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Air conditioning could 'heat up' London

The large scale installation of air conditioning to combat rising temperatures in London could make conditions in the capital even hotter – according to a draft report on climate change issued by the mayor’s office.

The draft London climate change adaptation strategy issued by Mayor of London Boris Johnson states: “In order to avoid unsustainable adaptation, when considering possible adaptation options, the wider implications of the action should be assessed over the lifetime of the action.

“For example, air conditioning is not considered to be a sustainable adaptation action except in extreme circumstances (because of the large energy demands),”

A particular concern raised by the report is the effect on the ‘urban heat island’ within London by waste heat from air conditioning systems.

This is where heat generated in the city by traffic, air conditioning systems and other energy uses adds to the heat being radiated from the buildings and roads, further raising temperatures in the area and meaning there is little let up during a heat wave.

The report says the contribution to the urban heat island by human activity – known as anthropogenic - is thought to be “minimal across” the whole of London at the moment, but significant in high density areas.

The report said: “In Westminster and the City of London modelling suggests that the anthropogenic contribution, calculated using the total energy demand for buildings and traffic, may be a significant contribution to urban heating.

“If the use of air conditioning were to become widespread, the area affected by a significant anthropogenic contribution would increase.”

The effect of an urban heat island cam lead to an increase in mortality rates as people are less able to recover from the hot temperatures they experience during the day as the heat does not decrease significantly at night.

'It can also increase the demand for cooling and upset sleep patterns, while also putting pressure on water supplies and damaging temperature sensitive infrastructure. The increased reliance on electric cooling can also lead to blackouts.

The report said London had to look carefully at measures to limit the use of air conditioning and continue introducing further energy efficiency approaches.

Other issues highlighted included the threat of rising sea levels, wetter weather, a higher chance of heat waves and increased risks of flooding. Measures under consideration include better urban design and improved flood defences.

Mr Johnson said: ‘We need to concentrate efforts to slash carbon emissions and become more energy efficient in order to prevent dangerous climate change. But we also need to prepare for how our climate is expected to change in the future.”