Agenda for Urgently Cooling Cities of Bangladesh

1. Introduction 

Rapid urbanization in Bangladesh has resulted in densely built environments with impermeable surfaces and limited vegetation. They also emit high levels of heat from anthropogenic sources. Satellite-derived land surface temperature analyses revealed that central Dhaka's summer daytime temperatures can be 3–6 degrees Celsius higher than those of the surrounding rural areas. This gap has increased by approximately 0.5 degrees per decade in the last 20 years. This intensification of the urban heat island (UHI), which is a result of heat-related morbidity, especially among elderly people, children, and outdoor workers, can increase the burden on health. It also reduces economic productivity. For example, heat stress has been estimated to lower labor capacity by as much as 10% during peak months. In addition, the increased cooling demand places a strain on the national grid and contributes to higher greenhouse gas emissions. A data-driven, interdisciplinary agenda is needed to guide interventions that will reverse the trend and protect communities at risk. Future work should incorporate comparative UHI analyses for Chattogram, Khulna, Rajshahi, and Sylhet to capture region-specific heat drivers and vulnerabilities, such as port operations in Khulna, brick-kiln emissions in Rajshahi, and tea garden fringe effects in Sylhet. 

2. Cool roofs and reflective surfaces 

One of the most immediate strategies to mitigate UHIs is to use high-albedo paving and roofing materials. In low-income neighborhoods in Mirpur and Mohammadpur, field trials using reflective polymer and white cement coatings revealed that roof surface temperatures could be reduced by as much as 8 degrees Celsius during the midday peak. According to energy model simulations, if reflective coatings were applied to 30% of urban rooftops, the cooling energy consumption could be reduced by 12–18%. The peak electricity demand would also be lowered by 5 percent. To make this a reality, local building codes must mandate minimum reflectance levels for new constructions. Public‒private partnerships could subsidize retrofitting for informal housing. In addition, computer optimization algorithms combine vulnerability indices and land-surface temperature maps to identify priority zones. This will maximize the cooling benefits for each investment dollar. Combining reflective surface programs and local training workshops can also help develop a skilled workforce for sustainable roofing technologies. Additionally, extending reflective treatments to bus shelters, market canopies, and major road pavements—especially along arterial corridors in Dhaka and Chattogram—can reduce surface temperatures and improve pedestrian comfort. 

3. Urban Greening and Tree Canopy Expansion 

Each 10% increase in the tree canopy correlates to a 0.7°C decrease in the ambient air temperature. LiDAR imagery and multispectral images with high resolution can be used to map canopy gaps. This reveals that many hotspot corridors, such as the Gulshan–Banani axis, have less than 15% tree cover. Prioritizing native plants that can tolerate drought (e.g., Albizia regia and Delonix Saman) will provide resilience during the dry season. Residents can be engaged in site selection, community-driven planting campaigns, and maintenance via mobile participatory GIS platforms. Urban forestry policies can allocate public land parcels to green corridors or pocket parks. Urban greening not only regulates temperature. The benefits of urban greening include improved air quality and increased biodiversity. Long-term monitoring is essential for tracking canopy growth and microclimate changes over time. This can be accomplished via drone surveys and in situ sensors. There are city-specific strategies for greening. In Rajshahi, green buffers should be established around brick kilns. In Sylhet, canopy corridors connecting urban parks with peri-urban gardens must be expanded. In Khulna, mangrove-edged green belts can leverage the cooling effects of tidal waves. 

4. Water-centric urban cooling 

Bangladesh has seen its historic network of canals, ponds, and wetlands vanish due to infilling and encroachment, providing vital evaporative cooling. Hydrological and thermal remote sensing analyses revealed that each hectare of water can reduce ambient temperatures nearby by an average of 0.5–1°C during peak heat hours; restoring 15% of Dhaka's surface water—equivalent to approximately 600 hectares—could produce an overall cooling effect of 0.6°C and increase stormwater storage by 20% during the monsoon season. 

Implementation requires (a) geospatial prioritization of water bodies for regeneration via digital-twin simulations to model heat dispersion patterns and (b) the integration of green‒blue infrastructure such as bioswales, rain gardens, and constructed wetlands into public spaces. Urban hydrology and computational fluid dynamics (CFD) modeling tools can be combined to optimize the placement and size of features to increase evaporative flows while decreasing flood risk. Community stewardship programs coordinated via mobile-based participatory mapping can engage residents in maintaining and monitoring, leading to sustainable operation and social ownership. Special care should be given to revitalizing Chattogram's polluted canals, such as Karnafuli and Kathgora Khal. Desiltation quickly restored evaporative cooling. 

5. Community-Led Heat Resilience Plans 

Top-down policies cannot address heterogeneity in dense urban fabrics. A social network analysis of Dhaka's informal settlements revealed clusters of community leaders who can be trusted to support behavioral interventions. Agent-based modeling allows simulations of how early warning messages spread through SMSs and social networks, which allows for the identification of optimal seeding strategies. 

A heat action plan should include (a) block-level cooling hubs equipped with shaded seating and misting systems as well as safe drinking water and (b) subsidies to high-risk groups for portable cooling devices. Dashboards built around IoT sensors that provide real-time temperature data can alert vulnerable residents quickly, whereas GIS vulnerability mapping enables resources to be targeted toward areas with the highest heat indices and limited adaptive capacities. Engaging women's organizations and NGOs (such as the BRAC or WaterAid) in managing cooling hubs to incorporate gender-sensitive programs to ensure that women and children have safe, accessible cooling spaces is also key to ensuring resource allocation during emergency situations. 

6. Heat-Smart Urban Design 

Urban form adaptation is key to long-term resilience. Simulations using computational fluid dynamics applied to Dhaka neighborhoods reveal that maintaining at least 30% porosity within building envelopes and orienting streets toward southwest breezes can reduce street temperatures by up to 1.8 degrees Celsius, whereas parametric modeling indicates that integrating courtyards with pervious surfaces can increase cross ventilation and reduce diurnal indoor/outdoor temperature differences by 2.5 degrees. 

Policy instruments must incorporate these insights into land-use regulations governing wind corridor preservation, shaded public promenades, and high albedo façade standards. National housing programs could adopt modular designs featuring deep overhangs and thermal insulation. These solutions can also incorporate passive stack ventilation, making rapid replication possible in both formal and informal settlements. Workshops designed for architects and planners, coupled with practical CFD and GIS training, can ensure that heat-smart principles are translated into practice for cooler and healthier built environments. District cooling with waste heat recuperation in industrial clusters such as Chattogram shipyards or Rajshahi brick-making zones may be employed; additionally, solar-powered off-grid microcooling systems may be viable options in informal settlements. 

7. Conclusion 

Bangladesh needs an evidence-based, integrated framework that incorporates reflective materials, green infrastructures, water management systems, community engagement initiatives, and heat-smart designs to successfully cool its urban areas. The use of computational tools, such as remote sensing, agent-based models, and participatory mapping, can optimize resource allocation and intervention selection. Policymakers and practitioners who prioritize inclusive and data-driven strategies can protect public health, enhance urban livability, and build resilience to intensify heat stress. A national UHI monitoring network that integrates IoT sensors and citizen science temperature logs for effectively tracking the effectiveness of interventions and informing policy refinements should be established.