Three of the most important things that New Yorkers take into consideration when it comes to housing are size, location, and light, and yet only the first two are easy to control. You can know the orientation of a building and your particular apartment’s location, but that still might not offer a full picture of how much sunlight that place receives.

This is why Localize.city, which provides neighborhood insights based on available New York City data, has rolled out a new feature that tells you precisely how much light a building receives.

Here’s how it works: In Localize’s app, you can search the address of any building within the five boroughs; the feature will then provide you with a description on whether the building is sun-drenched or cast in shadows. The feature even includes intel on how different floors within the building are affected by incoming light (or the lack thereof), the time of day when light will be the brightest, and if surrounding buildings cast shadows.

“It was overwhelming to hear how many New Yorkers regretted choosing their apartment because it had less sunlight than they expected,” said Localize’s founder Steve Kalifowitz, who says this tool is an “important addition” to its various studies on livability in the five boroughs. (In the past, Localize has looked at dangerous areas for cyclists and neighborhood alternatives for those who’ll be displaced by the L train shutdown.)

The New York Times had previously done its own extensive shadow study for every building in the city, but Localize’s tool makes every address easy to search. (It’s also worth noting this tool was unveiled at the Municipal Art Society’s annual summit; that group has been one of the most vocal critics of supertall buildings and the shadows they cast over surrounding areas.)

If you’re wondering just how Localize.city was able to determine how much light a building receives, allow them to explain:

Localize.city calculated the azimuth (arc of horizon) of every outward-facing facade in New York City to determine how much direct sunlight exposure there was throughout the year. To do this, data scientists and GIS experts took complex, three-dimensional out-facing geometrical shapes of every building in New York City and measured the amount of sunlight exposure they could potentially receive. To simulate the shading over the walls of the entire city, Localize.city used detailed three-dimensional building models of the five boroughs. The team overlaid a shadow map on an area and recorded whether a three-dimensional location on a wall was inside a shaded area or not. Those measurements were aggregated for each point in space and time. This enabled the team to analyze the amount of direct sunlight that is blocked by shadows cast from neighboring structures.

The features also takes into account how street orientation affect that amount of incoming light and gives a “general assessment” on what it’s like to live on a particular street, given its orientation. Ready to test it out for yourself? If so, head over to Localize’s site.