How to Use - Cooling Where It Counts

How to Use This Tool

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 a dozen football fields. 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.

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 spatial constraints faced by decision-makers, affect the analysis.

First, you can select which set of assumptions about the effectiveness of reflective pavements you would like to use - conservative, baseline, or optimistic. Each of those labels controls the following three parameters in the analysis:

Street albedo: Target reflectivity for streets and parking lots. Albedo is defined in the range 0 (full absorption) to 1 (full reflectivity). Targeting a higher street albedo when repainting means more cooling and more larger reductions in mortality risk.
Rooftop albedo: Target reflectivity for rooftops. This works the same way as street albedo — a higher target albedo for rooftops means more cooling impact.
Albedo cooling rate: Temperature reduction (°C) per 0.1 increase in albedo. 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.

The scenario labels refer to the following sets of parameters:

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

Once you've set all the parameters the way you'd like, click "Update Map" to calculate 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 over 10% 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!