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city sun

How Much Sun or Shade Does Your Building Get?

When it comes to finding a new home, ask any New Yorker for their top three must-haves. Good sunlight is often one of them – and for good reason. A growing body of research points to the benefits of sunlight exposure from lowering blood pressure and anxiety to improving productivity and sleep.

Yet, knowing the quality of a home’s sunlight is one of the most difficult things to verify before moving in.

You can’t get a true sense of the light a home or apartment enjoys by browsing online. Real estate websites aim to show off the best side of every listing. Images are sometimes brightened, and many listings include words like “bright,” or “sun-drenched.”  You must make the time and effort to visit every home you’re considering — and still struggle to get the complete picture. Open houses are often held during the brightest times of day, making your visit (typically only 15- to 30-minutes) a potentially different experience from actual day-to-day life. Furthermore, visiting on a summer day rarely helps you understand what it will be like in winter. Ultimately, this leads to many New Yorkers having regrets about their choice of apartment.

This is just one of many problems that we set out to solve at

We designed our search so that you will find dozens of insights describing what it’s like to live at any NYC address, today and in the future. We just introduced a brand new category: sunlight. You can now find a description of the amount of sunlight every facade of every building in NYC gets throughout the year, from top-to-bottom. The descriptions include hours of the day it will be brightest, along with how different floors are affected by shadows cast from surrounding buildings.

No sunlight and shadow analysis has ever been done at this scale and released freely to the public.

The sunlight and shadows insight was an important addition to our knowledge-base at We have what we like to call our AI-powered “Insight Engine” – created by a team of data scientists, GIS experts, urban planners and cartographers – that generates thousands of insights in real-time, presenting only the most relevant and current knowledge for each address. The Insight Engine generates new knowledge on everything from the impact of new construction to noise from airplanes (or bars, the  ice cream truck jingle, and more). You can learn if the streets and intersections near your home are dangerous for pedestrians and cyclists. You can learn about local public schools and how well they perform. The Insight Engine even offers a predictive algorithm estimating the probability that an elevator, which has broken down, will (or won’t) continue to have problems.

Conducting an analysis of sunlight and shade for every building in New York City required a tremendous amount of data aggregation, processing and analysis. Much of it was quite messy. Our data scientists and GIS experts spent months creating an algorithmic model of New York City that analyzes the amount and quality of sunlight you can expect in your home using elevation models, three-dimensional building models and solar position data.

To simulate the shading over the walls of the entire city, we used detailed three-dimensional building models of the five boroughs. The team overlaid a shadow map and recorded whether three-dimensional locations on walls were inside shaded areas 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.

While the analysis itself was extremely complicated, translating the results into text that everyone can easily understand, was just as challenging. The average person just wants to know what is happening at their home or the one they’re thinking of moving to. Issue-by-issue, their primary question is: “What does this mean for me?” Answering that question is our primary focus.

The next iteration of the sunlight and shadow analysis will help New Yorkers understand the impact of new construction on the existing sunlight they enjoy. New Yorkers might be aware that new buildings will soon be built near their home. Until the building is fully built though, it’s not possible to know if, or how much sunlight it will take from you throughout the year. This is one of our next projects.

Once complete, the impact of new construction on sunlight will be added to the list of  “updates” we send New Yorkers about their home. New York City is one of the most dynamic urban environments on the planet, and it’s hard to keep up with all the changes. For that reason, we built an “update me” feature. As soon as we learn about new phenomena happening in or around a given address, residents at that address who subscribed for our updates will get an email explaining the changes and options for what can be done (if anything).

By offering valuable information on a wide range of complicated topics, in language anyone can understand, we’re hoping to make home buying and renting a more transparent process. Giving insight into the amount and quality of sunlight one can expect at every address is an important step.

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