The heating and feeling effect of Sky View Factor (SVF) based on the direction of urban streets (Case study: Isfahan streets)

Growing urbanization has different consequences which one of them is increasing the temperature of cities thus, more usage of mechanical air-condition, more energy consumption and environmental and health consequences are inevitable. The necessity of thermal mitigating methods in designing sustainable cities, especially by adjusting received radiation, has been emphasized. Therefore, Sky View Factor (SVF) as a quantitative index has been proposed.  Considering the fact that, urban streets have the largest area among other urban spaces and play an important role in thermal comfort in cities, streets in hot and dry climate (Isfahan) in two directions of N-S and E-W were selected.

In this study, field studies and simulation have been applied. Field study has been conducted in 17 streets with different width, closeness and green coverage, in summer 2014.. In ENVI-met  5 green arrangements in 3 closeness scale (1, 1/2, ¼) were simulated to investigate green and physical SVF separately. Data gathering, calculating SVF (Rayman has been applied in field study), homogenizing data and statistical and logical analysis between variations, in the procedure applied in both methods.

The minimum SVF, which is effective to heat mitigation in Isfahan, is 0.6, which can be greenery or buildings. In addition, the most effective SVF is less than 0.2. As a result, Sabat with SVF equals to zero have been a traditional smart choice in this climate. 

Discussion and Conclusion:

Finally, the results indicate a relatively high accuracy of three methods in estimating the transmission potential for land use and land cover changes, but according to the kappa coefficients, the accuracy of Similarity Weighted Instance based Learning method more than the other two methods.