In February 2021, the state of Texas suffered a major power crisis which came about as a result of three severe winter storms sweeping across the United States.Extreme weather events like this are becoming more and more common and have begun to expose how venerable our current power grid is to extreme weather events resulting from climate change. To ensure that our cities are resilient in the face of climate change we need to begin developing a distributed power grid which utilizes a diverse set of energy sources including traditional forms of energy as well as renewable energy sources such as solar and geothermal energy.

Houston Texas is one of the fastest growing solar energy markets in the United States, it represents a model of success for other American cities looking to reduce their carbon footprints. Houston has a naturally high solar potential due to its location. Additionally, it is located in a class 3 geothermal zone which makes geothermal heating and cooling an attractive option for homeowners and businesses looking to save money and help combat climate change.

What it does

This app allows homeowners, entrepreneurs, and government personnel the ability to investigate the benefits of leveraging solar and geothermal energy in their homes, businesses, and facilities.

Users can view the roof area of each building, which are styled by the building's suitability for both geothermal and solar energy installations. The map uses a bivariate color palette which allows users to simultaneously view how well suited a building is to solar energy generation based on number of hours of sunlight the building receives and how well suited a building is for geothermal based on the estimated savings from installing a geothermal heating and cooling system.

When a building is clicked on a pop-up appears with the name of the business or address of the building (which is generated on the fly by the reverse geocoding API), the area of the buildings roof, the annual hours of sunlight the roof receives, how much energy the rooftop could generate with a solar installation, as well as the amount of money you could save each year by switching to a geothermal heating and cooling system.

Home and business owners may use this tool to investigate the financial benefits of switching to solar power and geothermal heating/cooling systems. Government personnel may use this app to identify which buildings or areas of the city would benefit most from solar and geothermal retrofit incentive programs. Additionally, renewable energy businesses may use this tool to help educate potential customers and sell their products.

How we built it

This app was built in three stages. First we modeled solar and geothermal potential for each building in Texas in ArcPro using the Microsoft building footprints data layer, the photovoltaic electricity output variable from the Global Solar Atlas layer in the Living Atlas, cloud free days data from the NOAA weather database, and geothermal potential calculated from the area of each building footprint. This data was added to ArcGIS Online as a feature layer service and styled using ArcGIS online. The second step was to create the mapping app. Given that the building layer didn’t include any address information about the buildings, we decided to use the reverse geocoding API to display the name of the business or address of the building when a user clicked on a building. We also added a custom pop-up to the map telling users information about the renewable energy potential of each building when clicked. After this we just added other map widgets and elements such as the legend, a search/geocoding widget and a small info box to guide users. The last step was to build a front end to host the mapping application. We chose to use a story map for this because they are beautiful, super easy to deploy and pre-formatted for mobile devices and different screen sizes. We populated this story map with contextual information about the energy crisis in Houston, facts about solar and geothermal technologies and tax incentives available for people interested in adding renewable energy technologies to their properties.

Challenges we ran into

The most difficult aspect of developing this app was accurately modeling annual hours of solar energy across the city. I chose to model solar hours using weather data obtained from the NOAA weather database in Houston. I was able to calculate the number of cloud free hours of annual sunlight at each monitoring site near Houston and then interpolated these values across the entire city. Once I generated the city-wide solar hours surface, I was able to aggregate an average annual solar hour’s value for each building footprint. This analysis was conducted in ArcPro and was a seamless process given how easy it was to download and enrich the building layer obtained from Microsoft/Bing Maps. In the future I would like to scale the project to all of the United States given that the Microsoft building layer covers the entire United States. I would also like to use lidar data from the Texas State Geoportal to build really accurate solar potential tools using the ArcPro Solar Radiation Tools.

Accomplishments that we're proud of

I am really pleased with the cartographic work we did in this project. ArcGIS online made this process super simple and I really liked how the smart mapping interface helped us choose the right styles for our data.

What we learned

The Esri JavaScript API makes it very easy to deploy performant apps even when rendering thousands of features at once. We also learned that the story map builder can be used to build a front end for web mapping apps by simply embedding the link to the app within the story map. This step really helped us save time building the full app.

What's next for Houston Goes Green

The next steps for Houston Goes Green is to improve the UI by allowing users to dynamically calculate solar and geothermal saving by specifying attributes about a building such as the type of heating/cooling system, insulation quality, the type of solar system they would like to install etc.

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