Keeping Sutton Hoo toasty

Tranmer House biomass boiler at sunset

Phase two of our move towards green energy and away from fossil fuels is complete with the installation of a biomass boiler at Tranmer House, Sutton Hoo.

January 2016 saw the installation of 172 solar panels to the roof of our Visitor Reception building here at Sutton Hoo, which went on to generate 48MWh of electricity in just the first year – comparative to the average consumption of 10 UK homes – and proving a fantastic success.

By the end of 2016 we moved to phase two with the installation of our biomass boiler into an outbuilding adjacent to Tranmer House. It replaces the need for numerous liquid petroleum gas (LPG) boilers and instead runs on sustainable wood fuel pellets.

This, as well as the solar panels, has meant that we are able to reduce our carbon emissions by an estimated 68 tonnes per annum.

The boiler now helps us heat Tranmer House, including the three holiday flats and lives in what is believed to be the old coal store.

A new chimney was added on top of this outbuilding, specifically designed to match the existing ones and with the pellet delivery tubes, the only visible external changes.

Biomass boiler extension trench at Sutton Hoo
Biomass boiler extension trench at Sutton Hoo
Biomass boiler extension trench at Sutton Hoo

In May 2017 we were able to extend our work further, with a trench dug from the boiler to the stable block, allowing heat to be supplied here too, which includes our bookshop, conference room, a workshop, and volunteer and staff accommodation.

There’s potential to extend this even further in the future too. We even ended up finding a Prehistoric piece of pottery and worked flint – probably used as a scraper - within the trench!

How does it work?

Running on wood pellets, sourced from sustainably managed woodland, the fuel is fed into the boiler via a screw augur and into an automatically maintained fire. Water is then passed through a heat exchanger over the combustion chamber, absorbing the heat as it goes. This is delivered to two 2200 litre buffer tanks, which allows the boiler to run more efficiently during periods of low demand, and is then ready to be pumped throughout the house whenever heat or hot water is needed.

How biomass works
Diagram of how biomass works
How biomass works

Using wood pellets instead of wood chips has meant that fewer deliveries are needed due to their higher density, which means lower transport pollution from the fuel being used in the lorries.  

We even remove the ash from the boiler to add to our compost, which goes on to help fertilise new plants and trees across the site; nothing goes to waste!

This project at Sutton Hoo is part of the National Trust’s Renewable Energy Investment (REI). It includes the aim to source 50 per cent of our overall energy from renewables by 2020, reducing our reliance on, and the effect of fossil fuels.