28 April 2021

Costing, carbon and quality construction: is MMC the answer?

TRADA image

Photo: Stewart Milne via the Confederation of Timber Industries.


The Riverside Sunderland: University Design Challenge asks current students and 2020 graduates from UK-based Built Environment courses including but not limited to architecture, engineering, landscaping and quantity surveying to team up and collaborate to design one 3-bed family home in detail and an indicative masterplan which includes landscape, streetscape with green and open spaces, and 100 homes.


The home designs must meet or exceed the operational and embodied carbon targets in the RIBA 2030 Climate Challenge and be based on timber or hybrid systems that reduce the greenhouse gas (GHG) emissions associated with construction and operation, and account for Whole Life Carbon (WLC). WLC encompasses production, construction, use, maintenance, deconstruction and disposal.


The system should be designed for modern methods of construction (MMC) and off-site manufacture (OSM), helping to regenerate the local area by developing skilled jobs in manufacturing, construction and a holistic new-build delivery that enables the UK to reduce construction emissions and meet our legally binding climate commitment to reach Net Zero by 2050.


Why timber? The Climate Change Committee identified biomass – wood and plants – as having an import role in enabling the UK to drive down emissions as we transition to a low carbon economy. The stocks of biomass are not limitless and therefore must be used in the most effective way with uses that enable long-term carbon storage being prioritised, such as more timber use within buildings. See Wood – Building the Bioeconomy


Any new build will increase the use of resources and hence GHG emissions significantly more than refurbishment, extension or conversion. Therefore, all new builds must be designed and constructed to an absolute measured target that exceed or at least meet the RIBA 2030 Climate Challenge. Meeting these absolute targets will reduce our emissions and drain on resources but could come at an increased financial cost – opening up the cost versus value conversation. But can we have it all by procuring smarter and utilising MMC?


MMC’s costing and procurement require a different approach

We asked leading costing professionals Oliver Hartley-Booth, Partner at Gardiner & Theobald, and Rob Littlewood and Danny Garwood, Director and Associate Director of Cast Consultancy respectively, to guide our students as they wrestle with working in a design team for the first time, address OSM, MMC and WLC.


Oliver Booth set the scene with a discussion on the significant decline of house-building. After WWII, he said, approximately 350,000 homes were being completed annually, falling to a low of 100,000 in the early years of the 21st century, although this has since increased again. The Government wants to see more housing built and has set out an initiative to increase OSM and MMC, whether modular, volumetric, or open or closed panelised systems. How we cost these systems requires a different approach.


Traditional build projects can include 30-50 separate subcontract work packages. MMC, which can significantly reduce these packages by going off-site, requires a rethink in the approach to estimating and costing buildings. QSs are accustomed to costing structures made from reinforced concrete, structural steel and loadbearing brick work – but are less used to costing SIPs, Glulam and the species that may be used to make it, CLT, LVL and hybrid systems.


The different approach to estimating and costing needs to look at: engaging the supply chain early; alternative procurement strategies; collaboration; economic design principals: effects of building typology; programme savings & effects on preliminaries; lighter structure; contractor experience; reduction in trades; and transport restrictions.


Oliver encouraged the competition participants to consider the best solution for the location in order to meet Sunderland City Council’s ambition to both manufacture and build sustainable, carbon neutral homes, and create local skilled jobs, thereby restoring and regenerating the community.


Rob Littlewood noted that while Cast was a relatively new consultancy, they are the only specialist residential cost and management consultant in the UK. They focus on the adoption of pre-manufactured solutions.


He began by bringing forward the rise of the ‘Cost Consultant or Manager’, as opposed to the ‘Quantity Surveyor’ – a term he saw as antiquated. At its heart, the cost manager sits alongside the designer to control costs in ways that maximise value, minimise future liabilities, and maintain the required standard of quality and safety. The cost manager should be fully integrated into the planning and design process from day one.


While the creation of an MMC definition framework with seven categories by the Ministry of Housing, Communities & Local Government (MHCLG) in 2019 is helping broaden understanding of these methods, in many ways it will be pushed into the mainstream by an impending shortage of labour in the UK, highlighted in the Farmer Review in 2016.


Danny Garwood explained in detail how to put a cost plan together and how to align it to the RIBA Plan of Work 2020. To enable participants to produce a realistic cost estimate, Cast will provide a costing template and return to run surgeries with the teams to support them as they and their teams bring costing, carbon, MMC and quality construction together.


Carbon and employability

A question from an audience member prompted discussion of whether the traditional ‘scope triangle’ of time, cost and quality could in future become a square with the inclusion of carbon emissions. Littlewood, Garwood and Booth all agreed this would likely be the case in the future, particularly as agreement was reached on how best to calculate embodied carbon costs and how this effects value.


QS or Cost Consultant graduates who understand MMC, can calculate WLC costing and its value, will be highly employable. Both Cast and G&T are always on the lookout for their next employees, and watching the Riversuide Sunderland participants closely.


The Riverside Sunderland: University Design Challenge concludes at the end of May.


Special thanks to our gold sponsor CTI, our silver sponsors RothoblaasAccoyaPEFC UK, and TDCA, and our bronze sponsors ASBPBSW, and Wood for Good


Watch the webinar on Procurement, Costing and Placemaking here


About the author

TRADA’s Tabitha Binding drives our busy University Engagement Programme, which proactively seeks to encourage lecturers of architecture, engineering and other building-related courses to teach timber as an equal to other materials. To facilitate this, TRADA has developed a range of free teaching materials, runs high-profile design competitions for students, and creates opportunities to collaborate, uniting universities with members of the timber industry.