Figure 32 table showing annual rainfall and average teperature

TABLE SHOWING ANNUAL RAINFALL AND AVERAGE TEPERATURE 32

F IGURE

4.1. INTRODUCTION

The composite zone covers the central part of India. Some cities that experience this type of climate are New Delhi, Kanpur and Allahabad. A variable landscape and seasonal vegetation characterise this zone. The intensity of solar radiation is very high in summer with diffuse radiation amounting to a small fraction of the total. In monsoons, the intensity is low with predominantly diffuse radiation. The maximum daytime temperature in summers is in the range of 32 – 43 ºC, and night time values are from 27 to 32 ºC. In winter, the values are between 10 to 25 ºC during the day and 4 to 10 ºC at night. The relative humidity is about 20 – 25 % in dry periods and 55 – 95 % in wet periods. The presence of high humidity during monsoon months is one of the reasons why places like New Delhi and Nagpur are grouped under the composite and not hot and dry climate. Precipitation in this zone varies between 500 – 1300 mm per year. This region receives strong winds during monsoons from the south-east and dry cold winds from the north-east. In summer, the winds are hot and dusty. The sky is overcast and dull in the monsoon, clear in winter and frequently hazy in summer. Generally, composite regions experience higher humidity levels during monsoons than hot and dry zones. Otherwise most of their characteristics are similar to the latter. Thus, the design criteria are more or less the same as for hot and dry climate except that maximising cross ventilation is desirable in the monsoon period. On an annual basis, the heating load is negligible and the cooling load is predominant. The monthly load profiles generally follow the climatic conditions, the highest cooling load occurring in June (summer) and the lowest in January (winter). In fact, some heating is also required in December and January. The months from April to October display relatively higher cooling loads. Lesser cooling is required in the winter months of November to March. The convective heat gain dominates from November to March (five months), whereas from April to October, the surface gains are more. Air exchanges help to reduce heat gains from November to March, while it adds to the cooling loads during the other months. Hence, a scheduling of air changes to promote ventilation from November to March and control of infiltration in summer could lead to a reduction in cooling loads. It is also essential to reduce surface gains in all months except December and January, to reduce the cooling loads. This can be achieved by reducing glazing areas and shading of surfaces exposed to direct solar radiation. As the cooling requirement is primarily due to surface gains, it is essential to reduce the heat gain by choosing appropriate materials, shading, colour, reducing exposed glazing area, etc. In summer months, air exchanges add to cooling loads and hence need to be controlled. The scheduling of air change rates can reduce cooling loads. The internal gain during winter months is responsible for cooling loads and hence can be reduced by decreasing lighting and equipment loads through energy efficient devices. The room-wise distribution of monthly and annual loads is presented in Table 5.38. It may be noted that the usage of the building and the configuration of spaces have a significant impact on the loads. The cooling load of the living room is higher than that of the other