Indoor Temperature Model

Estimating Heat in Urban Environments

For city-dwellers who wonder why certain upper floors resemble sauna conditions in late August, we've set out to combine multiple datasets and glean a better understanding of indoor building temperatures. Our approach folds together local meteorological data, solar irradiance stats, and structural building attributes to provide a model that approximates your indoor climate. We combine sources like Weather.gov, the National Renewable Energy Lab, the US Army’s National Structure Inventory, and OpenStreetMap footprints in a single interactive environment. Our estimate might help to explain why your living room is a balmy 91 degrees when the weather app claims 85.

When you load the map, you’ll find yourself over New York (or whichever locale we decided to amuse ourselves with). Zoom in to a building, and you can click or tap to view its basic structural data from the National Structure Inventory (NSI). That includes square footage, number of floors, year built, or other relevant bits. Then we combine those details with current outdoor conditions from Weather.gov. The model draws upon NREL’s solar irradiance data—particularly the average Global Horizontal Irradiance—to approximate how much additional heat might be pouring into that structure. Finally, it factors in the building’s age-based insulation factor, culminating in an estimated indoor temperature.

This entire approach is layered on top of a Cesium 3D environment, letting you visually scan across the city and see the different thermals of neighborhoods. The map’s polygons come from OpenStreetMap footprints, joined with the US Army’s NSI data. If your building shows up extra red, you’re not imagining things—it’s probably that neglected roof insulation from the 1970s.

We’re still refining the model for accuracy by getting baseline geothermal datasets from thermostat companies and public data. But for many standard scenarios, it’s a decent (relative) guess at how a building’s design and environment shape your day-to-day indoor climate. If you’re feeling academically curious—or just want to wave a data-laden finger at your landlord for why your living room is 88 degrees—then check out the repository or the live interactive version to look at real-time updates. We disclaim that it’s a heuristic model, not a guarantee.