Urban growth and pedestrian thermal comfort

Melbourne is the second largest city in Australia, and its population is anticipated to reach 6.5 million by 2050. In October 2013, Plan Melbourne was released by Victorian government, aiming to intensify several districts to protect the suburbs from urban sprawl. The City of Melbourne’s draft municipal strategic statement identified City North as a great urban renewal area which can accommodate a significant part of the growth. Given the previous heat-related incidence in Melbourne in 2009, the potential threat to human health and pedestrian comfort will be exacerbated, if planning professionals exclude climatic conscious urban design in their practices. Therefore, this study aims to investigate the effect of the future structural plans on the microclimate and pedestrian thermal comfort in City North through numerical simulations. A three dimensional numerical modelling system, ENVI-met was used for the simulation. Field measurements were conducted across the study area to validate the simulated outputs. A clear reduction was reported in the average daytime mean radiant temperature, surface temperature and PMV values after implementing “Plan Melbourne” strategies. The outcomes of this study will assist urban planners in developing the policies which can effectively decrease the vulnerability to the heat stress at pedestrian level.

The effect of green roofs on pedestrian level air temperature

Man made alterations have resulted in higher air temperatures in cities, compared to their surrounding rural areas. There are many attempts to modify the urban design elements to ameliorate urban heat island effect. One among them is the concept of green roofs. There is a potential to incorporate vegetation to the large roof area of the buildings. Several studies investigated the effect of micro and macro scale implementation of green roofs. Most of these studies examined the impact of green roofs on the air temperature variation at the roof level, whereas studies are lacking on the effect of green roof at the pedestrian level. Therefore, this study aims to explore the impact of green roofs on the air temperature at pedestrian level, in the central business district (CBD), using Melbourne as a case study. A generic layout of Melbourne's CBD is modelled using ENVI-met 3.1 BETA 4. A number of different scenarios with different green roof coverages and building heights are examined. It was found that green roofs did not have significant impact on the temperatures at pedestrian level.