The lowest average journeys to work (20 minutes) is again building D. As might be expected, Building G, the London case, has the highest average, 55 minutes: this equates to nearly two hours commuting on a normal day, taking into account journeys both ways. Congestion and delays can make this much worse.
The average worse case journey time for building G is 93 minutes (not shown in table 3). If this is divided into the average best case time (47 minutes), this gives a congestion index for the building: a score of 1.97. If all the journey times were the same every day, the index would be 1, the best possible case. The congestion index for building D with its low contribution is 29/19, a score of 1.53.
What it all means
So what does this tell us? It shows that the study buildings with over 80 percent of people commuting to work by car are up to six times worse for commuting-related carbon dioxide emissions than those where 80 percent walk or cycle. It also tells us that buildings with occupiers with a committed green agenda are likely to get commuting-related emissions down by a half, even if they have locational problems, such as being located on an out-of-town business park with relatively poor public transport where the temptation to drive is overwhelming.
However, the study is only based on eight cases, so it important that these results should be seen only as a first stab at understanding orders of magnitude and difference. The next step is to compare commuting emissions alongside building emissions, in order to look at their relative contributions. There is little point in being painstaking about reducing building emissions through better design and management if these are cancelled out or swamped by emissions from travel and the downsides of congestion.
If long commuting times mean that it becomes even harder to recruit staff to run buildings efficiently, especially in city centres, then this is a further nail in the carbon coffin.
1 Kate Fewson is with Design Group 3 Architects.
2 Adrian Leaman is with Building Use Studies and The Usable Buildings Trust.
3 Further details about the Building Use Studies survey method may be accessed on the Usable Buildings Trust website.
4 MSc Architecture, Advanced Environmental and Energy Studies, Centre for Alternative Technology, Machynlleth
5 Hampton, D. (2006) The Edge Pledge: Carbon Audit Excel Spreadsheet. www.at-the-edge.org.uk/edgepledge/edgepledge.htm Accessed 31 May 2007 and 27 April 2008
Hampton, D. (2007) MSN Carbon Emissions Calculator: Assumptions and calculations.
news.uk.msn.com/carbon_calculator_assumptions.aspx. Accessed 11 June 2007 (Thanks to Dave Hampton.)
6 A further useful source on carbon calculators is Botterill C, Internet-based tools for behaviour change, Paper presented at sEuropean Council for Energy Efficient Economies. Summer Study 2007 Dynamics of Consumption Session 9.