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.

Performance assessment of earth pipe cooling system for low energy buildings in a subtropical climate

Energy consumption in heating and cooling around the world has been a major contributor to global warming. Hence, many studies have been aimed at finding new techniques to save and control energy through energy efficient measures. Most of this energy is used in residential, agricultural and commercial buildings. It is therefore important to adopt energy efficiency measures in these buildings through new technologies and novel building designs. These new building designs can be developed by employing various passive cooling systems. Earth pipe cooling is one of these which can assist to save energy without using any customary mechanical units. This paper investigates the earth pipe cooling performance in a hot humid subtropical climate of Rockhampton, Australia. A thermal model is developed using ANSYS Fluent for measuring its performance. Impacts of air velocity, air temperature, relative humidity and soil temperature on room cooling performance are also assessed. A temperature reduction of around 2 °C was found for the system. This temperature reduction contributed to an energy saving of a maximum of 866.54 kW (8.82%) per year for a 27.23 m3 room.

Review on the impact of urban geometry and pedestrian level greening on outdoor thermal comfort

The number of hot days is increasing in many parts of the world because of the heat island phenomenon and global climate change. High air temperature greatly affects human thermal comfort and public health, particularly in urban areas. Therefore, the challenging task of, urban designers and urban planners in accommodating the increasing population is to make cities with the least level of vulnerability to future climate change. Interest in transferring urban climatic knowledge into urban planning practices, and developing mitigation strategies to adapt to climate change, has been increased in recent years. The use of vegetation and appropriate urban geometry are shown very promising in mitigating the adverse effects of heat island and providing a better pedestrian thermal comfort. This article reviews studies on pedestrian level urban greening and geometry in improving thermal comfort in cities. Such strategies can be applied at the preliminary stages of urban planning and thus directly affect the microclimate. The analyzed data include simulation and field measurement studies. The discussion of this research clearly reflects how urban design guidelines can be applied to enhance outdoor thermal comfort and minimize the heat island effect. This study is helpful in controlling the consequences of city design from the early design stage.

Comfort models as applied to buildings

This investigation is about applying the ISO-7730 Fanger (static) Comfort model to two fully air-conditioned, yet, differently performing buildings, based on research into on-site comfort performance measurements using comfort carts. The results challenge the common perception that the ISO-7730 model is concerned with a narrow temperature band. Regardless of the environmental variations encountered temporally and spatially throughout real office environments, occupants appear to achieve comfort with reasonable success. The paper explores this flexibility within the ‘static’ model, more than perhaps is commonly realised. We consider the possibilities that many of Australian office buildings can operate under much greater temperature variation than expected and that there are mechanisms for occupants to adapt to varying conditions.

Erratum: selection of suitable passive cooling strategy for a subtropical climate

In the original version of this article (Ahmed et al. 2014), the authors noted that the author list was published with errors. The correct author list can be found in this erratum. The publisher would like to apologise to the authors for this error.

Salt promotes passive overconsumption of dietary fat in humans

BACKGROUND: Excess fat consumption has been linked to the development of obesity. Fat and salt are a common and appetitive combination in food; however, the effect of either on food intake is unclear. Fat taste sensitivity has been negatively associated with dietary fat intake, but how fat taste sensitivity influences the intake of fat within a meal has, to our knowledge, not yet been investigated.

OBJECTIVES: Our objectives were, first, to investigate the effects of both fat and salt on ad libitum food intake and, second, to investigate the effects of fat taste sensitivity on satiation responses to fat and whether this was affected by salt.

METHODS: Forty-eight healthy adults [16 men and 32 women, aged 18-54 y, body mass index (kg/m(2)): 17.8-34.4] were recruited and their fat taste sensitivity was measured by determination of the detection threshold of oleic acid (18:1n-6). In a randomized 2 × 2 crossover design, participants attended 4 lunchtime sessions after a standardized breakfast. Meals consisted of elbow macaroni (56%) with sauce (44%); sauces were manipulated to be1) low-fat (0.02% fat, wt:wt)/low-salt (0.06% NaCl, wt:wt),2) low-fat/high-salt (0.5% NaCl, wt:wt),3) high-fat (34% fat, wt:/wt)/low-salt, or4) high-fat/high-salt. Ad libitum intake (primary outcome) and eating rate, pleasantness, and subjective ratings of hunger and fullness (secondary outcomes) were measured.

RESULTS: Salt increased food and energy intakes by 11%, independent of fat concentration (P= 0.022). There was no effect of fat on food intake (P= 0.6), but high-fat meals increased energy intake by 60% (P< 0.001). A sex × fat interaction was found (P= 0.006), with women consuming 15% less by weight of the high-fat meals than the low-fat meals. Fat taste sensitivity was negatively associated with the intake of high-fat meals but only in the presence of low salt (fat taste × salt interaction on delta intake of high-fat - low-fat meals;P= 0.012).

CONCLUSIONS: The results suggest that salt promotes passive overconsumption of energy in adults and that salt may override fat-mediated satiation in individuals who are sensitive to the taste of fat.