Case study

Lamellen House, Cornwall

176kW Miscanthus / Woodchip district heating system

Key facts

Commisioned

September 2012

Scheme

Supply of hot water and heating to Lamellen House, an indoor swimming pool and a barn conversion

Boiler and plant

A pair of ETA Hack 90kW boilers connected to a 5,000 litre accumulator tank within a purpose built plant room. The two 40kW oil boilers from the main house have been re-installed in the biomass plant room to provide a limited back-up and peak-load facility. The properties being heated are connected by 120m of pre-insulated district heating main.

Fuel

The boilers are set up to use either miscanthus or wood chips depending on local availability and cost. Due to its relatively low energy density, fuelling the boilers with miscanthus reduces their rated output from 88kW to 60kW each.

Fuel storage

Fuel is purchased from local suppliers and tipped directly into the 6m×6m sunken fuel store from above. No other fuel handling is required.

Grant / Funding

The system was funded from estate resources and is accredited under the non-domestic Renewable Heat Incentive scheme.

Savings / Investments

The previous oil and LPG heating systems were generating bills of around £14,000 per year and this has been halved by the biomass system. Additionally, it is expected that the system will generate RHI income of approximately £19k. The return on the investment is expected to be around 20%.

CO2 saving

Estimated at 65 tonnes per annum

Lamellen House is a Cornish Victorian country house let for luxury holidays. It includes seven bedrooms and a large indoor swimming pool, together with gracious reception rooms in a beautifully landscaped garden. Adjacent to the main house is a converted barn. As both properties were heated by expensive to run oil and LPG boilers the owner asked Dunster to produce a feasibility study and, after a number of iterations, decided to install a pair of boilers with a sunken fuel store capable of being fuelled by either wood chip or miscanthus.

Fuel supply and chip handling

Fuel, either wood chips or miscanthus, is tipped directly into the sunken fuel hopper from delivery lorries. This means that there is no requirement for fuel handling on site and deliveries can be made quickly and easily by any local supplier. The hopper needs topping up with miscanthus every two to three weeks in winter or once a month if woodchip is used.

System design and installation

The system was designed to satisfy 100% of the heat and hot water demand of the properties from Biomass. However, when fuelled by miscanthus, the slighter lower heat output means that heating the pool either requires supplementary heat from the oil boilers or needs to be timed when demand from the other properties is low. The oil boilers which act as both a peak load or back up facility are automatically controlled by the biomass boilers to ensure the seamless delivery of heat. Given the nature of the properties this was considered a sensible precaution and avoided the installation of a larger system that would have produced smaller financial benefits.

Lamellen House

Benefits

The project has brought substantial environmental and financial benefits to the estate and is contributing to the local economy through the fuel supply contract.

Download Lamellen House case study

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