Building schools the modular way

08 May 2019
Mott MacDonald and Bryden Wood have developed a prefabricated way to build more schools in a short period of time

Ninety new schools in five years? That would be a tall order using conventional construction, but a standardised, prefabricated solution developed by the UK’s Mott MacDonald and architect Bryden Wood promises to deliver, making life better for children and their teachers across the UK.

In 2015, Mott MacDonald was brought on board by the Education Funding Agency (EFA) in the UK during the first phase of the latter’s Priority Schools Building Programme (PSBP). Mott MacDonald was to conduct research on the modular construction market and lead procurement of a contractor. Phase one involves delivering six design for manufacture and assembly (DfMA) primary schools.

The US’ Portakabin was appointed to construct the schools using its Yorkon system that has been tested on dozens of schools, hospitals, offices and warehouses. Yorkon is described as a ‘design and build’ solution. It employs an off-the-shelf approach, but allows a high degree of variation in the way designs are combined, offering the client a bespoke end-product.

Portakabin reckons that Yorkon buildings are about 50 per cent faster to erect than a conventional building of the same size.

Mott MacDonald wanted to know how much more efficiency it could achieve if it came up with a brand-new module range designed specifically for schools.

Not only was Mott MacDonald tasked to develop a solution offering real economies of scale, it needs to work equally well for a wide range of school sizes – from the smallest taking in only one class a year, to the largest taking in three. The firm’s modular design would need to make a functional, comfortable and replicable school that met stringent EFA rules for natural light, thermal comfort and ventilation. A 2.7-metre ceiling height and depth (corridor to wall) of 7.2 metres was specified.

Building blocks

Transportation set the basic dimensions of the new modules: measuring 13.6 metres long and 3.5 metres wide, they can fit on the back of a lorry.

Then came the process of configuring the modules to provide all the functions needed in a school. Internal walls can be fitted during manufacture to divide modules into smaller rooms; or several ‘empty’ modules can be combined to create large assembly or dining spaces. Modules are pre-fitted with mechanical parts, electrics and plumbing where needed.

Rooms serviced by water, wastewater and air are clustered to keep pipe and duct runs short and simple. This helps keep capital costs down and minimises disruption to the school during maintenance.

Modules were digitally mapped onto several real-life locations to show how they tessellate to form a whole school. They are designed for use in single and multi-storey arrangements. A linear plan offers the most spatially efficient layout. But almost unlimited permutations are possible.

Some clever thinking was required to arrange the anatomy of a school in such a way that it can be ‘cut apart’ into modules.

“We needed a standardised, replicable layout that could be constructed from the same pieces, used in different ways, to meet the diverse needs and site constraints of many different schools,” says Andrew Williamson, project director  at Mott MacDonald.

“It’s like creating a jigsaw: we needed to know what the final picture would look like in order to create the pieces and put them back together.”

Many types of room, including plant rooms, are split between modules for transit, then bolted together on site. Taking the linear school layout, Mott MacDonald modelled solar gain and natural lighting. Potential for overheating was modelled using TAS software, using temperature data for a scorching summer. The EFA’s indicative design brief suggested mechanical ventilation. The firm found it could largely avoid that by opening windows.

Natural lighting throughout the year was studied from all points of the compass. The initial glazing configuration, accounting for about 35 per cent of the facade area, was optimised by raising the height of the windows.

“Making them higher ensures incident light reaches across the 7.2-metre room depth,” says principal simulation engineer Yudish Dabee. The EFA demands that 80 per cent of teaching and learning spaces are naturally lit. The design passed comfortably, with 90 per cent daylight.

Flexible design

The full array of modules has been created using building information modelling (BIM) and each is saved in a digital catalogue as a BIM object. This means designing and specifying for new schools can be massively accelerated. Primary school designers can use BIM to create a school that will be correctly configured, fully costed and compliant with the EFA’s requirements.

In principle, BIM designs can be used for automation of the fabrication and assembly processes, with digital information enabling just-in-time delivery of the components required for each module to the factory. BIM models are level 2-compliant, providing data for the schools’ operations and maintenance crews.

Mott MacDonald estimates fabrication and construction time will be comparable with that for a school made by Portakabin – about half the time of a traditional school build. Excluding time taken to complete groundworks and enabling, the modular school could be constructed in three months, compared with 10 for a conventional building. The weatherproof school envelope itself can be built in just 14 days.

Mott MacDonald and Bryden Wood have now been awarded the next stage of the EFA’s modular schools project, which focuses on secondary schools.

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