The Optimum Solution

Innovaré Systems are at the forefront of innovative timber design and this was showcased recently at two new education projects at Kingsteignton and Stonebridge Primary Schools – both using the award-winning i-SIPS, the BBA Approved structural insulated panel system.  

Delivered under the Priority Schools Building Programme (PSBP), Kingsteignton Primary School in Devon, saw the Innovaré team manage the structural design, manufacture, and installation of the structure developing a simple, yet effective solution. Combining the architectural expertise of Scott Brownrigg with Galliford Try’s award-winning Optimum Schools principles, Innovaré’s i-SIP full structure met the stringent performance specifications defined in the Optimum Schools protocols. 

As the construction industry is being challenged to rethink the way schools are designed and constructed, Galliford Try published ‘The Optimum Primary School’ – an education-led response to primary school design. The basic principles being:

• An approach to standardisation which would not result in a one-size fits all methodology
• Potential for offsite manufacture for the benefit of cost and programme
• A solution which suits newbuild, remodelling, refurbishment and extension
• Flexibility of choice of construction materials to meet regulations, constraints and preferences
• Integrated architecture, M+E, FF+E, ICT and external space.

As part of a hybrid offsite approach for the two-storey school, the core structural SIP solution formed the high-performance structure, encompassing external walls, internal partitions and floors. Perpendicular steel and timber beams together with pre-cast stair units and the external pre-fabrication of the M&E system, all came together to deliver programme efficiencies.

The i-SIP system comprises structurally insulated panels manufactured from two skins of OSB/3 to BS EN 300: 2006 bonded with a two-part polyurethane adhesive to an insulated core of expanded polystyrene (EPS) 100E to BS EN 13163: 2008. The end result is an airtight, thermally efficient building envelope across the entire structure. 

Performance efficiency modelling carried out by Innovaré, facilitated the design of key details to minimise cold bridging and vastly reduce air permeability to achieve U- value of 0.15w/m²k via a 206mm i-SIP. The i-SIP system has a typical Y-value of 0.025 W/m²K exceeding the accredited and enhanced construction details values of 0.08 and 0.04 W/m²K respectively. With an A+ rating in the Green Guide to specification, the i-SIP hybrid construction method generated a high BREEAM contribution for the Kingsteignton School, reducing expected capital and life-time costs by a predicted 50%. 

From concept to completion, the development delivered both cost and programme certainty, ensuring the new £5million state-of-the-art primary school opened on time and within budget, providing places for 420 pupils. At a total project cost of £12.6million, delivery of this new facility is a key element in the area’s continued expansion plans with more than 12,000 new homes being scheduled in the coming years. 

Using scaffoldless erection and a lean team of installation operatives, the school structure covered 2,330m2 gross internal floor area (GIFA) and was built in just 14 weeks. The enhanced performance benefits will reduce ongoing maintenance and energy costs for the lifetime of the building.  

“The building proceeded at a pace which can only be described as amazing,” said Dr Penny Fitch Principal, Kingsteignton Primary School. “We do not feel that there are any areas that could, so far, be improved on in terms of communication, quality and speed of the programme. Delivery of this new facility is a key element in the area’s continued expansion.”

A slightly different approach was taken at Stonebridge Primary School, an existing school in the London Borough of Brent, that was looking to expand and consolidate from two sites on to one site. The project involved the construction of a new, architecturally impressive hall, that will be fully accessible to the wider community and the school alike. It also includes six new classrooms, three each for Foundation and Year 1. The building also had to complement the existing Grade II-listed Victorian School. The architectural intent was a multi-dimensional roof that would reflect that of the existing school building.

A SIP solution was identified to offer multiple benefits to the local authority and school. Innovaré were appointed to develop a solution that would meet the demanding needs of the school and the Borough. The Innovaré team worked closely alongside Mid Group and the design team, McBains, to develop a solution that would meet the demanding requirements of all the project stakeholders.

The Stonebridge School extension was delivered using a full timber solution. The structure for the main hall area is a mixture of SIPS and cross laminated timber (CLT), whilst the remaining teaching spaces are built with SIPS and timber roof cassettes. This allowed the building to be watertight in just four weeks, with MEP starting three weeks after the commencement of the structural frame – this was erected by a group of just four people, meaning numbers on-site were low and distractions to pupils were minimised.

The building achieved an exceptional EPC score of 13, demonstrating high quality and low, ongoing running costs. The Stonebridge School is a perfect example of efficiency in building design and delivery. The building has a building emission rate of just 5.9kg/CO2/m2/yr, demonstrating the truly low carbon nature of the building. Furthermore, the primary energy usage of just 61.5kWh/m2/yr is 20% below the benchmark rate, saving the school 20% on their annual utility cost. 

All timber used was FSC-certified, with the majority coming from Vida in Sweden. Absolutely no waste was generated during the construction of the structural frame as only complete components were delivered. The building was a continuous improvement on a previous successful Innovaré project at Greatfields School. This adopted the same construction solution, with learning from Greatfields used at Stonebridge. Evidence of the improvement includes the improvement in EPC score on Greatfields of 20 reducing to 13 on Stonebridge. 

The Stonebridge caretaking team have also been incredibly positive about the ongoing ease of maintenance and low running costs of the building, with the difference between the new building and the existing Grade II Victorian building markedly different. The works also included improvements to the existing building, including new windows to the listed building, but even so, the performance is nowhere close to the new extension.

Innovaré’s i-SIPs system is a fundamentally strong and sustainable way to use the best of an offsite methodology and timber construction. Both projects also show the value of using a timber-based SIP solution to not only create energy efficient buildings but also a contemporary, healthy and natural environment for staff and students to work and learn. 

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