Daylighting: Natural Light in Architecture

Cummins Power Generation

Architect Bennetts Associates

Engineer Ernest Griffiths and Sons

Client Cummins Engine Company

As a client the Cummins Engine Co. of
America is an active promoter of sound
architecture; their corporate HQ in the US
being noted for a catalogue of thoroughbred
public and institutional buildings, whilst in this
country the tradition has been carried on, of
which the Cummins Power Generation plant
by Bennetts Associates is no exception.
In the US there has been a tradition of
windowless factories (as sadly also of
windowless schools) leading to high levels of
concern as to the psychological effect on the
workforce, though Cummins have led a
change in attitude away from this approach in
recent work.
In the UK there is now an ethos of work
spaces providing adequate levels of daylighting
and the method of daylighting adopted at
Cummins is a further example of this.
The central lines of rooflights which follow
the lines of the three bays of the building,
together with the clerestory windows along

the sides, flood the building with natural light,

even allowing a welcome degree of sunlight to

enter.

The brief to the architects was for a general

light level of 500 lux, and this can be

maintained by the pattern of metal halide high

bay light fittings at all times, but during the

day when there is ample daylight outside the

building, some rows of the artificial lights may

be switched off, when the level of daylight

approaches 700 lux or more in the interior.

There is no sophisticated daylight linking

control, and the payback for such controls in

terms of energy saving should be considered.

This would have to address the problem that

the metal halide lamp is not amenable to

dimming.

The exterior elevations of the building do

not suggest the building’s daylight credibility,

since the rooflighting is not immediately

apparent; but it can be seen that the

daylighting available from the low level

windows along the south-western face provide

a welcome degree of high contrast in an area

used for circulation rather than production.

Another important factor is that the specialist

floor specified provides a light reflective finish,

unusual in a factory making heavy metal

generator equipment.

As is the case with most modern offices, the

use of computer screens ensures that the side

windows which apparently cause unacceptable

glare tend to be monitored by venetian blinds.

As computer screens are developed and

‘flattened’ this may prove to be unnecessary.

One effect of being close to the flight path

of Manston Airport, is that after two years the

outer surface of the rooflights suffer from a

thin layer of aviation film, which diminishes

the level of daylight to the interior, an aspect

which requires determined maintenance if the

level of the daylight is to be maintained.

190 Daylighting: Natural Light in Architecture

The plan of the complex

Cross section through the three bays

Bennetts Associates

Bennetts Associates