Ground source heat for listed wedding venue


03 November 2020

A Grade II listed wedding and events venue in Norfolk has upgraded to a ground source heat pump installed by renewable heating expert Finn Geotherm.

Located just outside Norwich, the eight-sided Octagon Barn was originally built as a non-conformist Methodist meeting chapel in the 1680s. The building had wings added at either end but, after falling out of use, it became a grain store and latterly a cattle barn. In 2008, owners Joe and Katie Wiley began an extensive refurbishment project to open it up for event hire. In 2012, the building was reroofed and in 2015, new main doors and a toilet block were installed, plus two commercial offices built on the side.

Heating Octagon Barn was a challenge – the single skin walls, vast 5,000sq ft open space and 50ft high vaulted ceiling made distributing and retaining heat difficult and expensive. A diesel space heater was ineffective and noisy. Joe looked at a range of renewable options to provide a more sustainable solution for the barn and also the newly-built 7,000sq ft commercial offices next door.

Joe Wiley, owner of Octagon Barn explained: “As a beautiful listed property, it wasn’t viable to add extra insulation or cladding to improve heat loss without altering Octagon Barn’s appearance. We wanted to step away from fossil fuels and considered other renewable options. We looked at biomass but felt it would be too labour intensive and time consuming, plus we’d also have to build somewhere to store and burn the fuel. With a barn of this size, it wasn’t practical to keep turning the heating on and off in-between events. We needed something to maintain a steady, warm temperature without costing a fortune in fuel.”

Inside the Grade II listed Octagon Barn

Having previously completed an installation at another commercial office on the site, Finn Geotherm specified and installed a Lämpöässä T120 ground source heat pump with 3000 litre thermal store for Octagon Barn. 6km of ground loop was laid via 16 loops in the field, with the pipes running back to the barn underneath the car park. The heat pump is used to heat two very diverse properties with two very different heat requirements – the 17th Century barn and the newly built, A* energy rating commercial offices. Heat is emitted in the barn through four large Jaga AVS fan units and throughout the barn toilets and office premises using underfloor heating.

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While a ground source heat pump was more expensive to install than a conventional boiler, it offers much lower running costs for Octagon Barn. The added benefit of the Non-domestic (Commercial) Renewable Heat Incentive (RHI) means the system will pay back in less than seven years. Plus, annual servicing and maintenance costs are minimal. With no fuel deliveries or adjustment needed, the heat pump is left to run on its own.

Joe said: “Finn Geotherm provided great customer service while installing this cost effective and energy efficient, passive ground source heating system. It has allowed us to convert the totally redundant Octagon Barn into a very successful venue for weddings, parties and conferences. The heat pump was installed in 2014 and it has been working perfectly ever since to ensure our venue is warm and welcoming all year round. The adjacent offices are always very comfortable too and our commercial tenants are certainly enjoying the low heating bills!”

In 2019, Octagon Barn was presented Broadland District Council’s Enhancement Award, which recognises the best enhancement to an existing building. Judges were impressed by the scale of the venue and its sensitive conversion, complete with sustainable ground source heating.

Plans for a further eight commercial offices at the site are in development. Under the guidance of Finn Geotherm, Joe is intending to run these using the existing Lämpöässä T120 heat pump system, which has more than enough capacity to meet demand.