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Natural Lighting. Christina McHugh. Building Services Engineering Dublin Institute of Technology. Designing for Natural Light. Benefits of Natural Light Type of Daylight Available Daylight Factor Room Dimensions Thermal Impact. Benefits of Natural Light. Savings in electricity
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Natural Lighting Christina McHugh Building Services Engineering Dublin Institute of Technology
Designing for Natural Light • Benefits of Natural Light • Type of Daylight Available • Daylight Factor • Room Dimensions • Thermal Impact
Benefits of Natural Light • Savings in electricity • Electric Lighting 12W/m2 • Mood and productivity • General well-being • Improved visual performance • Enhances building aesthetics
Daylight Available Direct - Light shining directly from the sun. Diffuse - Light given off by the sky. Clouds + Pollutants Diffuse Direct
Daylight Factor • – ratio of daylight inside to daylight outside Appearance Less than 2 % Gloomy appearance Electric lighting needed Between 2% and 5 % Predominantly daylit appearance Some supplementary electric lights needed Greater than 5 % Strongly daylit, no electric lighting needed High risk of overheating
Daylight Factor SC = Sky Component ERC = Externally Reflected Component IRC = Internally Reflected Component IRC SC ERC P Daylight Factor = SC + ERC + IRC
Daylight Factor Overall Reflectance, R Total Surface Areas, A Window Area,Aw Angle of Visible Sky, θ Transmittance of Glazing, T (%) (m2)
Room Dimensions Window height ∝ Depth of light Room depth ≤ 6metres
Thermal Impact of Windows Size and Type of Glazing Summer Winter Low daylight factor Excessive heat loss Insufficient daylight Low heat loss, Good daylight factor Low daylight factor Overheating Low solar gain, Low DF Thermal barrier, Prevents overheating and glare Small area Large area Reflective Low emissivity
Thermal Impact of Windows Shading Devices Summer Winter Admit low angle winter sun Fully retractable for maximum daylight Shield high angle summer sun Prevent glare and overheating External Shading Internal Blinds
Sainsbury Wing National Gallery London Windows provide entrance hall with side lighting Placed behind a large glass wall to overlook Trafalgar Square
Sainsbury Wing National Gallery London 650,000 kilolux hours in a year Automatically adjusting louvres Combination of the artificial and natural light
Conclusion Savings in electricity Improved mood Aesthetically pleasing Type of Natural Light Direct & Diffuse Daylight Factor 2% - 5% Room Dimensions Thermal Impact 30% Glazing, Low emissivity
Natural LightingChristina McHugh Thank You for Listening. Building Services Engineering Dublin Institute of Technology