NATURAL LIGHTINGChristina 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 electricityElectric Lighting 12W/m2

Mood and productivity

General well-being

Improved visual performance

Enhances building aesthetics

Direct -Light shiningdirectly 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

IRCSC

ERC

SC = Sky ComponentERC = Externally Reflected ComponentIRC = Internally Reflected Component

P

Daylight Factor = SC + ERC + IRC

Daylight Factor

Overall Reflectance, R

Total Surface Areas, A

Transmittance of Glazing, T

Window Area, Aw

(%)

(m2)

Angle of Visible Sky, θ

Daylight Factor

Room Dimensions

Window height ∝

Depth of light

Room depth ≤ 6 metres

Thermal Impact of WindowsSize 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 WindowsShading 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

SAINSBURY WING

NATIONAL GALLERYLONDON

SAINSBURY WING

NATIONAL GALLERYLONDON

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 LightDirect & Diffuse

Daylight Factor2% - 5%

Room Dimensions

Thermal Impact30% Glazing, Low emissivity

THANK YOU FOR LISTENING.

Natural Lighting Christina McHugh

Building Services Engineering Dublin Institute of Technology