REPORT 5 Daylighting and Shading

Transcription

1 REPORT 5 Daylighting and Shading

2 Name: Sanam Mulani Course: AR50347 DAYLIGHTING AND SHADING Year: WORD COUNT : 650 (EXCLUDING REFERENCES AND QUESTIONS) 1. The differences between your measurements in the artificial sky and Ecotect. (max 150 words) MEASUREMENTS IN THE ARTIFICIAL GROUND FLOOR % Point values WITHOUT ROOFLIGHT MEASUREMENTS IN THE ARTIFICIAL FIRST FLOOR % Point values WITH ROOFLIGHT MEASUREMENTS IN THE ARTIFICIAL FIRST FLOOR % For the ground floor overall daylighting level measured in artificial skylight is lux and in Ecotect model it is lux which is 50lux more than the artificial skylight.for first floor without rooflight the difference is just 7 lux which is very minimal.but there is major differnce of 1750 lux in daylighing level of first floor with rooflight caculation.daylight factor calculated in artificial sky lab is 39.51%.This difference may have occured because in artificial sky room there were many people around so it can obscure light above the horizon. Reflectance of the cloths of the observer also affects the daylight factor. Slight deviations in photocell position can be the reason for different results.the artificial sky lab mimics CIE overcast sky. Page 1 of 4

3 2. Whether the building geometry will provide sufficient daylight and visual comfort on the working plane if it was an architect's studio.[option considered with no roof light on the first floor] Too bright Too bright less lit area Less lit area GF DAYLIGHTING LVL : lux [DF= 25%] FF DAYLIGHTING LVL : lux [ DF = 6%] For the Architect s studio the working plane level for daylighting calculation is considered at 900mm.On ground floor,as recommended daylight factor for Architect s office is 5%,the 25% daylightfactor of given room gives too bright daylight appearance.also beacause of the inclined walls and windows, only the area near windows is too bright (i.e lux) and area towards the center is properly lit(i.e 600 to 1000 lux). On the first floor the daylight factor without roof light is 6 % but towards center there is very less light with jus 2% daylight factor. So more electrical light is required to increase illuminance, enhance uniformity and reduce glare from a bright window. The window area below the working plane on the first floor doesnt contribute much to the light reaching working plane.it only contributes about 15% of the light reaching the working plane as an equivalent area above.(dr.steve Lo,2012)(BS (2008))(Dr Steve Lo,2012. Daylight Factors and their calculation.ar50347.[online VIA MOODLE]University of Bath,Available at : [accessed on: 11 th January 2012]) Uniformity ground floor = Minimum DF /Average DF = 6/25 = 0.24 which is little less.but there is lot of glare towards window area. With roof light on the first floor the uniformity is satisfactory and sutaible for an architect s office. As the average daylight factor of the ground floor is 25% which because of the window position and building shape it creates glare near the window wall. To avoid this as acknowledged in BS- 8206,2008, additional illumination on the window wall from other windows, translucent blinds, curtains or tinted/solar-control glazing can be provided to achieve a subtle gradation of luminance from the darker parts of the room to the visible sky. (BS-8206, 2008). Page 2 of 4

4 3. What impact would this have on the overall energy consumption and CO2 emissions of the building? Windows can affect the energy balance of the building by increasing both conduction heat loss and solar gain, and to a lesser extent and in certain cases, by infiltration losses. (BS-8206, 2008) Double or triple glazing can be used in this option /building which will help in reducing glare and won t affect much on interior daylight levels. Control of glare is a legal requirement in most spaces where people work with display screen equipment, such as computer workstations.windows shall be fitted with a suitable system of adjustable covering to attenuate the daylight that falls on the workstation. (BS- 8206, 2008). Daylight illuminance in interiors here on ground floor exceeds lx. For many display materials a limiting level of 200 lx is recommended and only 50 lx is recommended for materials very sensitive to light. (BS-8206, 2008) So this can affect the overall energy conservation. Essential drawings from ecotect showing daylight analysis : GROUND FLOOR DAYLIGHING LEVEL : lux FIRSTFLOOR DAYLIGHING LEVEL :WITH ROOFLIGHT: lux WITHOUT ROOFLIGHT : lux Page 3 of 4

5 Bibliography BS-8206, 2. (2008). Lighting for buildings Part 2: Code of practice for daylighting. british standards. BSI Dr Steve Lo,2012. Daylight Factors and their calculation.ar50347.[online VIA MOODLE]University of Bath,Available at : [accessed on: 11 th January 2012] Page 4 of 4