Title page 1

Contents 3

Preface: How to use this Technical Note 4

1. Planning a heat risk assessment: scope, objectives, activities 7

2. Assessment of Extreme Heat Risks: Key Methodologies 13

2.1. What extreme heat hazard does my city face? 15

2.2. How does extreme heat affect my city's population? 25

2.3. How does extreme heat affect my city's infrastructure and economy? 34

Conclusion 39

References 40

Tables 10

Table 1. Designing a heat risk assessment 10

Table 2. Aspects of heat risk, key questions to ask, and relevant assessment methods 14

Figures 6

Figure 1. Roadmap for conducting an urban heat risk assessment 6

Figure 2. Conceptual model for urban heat risks (A) and a process diagram for heat risk assessment considering impacts through the health,... 12

Figure 3. Use of satellite imagery and land surface temperature maps to identify areas of high surface temperature in Nairobi, Riyadh and... 16

Figure 4. Suggested stages for a participatory heat mapping campaign using the vehicle traverse method 17

Figure 5. Expected number of heatwave days per year for the city of Pnomh Penh, Cambodia 21

Figure 6. Thermal comfort benefits of shade structures - Nairobi case study 22

Figure 7. Key findings from applying architectural thermal comfort modelling to assess overheating risk in typical slum housing in Djibouti... 24

Figure 8. Exposure-response curves for heat-related mortality risk in India 29

Figure 9. Heat risk vulnerability index for New Delhi 30

Figure 10. Working hours exposed to indoor and outdoor thermal environments for selected occupations 32

Figure 11. Work-ability curve depicting loss of work output with respect to heat stress for workloads of different physical intensity 36

Boxes 9

Box 1. Initial questions to ask when reviewing the policy landscape for urban heat resilience 9

Box 2. Identifying vulnerable groups and their risk factors 26