N ATURAL L IGHTING Christina McHugh Building Services EngineeringDublin 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 Lighting12W/m 2 Mood and productivity General well-being Improved visual performance Enhances building aesthetics

Direct - Light shining directly from the sun. Diffuse - Light given off by the sky. Clouds + Pollutants Direct Diffuse Daylight Available

Daylight Factor – ratio of daylight inside to daylight outside Greater than 5 % Between 2% and 5 % Less than 2 % Gloomy appearance Electric lighting needed Predominantly daylit appearance Some supplementary electric lights needed Strongly daylit, no electric lighting needed High risk of overheating Appearance

IRC SC ERC SC = Sky Component ERC = Externally Reflected Component IRC = Internally Reflected Component P Daylight Factor = SC + ERC + IRC Daylight Factor

Overall Reflectance, R Total Surface Areas, A Transmittance of Glazing, T Window Area, A w (%) (m 2 ) Angle of Visible Sky, θ Daylight Factor

Room Dimensions Window height ∝ Depth of light Room depth ≤ 6 metres

Thermal Impact of Windows Size and Type of Glazing Summer Low daylight factor Overheating Low solar gain, Low DF Thermal barrier, Prevents overheating and glare Winter Low daylight factor Excessive heat loss Insufficient daylight Low heat loss, Good daylight factor Reflective Low emissivity Large area Small area

Thermal Impact of Windows Shading Devices Summer Shield high angle summer sun Prevent glare and overheating Internal Blinds External Shading Winter Admit low angle winter sun Fully retractable for maximum daylight

Windows provide entrance hall with side lighting Placed behind a large glass wall to overlook Trafalgar Square S AINSBURY W ING N ATIONAL G ALLERY L ONDON

S AINSBURY W ING N ATIONAL G ALLERY L ONDON Automatically adjusting louvres Combination of the artificial and natural light 650,000 kilolux hours in a year

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

T HANK Y OU FOR L ISTENING. Natural LightingChristina McHugh Building Services EngineeringDublin Institute of Technology