About

This interactive map helps you explore where targeted albedo cooling (applying reflective coatings to rooftops, parking lots, and roads) would be most effective in reducing urban heat and preventing heat-related deaths across Los Angeles County.

The map is divided into squares, each representing a 250m by 250m area — about the size of three city blocks in Los Angeles. Each square is colored to show how effective albedo cooling would be in that area. The specific measure we use for effectiveness is life years saved per adaptable surface area, which captures how efficiently the mortality-reducing benefits of albedo cooling can be achieved.

The information displayed here is derived from "Cooling where it counts: A Spatial Framework for Cost-Effective Urban Heat Mitigation Investments" by Shreevastava, Druckenmiller, Dehaene, Halsey, Prasanth, Yoo, Hulley, Frankenberg, and Yin. Please see the research article for detailed methodology and discussion of results.

How to Use This Tool

1. Choose Your Visualization

Select between two viewing modes:

Life Years Saved: Identify where, in the county, applying reflective coatings to pavements would save the most life years based on historical relationships between temperature, demographics, and heat-related mortality risk (darker blue = more life years saved)
Cooling Potential: Show temperature reduction achievable by applying reflective coatings to all impervious surfaces (yellow = highest cooling potential)

2. Adjust Parameters

The control panel on the right lets you explore how assumptions about albedo cooling, as well as budget constraints faced by decision-makers, affect the analysis.

You can individually select values for three parameters that control the cooling scenario:

Street albedo: Target reflectivity for streets and parking lots (0.3, 0.4, or 0.5). Albedo is defined in the range 0 (full absorption) to 1 (full reflectivity). Targeting a higher street albedo when repainting means more cooling and larger reductions in mortality risk.
Rooftop albedo: Target reflectivity for rooftops (0.5, 0.6, or 0.7). This works the same way as street albedo — a higher target albedo for rooftops means more cooling impact.
Cooling rate: Temperature reduction (°C) per 0.1 increase in albedo (0.3, 0.45, or 0.6). Values from other climate research range from 0.3 to 0.6. The higher the albedo cooling rate, the more effective repainting would be for reducing temperatures.

For reference, three preset combinations used in the underlying research are:

Conservative: street albedo = 0.3, rooftop albedo = 0.5, cooling rate = 0.30
Baseline: street albedo = 0.4, rooftop albedo = 0.6, cooling rate = 0.45
Optimistic: street albedo = 0.5, rooftop albedo = 0.7, cooling rate = 0.60

You are free to select whether to include parking lots, rooftops, or streets in the analysis, as well as any combination of those elements.

You can also optionally add an area constraint. This represents the surface area of rooftops, parking lots, and roads that you would like to treat. When this parameter is set, cells are ordered by life years saved per adaptable area, and the most effective cells to treat under that area constraint are colored purple on the map. As a point of reference, reflective surface coatings cost about $10 per square meter for materials and application.

Once you've set all the parameters the way you'd like, click "Update Map" to display the results.

3. Explore the Map

In the County-Wide Results section under the control panel, you can see aggregated impacts of albedo cooling across the county for the parameter set you have chosen. If you input an area constraint, the results will be limited to what is achievable by applying reflective coatings to that surface area. Otherwise, the county-wide results will show what is achievable by applying reflective coatings to the surfaces you have selected.

In the Prioritization section, you can see a curve of what share of the benefits can be achieved by treating varying amounts of the adaptable surfaces. Strikingly, under baseline assumptions about parameters, 50% of the benefits can be achieved by applying reflective coatings to just 9% of the adaptable surfaces in the county.

You can also hover over the map itself to see aggregated results for each neighborhood in the county (formally each CSA, or community statistical area). You will see a pop-up with information about the effects of albedo cooling on that specific area, such as the adaptable surface area in that neighborhood, the average and maximum temperature reduction achievable across the squares in that neighborhood, and how many life years could be saved for residents of that neighborhood.

Enjoy!