MODERN BUILDING

Evening Star, Issue 22084, 18 July 1935, Page 3

MODERN BUILDING

PLANNING FOR LIGHT AND AIR THE ARCHITECT'S WORK 4 Planning for Light and Air ’ was the subject upon which Mr A. L. Salmond addressed an audience of the Town Planning Branch of the Otago Institute in the Medical School on Tuesday night. “ The object for applying town-plan-ning principles to the development of a town is to promote human welfare, i.e., to promote, health, safety, and convenience for the good of the citizens,” said Mr Salmond. “ Towns have been allowed to grow in a haphazard way with narrow streets completely shaded by high buildings on each side. Badly lighted rooms look out on to the sides of the buildings next door, too many people are crowded into small areas, and parks are badly distributed, if sufficient park area has been provided atj all. Only of recent years has it been realised that light, air, sunshine, and room for recreation in places of work and residence are essential to- preserve the physical and mental energy of the citizens, and that the most healthful conditions that are practicable in a city are essential to its prosperity and economic attraction. Scientific research in recent years has proved beyond question the therapeutic and bactericidal value of sunlight and fresh air. It is now realised that light penetration and fresh air in habitable rooms are necessary to maintain the health and efficiency of the occupants at reasonable level, and to enable them to resist the attacks of tuberculosis and other diseases, so that conditions which deny the inhabitants sunlight, fresh air, and room for recreation lead to the deterioration of the physical qualities of the citizens.” ' i

NATURALLY LIT ROOMS

After dealing with the modern methods for determining before it was built the amount of sunshine each room in a building would receive, Mr Salmond said that the factors affecting the daylight received at any point in a room were dependent on four main points;—(a) The amount of sky visible from the point; (b) the transmission of the glass; (c) the amount of light reflected by 'external objects; (d) the amount of light reflected from the walls and ceiling of the. room. From a town-planning standpoint, the important point to be borne in mind about natural lighting within rooms was that the only portions of a room which were adequately lit were those from which the open sky was visible from the working plane. *lt was obvious that the amount of sky visible from any window was of considerable importance to the adequate lighting of a room. Not only was this so, but if they considered for a moment the question of ultra violet glazing they would see that there, too, an unobstructed sky was a necessity. The ultra violet rays were in that region '6f the spectrum beside the visible violet, but they were themselves invisible to the human eye. These vital rays were present, not only in the direct sunshine, but also in rays reflected from the sky, known as a skyshine. Ordinary window glass would not transmit them, and even bright sunshine through a window would have no biological action whatever. . Since the ultra violet rays played a big part in the prevention of such diseases as rickets, and , their presence in direct sunshine was such an essential to the sun’s power of destroying disease producing organisms, it was desirable that those rays should be enabled to penetrate into the rooms themselves. In using the ultra violet glass it was essential that sky exposure bb as wide as possible, as more therapeutic radiation was received from the full blue sky than from the sun; When thd sun was at lOdeg altitude, the therapeutic values of sunshine and skyshine were respectively 2 and 112. As the sun altitude increased up to 60deg we find the therapeutic values of the sun and the sky increased to 884 and 982 respectively. This showed that 'he sun’s therapeutic value was fairly low unless the sun was high in the sky, while that from the sky was also fairly low unless the sun was high. It was a waste of money to use vita glass in windows from which the sky is blocked entirely by buildings over the road. An increase in thickness of the glass always meant a serious decrease in the ultra violet transparency.. It was better, therefore, to use smaller panes, so that the thickness should be kept down to about 21oz glass. Only close to the window was sky radiation received in any quantity, and the intensity at some distance from the window was very minute. Within a few feet of a medium-sized south window, therapeutic action could be received, but diminished rapidly with increasing distance from the window, anti at most points of a room the amount available was small. In the case of a north window, which admitted sunshine as well as skyshine, provided one sat in the rays of the sun } considerable therapeutic radiation might be received at places some distance from the window. Therapeutic values in the shaded portions, however, were still low Except near the window. All this pointed to the fact that if the ultra violet glass was to be used to the best advantage buildings must be designed specially for sun treatment, so that windows received a great amount of sunshine and skylight. Speaking of light wells, Mr Salmond said they might be useful for lighting corridors or staircases, but unless they were very large they could seldom give adequate lighting for rooms. HEALTH FACTORS. After referring to the subject of the aspect of buildings, Mr Salmond said that, unfortunately, it was not always possible to give a building the aspect most suitable for it to receive a maximum of sunshine, because no thought hud been given to this question by those responsible for the original laying, out of the streets. By means of the Heliodon, however, it was possible to determine before hand the aspect for a street, which would give the buildings on either side the maximum of sunshine. Generally speaking, in the case of very wide streets where the height of the buildings was fairly small, compared with the width of the street, the best aspect was north, and all aspects between north-west and north-east were good. For narrow streets in business areas, the best direction is north and south; whatever sunshine was available was then shared equally between the two facades. Even small deviation frorti this direction resulted in serious, diminution of the isolation of one facade in the winter months.

To give buildings the correct amount of light, air, and sunshine, and thus help to bring health to the occupants, there were certain factors necessary, such as space between buildings and the need to have the sky visible from the windows, to give adequate lighting and to allow the sun to shine in. These were beyond the control of the building owner. He could put large windows in his' building and glazo them with ultra violet glass to give the occupants every

chance of good health, yet his neighbours could render all his good work useless. This was where they found the need for town planning. In fact, it had been said that the question of air space about buildings touched directly or indirectly all the major problems of town planning. Generally speaking, the factors affecting air space about buildings were as follow:—(a) The width of streets and distance between street intersections; (b) the frontage, depth, shape, and superficial area of building sections; (c) front, rear, side, internal'courts, and yards; (d) the percentage of individual sites which may bo covered by buildings; (e) th* height and bulk of buildings in relation to their sites or to the width and area of the street on which they front; (f) the number of family units or people to the net or gross acre; (g) the provision of ample open spaces, parks, recreation areas, etc. “ ZONING.” Town planning practice as a method of controlling the air space around buildings could be summed up in one word, “ zoning ” —i.e., the control by zones or districts of the character ami intensity of land uses in the interests of public health, safety, and general welfare. The need for laws regulating the use and density of certain areas had been felt for quite a long time. Napoleon realised that there were certain industries which were not pleasant to live beside, and in 1810 published a decree providing that any use of property which involved the emission of an unhealthy or unpleasant odour would only be permitted under special license. lie speaker went on to deal with the three factors of use, height, and density, which might be taken as the principal matters for town planners to attack when trying to improve light and air conditions. In zoning for use, they were controlling the type of light and air. By setting off definite districts for residences, factories, noxious industries, and so on, they were ensuring that the air in their homes was not polluted by unhealthy fumes or disagreeable smells. The sun would not be obscured by dense smoke, which greatly reduced the biological action of sunshine and skyshine. Zoning for use, although it was a restriction on the use to which an owner might put his property, was really a protection to the public. A citizen would feel much safer buying a property in a residential area, knowing that it would be impossible for anyone to depreciate its value by erecting & factory next door just a few weeks after he had built a new homo for himself.

Height and density were closely related to each other. Most of the city by-laws restricted the height of buildings, but it should be realised that height was not important in itself. The important thing to regulate wan the bulk or density of buildings. It has been said that all buildings should have sufficient space at front and rea' to give them an angle of light of 45de; —i.e., from its lower windows to the top of the building opposite—and thn; nil rooms in use, either for work or fc habitation, should have natural ligh during a substantial part of the day and should also have through ventiln tion. It would be understood tha* regulation by means of angle of light was more logical than regulation of height. With this in mind let them consider the case of a building such as the new post office, which had been erected with no restrictions except as to height. Its walls rose sheer up to that height limit, making a building which restricted the lighting of buildings round about. If Princes street were lined with buildings of that height on each side the adequacy of lighting of "‘the lower stories would be considerably lowered By stepping the upper floors of the building back from the street frontage,

in conformity to a definite angle of light from the lower windows of the buildings over the road, the building under consideration could possibly go to, a greater height' and at the same time give better lighting to the buildings opposite. . “ The conference of the International Congress of Modern Architecture passed a regulation t that all countries should be urged to investigate the skyscraper tenement from a. sociological and economic point of view,” said Mr Salmond. “ They say that if the city is to be confined to the smallest superficial area in order that minimum distances from one business centre to another may be maintained, then there is only one rational solution for securing better light and air, and, paradoxical as it may sound, it is an increase of space—the multiplication • of floors. Suppose we have two sites of equal area on each of which we intend building a number of free standing blocks of buildings arranged on a north-south axis. On one site our building blocks are two-stored, on the other tliey are 10-storied ? but the angle of light between blocks is the same in each case. In such a, case, given an equal area of site and an equal angle of light between blocks fSOdeg), the amount of utilisable floor space increases with the. number of stories. In comparison with the twostoried blocks, the 10-storied blocks have over 60 per cent,, more utilisable superficial area, in spite of the fact that they enjoy an identical amount of light and air. Again, if these two equal sites are built on with building blocks of different number of stories, each with the same utilisable floor area and same angle of light between blocks, we find there is a savng of about 40 per cent, of land wth the 10-story blocks ip comparison with the two-stqry blocks —again in spite of each enjoying an identical amount of light and air. “ If we neither reduce th© amount of building land nor increase the utilisable floor area we find that the angle of

light falls from 30 per cent, in the case of the two-story blocks to 17$ per cent, in the cas'e of the 10-story blocks. That is to say, we gain the immense advantage of a muon more generous amount of light, sun, and,air through an almost 10 times as wide interval between the blocks as in the case of two-storied buildings without any practical drawbacks. This apparent paradox of high buildings causing less obstruction than low follows from the economy in ground space. Multi-storied blocks occupy so much less room on a site that for a given amount of accommodation it, is possible" to reduce obstruction by increased spacing to a greater degree than it is increased by additional height. Restriction in the density of dwellings is, of course, but it should bo remembered that this has nothing to do with the height of buildings concerned. The density of population can be far more effectively controlled by reducing the mass of the buildings oi their superficial, areas in relation te their site areas.

“ Generally, 10 per cent, of the land area of the city should be set aside foi public parks.” Mr Salmond concluded “but it is most important that this area should be well distributed throughout the city. Nine per cent of the area of London is devoted to parks, but these are so badly distri huted that only a section of the community can _ take advantage of them without having to take long bus rides to reach them. Dunedin has much to thank its early city fathers for in that it is fairly well provided with parks and playing areas, but now is the time to see that more areas are set apart in the suburbs and on the outsk'

to be the open spaces of the future a‘the city expands. Street planting, too is beneficial to the public health of the city, and in residential areas where wide paved streets are not warranted by the amount of traffic the sides of the streets should be planted, not only for the improved appearance of the street, but also for the cleansing of the air which is carried out by the trees.” Mr Salmond was accorded a vote of thanks for his address.