Design Review: Volume 3, Issue 2 (September-October 1950)
Lighting the House
Lighting the House
Let us start with two simple and self-evident propositions: the first is that the eye is a sensitive and delicate organ; the second is that electricity provides the most convenient and flexible artificial light the world has yet seen. That being so, one is tempted to ask why the usual way to light our rooms is to hang a globe from the centre of the ceiling and cover it up with a shade. Because, one supposes, that is how it has always been done: the chandelier, the oil lamp, gaslight, and now electricity.
Good light is light where we need it and strong enough for us to be able to see in comfort. When you consider that 100 foot-candles is very high for artificial lighting in a normal room, and that natural daylight gives 200 foot-candles in a sunny room, you will realize that most houses are quite inadequately lit.
What I want to emphasize in the remarks that follow is that the placing of the source of light is all-important, and that, with electricity, we can organize our lighting as we want to.
(a) Good vision in an interior depends not only on the standard of lighting itself, but also on the type of decorative scheme employed. Generally speaking, when light is thrown upwards from a fitting, the effect is minimized by dark surroundings and such dark surroundings will have greater effect in small rooms than in large rooms.
(b) Fittings should be designed from a functional point of view, but this does not mean they cannot at the same time be æsthetically pleasing; in fact, severity of design often meets both these requirements. Ornamental ridges and bars and other similar dust-trapping features should be avoided. Dusty and dirty fittings can consume as much as from 25% to 50% of light output and therefore they should be kept clean.
(c) Renewal of any fitting should not involve damage to or renewal of any part of the structural fabric and hence co-operation between the architect and the services engineer at the inception of design is very necessary.
(d) Fittings, with the contained lamp considered as a part, should be designed so that brightness should preferably not exceed a level of 2 candles per sq. in. and on no account 10 candles per sq. in. at any angle of vision between the horizontal and 30 degrees below the horizontal in rooms, and in any direction within the field of vision of a person descending a staircase. In the latter case, a source of light should be outside the field of vision, if possible.
(e) Fittings should be kept as high as possible above eye level, consistent with economy of lamp size and hence consumption, and with the efficient use of the reflective qualities of a light ceiling.
(f) The weight of suspended fittings should be kept to the minimum and such weight should be carried by a pipe or a chain and not by the flexible cord supplying the fitting.
(g) Flexible cords to standard lamps and the like should be kept as short as possible and preferably should be avoided altogether. Where their use is essential, care should be taken that heat from the lamp does not cause deterioration of the insulation.
(h) Table and standard and bedside page 49 page 50 lamps should be of stable design (i.e., not easily overturned — a heavy base usually takes care of this requirement) and should give adequate electrical and mechanical protection to the user. When a switch is necessary for the control of the appliance, this should be incorporated as an integral part of its design and not fitted extraneously in the flexible supply cord.
(i) Ideal illumination demands the absence of contrast and the elimination of alternate patches of lightness and shadow; therefore an even distribution of light should be a first consideration. Small areas of brightness only emphasize isolated pools of shadow and except for local intensities such as are called for by a reading lamp, a room should give a general impression of even, cheerful light.
(j)Fluorescent tubes, at least in their present stage of development, are not generally desirable in domestic lighting application, largely on account of their lack of a “cosy” appearance and for reasons referred to below; also because the area to be illuminated is usually too small and ceilings are too low, for the proper utilisation of their high light-output. In the incandescent tungsten field, “pearl” lamps are preferable to the “clear” type to avoid glare.
Some suitable sizes of lamps for domestic purposes of various types are suggested below.
(a) Kitchens and Sculleries
Usually two points should be provided, these being conveniently disposed to avoid shadows at working places, and supplying not less than 100 watts of tungsten lighting for a room 10ft. by 8ft.
(b) Living Rooms
Two fixed points for general lighting suitably disposed and aggregating 100 watts for a room 10ft by 10ft plus local lighting for reading, sewing, etc.
One 60 watt fitting conveniently disposed in relation to toilet basin, shaving mirror, etc. The fitting should be so located that condensation of moisture affecting live parts is avoided and the switch should be outside the room.
One or two fixed brackets or socket outlets for reading lamps; one fitting for general lighting suitably disposed in respect to furniture. The latter to be 60 watts in a room 10ft by 10ft; 75 watts in a room 10ft by 12ft; and in rooms above this, 100 watts, where these rooms are not abnormally large.
One 40 watt lamp in an enclosed non-metallic fitting, with a switch outside the door, or where practicable a door-operated switch.
Not less than a 40 watt lamp in a fitting giving direct distribution every 20ft.
(g)Cupboards and Larders
If these are not deep, they can be illuminated from the general room lighting; in this case, care should be taken that the doors, when open, do not obscure the light source. Where the cupboards are deep or of the walk-in type, a lamp 15 watts or so, can be fitted inside. The switch can be fitted outside, or a door-operated switch can be fitted, closing the circuit when the door is open.page 51 page 52
Two lamps of 60 watts each in enclosed robust well glass fittings, either both inside or one inside and one outside, with adequate and proper provision for portable lighting. Preferably, in the latter case a transformer should be used to give not more than 25 volts at the lamp.
One 60-watt lamp suitably disposed and protected, and subject to the same conditions as for bathrooms.
Lighting points, consisting of 60-watt lamps in weatherproof well glass fittings and preferably illuminating the name or number of the house, at front and back entrances.
Fluorescent v. Tungsten Lighting
Any decisions having to be made regarding the possible utilisation of either of the above two main forms of electric lighting should take into account the following factors:
Compared with incandescent lighting fluorescent lighting has:
(a) High capital costs.
(b)High maintenance charges.
(c)Low running costs (i.e. less electricity consumption). Hence, where use has to be made of artificial lighting for considerable continuous periods, fluorescent lighting is favoured, as then full advantage can be taken of (c) above.
Other general advantages are:
(d)Low surface brightness, greatly reducing direct and reflected glare.
(e)High efficiency; approximately 45 lumens per watt as against the 13 lumens per watt of the modern 100-watt tungsten lamp.
(f)The large area of the source of light tends to give a general evenness of illumination.
(g) Colour rendering can be arranged to approach natural daylight.
Another advantage often claimed for fluorescent tubes, that of long life, is sometimes more apparent than real. There is a noticeable falling-off of efficiency the longer a lamp is used and this is immediately obvious if a new tube is fitted alongside one which has had a long period of usage.
Auxiliary starting gear is necessary and constitutes an additional complication. Frequent switching has an adverse effect.
It will be seen that factors (a) and (b) prevent its general adoption for domestic use, except in situations such as sitting or living-rooms where long periods of continuous use would justify the high capital cost.
All electrical installations should be designed by qualified registered engineers and carried out under their supervision by wiremen with recognized training and experience. Any attempt by a consumer of electricity or by any prospective employer of an electrical wireman to by-pass the statutory regulations is to be deplored. Appliances and fittings should be of the highest quality, purchased through recognized channels and from reputable merchants. Finally the installation as a whole should comply with the relevant New Zealand and British Codes of Practice, which have been freely drawn upon in the compilation of this article.