Editorial Indoor and Built uilt Environment Indoor Built Environ 2009;18;5:380–381 A Low Carbon Built Environment Phil Jones Welsh School of Architecture, Cardiff University, Cardiff, UK There are many technical challenges and opportunities ahead as sustainability in the built environment becomes a major economic force in relation to both building construction and energy supply. Climate change, the depletion of fossil fuel energy sources, and the security of future energy supplies are becoming a major concern for all countries. Materials and water are also becoming short in supply. All these issues are a clear indication that we are living in unsustainable ways. Many countries are devel- oping at a rapid pace and the global rate of building construction is unprecedented, generally with little atten- tion given to the impact that the construction and operation of these building will have on the environment, both locally and from a global perspective. In 2007, the Intergovernmental Panel on Climate Change (IPCC) reported a 90% certainty that global warming is caused by human activity associated with greenhouse gas emissions. The increased CO 2 level in the global atmosphere is now a major concern. The reports states that if we are to avoid catastrophic climate change, average temperature rises must be maintained within 28C which equates to carbon dioxide (CO 2 ) levels in the atmosphere staying below 450 ppm. Perhaps the most alarming aspect of this is that we must take action within 10 years from 2007. That means we have only 8 years, not just to plan, but to act on the sustainability issues concerning the built environment. In the longer term the planet needs to achieve carbon neutrality. If we take the view of climate change modellers that we have a finite amount of CO 2 that we can put into the atmosphere before the 28C limit is exceeded then we must budget this over a period of time. We might take the view that the carbon neutrality target is to be achieved by the end of this century and that the amount of emissions must be agreed globally, with some countries allowed to continue to increase their emissions, whilst other more developed countries begin to reduce sooner. At some stage all countries would emit the same per capita and then reduce to zero carbon. This is called the contraction and convergence principle. So what role should the built environment play in this? In a global context the built environment is said to be responsible for about 50% of emissions and 70% if we include transportation associated with mobility within the built environment. It is convenient to divide the built environment into new build, existing buildings and supporting infrastructures (for transport, water/sewage, waste and energy supply). Probably the easiest sector to deal with first is new build. As they are likely to be around for some time it is important that they perform well in relation to CO 2 emissions. Many governments worldwide are developing policies to reduce CO 2 emissions. In the UK, the government has set a target for all new houses to be ‘‘zero carbon’’ by 2016, and in some regions of the UK, for example Wales, the regional government has set a target for all new buildings to be zero carbon by 2011. The definition of a zero carbon building in its simplest form is that it has a reduced energy demand for thermal energy and power and that the supply is from renewable energy sources, integrated into the building, ß SAGE Publications 2009 Los Angeles, London, New Delhi and Singapore DOI: 10.1177/1420326X09344275 Accessible online at http://ibe.sagepub.com Professor Phil Jones, Bute Building, King Edward VII Avenue, Cardiff, CF10 3NB, UK. Tel. 029 20874078, Fax 029 20874623, E-Mail jonesp@cardiff.ac.uk