Surface
100% Internal Gain
80% 60% 40%
Air exchange
20% 0% -20% -40% -60% -80% JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Month
Fig. 5.70 Component-wise distribution of percentage heat gains and losses on a monthly basis of the commercial building – Srinagar (cold and cloudy climate)
(iii) Window size The reduction of the glazing size to 1.2 m height, compared to a fully glazed curtain wall, decreases the annual load by 11.8%. Thus, the use of larger expanse of glass in such a building is not desirable as it leads to higher annual loads. This is due to high internal gains of the commercial building. (iv) Shading The shading effect is insignificant in this climate for the commercial building because the internal gain of the building is very high. (v) Wall type Walls having a low U-value (insulating type such as autoclaved cellular concrete block) reduce the load compared to the concrete block wall (base case) by 10.9%. Thus insulation of walls is recommended. (vi) Colour of the external surface Dark colour of the external surfaces does not show any significant effect as the building has high internal gains. (vii) Air exchanges A lower air change rate of 0.5 ach is better than air change rates of 1, 2 and 4 ach. The percentage reduction in the annual load is 8.8 compared to the base case of 1 ach. (b) Operational Parameters The operational parameters such as internal gain, set point and scheduling of air changes can help in reducing the annual load of the building. The effects are summarised as follows. (i) Internal gain