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The daylight factor can be improved by increasing SC (for example placing a window so it "sees" more of the sky rather than adjacent buildings), increasing ERC (for example by painting surrounding buildings white), increasing IRC (for example by using light colours for room surfaces). In most rooms,
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and building design to assess the internal natural lighting levels as perceived on working planes or surfaces. They use this information to determine if light is sufficient for occupants to carry out normal activities. The design day for daylight factor calculations is based on the standard CIE
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the ceiling and floor are a fixed colour, and much of the walls are covered by furnishings. This gives less flexibility in changing the daylight factor by using different wall colours than might be expected meaning changing SC is often the key to good daylight design.
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to perform all lighting calculations. One failing in many of these calculations is that they are often completed without wall hangings or furniture against the walls. This can lead to higher predictions of the daylight factor than is correct.
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A study of daylight factors within a single storey building resulting from different perimeter glazing and rooflight designs and glass types. Undertaken using the IES Radiance software Module.
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To assess the effect of a poor or good daylight factor, one might compare the results for a given calculation against published design guidance. In the UK this is likely to be
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Simm, S. and Coley, D., 2011. The relationship between wall reflectance and daylight factor in real rooms. Architectural
Science Review, 54 (4), pp. 329-334.
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Simm, S. and Coley, D., 2011. The relationship between wall reflectance and daylight factor in real rooms. Architectural
Science Review, 54 (4), pp. 329-334.
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Light entering through the window but reaching the point only after reflection from an internal surface, known as the internally reflected component (
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Calculating daylight factors requires complex repetition of calculations and thus is generally undertaken using a complex software product such as
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Over 5 – Well lit – artificial lighting generally not required, except at dawn and dusk – but glare and solar gain may cause problems
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Light reflected from an exterior surface and then reaching the point considered, known as the externally reflected component (
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119:(DF) is the ratio of the light level inside a structure to the light level outside the structure. It is defined as:
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Lighting Guide 10 (LG10-1999), which broadly bands average daylight factors into the following categories:
148:= simultaneous outdoor illuminance on a horizontal plane from an unobstructed hemisphere of overcast sky.
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Direct light from a patch of sky visible at the point considered, known as the sky component (
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The sum of the three components gives the illuminance level (typically measured in
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Under 2 – Not adequately lit – artificial lighting is required all of the time
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as well as many other tools for measuring simulated light levels. It uses
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CIBSE Lighting Guide 10: Daylighting and window design, Year: 1999,
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overcast Sky for 21 September at 12:00pm, and where the
304:"Daylight Factor | Daylighting Pattern Guide"
210:Architects and engineers use daylight factors in
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48:introducing citations to additional sources
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144:at a point on the indoors working plane,
357:International Commission on Illumination
226:International Commission on Illumination
221:Commission Internationale de l´Eclairage
219:light level is 11921 Lux. CIE being the
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38:Relevant discussion may be found on the
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284:Climate based daylight modelling
31:relies largely or entirely on a
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192:Illuminance = SC + ERC + IRC
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185:) at the point considered:
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383:Energy-saving lighting
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126:DF = (Ei / Eo) x 100%
44:improve this article
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274:Daylighting
246:ray tracing
138:illuminance
378:Visibility
367:Categories
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100:July 2013
40:talk page
388:Lighting
268:See also
242:renderer
234:Radiance
142:daylight
140:due to
132:where,
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373:Light
290:Notes
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223:, or
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63:news
183:lux
175:IRC
168:ERC
111:In
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