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. Clouds + Pollutants Diffuse Diffuse Light given off by the sky. 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 Transmittance of Glazing, T Angle of Visible Sky, θ (%) (m2) Room Dimensions Window height ∝ Depth of light Room depth ≤ 6 metres Thermal Impact of Windows Size and Type of Glazing Summer Winter Small area Low daylight factor Low daylight factor Large area Overheating Excessive heat loss Reflective Low solar gain, Low DF Insufficient daylight Thermal barrier, Prevents overheating and glare Low heat loss, Good daylight factor Low emissivity Thermal Impact of Windows Shading Devices Summer Winter External Shield high angle Admit low angle Shading summer sun winter sun Internal Prevent glare and Fully retractable for overheating maximum daylight 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 Lighting Christina McHugh THANK YOU FOR LISTENING. Building Services Engineering Dublin Institute of Technology