Build costs on the 2012 Olympic Velodrome were slashed by £1.5 million by changing the roof design, a new government report has found
The Hopkins-designed building was initially conceived with a ‘more traditional’ steel arch roof structure. But, report’s the AJ’s sister publication Construction News, the team changed this to a lighter cable net design because of poor ground conditions and uncertainty about how the original design would be erected.
The change not only saved money but also used about 1,000 tonnes less steel (a 10 per cent cut), cut carbon dioxide used in making the materials by over 25 per cent and reduced the build time by six months.
The figures were revealed in a report, The legacy: sustainable procurement for construction projects, published by the Department for Environment, Food and Rural Affairs published last month (see attached).
The report also said that the Olympic Delivery Authority’s strategy to make all the contractors use sustainable concrete sourced by the ODA - which contained at least 20 per cent recycled material - resulted in the amount of embodied carbon being slashed by 30,000 tonnes (24 per cent).
Contractors had feared that being contractually tied to the Olympic Delivery Authority’s chosen concrete supplier could result in higher costs largely because of the costs of handling the material at the Olympic Park railhead. But the ODA allayed these worries by negotiating with the railhead operator to reduce the handling fees passed to construction suppliers, the report said.
The ODA linked the remuneration of some key ODA staff to sustainability targets and allowed contractors to share in savings in order to incentivise them to meet sustainability goals.
The DEFRA report found that the ODA’s publication of sustainability goals ensured they could not be rejected because of costs and it monitored contractors’ performance against targets.
Excerpt from the report (page 16)
The project highlights the benefit of the collaborative approach pursued by the ODA. Use of a contract based on a target price created the space to evaluate alternative designs. The choice of a cable-net roof design contributed to bringing the project within budget with a £1.5million saving over the steel arch design and it also used about 1,000 tonnes less steel and resulted in embodied carbon savings of over 27 per cent. It achieved 31 per cent energy efficiency savings over and above what would have resulted from simply meeting Part L of the Building Regulations. Additionally, the design provided a cleaner internal roof design, enabled erection without major disruption to other site works, reduced the safety risk and saved six months on programme timescales.