CPD PROGRAMME | PREFABRICATION Figure 2: Bespoke domestic hot-water booster set and associated pipework, controls and fittings mounted on skid (Source: Packaged Plant Solutions) to 20% productivity of onsite workers. The wider adoption of offsite manufacturing can benefit from the increasingly sophisticated manufacturing techniques that can deliver quality, customisation and cost benefits with reduced waste. By employing a controlled manufacturing environment and by following appropriate standards, the subassemblies of the structure can be built to a uniform quality to meet the needs of the end user while also conforming to the demands of the regulatory authorities. In Bryden Woods 2017 document,4 which considered the creation of a marketplace for manufactured spaces, it was estimated that poor productivity and manpower shortage account for up to 37% of delays on site. A DfMA approach reduces hours on site and increases productivity of those hours, and the reduction in the number of site-based workers reduces the need for temporary site accommodation saving space, time, and associated environmental and cost impacts. That same report indicated that DfMA can reduce site waste by 70-90% and reduce vehicle movements local to the site that, aside from reducing congestion in the neighbouring streets, is considered as contributing to a reduction in local pollution by up to 20%. By manufacturing off site, fewer decisions are required on site, reducing the potential for delay and improving the opportunity for meaningful monitoring and quality assurance, with standardised solutions encouraging more thorough testing, feedback and development. Improved performance-in-use of environmental controls (better assembly and factory-based commissioning) can result in a reduction of up to 30% in equivalent carbon dioxide emissions.4 Equipment systems can be assembled in fully accessible manufacturing bays, with purpose-made lifting, tooling and safety equipment, and benefiting from appropriate task lighting, ventilation and noise control. By limiting the number of hours on site, there is an 80% reduction in incidents.4 The components may be readily tracked through the stages of supply and production (using such methods as attached RFID tags and QR codes), which can follow through into use, maintenance and eventual replacement and disposal. Combined with technologies such as BIM and blockchain, these are, potentially, able to provide permanent and irrefutable records for operational, user feedback and auditing purposes. This can also deliver in-use data, so that life-cycle costs and impact may be more properly measured and, ideally, enhance the opportunities for a meaningful circular economy. In the UK Health and Safety Executive (HSE) overview document on offsite production,5 Taylor highlights the significance of the opportunities for creating employment in areas away from the building site. This can be particularly beneficial where there are skill shortages local to the site, and it can expand opportunities for the long-term development of skilled workers, as well as reducing the need for skilled workers to travel (with all the associated environmental and financial impacts). Where projects call for the production of numerous subsystems, there may be a case for a fabrication facility local to the site, which may also encourage and promote the use of local labour resources, as local employment will always benefit where factory units are established. DfMA does not limit the opportunities for innovative design or require compromise in the quality of the systems. As discussed in the RIBA document that considers DfMA in the standard Plan of Work,1 such an offsite fabrication approach may encourage design rationalisation, materials optimisation, just-in-time delivery or logistics planning in order to achieve high rates of productivity on site. The goal is to deliver a project that meets the needs of the building user while minimising resources (carbon, cost or time) and optimising the delivery of positive aspects (health and safety, quality and certainty). As reflected in the RIBA document,1 DfMA can be applied to one-off, small-scale projects, as well as to large-scale projects and frameworks. The underlying goal is to use design processes that help facilitate a collaborative approach along the whole value chain, embracing design teams, clients, contractors and offsite manufacturers. It indicates that a concept design that has been developed with DfMA in mind during [RIBA Plan of Work] Stage 2 will be robust, leading to a more efficient design process at Stages 3 and 4. For larger clients and organisations such as the UK government a platform approach to DfMA can mean that a set of digitally designed components may be applied across multiple building types, so minimising the need to design bespoke components. So, for Figure 3: Internal view of boiler plantroom integrated into standard ISO container. (Source: Remeha) 88 November 2019 www.cibsejournal.com CIBSE Nov19 pp87-90 CPD v4.indd 88 25/10/2019 16:00