Daylight factor


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Daylight factor

The ratio of interior illuminance at a given point on a given plane, usually the workplane, to the exterior illuminance under known overcast sky conditions. This is one of the key values when analyzing the quantitative aspects of daylighting. Since the outside illuminance varies a lot with weather conditions (8,000–25,000 lux), the interior illuminance alone does not provide much useful information. The acceptability of the amount of daylight reaching an interior space for a specific task can only be determined in relation to the situation outside. There is little use in computing the relation of outside and inside illuminances under sunny sky conditions.

daylight factor

The ratio of the illumination at a point on a given plane to the illumination on a horizontal plane from the whole of an unobstructed sky of assumed or known luminance distribution; a measure of the daylight illumination at that point.
References in periodicals archive ?
The results have indicated the minimum, average and maximum illuminance and daylight factor in the high-rise residential building affected by building shading effect, whereas, 30m of building separation is the best distance between buildings in terms of planning to obtain the acceptable daylight and to enhance the daylight performance in the building.
Realistically, there is no uniform sky that is uniformly illuminated so that values of the percentage daylight factor in building spaces can be directly measured.
The performance of building for daylighting is commonly evaluated regarding to daylight factor (DF), through themethod of daylight factor accepted several years ago by the Commission International de l'Eclairage.
Below we present the daylight factor and the daily total radiant energy of the courtyard space.
For the simulation of this new single zone atrium house, we used Autodesk Ecotect program to calculate the daylight factors in the worst case condition (mid winter at noon) and chose a better fenestration design for the house.
Clearly, a static metric such as this was never meant to be a means of measuring or quantifying daylight design, but was meant as a minimum legal daylight standard; however, over the last half-century, due to the lack of a standard, universally accepted dynamic daylight metric, daylight factor has been the default metric over which criteria for acceptance of daylight performance has been created.
interior surfaces which influence internally reflected component of the daylight factor calculations are: walls with white plaster [rho] = 0.
An ambitious aim was to make the classrooms fully daylit, but even a complete side wall of glass allows a daylight factor only of 3.
Reductions in lighting consumption are awarded for increasing daylight factors; a 20% reduction is available for a daylight factor greater than 10%, a 10% reduction available for a factor greater than 5%, and a 5% reduction available for a factor greater than 2%.
This study shows that toplighting systems designed to meet a 2% daylight factor are not optimal.
0 provides live alerts and estate-wide energy generation monitoring across all renewables investments, with support for multiple sites and taking full account of both weather and daylight factors.
For, while Libeskind would inevitably have tested his compositions himself to understand the visual effect of light falling on internal surfaces (a process which physical models are perfect for as light is scaleless), a more sophisticated animation technique is required for more quantifiable analysis before the lighting consultants can make recommendations to introduce controls where necessary (especially in spaces where the contrasts between low daylight factors and dramatic shafts of direct sunlight are common).