Aldenham School

A Remeha R-Gen SenerTec Dachs Gen 2 5.5 CHP and three Potterton Commercial Sirius three 110 kW Wall Hung condensing boilers have been installed in Paull’s House, Aldenham School in Elstree.

A Baxi Commercial Solutions Combined Heat and Power (CHP) system is successfully meeting the requirement for more reliable and sustainable heating and hot water at one of the UK’s finest independent schools.

Improving the way school buildings are heated can be a huge challenge, especially in historic buildings like Paull’s House, one of the five boarding houses at Aldenham School in Elstree which dates back to 1597. While driving improved sustainability is increasingly a priority for many school estates managers, the technically and financially feasible options can be limited in older, poorly insulated stock.

“When the ageing gas boilers at Paull’s House reached end of life, we were keen to explore solutions other than replacement to make a greater contribution to the school’s wider sustainability commitments,” explained Tony Albon, Aldenham’s Head of Estates.

“Our key requirements were to improve outcomes for students and staff through a more efficient and reliable system, and simultaneously reduce the associated running costs and greenhouse gas emissions associated with heating,” he continued. “But we were working with an extremely old building in which parts of the parts of the fabric date back to the sixteenth century. So, we decided to call in the heat experts for advice.”

The Baxi Commercial Solutions team, led by Key Accounts Director Neville Small, had lengthy discussions with Tony and Karl Mahon, Aldenham’s Bursar, to gain a thorough understanding of their exact requirements. Included within this was the need to connect the new system to the neighbouring science block that was being refurbished. Detailed site visits were carried out to ensure that the proposed solution would be an energy-efficient system tailored around the needs of the buildings.

Paull’s House is leaky and made of solid brick, so renewable technologies had to be ruled out as they perform most effectively in well-insulated premises. CHP was considered the most viable option due to its ability to meet the heating and hot water requirements more efficiently, reduce energy bills, and simultaneously produce on-site electricity via the CHP.

CHP produces useful heat and electricity at the point of use in a single, highly efficient process. Rather than rejecting ‘waste’ heat to atmosphere like traditional power stations, CHP captures it and feeds it into the building’s heating network to produce useful thermal energy.

This energy can then be used to provide primary space heating and/or pre-heat for domestic hot water within the building. By simultaneously generating heat and onsite power, the system can typically achieve total fuel efficiency of 85-90%, double that of conventional technology. That means primary energy savings of up to 30% and an emissions reduction of around 20%, compared with traditional generation.

After completing a feasibility survey and a final assessment of the heating and hot water demand, Mark recommended installing a Remeha R-Gen SenerTec Dachs 5.5 CHP supported by three Potterton Commercial Sirius three 110kW wall hung condensing boilers.

The selected 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.

The project contractors were Keeble Environmental Services Ltd.

“We’ve had a very good experience working with Baxi,” Tony added.

“The CHP team has been by our side throughout the project. They helped our contractors at the design stage, providing useful schematics and monitoring the planning of the system install. They then continued to support our contractors throughout the installation period, offering expert advice and helpful tips to smooth the process. And of course, their CHP engineers carried out the all-important commissioning for optimal operation and maximum efficiency.”

The CHP was handed over in December 2021.

“CHP was absolutely the best possible solution at Paull’s House, given the retrofit challenges,” explained Mark. “Not only did our CHP commissioning engineer say it’s the best installation he has seen all year, but the system has actually been performing better than anticipated. We’re delighted to have helped deliver another highly successful CHP installation.”

“We have had no problems whatsoever,” confirmed Tony. “And it’s reassuring to know that Baxi’s specialist team will be carrying out all future maintenance and servicing. This, along with the training they are providing us, will ensure that the CHP continues to deliver as designed."