Hollycroft Primary School was Leicestershire County Council's first net-zero carbon in operation school. Delivered in 2023, by Procurement Hub contractor Willmott Dixon, the project exemplifies the benefits of early engagement and collaboration, as championed in David Mosey’s Constructing the Gold standard.
Collaborative process
The journey between the customer and Willmott Dixon began at RIBA Stage 0, where they jointly established the project’s sustainability goals. The customer had originally thought that a net zero carbon school was beyond their budget. However, Willmott Dixon’s comprehensive net zero carbon options report (which they provide as standard on every project) showed it was possible, and empowered the council to make informed decisions based on cost and carbon impacts.
Energy modelling
Willmott Dixon applied its award-winning, in-house Energy Synergy® process to maximise building performance. Using TM54 modelling and analysis, their process went beyond Part L Building Regulation requirements by accounting for both regulated and unregulated energy. At design stage, Hollycroft School’s modelled energy usage intensity was 50.9 kWh/m2yr – up to 60% less than the Department for Education’s primary schools benchmark at the time (100-140 kWh/m2yr). It was also up to 18% ahead of the DFE’s new, enhanced benchmark levels of 52-67 kWh/m2yr.
Embodied carbon
Operational and embodied carbon were key considerations in the decision to choose a timber frame rather than steel – this reduced carbon emissions by an equivalent of 38,946kg CO2. The timber had already absorbed an equivalent of 566,065kg CO2 while growing. The timber frame had other benefits too – it reduced the construction programme by five weeks, compared to a steel, and this gave the school’s Trust earlier access to the building so they could prepare for the pupils.
Renewable energy
Hollycroft Primary School’s 381m2 of rooftop Photovoltaic (PV) panels power the building’s air-source heat pumps, providing carbon-free heating and cooling during the day. The panels were designed to generate more energy than the school needed, so that they could remain net zero even if they expanded from a single to a two-form entry. To keep costs manageable, Willmott Dixon introduced Leicestershire County Council to a community energy group, who covered the £70K cost of installing the PV. Now the school pays the community group for the electricity they use, at a reduced rate, and the energy group benefits from any excess sold back to the grid.
Building fabric
To minimise the energy requirements for heating and cooling, the design maximised the building’s thermal efficiency by using low u-value materials, with enhanced fabric walls, floors and roof, as well as enhanced performance windows.
Continuous improvement
Since completion in 2023, Hollycroft Primary School is benefitting from the three-years post-occupancy support the contractor provides through its Energy Synergy® process. This is to fine-tune the building’s energy performance and involves vigilant monitoring of real-time data, such as room temperatures, hot water usage, and overall energy consumption in order to identify and address inefficiencies. The insights from the data have helped the customer make many energy-saving adjustments. For example, turning down the heating where occupants had opened windows during the winter months, and turning off the heating in unoccupied spaces. Additionally, thermostat settings, heating flow temperatures and hot water availability have all been recalibrated around key operating hours.
Educational opportunity
As the first-ever Science, Technology, Engineering and Maths (STEM) Primary School, Hollycroft wanted their building to inspire enquiring minds. So the collaborative design left Mechanical and Electrical services exposed to create a STEM-rich learning environment. Now children can see and understand how the building operates. This connection between customer vision and completed building was a key reason why they rated Willmott Dixon 10/10 for meeting customer expectations.
Customer savings
Based on current performance improvements, made since April 2024, Hollycroft School is set to make savings of nearly £30k over the five years post-completion (this is an estimate, since seasonal changes can make a big difference to the gap between expected and actual building performance, and monitoring of heating, hot water and ventilation systems at the school is not yet complete). In terms of carbon savings, the use of Energy Synergy® has currently resulted in 2,216 kgCO2e of emission reductions from the running of the building, with projections suggesting the savings will eventually be 5,652kgCO2e every year. That’s the equivalent emissions to more than five flights from London to New York, or nearly 400 car journeys from Hinkley to Birmingham every year.
Customer satisfaction
Hollycroft Primary School was delivered defect-free, on time and within budget. The customer awarded Willmott Dixon a customer satisfaction score of 9/10 and a net promoter score of 10/10. As a result of the successful delivery of Hollycroft Primary School, the customer subsequently awarded Willmott Dixon another primary school project – also through Procurement Hub – where they could build on lessons learned and develop their partnership further.
Peter Merry, CEO of the Owls Academy Trust/Hollycroft, said: “The whole process was efficient and knowledgeable. Communication was great and information has been passed on in a format we understand. Willmott Dixon explained and sorted out all our concerns and continue to provide support to us. Working with the Energy Synergy® team has been a most pleasing experience, and we unreservedly recommend them to anyone seeking such expertise and true partners.”
Legacy
Through genuine collaboration, Willmott Dixon was able to deliver a net zero carbon building which supported the customer’s climate commitments, and inspire the next generation, within their budget constraints. By maximising the school’s energy efficiency the customer will save on energy bills for years to come. Hollycroft school sits in the top 10% of all new non-domestic buildings for environmental best practice and Leicestershire County Council is using it as a template for their future schools.
Find out more about the Major Projects Framework 2 here.