have higher heat loss due to glass or polycarbonate walls. However, with proper insulation and a correctly sized heat pump, significant energy savings can be achieved. 

According to the Energy Saving Trust, an air source heat pump can deliver 3 to 4 units of heat for every unit of electricity it consumes, making it far more efficient than traditional electric or gas heaters.

What Are the Benefits of Using an Air Source Heat Pump in a Greenhouse?

Installing an ASHP in a greenhouse offers multiple advantages:

Consistent Climate Control

Maintaining optimal growing temperatures year-round is essential. ASHPs provide precise temperature regulation, reducing the risk of frost damage and promoting plant health and productivity.

Lower Heating Bills

Compared to traditional electric or gas heaters, air source heat pumps can reduce energy usage by up to 50%. 

According to the Energy Saving Trust, an ASHP could save a detached home between £260 and £455 per year when replacing an old electric heating system. While figures for greenhouses vary, the proportional savings remain significant.

Reduced Carbon Footprint

For sustainability-focused homeowners and commercial growers, ASHPs offer an environmentally friendly way to heat greenhouses. They produce three to four units of heat for every unit of electricity consumed, significantly reducing greenhouse gas emissions.

According to Ofgem, using a renewable heating system can significantly reduce greenhouse gas emissions and contribute to the UK’s net-zero targets.

Compatibility with Existing Heating Systems

Air-to-water heat pumps can integrate with underfloor heating or existing radiator systems often repurposed in larger or commercial greenhouses.

What Should You Consider Before Installing an Air Source Heat Pump in a Greenhouse?

Despite the advantages, certain considerations must be addressed before installation:

Insulation and Heat Retention

Greenhouses, especially those made of single-pane glass or polycarbonate, lose heat rapidly. For an ASHP to be effective, upgrading insulation and sealing draughts is vital. Consider using thermal screens and double glazing to retain heat and improve efficiency.

Electricity Supply and Infrastructure

ASHPs require a consistent power source. For off-grid greenhouses, ensure there’s enough capacity to support the unit. Solar PV panels may help offset electricity use and improve sustainability.

Space and Sizing

Correctly sizing your heat pump is crucial. Oversizing can lead to inefficiency, while undersizing will not provide adequate heating. Professional assessments based on the greenhouse’s volume, structure, and use will determine the ideal system.

Placement of the Outdoor Unit

The ASHP outdoor unit must be located in a position with sufficient airflow and away from potential obstructions. You’ll also need to ensure it doesn’t create excess noise or disrupt operations.

What Size Air Source Heat Pump Do You Need for a Greenhouse?

The size of the heat pump you need depends on various factors, including:

  • Greenhouse size (m²)
  • Glazing material (glass vs polycarbonate)
  • Insulation quality
  • Desired internal temperature range
  • Local climate

As a rough guide, you may need approximately 50–70 watts per square metre in a moderately insulated greenhouse. For example, a 20m² greenhouse may require a 1kW to 1.4kW heat pump.

It is always recommended to carry out a proper heat load calculation by a qualified installer. This ensures your system is neither undersized nor oversized, both of which can affect performance and efficiency.

Estimated Heat Pump Sizes for Different Greenhouse Sizes

Greenhouse Size (m²)Estimated Heat Load (Watts)Recommended ASHP Size (kW)
10500–7000.5–0.7 kW
201,000–1,4001.0–1.4 kW
301,500–2,1001.5–2.1 kW
402,000–2,8002.0–2.8 kW
502,500–3,5002.5–3.5 kW
753,750–5,2503.8–5.3 kW
1005,000–7,0005.0–7.0 kW

Note: These figures are estimates based on moderate insulation and average UK winter conditions. Always consult a heat pump specialist for a bespoke calculation.

How Much Does It Cost to Heat a Greenhouse with an Air Source Heat Pump?

Initial installation costs for an ASHP typically range between £7,000 and £13,000, depending on system size and greenhouse specifications. 

However, grants such as the Boiler Upgrade Scheme (BUS) can reduce upfront costs by £7,500 for eligible applicants.

Operational costs depend on electricity rates, insulation quality, and temperature requirements. With good thermal management and integration with renewables, running costs can remain low, even in winter.

How Much Can You Save by Using an Air Source Heat Pump?

Compared to traditional electric and LPG heating systems, an air source heat pump can offer significant annual savings. According to the Energy Saving Trust, ASHPs can reduce heating bills by up to 50% in some cases. 

The table below provides estimated annual heating cost comparisons for greenhouses of different sizes.

Greenhouse Size (m²)Annual Cost – Electric Heater (£)Annual Cost – ASHP (£)Estimated Annual Savings (£)
20£480£240£240
40£960£480£480
60£1,440£720£720
80£1,920£960£960
100£2,400£1,200£1,200

Estimates assume average UK electricity prices (as of 2025), moderate insulation, and continuous heating in colder months.

How Can You Improve the Efficiency of an Air Source Heat Pump in a Greenhouse?

Due to high heat loss in greenhouses, ensuring the pump runs efficiently is essential. Here are key strategies:

  • Use thermal curtains: These reduce heat loss overnight.
  • Install insulation: Insulating the base and edges can dramatically reduce energy waste.
  • Zone control: Heat only specific zones where plants are located.
  • Pair with a buffer tank: This allows heat to be stored and used when needed, reducing short cycling.

According to the UK Green Building Council, integrating efficient renewable technologies in agricultural settings can improve building performance and energy resilience.

Can Air Source Heat Pumps Cool a Greenhouse Too?

Most standard ASHPs are designed primarily for heating. However, many models come with reversible features that allow them to provide cooling in summer, a major advantage for temperature-sensitive crops.

Keep in mind that using a heat pump for cooling will increase electricity consumption, so it’s vital to assess energy costs and consider pairing the system with solar panels for sustainability.

Are Air Source Heat Pumps Suitable for Commercial Greenhouses in the UK?

Absolutely. The commercial horticulture sector in the UK is under increasing pressure to decarbonise. According to Ofgem, the energy used in greenhouse heating accounts for over 50% of total energy consumption in commercial growing environments.

The Carbon Trust estimates energy savings of up to 60% when switching to a heat pump from an electric or oil-based system in commercial applications. Over time, the system can pay for itself through reduced energy bills.

ASHPs can be integrated into smart climate control systems, reducing reliance on fossil fuels and meeting compliance requirements for future sustainability standards.

If you’re a business or landlord, you may also qualify for tax relief under the UK Government’s Enhanced Capital Allowance scheme or support via local net-zero funding initiatives.

How Long Do Air Source Heat Pumps Last in Greenhouse Applications?

With regular maintenance, air source heat pumps can last 15–20 years. Key maintenance tasks include:

  • Cleaning or replacing filters
  • Ensuring airflow is unobstructed
  • Annual servicing by a certified engineer

According to Ofgem, long-term performance is closely tied to quality of installation and regular upkeep.

What Are the Planning and Installation Considerations in the UK?

In many cases, air source heat pump installations are considered permitted development in the UK. However, specific rules apply:

  • The unit must be more than one metre from the property boundary.
  • Only one ASHP unit is allowed per property without planning permission.
  • The external unit must not exceed 0.6 cubic metres in size.

For greenhouses on commercial or listed properties, or those in conservation areas, planning permission may be required. Always check with your local planning authority before installation. Details are available on the Planning Portal.

Get a Free Quote for an Air Source Heat Pump for Your Greenhouse

If you’re considering installing an air source heat pump in your greenhouse, Eco Happy can help. Our accredited installers assess your unique needs and deliver a system optimised for efficiency, performance, and return on investment.

Whether you’re a homeowner, landlord, or business owner, we offer:

  • Free bespoke quotes
  • Advice on funding and grants
  • High-performance systems designed for UK climates

FAQs 

1. Can I install an air source heat pump in a polytunnel instead of a glass greenhouse?
Yes, but it may require additional insulation since polytunnels have higher heat loss rates than glass greenhouses.

2. Can I use an air source heat pump with an existing gas heating system?
Hybrid systems are possible. A heat pump can provide base-load heating, while your gas system kicks in only when necessary.

3. Will using a heat pump increase humidity in the greenhouse?
Not directly. However, warmer air can hold more moisture. Ensure proper ventilation to maintain a healthy humidity balance.

4. Can I install solar panels alongside a heat pump in my greenhouse?
Absolutely. Solar PV can offset the electricity used by the pump, increasing cost savings and reducing environmental impact.

5. Are there noise concerns with heat pumps in a greenhouse?
Most modern ASHPs operate quietly (around 40–60 dB). Proper placement and acoustic housing can further reduce perceived noise.

Conclusion

Air source heat pumps are a viable, eco-friendly solution for heating greenhouses across the UK. With rising energy costs and growing interest in sustainable gardening and agriculture, now is the time to consider making the switch. 

From reducing emissions to improving energy efficiency, an ASHP system tailored to your greenhouse setup can provide year-round benefits.

Whether you’re a homeowner growing tomatoes or a commercial operator cultivating delicate herbs, investing in a heat pump is a forward-thinking choice that aligns with the UK’s net-zero goals. 

Get expert advice, explore funding options, and make your greenhouse greener with Eco Happy today.

James Elston

James Elston

Boiler Expert


James Elston is the top boiler replacement and heating expert at Eco Happy. He has over 20 years of experience in the industry, focusing on Gas Safe boiler installations and offering home-heating and energy-saving solutions to homeowners across the UK. From sourcing the most energy-efficient combi boiler to providing specialist heating advice, James ensures that Eco Happy maintains the highest standards and best customer service.

Leave a Reply

Your email address will not be published. Required fields are marked *