Material efficiency in building design
23 May 2019
Our CPD this week was a thought provoking comment on structural engineers and how they can directly influence the effects of climate change.
Tim Ibell Professor at the Department of Architecture and Civil Engineering started with a reminder that climate change is happening, leading to a scarcity of resources which results in war.
The construction industry is one of the highest contributors to CO2 emissions and the structure of a building accounts for 16%. Tim reviewed the three areas that structural engineers can help: operational, material efficiency and loading. Operational environmental considerations are now relatively well understood but there is more to say on materials and loadings.
Drawing on an ongoing research project by the University of Cambridge and the University of Bath “Minimising Energy in Construction” (MEICON) Tim drew our attention to some concerning observations on the Industry. Part of this project was to ask structural engineers on their behaviour with regard to specifying materials, loading and engagement with clients.
Issues discussed included that the UK procurement framework in construction does not encourage specifying materials leanly for the most elegant design nor does it support the reduction in construction costs. Put bluntly design teams profit from larger project costs and not from the material savings they could make. The codes for loading vary significantly worldwide and the UK is conservative. In the results of the UK questionnaire of structural engineers there was a wide variety of responses on what is an appropriate loading for project scenarios given. Structural engineers are generally not seeing how they can influence the carbon usage of a building and where they can, they find it hard to convey this to clients. There is a huge variation within each design disciplines on the base line potential occupancy for certain types of buildings. For a given example of an office building, structural engineering loads have to be for thousands more people than say a ventilation design – far in excess of what they will actually be used for. There is a tendency for engineers to design for future uses that may never happen. More depressingly clients are not driving the environmental agenda or realising the impact the structure of their building has on the environment.
Our conservation engineers note a different approach. In an historic reuse context clients are engaged. Typically they want minimal material structural interventions as this lessons the damage to the historic fabric. Rather than use more materials, to solve loading risks, the building is managed by setting maximum occupancy levels.
Integral care about our environmental impact for both refurbishment and new build and support the ongoing research MEICON is doing in this area.
MEICON hope to raise awareness and reduce our use of materials by reappraising what is necessary. Looking at areas such as mean versus characteristic strengths, serviceable loadings, incentives for using less materials, engaging the client, managing buildings and engagement of the industry and the various existing codes.