Stoking the fires of change

As part of an extensive £2 million refurbishment of its Lincoln-based HQ, roastery and training academy, the company installed a cutting-edge heating system that is set to cut carbon emissions by at least a third and potentially to allow the integration of renewable heating technologies in the near future.

Efficiency improved by up to a third

The two-year refurbishment project at Stokes’ HQ, a Grade II*-listed 19th Century former asylum, the Lawn Building, was overseen by Project Manager, Andy Jackson. He comments, “We like to make things last at Stokes, but, after 43 years of service from our boilers, it was time for an overhaul. Historic buildings are notoriously difficult to heat and we were determined to find a system that would rise to the challenge in terms of both efficiency and emissions.”

Two 200 kW Viessmann Vitocrossal 100 commercial boilers were specified and installed by commercial heating specialists, the JLA group, whose contract also includes servicing and breakdown cover for the next 10 years. With a redundant air handling system removed, the Vitocrossal units now do the work of the previous three 180 kW cast iron boilers, and at 30% greater efficiency. The boilers are controlled by a Viessmann Vitotronic 300-K digital cascade control unit, while weather compensation through external and internal pipework sensors, generate further savings by automatically adjusting boiler operation according to external temperature demand. 

The efficiency measures underpinning the new heating system don’t stop there:

“We needed to design a system that could operate in zones when necessary because, like with many other businesses’ properties, the demands on Lawn Building vary across the week,” explains JLA Group’s commercial heating manager, Simon Worsdall. “We created two weather-compensated heating circuits, which can be time- and temperature-set by the same controls. The redundant constant temperature circuit was re-purposed to include a second mixing valve, and we modified the internal pipework to enable the café and function room to be controlled independently. This means these spaces can be heated for special events and weekend working, without fuelling the whole building. The fact that the basement plant room is situated directly below the café, which in turn is below the Blue Room, made this easier to achieve as pipework could be kept in a block.”

Added benefits

But efficiency isn’t the only benefit to come from the new heating system: 

“As the existing boilers were of an open flue, natural draught configuration; a booster fan had been installed to the top of the chimney, while a fan assisted duct system provided low level ventilation,” explains Worsdall. “As the new units required a condensing compatible flue liner, we had to remove the old fan assembly which – due to the noise it created – had been housed within a sound box.

“With the fan removed, the new flue termination was housed within the box. The new system has an added benefit of reducing noise levels, particularly towards the adjacent hotel.”

Sustainability across the board

The team at Stokes boasts ambitious sustainability standards; a zero-waste scheme, smart logistics and eco-friendly roasters are just some of the ways they keep emissions down. When it came to the heating system, it was important to have a set up whereby renewable heating technologies could be added in the near future. Heat pumps are currently being considered to supply a new underfloor heating system, while it is hoped that solar thermal technology will heat water for the café and toilet facilities, as part of phase two developments.

Jackson comments, “We are striving to make our Lawn Building into an eco-showcase where we can help share our knowledge and experience in waste and emissions reduction with anyone facing the challenges of owning or occupying historic buildings like ours.”