Shaping cities for health

May 2012: Researchers  have set out in a paper published in the most recent issue of The Lancet  that climate change will mean that London will have temperatures more like Hong Kong in the future.  Shaping cities for health: complexity and the planning of urban environments in the 21st century highlights that:

The research paper highlights that: “There are 3·2 million dwellings in London, almost all of which will need some modification to meet decarbonisation targets. This huge scale of refurbishment presents enormous and complex challenges—in part because of the nature of London’s buildings. This stock is not only diverse in its construction methods, which span several centuries, but also in ownership. The level of energy efficiency of the stock is also highly variable. Many properties have already undergone some energy efficiency refurbishments that are not, however, adequate for the 2050 commitment. Indeed, these moderately refurbished properties might provide the greatest retrofit challenge.”

The paper picks up on a potential health issue associated with improving the energy efficiency of homes as a result of increasing the air tightness of homes.

“One of the key problems for retrofit policy is to ensure that greater energy efficiency does not compromise health. If energy efficiency is in part achieved though greater ventilation control (reductions in air exchange), ventilation might become insufficient to remove pollutants from indoor sources. Conversely, uncontrolled ventilation impairs protection against outdoor pollution. The optimum ventilation rate for buildings has not been adequately researched, but decarbonisation strategies are prescribing ever tighter ventilation controls. For example, in a mechanical ventilation with heat recovery (MVHR) system, warm, moist air is extracted from kitchens and bathrooms via a duct system and is passed through a heat exchanger before being released into the environment. …Mitigation measures might affect health through a range of pathways, several of which are likely to be as important as the usual exposures, if not more important. Thus a wider array of pathways than has been attempted previously should be considered. Encouragingly, there is at least a growing recognition of the associated complexities, and, for example, relevant guidance for the Building Regulations for England and Wales is continually updating its treatment of building-material permeability and ventilation control.”