Rectory Farm in Safron Walden, Essex houses RAGT Seeds who grow and market seeds around the world. As a business, Rectory Farm is dependent on the successful, healthy growth of its crop seeds and can’t always rely on the British weather.
The seeds are grown in huge greenhouses, which need to retain an even, optimal temperature all year round. With heating required on many days of the year to achieve the target temperature of 21°-22°C, the existing LPG heating system proved prohibitively expensive to run. It was also slow to respond to external changes in climatic conditions - such as the sun going down on bright winter days - and offered no cooling, meaning that in summer, temperatures in the greenhouses peaked at 45°C.
Faced with these challenges plus the ambition to improve air circulation to reduce fungus growth and improve plant health as well as accessing the Non-Domestic Renewable Heat Incentive (RHI), RAGT Seeds sought technical advice from Finn Geotherm. They in turn consulted Jaga in order to design and specify a heating solution that met this mandate.
The result of this consultation was a brand new system with three Lampoassa T120 ground source heat pumps linked to Akvanti 2400 litre thermal stores installed within a purpose-built plant-clad building. These are connected by high insulation underground pipework to the network of greenhouses where existing grow tubes and 26 Jaga Unit Heaters now provide overall heat distribution with four units per greenhouse. The Unit Heaters incorporate Jaga’s innovative Air Venturi System (AVS) technology that mixes heated and ambient air to provide an accurate, controllable level of heat at a constant rate.
Within the greenhouses, the Unit Heaters are mounted from the ceiling in order to heat the entire facility whilst not taking up valuable floor space. The combination of the Jaga AVS fan coil units with aluminium distribution pipes allows exact temperature control throughout the year and rapid response to variations in external temperature. Control of the heating and cooling system is via the wifi-enabled BMS and is set to activate should the temperature in the greenhouses vary by more than 1°C from the target temperature. The result has been enhanced plant growth with a dramatic increase in the organic signature, increased crop yield, and elimination of the use of fungicides in the greenhouses thanks to the better air distribution provided by the Jaga products.
There have also been significant financial benefits for RAGT Seeds too as the new system at Rectory Farm has halved the annual running costs of the former LPG system. It has also been approved by Ofgem, successfully registered for the RHI and is expected to give an annual RHI return of £48,189 which is almost twice the running cost of the system.
When talking about the use of Jaga products at Rectory Farm, Guy Ransom, Commercial Director, Finn Geotherm UK said: “RAGT Seeds was a desperately important project for us. Not only, being 360kW was it one of the largest that we had undertaken, but it also gave us the opportunity to develop and apply new applications for ground source heat pumps. In approaching a project such as this we needed to know that we could depend upon each link in the system. As the Jaga fan coil AVS units not only represented a significant part of our heating load, but also the vehicle for us to provide passive cooling, they formed a vital part of the overall system.
“Throughout the design, specification and installation process Jaga provided every level of support that we could possibly have wished for. Once installed, the Jaga AVS units were superb – not only enabling our heat pump system to meet the required heat load, despite the low insulation levels of the horticultural glass, but also allowing the passive cooling system to maintain the growing environment within target temperatures, even during periods of full sunshine. This project was an excellent example of Jaga’s partnership approach and high quality systems, enabling Finn Geotherm to deliver innovative solutions and excellent results for our clients.”