Higher sustainability costs less says report

Building 1 – Out of town office block

Building 2 – City centre office block

A new report based on research by quantity surveyor Gardiner & Theobald, consultant Peter Brett Associates (PBA) and contractor Mace shows higher sustainability being achieved on steel framed buildings than concrete alternatives. The steel frames’ sustainability benefits such as lower embodied carbon are also being delivered at a lower cost than alternatives.

The report, the latest in the Cost Comparison Study series commissioned by the BCSA and Tata Steel, shows the cost and lower embodied carbon benefits of steel being delivered on two typical modern office blocks – a three storey business park office building, Building 1, and an eight storey city centre office, Building 2.

The frames were designed by PBA, with cost information for each option from G&T with Mace considering buildability, logistics and programme. PBA also carried out an embodied carbon assessment for Building 2.

The report shows that the total building cost for the steel options are on average 5% lower than the concrete options because of lower floor and frame costs, smaller foundations, lightweight roofs, lower storey heights, reduced cladding costs and reduced preliminaries costs.

The steel framed options were up to 9% lower than for concrete when the frame and upper floors alone were considered. Construction programmes for steel framed solutions were 13% shorter compared with concrete framed buildings for the three storey office, and 11% shorter for the eight storey city centre office.

The city centre office cellular steel option also had an 18-30% lower embodied carbon total than the post tensioned band beam option.

“To benchmark steel against alternative materials on cost and sustainability, we commission construction experts to design real buildings as they would for any client,” says Alan Todd, Tata Steel Construction General Manager.

“We look at the frame individually and also the whole building as a steel frame generates a cost and carbon
saving for other elements, such as foundations and cladding.”