Shading

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Functions of Shading

Shading systems have three main functions. They should protect a room from overheating or glare and offer the opportunity to occupants to increase privacy. There are many different shading systems available such as overhangs, venetian blinds, louvers, fins, awnings, screens, and shutters and they can be fixed or movable.

The system should be chosen depending on the requirements of the specific project, considering the location, the building type, orientation, predominant sky conditions, wind sensitivity and influences of the environment. It can be focused on one or more of the following parameters: blocking of direct solar radiation, the control of diffuse solar radiation, the prevention of glare and the distribution of daylight. While some systems (e.g. shutters) are predominantly designed to block light entering the room other systems such as prismatic glazing and light shelves are designed to combine the shading and daylighting function.

Additionally an activated shading system will have an impact on heating, cooling and lighting loads, effectiveness of natural ventilation as well as on daylight levels in the room and the view out of the window, and these interactions should be well balanced.

In case of movable shading systems control is an important issue. Automatic control tends to have low occupant acceptability. Manual control is preferred and the most important reasons for manual blind switching are (in order of likelihood) a reduction of glare on the computer screen, reduction of the brightness of work surfaces, reduction of direct glare from sunlight, reduction of heat, and increase of privacy. Occupants were observed to be either passive (not changing the shading throughout the day) or active (more frequent adjustment). Passive users prefer settings of the shading control which tend to be a compromise for visual and thermal conditions throughout the day.

Section Key Resources
  • Littlefair, P.J. (1996): Designing with innovative daylighting, Building Research Esablishment Report, Garston, Watford, UK
  • Dubois, M-C. (2001): Solar Shading for Low Energy Use and Daylight Quality in Offices, Simulations, Measurements and Design Tools, Lund University, Lund Institute of Technology, Report No TABK--01/1023
  • Inkarojrit, V. (2005): Balancing Comfort: Occupants’ Control of Window Blinds in Private Offices, PhD thesis at University of California, Berkeley
  • Rea, M.S. (1984): Window blind occusion, a pilot study, Building & Environment, Vol. 19, No. 2, 1984, pp. 133 –137
  • Newsham, G.R. (1994): Manual control of window blinds and electric lighting: implications for comfort and energy
  • Consumption, Indoor and Built Environment, v. 3, no. 3, May-June 1994, pp. 135-144
Links

Lead Author(s): Aris Tsangrassoulis

Approaches

Exterior building shading is the most effective way of preventing sun penetration and glare and reduce thermal load. However, such sun control measures need to be carefully designed, as these controls may also reduce daylight. Vegetation can also be used as seasonal shading devices.

Source: Daylighting Guide for Canadian Commercial Buildings, Public Works and Government Services [1]

Following are the other shading options:

Screens.gifOverhang.gifVertical horizontal louvers.gif

Source: Daylighting Guide for Canadian Commercial Buildings, Public Works and Government Services [1]


Following are the various exterior shading options for the windows:

overhang Overhang.jpg
venetian blind Venetian blind.png
horizontal louvers Horizontal louvers.jpg
fins Fins.jpg
awning Awning.jpg
screen Screen.jpg
shutters Shutters.jpg
prismatic glazing Prismatic glazing.jpg
lightshelf Lightshelf.jpg

Shading can be optimized using tools such as Sketchup.

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Lead Author(s): Vinay Ghatti

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Citations
  1. ^ a b this reproduction is a copy of an official work that is published by the Government of Canada and has not been produced in affiliation with, or with the endorsement of the Government of Canada.
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