Submitted by Angela Walters on Thu, 04/10/2018 - 11:45
Dr Alice Moncaster, Senior Lecturer at the School of Engineering & Innovation at the Open University and Visiting Fellow at the Department of Engineering at the University of Cambridge considers how increasing digitisation will make buildings more sustainable.
digitisation of construction should improve the environmental and economic sustainability of building"
What is a ‘sustainable building’? Fifteen years ago in the report by the Strategic Forum for Construction titled Accelerating Change, Sir John Egan defined ‘sustainability’ for the construction industry as the “triple bottom line … maximising economic and social value and minimising environmental impacts”. These days, critical concerns about climate change have reduced the focus, for buildings at least, to just environmental impact, and often then further restricted to carbon emissions.
There are two important questions: are we doing enough to reduce carbon emissions from buildings; and has this narrow focus lost important aspects of sustainability along the way?
To answer the first of these, we need to look at what is being done to measure and reduce carbon emissions from buildings. UK policy is enabled for the most part through the building regulations, which in turn (at present) respond to the EU Energy Performance of Buildings Directive. This directive focuses on improving the energy performance (and the associated greenhouse gas emissions) from the use, or operation, of buildings.
However the energy used by building inhabitants in heating, lighting and cooling excludes a large proportion of the whole life energy and carbon of a building. This missing proportion is the embodied impacts due to the materials, their transport to site and construction, and also to their maintenance and replacement over the life of the building, and the demolition and end of life processes. As research in this field matures, it has found the embodied energy not to be 10 per cent, as quoted a few years ago, but more like 50 per cent of the whole life energy. For carbon, the embodied proportion of the whole life is likely to be even higher.
Within the UK the rapidly decarbonising national grid means that electrical energy expended now in the manufacture of building materials will emit more carbon than electrical energy expended over the next 50 years in heating and lighting. Some researchers argue that the embodied carbon, which is often front-loaded with most being emitted by the end of construction, may in fact be far higher than the whole life operational carbon. By this argument, reducing the operational energy through increasing materials such as insulation may even increase the whole life carbon emissions.
We are not, therefore, doing enough to reduce carbon emissions from buildings, and the focus on operational energy to the exclusion of embodied impacts may be moving us in the wrong direction.
However things are changing. The publication in 2011 and 2012 of the European TC350 standards on Sustainability of Construction Works, has led to a huge increase in manufacturers’ data on the environmental impacts of individual construction materials and components, and the inclusion of this data into increasingly comprehensive national and international databases. In the UK the Royal Institution of Chartered Surveyors (RICS) published a Professional Statement at the end of 2017 translating the standards into a usable methodology for assessing the whole life (embodied + operational) greenhouse gas emissions at early design stage. This methodology is set to become a requirement within the updated London Plan.
The methodology is complex and each building is unique. However, the evolution of BIM, with the capacity to embody multiple alternative data sets through all lifecycle stages, is making the collection and analysis of data for the whole life of buildings a real possibility, and will lead to the establishment of benchmarks which will help further drive down carbon emissions.
Returning to the second question, has the narrow focus on carbon diverted attention from other important aspects of sustainable buildings, such as their economic and social value?
The relationship between whole life carbon (WLC) and life cycle costs (LCC) of a building appears straightforward. Costs are closely related to energy expenditure, whether in heating or lighting a building, or in the manufacturing of complex components and energy-intensive materials, or in transportation and construction activities. Therefore carbon should serve as an effective proxy for economic as well as environmental sustainability.
The one aspect that doesn’t follow this direct relationship is the high cost associated with perception of risk. Currently calculations of WLC and LCC are limited by a lack of data, particularly for innovative and niche materials which may be lower carbon. There are additional and multiple uncertainties in the future life of a building. Major discrepancies in calculation approach and results persist, giving low confidence to industry, higher perceived risk and sub-optimal choices of materials, leading to higher costs and carbon emissions.
Again the increased use of BIM should help address these uncertainties. BIM will enable the collection, analysis and collation of carbon and cost data through the life of multiple buildings, radically improving data and reducing uncertainty, thereby reducing risk and resultant costs. Meanwhile, real and perceived risks of onsite construction are also being reduced by the move towards digital manufacture offsite. This too should increase cost and carbon certainty and reduce costs of building.
The evidence suggests then that the digitisation of construction should improve the environmental and economic sustainability of buildings.
The social sustainability of buildings is harder to define. Research in this area tends to consider whole neighbourhoods rather than individual buildings. A recent paper suggested there were three themes: social cohesion; participatory processes; and accessibility to living opportunities (Stender and Walter, 2018). It is hard to see at first how these relate to carbon emissions. The idea of increasing new building durability and extending the life of existing buildings through energy retrofit rather than demolition and rebuild, are both associated with reducing embodied carbon. The stability of buildings in an area can often build character and a sense of place, which can aid social cohesion. A method called Participatory GIS (Geographic Information Systems) uses GPS data, digital mapping tools and satellite pictures to enable community input and even control over the design of their built environment. Increasingly used in reconstruction after disasters, the growing availability and reduced costs of digital tools and data sets is making this a possibility at the planning stage of mainstream developments, and has the potential to empower sections of the community hitherto under-represented in professional design teams. This should enable particularly poorer communities to have a say in aspects of neighbourhood planning, such as street safety and access to play areas and transport links, which will positively impact their lives. Therefore social sustainability of buildings and communities could also be improved by digital approaches.
The development of digital databases of the environmental impacts of building materials and components, and their increasing incorporation into BIM alongside whole life modelling, will enable designers to gather and analyse data across multiple buildings, reducing risk, life cycle costs and whole life carbon. Parallel developments in offsite manufacture will further improve efficiency across the construction sector, while tools such as participatory GIS offer the chance to create more sustainable neighbourhoods. The digital future of the construction industry offers huge potential for a more sustainable built environment; it is up to all of us to make it happen.
Dr Moncaster was the UK expert for the International Energy Agency Energy in Buildings and Communities (IEA EBC) programme, from 2011-2016 as part of Annex 57 on 'Evaluation of embodied energy and greenhouse gases in buildings', and from 2017-2021 as part of Annex 72 on 'Assessing life cycle related environmental impacts caused by buildings'. She was an invited expert in 2018 for the IEA Energy Technology Policy Division on ‘Materials trends in building construction’. In the UK Dr Moncaster led the academic research which developed the new Royal Institution of Chartered Surveyors Professional Statement on 'Whole Life Carbon Assessment for the Built Environment'.
Contact: Dr Alice Moncaster