The importance of office internal heat gains in reducing cooling loads in a changing climate

Despite the temperate climate, cooling loads in UK non-domestic buildings (specifically offices) have a highly significant effect on the energy use of urban areas. Recent summer heatwaves (as seen in 2005) caused blackouts in areas of London, where the requirement for cooling resulted in an electrical demand that exceeded the capacity. With summer temperatures predicted to rise, this problem is likely to be exacerbated, and the need to mitigate for such a scenario is vital. Passive and low-energy cooling techniques can play an important role in reducing official electrical demands. However, the more fundamental problem relates to the internal heat gains being generated from, in particular, IT equipment and lighting. For a country such as the UK, cooling systems in offices (and other non-domestic buildings) only exist at all due to these gains. Through the use of energy management and technologies that might be available by 2030, internal equipment gains can be reduced such that the requirements on the office cooling system are completely different, and the likelihood of a passively cooled office (or low-carbon office) greatly increased. This study thus proposes an approach for reducing office cooling loads for a UK climate, using a defined exemplar London office building to demonstrate the effect of IT equipment and lighting on cooling for the existing buildings. In addition, the effect of fabric changes and thermal adaptation of occupants (for a warmer future climate) is estimated. Finally, taking a 'make tight, ventilate right' approach (i.e. reducing infiltration and using mechanical ventilation appropriately) is looked at with regards to cooling loads and, specifically, the effectiveness of night-time ventilation. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.