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Solar Access & Exposure


Solar access
Source: Cornell University

The solar access and exposure of a building, site, or street (and district) determines the availability of sunlight, and affects human health and mental well-being, plant growth, heating and cooling needs (including window size and shading) and performance of photovoltaic panels. Solar access and exposure can be discussed as they pertain to site design and urban/thoroughfare design.

Individual Site and Building Design

Sun path
Source: FL Solar Energy Center

The solar access and exposure of a building and its site influence the quantity of unobstructed sunlight that can fall on a given building and/or site. The angle of the sun above the horizon, the resulting strength of the sunlight, and the length of exposure time are affected by the building’s or site’s latitude, the time of year, cloud cover, and air quality.

Since morning solar exposure comes from the east and south and afternoon sunlight comes from the west and south, the orientation of the building or site also affects solar access and exposure.

Daylight plane
Credit: FTB

Nearby buildings, trees, and landforms may shade a building or site and obstruct sunlight. The diagrams at right show the impact of solar angle and building orientation on the sunlight a building receives.

Urban / Thoroughfare Design

From an urban/thoroughfare design perspective, solar access and exposure relate mainly to the shadowing effects of groups of buildings, trees and landforms on buildings and spaces, with a particular emphasis on open spaces such as streets and plazas.

Solar access on Park Avenue, Manhattan
Credit: FTB

The research of William H. Whyte - The Social Life of Small Urban Spaces - has shown that solar access and exposure are key factors in creating attractive settings for pedestrian gathering in streets and plazas.

As such, urban design controls for regulating building height, bulk, setback, and related factors are important in maintaining solar access and exposure for livable, active streets and corridor spaces.

Also see the article on Urban Scale