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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.
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

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