Thursday, April 11, 2024

School embarks on third energy-saving CHP installation

Mark Gibbons

Prioritising more energy-efficient heating can be challenging for schools, especially when dealing with older estate. At Aldenham School in Elstree, a Baxi CHP and boiler system installed at one its boarding houses continues to successfully tick all the efficiency boxes. So much so that the School is now embarking on its third CHP installation. Baxi’s Renewables Sales Manager Mark Gibbons reports

Eighteen months since installing a combined heat and power (CHP) and boiler system in one of its boarding houses, independent school Aldenham has reported a 35-40% fall in annual gas consumption with an additional £4,500 of on-site generated electricity going back into the building each year.

A similar CHP and boiler system installed in the plant room of a second boarding house is showing a parallel trend in total energy savings. The success of the solution is such that Aldenham’s Head of Estates Tony Albon is currently refurbishing a third boarding house plant room with a Baxi CHP system during the summer shutdown period. A fourth CHP installation is planned for later in the year.

The School’s partnership with Baxi began a few years back, when Aldenham School first identified that the three floor-standing boilers at Paull’s House, one of its five boarding houses, were reaching end of life.

Like many independent schools, Aldenham has a stock of older existing buildings. At Paull’s House, parts of the building date back to the sixteenth century.

“We have 60 children staying at Paull’s House in the evening,” Tony explained, “so it’s essential that the building is warm and comfortable with enough hot water for showers and catering. At the same time, we wanted to reduce energy usage and emissions associated with heating. Reliability, sustainability and affordability were therefore the main considerations.”

When exploring the options, Tony looked into heat pumps as a possible solution but had to rule them out due to the building fabric at Paull’s House and the upfront cost.

“We were working with an extremely old and leaky building,” he added, “which added to the complexity of the retrofit challenge. So, we decided to call in the heat experts for advice.”

The Baxi team had lengthy discussions with Tony and Karl Mahon, the School’s Bursar, to understand the exact requirements at Paull’s House before presenting the feasible options. This included the need to connect the new system to the neighbouring science block that was being refurbished. Multiple site visits were carried out to ensure that the proposed solution would be an energy-efficient system tailored around the needs of the buildings.

When Baxi proposed a CHP and boiler solution as the most viable solution to meet all requirements, they immediately put Tony and Karl in touch with a school using a similar system to understand how it worked and the benefits it was delivering.

“They really took the time to explain the proposed solution,” said Tony. “It was great to be able to see the CHP in situ, hear the other school’s experiences and come away with an accurate, realistic idea of the energy-saving benefits.”

“The CHP and boiler system seemed the perfect solution, meeting all our requirements,” he continued. “Once we had the go-ahead from the Governors, the Baxi team worked closely with our heating contractors, supporting them with the design and installation phases. Their engineers then carried out the pre-commissioning and final commissioning to ensure that the system worked right first time.”

The Remeha R-Gen SenerTec Dachs CHP unit provides a thermal output of up to 14.7kW and an electrical output of 5.5kWe. The unit is controlled according to the heat demand, while the internal microprocessor controller tracks the electrical output to match the thermal output.

Three Potterton Commercial Sirius three WH stainless steel boilers operate alongside the CHP to meet peak load. With a wide 9:1 modulation ratio for improved efficiency and boiler longevity, the boilers boast high gross seasonal efficiency of up to 97.3% with ultra-low NOx emissions under 24 mg/kW to minimise environmental impact. The boilers are supplied with the latest Siemens controls and state-of-the-art PCB to enable enhanced control options.

Accurate sizing of the CHP unit was critical to maximise the energy and carbon saving benefits. A year and a half since handover, the system continues to operate trouble-free and better than anticipated.

“The CHP has been running flat out, 24 hours a day, 365 days a year, improving the efficiency of the system and meeting the needs of the building all year round,” Tony said.

“We are seeing a 35-40% decrease in annual gas consumption at both Paull’s House and McGill’s with an added £4,500 of electricity being put back into the buildings each year that reduces total energy costs still further. And the savings will only get better once the next installation is complete. We are delighted with the efficiencies of the Baxi CHP systems and how this technology is helping us reduce energy usage in what were energy-intensive buildings.”

Remeha and Potterton Commercial are part of Baxi.

For more information on the Remeha CHP range, visit:

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