Swimming Pool at night Swimming Pool during daytimework6002/9 floodlighting b.pdf · 2 types of calculation is usually sufficient a) an average illuminance calculation over a “window”

UNIVERSITY OF HONG KONG Department of Electrical & Electronic Engineering

M.Sc.(Eng) in Building Services Engineering MEBS6002 Lighting Engineering

K.F. Chan (Mr.) Page 1 of 6 Jan., 2008 All rights reserved

Floodlighting of buildings

The aim is to display the building after dark. Only attractive or notable buildings

merit being lit up after dark.

Swimming Pool at night Swimming Pool during daytime

There are other reasons for lighting exterior of a building after dark such as for

security or for publicity reasons.

Exterior of buildings is often over lit probably due to installer’s fear that client may

consider the building not sufficiently lit and thus dissatisfied. This is especially true

of buildings lit for commercial reasons.

When the purpose of exterior lighting is to reveal the architectural excellence, then

shadows produced are as important as the illumination produced on the building’s

surfaces.




Many notable buildings such as ancient churches are often best lit with just a few

floodlights aimed in such a way as to allow the variation of the orientation of the

surfaces and their varying distances from the floodlights to produce the light and

shadow patterns that best reveal the architectural features of the building.




2 types of calculation is usually sufficient

a) an average illuminance calculation over a “window” outlining the area to be lit

at an appropriate distance from the floodlight

b) Sufficient point-by-point calculations to ensure that the designer’s lighting

level and distribution objectives are being met by design.

It is necessary to decide on the appropriate average lighting level to be provided

before such calculations are carried out.

The lighting levels over the exterior of a building may vary considerably, but a

variation of 20:1 is not uncommon or unacceptable as long as it is not too sudden.




Public buildings

It is a tribute to designers of ancient buildings that they look so pleasing when lit from

below, when the builders long ago expected their buildings to be lit only from above.

Daylight appearance

Floodlit appearance




(Adopted from ‘The Hot Light is On’ by Debi MOEN, LD+A June 2002)




Many public buildings have pillared porticos. The problem with pillars is that it is

almost always best to light them at an angle to the direction of view and never from

the direction of view. When a portico has multiple pillars it presents a problem as to

where the floodlights should be sited. This is especially true of public buildings in

the center of a major city where there are severe restrictions on the position of

floodlights. One solution is to floodlight the part of the building behind the pillars,

so that the pillars themselves are seen in silhouette. The floodlights can then be

mounted behind the pillars.

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Swimming Pool at night Swimming Pool during daytimework6002/9 floodlighting b.pdf · 2 types of calculation is usually sufficient a) an average illuminance calculation over a “window”