A Review of Daylight Design for Sustainable Building. WU, Bin 1155022517 2012.12.15. Introduction. Fig.1 Sky light with large splayed distribution surfaces at Mt. Angel Abbey Library in St. Benedict, Oregon. . Historical review. Ancient Egypt Roman Empire. Preindustrial architecture.
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Fig.1 Sky light with large splayed distribution surfaces at Mt. Angel Abbey Library in St. Benedict, Oregon.
Innovations to free the building form
Daylight was replaced by artificial light
energy crisis– return to make use of daylight
Innovative technologies and materials of daylighting
Fig. 2 Conventional Greek and Roman atrium yards served as safe spaces and work spaces
Fig. 3 Seagram Building designed by Mies van der Rohe with Philip Johnson
The Daylight Factor（DF）
Climate-based metrics：Daylight Autonomy（DA），Useful Daylight Illuminance（UDI）
Daylight Factor is defined as a ratio of interior illuminance at a point in a building to the external horizontal illuminance under the CIE (International Commission on Illumination) overcast sky.
Daylight Factor indicates the efficiency of the building daylight system in harvesting the daylight from exterior environment.
Limitations: disregard the direct sunlight, building orientation and the climate condition.
Criteria and requirements of Daylight Factor can be found in codes or rating systems in many countries and areas.
Daylight Autonomyis defined as the proportion of occupied time of a building when a minimum illuminance is maintained completely by daylight.
Continuous Daylight Autonomy (DAcon) and Maximum Daylight Autonomy (DAmax)
Objective: 1 credit for 40%< DAcon <60%, 2 credits for 60%< DAcon<80%, 3 credits for DAcon>80%. When using Max DA as a method, it is required that no more than 5% of the space having a DAmax>1%.
UDI divides annual occurrence daylight illuminance into four defined ranges: 0-100 lux for fell-short UDI, 100-500 lux for supplementary UDI, 500-2000 lux for autonomous UDI, and over 2000 lux for exceeded UDI. The range of 100-2000 lux is for Useful Daylight Illuminance.
Currently, there are no official recommedations or rating systems for the object of climate-based metrics.Whereas it is admittedly deemed that the quantified UDI is reasonable that occupants usually are more satisfied in rooms with interior illuminancein the range of 100-2000lux.
Environment: location, sun path，cloudiness，the microclimate.
Architectural Factors: orientation, building form.
Daylight apertures: sidelight, rooflight, atria.
Innovative daylight technologies: prismatic glazing, light pipes, light shelves.
The relative position of the sun and the building
Determine the shading devices because of the different solar latitude
The placement and size of daylight apertures shall have a sensible respond to sky condition
Local condition: air pollution, obstructions, etc.
Usually implies the direction that main façade or facades face
Benefits more from the main facades facing south and north, rather than east and west
Different building in different climate zones have the different orientation to provide a better interior environment.
Fig. 3 plan of Jacbos House IIwith large glazing area facing to the south.
Fig. 4 plan of TheuerHouse with large glazing area facing to the north.
the width of the building form is sufficiently narrow
the orientation is important
Toplighting is needed when depth is relatively large
have an internal core
commonly design strategies are utilization of atria, lightwells, or courtyard to reduce the depth
toplighting is unavoidable
more beneficial to harvest daylightingcomparing with centric form
The large building envelope areas of clustered forms enable architects to organize the sidelighting and toplighting
Uses apertures located in the wall planes
Provide the visual connection of exterior and interior
The depth of a room and the window heightare two essential parameters to the interior illumination.
Uses apertures located at the roof plane
No restriction with depth
More effective for cloudy climate
Control the potentia problem of glare and overheated
For the building with large depth
The shape and form of atria
The structure of the atrium roof can reduce its transparency by between 20 and 50 percent.
The surface parameters : colourand reflectivity
to avoid direct sunlight coming into the building through the apertures because: i) the illumination of direct sunlight is usually not needed to provide useful daylight illuminance in most climates at most time; ii) direct sunlight always brings unwanted heat gain; iii) direct sunlight is deemed as greatly increasing of potential problem of glare
window is most common part to install shading devices, and sometimes the roofs and walls
To refract and redistribute the incoming light to produce a more diffuse distribution
use lenses or mirrors to concentrated daylight and then transmitted the light to a lower level in building by “pipes”
heavily reliant on the availability of sunlight and has to work with the artificial light
provide shade and reflected sunlightand relatively inexpensive
work most effectively under the condition of sunlight sky rather than cloudy sky