Earlier this week, Eco Brooklyn received an email for a South Park Slope resident who operates a community garden. She explained that the community garden on the corner of 6th ave and 15th called 6/15 Green is being threatened by the construction of a new building.  The developer plans to build a 4-story structure adjacent to the south side of the garden, which would cut off the some of the direct sunshine that the garden currently receives.

The shadow cast by the building, will not only threaten the lives of the plans but also the environmental and solar education programs as the garden is also equipped with solar panel and a pond. The solar panels power both the pond pump and an electrical outlet, which is intended for residents to use their laptops pond-side.

The garden organizers have launched awareness of this community problem through this site. 6/15 Green asked Eco Brooklyn to do a solar analysis to determine the shadow cast at different times of the year.

Developers often do not realize how the shadows cast by their new buildings affect the contextual community.  Residents of the existing communities are concerned about the changing environments for their gardens, flowers, pond etc. and they should be. Here, I will try to explain how we can calculate the shadow a building will project.  There are three things that you will need to accomplish this.

  • A scientific calculator
  • The height of the building.
  • Altitude of the sun

The sun’s altitude in the sky changes every day and every season.  These observations are relative to us observing the sun here on earth whereas the sun itself isn’t changing its position.  The earth is changing its location and angle in its revolution around the sun, which causes the sun to appear to change its position.

Length Of Shadow (LOS) = Height Of Building (HOB) / Tan (Sun Alt.).

The sun altitude can be obtained from this website this site.   If you’re having trouble with the equation this site will do it for you this site.

For the analysis for the 6/15 Green we used Google Sketchup, a 3D modeling program. We were able to construct a simple box representing the new structure then imported the geographic location from Google Earth into Sketch Up. Here is a youtube video which is a depiction of the shadows cast throughout a day in October.  As you can see, a very large portion of the garden will be affected by the shadow. As the year progresses, the shadow will length and eventually shade the solar panel from direct sunlight, which will affect the pond pump and the electrical outlet.

Marissa Reilly

Saf K.