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if the house orientation is corrected for the amount of deviation. Also, that street widths had to be consider- ed according to the different heights of buildings flanking either side. Other problems could be overcome by increasing street widths and distances between buildings(23).

Compare that approach with the one recalled by Fry and Drew(13), where at Bombay, to quote an exam- ple of bad planning, the buildings along the Marina Drive are so high that they break the breeze for the buildings behind. Now it should no longer be necessary for such mistakes to be made for in both Sweden(24) and U.S.A.(25) these air flow problems have been studied in great detail, to provide a guide to the likely influence of one building on another from the point of view of air flow (Table 2).

It may be seen that three-storey buildings require quite extensive dis- tances between them to ensure that the first building in the air-flow path does not affect the natural air flow and cross ventilation through a sec- ond building behind. Table 2 also shows the effects of width, length, and roof pitch on the extent of the calm area on the leeward side of the build- ing, and hence may be taken as a guide to the distances which must separate buildings in warm and humid climates, for ventilation purposes.

An alternative solution which is perhaps more economical in its use of space is to insist that all buildings shall be erected on stilts. This would be no new thing in Malaya, or many other humid tropical countries, be- cause the primitive dwellers in such

mechanical fan, optional or additional.

climates adopted this building tech- nique many centuries ago.

a

It is of interest to note that in Rio de Janeiro a law has been passed to the effect that the ground floor, when on pilotis, is not counted in the num- ber of floors by the Building Code (26), This is most useful bye-law in humid tropical climates, for if build- ings line the street and present a solid barrier, any prevailing sea breeze or land breeze from a hillside will be effectively blocked; but if all buildings are on stilts, then the entire city will benefit from the free, uninterrupted circulation of available breezes near to the ground, which will assist in re- ducing both day-time and night-time temperatures.

The architectural philosophy of total environmental design means ex- actly what it says, total

every-

thing It is not possible to con- sider sleeping comfort at night unless one considers the building

in a town planning context . . further- more, it is not possible to consider night-time comfort without consider- ing the daytime factors; such is the in- terrelated nature of the problem we face.

Ventilation and Noise

In designing buildings to avoid dis- turbance of people asleep at night, the acoustical environment is import- ant.

With high humidities and the need for free air flow, cross ventila- tion, and cooling drafts to enter through windows and pass through the house, it is probable that sleep will be disturbed by outside noises such as

Fig. 3. Modified plenum ventilation design (Eronimous)

54

thunder, and the sound of rain beat- ing on roofs and ground.

There are other sounds such as plumbing hammer, water cisterns and in closets, showers running, rain downpipes, and the increasing caco- phony of radio programmes until all hours of the night and early morning. These sounds will appear to be louder and more penetrating at night because the ambient sound level is lower than during the day.

Thus, the problem of natural ven- tilation is closely connected with that of disturbance resulting from noise. A decision has to be made as to which is the most disturbing factor in rela- tion to sleeping comfort.

Evidence at Batchelor(1) points to noise as having the more disturbing effect on restful sleep, but this does not mean that buildings should have fixed non-openable windows for sound insulation purposes. On the contrary, the more fundamental human require- ment is to be able to breathe fresh air and to live. In any event, with over- crowded conditions, where up to four persons may occupy one bedroom, adequate cross-ventilation and air change is still essential.

In passing, a study of the necessary ventilation, and air movement require- ments for such conditions would be valuable because with a rapidly in- creasing population such conditions could prevail for some time, and may constitute a hazard to health. In ad- dition the important human factor of personal privacy should be appreciat- ed and respected in building design.

The provision of adequate ventila- tion and air movement for thermal comfort when sleeping is further com- plicated by the old problem to use mosquito netting or not for such nets surrounding the bed will appre- ciably reduce the air movement. Fry and Drew have dealt with this in de- tail(13), but perhaps it would be as well to re-appraise the problem in a slightly different light. Increasing the air movement from 30 ft. per min. to 300 ft. per min., may be equivalent to reducing the air temperature by 3 to 4°F when the dry bulb temperature is above about 80°F. For temperatures a little below this level, the cooling effect would be a little less with the higher air velocity.

Perhaps the need is for research into possible further solutions of the ventilation problem. Normal recom- mended practice is to consider that buildings must be one room thick for cross-ventilation purposes, but Eroni- mous(27), when working on natural ventilation problems posed by the Bus- fee rehousing development in Cal- cutta, tested a two-room width build- ing incorporating a plenum ventilation system (Fig. 3), and concluded that this would allow maximum population density on the building site without prejudicing the natural air flow through the site, and the ventilation and air-flow requirements inside the buildings.

There was a possible alternative. The plenum ventilation design depend- ed upon natural air flow for its opera-

Far East Architect & Builder March, 1967

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