Climate service for resilience to overheating risk in Colombo, Sri Lanka: a multi-scale mapping approach (COSMA)

Sri Lanka, like many other developing countries in South Asia, experiences severe heatwaves that affect the health and livelihoods of hundreds of thousands of residents. The risk to heat exposure will be further exacerbated when 1) the heatwave coincides with urban heat island in the urban area in a non-linear manner; 2) there exists a 'cascading/concurrent' heat hazard indoors as the majority of the households in Sri Lanka have no access to air conditioning and people spend the majority of their time indoors. Living in such hot-humid climate for many generations, Sri Lankan people have established the unique and remarkable climatic, historical, cultural and architectural values and knowledge to be resilient to the extreme climate, reflected in the unique vernacular architectural and urban design. However, with rapid urbanization and economic development, the traditional Sri Lankan vernacular villages and dwellings are being replaced by fast-built, western-style brick-concrete structures. The indigenous Sri Lankan climate-sensitive design knowledge is being forgotten and disappearing. In the developed countries, it has been proved that new data streams, improved forecasts and better visualization techniques have the potential to improve the utility of predictions for early warning of adverse conditions. However, for the countries in the global south (e.g. Sri Lanka), it is vital to provide such climate services with embedded indigenous design knowledge and use of local resources to improve the resilience to extreme humanitarian disaster.

COSMA is a multidisciplinary study that will bring together a group of experts in urban meteorology, building environmental engineering, architecture, urban planning and social science, to work with local stakeholders to deliver SHEAR programme objectives. At the heart of the project are the studies of: 1) how the heatwave overheating risk prediction and assessment could be improved at finer urban and building scales; 2) what are the useful indigenous design knowledge in Sri Lanka to mitigate heatwaves, and how they could be regenerated and re-incorporated into the heatwave action plan and future design practice? COSMA aims to develop an integrated modeling approach by taking into account the urban heat island, building characteristics and vulnerable population to build effective early warning system and city-scale heat action plan. By closely working with local community, government and professionals, one important goal of COSMA project is to harvest and regenerate traditional design knowledge (both building and urban scales) from indigenous craftsmen embedded within local culture and traditions, and feed into the heat-exposure risk mitigation plan. The final outputs of the project will be a series of hierarchical overheating risk and mitigation potential maps across different scales for Colombo, Sri Lanka.

COSMA, led by the University of Reading (UoR), involves collaborations with Glasgow Caledonian University (GCU), and carried out in partnership with a group of well-established Sri Lankan partners-Department of Meteorology (DoM) and the Institute of Town Planners Sri Lanka(ITPSL) as well as researchers at University of Moratuwa (UoM).

The urban heat island (UHI) coupled heatwave places disproportionate economic burden on cities, on top of the wider climate change burden. This is especially the case in tropical cities where the increased cost of cooling buildings, cleaning air and treating heat stressed populations in an already warm climate could exceed 10% of GDP by the end of this century. The evidence base for heatwave warning as well as planning practice improvements suggested by the project could contribute to lessening this economic burden in Colombo, that will have important economic lessons for other developing tropical urban areas. The project will bring together UK and Sri Lankan researchers, practitioners and end-users to co-generate knowledge and understanding on heatwave resilience climate service in data-poor region of South Asia. The project will benefit a wide array of actors including 1) local community and residents- providing them tools for better preparedness planning and risk reduction advice; 2) local architecture and planning professionals- an improved understanding of heatwave-resilient design at both building and urban scales, and the revival design knowledge to be put into practice and for educating future young practitioners; 3) local stakeholders, e.g., government (heath, meteorology, planning) and local authority- an innovate early-warning system and heat exposure reduction solutions; 4) Art and cultural agencies- preservation and regeneration of indigenous knowledge on architecture and urban design in Sri Lanka.