Daylighting
Last Update: November 10, 2010
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Daylighting Strategies

Daylighting design refers to the consideration of key space design parameters that affect daylight performance, such as orientation and massing, size and placement of apertures, glazing and shading systems, and geometry and reflectance of interior surfaces.

Design decisions are based on their effect on luminous comfort, such as daylight levels and luminance ratios, and also on their effect on non-daylight performance, such as thermal and acoustic comfort, energy, view, privacy, safety, security, and economics.

Design decisions are greatly affected by design context, which includes space functions and building site characteristics, such as daylight availability and geometry and reflectance of exterior surfaces.

Since each building elevation is subjected to different incident angles of direct solar radiation, different orientations of the same building may require different window strategies and technologies.

Wings of the Sacramento, California Municipal Utility District Building
Daylighting Strategies Figure 1. Wings of the Sacramento, California Municipal Utility District Building. North windows (right) are large with .49VLTC and no shading. South windows (left) are smaller and recessed with exterior light shelves that shade the lower .37 VLT glazing below and reflect sunlight deep into the building through the .88 VLT glazing above.
+ Click image to enlarge.

Performance Parameters
Key daylight performance parameters are similar to those for electric lighting. They include daylight illuminance and luminance levels, ratios, and distributions, as well as various glare indices. Due to the dynamic nature of daylight, performance parameters need to be considered spatially, like electric lighting, and temporally as well.
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Design Parameters
Design parameters are those that designers have control over, such as the shape and orientation of the building, the shape and size of windows, the glazing and shading systems, etc. Each design decision turns design parameters into context for the decisions to follow. This is why early design decisions, such as building shape and orientation, are most important.
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Context Parameters
Context parameters are those that affect the values of performance parameters, but designers do not have control over them. Examples of context parameters include the site of the building, which defines views; building orientation; land terrain and external obstructions; building codes; weather patterns; and the architectural program, which defines building and space functions.
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Schematic Design Decisions
Architectural apertures are often referred to as daylighting luminaires because the geometry of the aperture and fenestration systems, along with the interior surfaces shapes the interior daylight distributions.
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Side-Lighting
Side-lighting refers to the placement of windows with vertical glazing on building perimeter walls. Side-lighting is very common, as windows provide views to the exterior, one of the most important psychological benefits of daylight. Moreover, it is the main way to provide daylight to all floors of multistory buildings.
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Top-Lighting
Top-lighting refers to introducing daylight in single-story or top floors of multi-story buildings through horizontal, sloped or vertical apertures that are part of the roof structure.
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Core Daylighting
Core daylighting strategies aim at redirecting sunlight in building core areas, i.e., areas not adjacent to the building envelope, which can be daylit through side-lighting and top-lighting strategies.
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