CHP system is class act at Aldenham School

Prioritising a more sustainable operation through more energy-efficient heating can prove challenging for schools, especially when dealing with older estate.

Baxi’s renewables sales manager Mark Gibbons checks in with the Bursar at Aldenham School to hear how the CHP system installed a year ago is exceeding expectations.


First published in the HVR magazine July addition. 

Faced with ambitious carbon neutral targets and inflated energy prices, and backed by a desire to lead by example, schools across the country are placing an ever-greater focus on sustainability. The heating and hot water system is typically a good starting point for improvement, especially in buildings relying on ageing systems. Where possible, an all-electric approach using heat pumps will be the favoured approach. But in historic, listed buildings, especially those with high heat losses and constant demand for heating and hot water, combined heat and power (CHP) could provide an effective option for improved sustainability.

Take Aldenham, an independent school with a stock of older existing buildings. When the time came to replace the ageing boilers at one of its boarding houses, Estates Manager Tony Albon and Bursar Karl Mahon knew they had a challenge on their hands. Paull’s House is leaky, with walls made of thick solid brick and parts of the building fabric dating back to the 16th Century.

Understanding the complexity of the retrofit challenge, they were keen to form a partnership with Baxi to understand the feasible options. Reliable, sustainable and affordable “We had a number of requirements,” Karl explained. “First and foremost, we needed to implement a new solution that would reliably and efficiently meet the heating and hot water demand in the building.

We have 60 children staying there in the evening so ensuring that the building is warm and comfortable with plentiful hot water for showers and catering was clearly a top priority. “Sustainability was another important factor,” he continued. “Across the education sector, there is an increasing focus on reducing carbon emissions as we move towards our carbon neutral goals. However, alongside this, pragmatism and affordability also have a part to play.”

The Baxi team had lengthy discussions with Karl and Tony to understand the exact requirements at Paull’s House and carried out multiple site visits to ensure that the recommended solution would be an energy-efficient system tailored around the needs of the buildings. When they proposed a CHP and boiler solution, they immediately put Karl and Tony in touch with a school using a similar system to understand how the system worked and the benefits it was delivering.

“The upfront capital expenditure relating to heating and hot water refurbishments is a challenge for the independent school sector, especially with the rises in energy prices, catering costs and salaries,” Karl added. “But this is a critical service, and we have to prioritise it. That’s why it’s absolutely essential to get it right and ensure we have a system that will deliver payback within the next five years or so and last a good number of years longer.”

35-40% gas savings

And get it right they did. The decision to install a Remeha R-Gen 5.5 SenerTec Dachs CHP and Potterton Commercial Sirius three WH stainless steel boilers continues to reap dividends for the School. The system was handed over in December 2021 and has been performing trouble-free and better than anticipated ever since.

Annual gas consumption at Paull’s House has fallen by 35-40% with an added £4,500 of on-site generated electricity going back into the building. So successful has the system been that Aldenham has since replicated it in a second boarding house where a parallel energy trend is now being observed. The school is preparing to fit a third CHP and boiler system in another of its boarding houses this summer.

Karl said, “We knew we had a challenge on our hands when refurbishing the heating system at Paull’s House. And we’re delighted to have achieved all our requirements in our boarding houses with CHP: economic and environmental sustainability, and a reliable, energy-efficient heating and hot water system that never fails to deliver. “We’ve been on a major learning curve.

For our new development, which will be designed for low temperature heating, we’re exploring installing heat pumps with Baxi to deliver the lowest carbon footprint. This is a complex area, and we believe that working with heat specialists is the best way to arrive at the right solution for each building every time.”

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