It is important to alleviate the “heat island effect” in urban areas, especially tropical cities. Microclimate is normally affected by the urban morphology parameters. The objective of this work is to investigate the correlation between air temperature variations and urban morphology parameters in tropical cities. Field measurement was carried out to record the air temperature at 27 points within an 8 km² urban area continuously in Singapore for one year. Geographical information system was applied to extract the urban morphology parameters. Generally, the maximum and minimum air temperature spatial differences in the study area ranged from 3.2 to 6.5 °C, indicating the significant effects of urban morphology on the air temperatures. Based on the fitting results of created multilinear regression models, parametric study has been performed to investigate the specific effects of urban morphology parameters on air temperatures. This work has proposed a much more precise regression model to predict the air temperature with various urban morphology parameters. In addition, meaningful value of reference has been offered for urban planners and landscape designers to effectively control the air temperature in tropical cities such as Singapore.

In recent years, there has been a frequent occurrence of extremely cold conditions which has had a serious impact on the life of residents of buildings in various locations around the world. However, there have only been a very limited number of studies on the effects of residential area building layout on the winter wind environments, which led to a lack of quantitative guidance for residential area planning in severely cold regions. This study aims to reveal the relationship between (1) the residential areas’ building density, floor area ratio, wind projection angle, average building height, and relative position of high-rise buildings, and; (2) the mean wind velocity ratio at pedestrian level in severe cold regions. In this study, the pedestrian-level outdoor wind environments in 24 typical residential areas of Harbin, China, are simulated using ENVI-met software. The results show that the relative position of high-rise buildings in multi-high-level mixed residential areas has little influence on the mean wind velocity ratio, and the maximum difference is 0.04. The factors of building layout have little influence on the mean wind velocity ratio of multistory residential areas. However, a significant linear correlation exists between the mean wind velocity ratio of high-rise residential areas and both the building density and wind projection angle. The prediction model of the mean pedestrian-level wind velocity ratio was then established.

Zhalantun city is located in a severely cold region of China. The cold climate and long winter bring challenges to the energy-saving design of rural dwellings in this area, while the poor economic conditions restrict the application of energy-saving technology. This paper aims to propose an optimal combination of passive design parameters by investigating, testing, and analyzing simulations of Zhalantun rural dwellings, which have a particular architectural pattern. Field measurements during winter show that the indoor temperature of a traditional house is low and fluctuates greatly, and the inner surface is prone to easy condensation. Through thermal comfort surveys, neutral and acceptable temperature ranges were obtained to provide indoor calculation parameters for an energy-saving design. Numerical simulations of heating energy consumption were conducted on the typical building models using DesignBuilder. The influence of different design factors on energy consumption was evaluated. Orthogonal experiments were designed to optimize a series of design parameter combinations to reduce the energy consumption of Zhalantun rural houses and to determine the sequence and significance of the effect of these design factors on energy consumption. Results show that the optimal parameter combination based on orthogonal experiments can obviously reduce energy consumption and have better economic benefits without considering mechanical methods. This can provide a basis for improved energy-saving designs and indoor thermal environments in such rural dwellings.

Climate change caused by CO₂ emissions is a controversial topic in today’s society; improving CO₂ emission efficiency (CEE) is an important way to reduce carbon emissions. While studies have often focused on areas with high carbon and large economies, the areas with persistent contraction have been neglected. These regions do not have high carbon emissions, but are facing a continuous decline in energy efficiency; therefore, it is of great relevance to explore the impact and mechanisms of CO₂ emission efficiency in shrinking areas or shrinking cities. This paper uses a super-efficiency slacks-based measure (SBM) model to measure the CO₂ emission efficiency and potential CO₂ emission reduction (PCR) of 33 prefecture-level cities in northeast China from 2006 to 2019. For the first time, a Tobit model is used to analyze the factors influencing CEE, using the level of urban shrinkage as the core variable, with socio-economic indicators and urban construction indicators as control variables, while the mediating effect model is applied to identify the transmission mechanism of urban shrinkage. The results show that the CEE index of cities in northeast China is decreasing by 1.75% per annum. For every 1% increase in urban shrinkage, CEE decreased by approximately 2.1458%, with urban shrinkage, industrial structure, and expansion intensity index (EII) being the main factors influencing CEE. At the same time, urban shrinkage has a further dampening effect on CEE by reducing research and development expenditure (R&D) and urban compactness (COMP), with each 1% increase in urban shrinkage reducing R&D and COMP by approximately 0.534% and 1.233%, respectively. This can be improved by making full use of the available built-up space, increasing urban density, and promoting investment in research.

In the context of global climate change and accelerated urbanization, the deterioration of the urban living environment has had a serious negative impact on the life of residents. However, studies on the effects of forms and configurations of outdoor spaces in residential areas on the outdoor thermal environment based on the particularity of climate in severe cold regions are very limited. Through field measurements of the thermal environment at the pedestrian level in the outdoor space of residential areas in three seasons (summer, the transition season and winter) in Harbin, China, this study explored the effects of forms and configurations of three typical outdoor spaces (the linear block, the enclosed block, and the square) on the thermal environment and thermal comfort using the Physiologically Equivalent Temperature (PET). The results show that the thermal environment of all outdoor space forms was relatively comfortable in the transition season but was uncomfortable in summer and winter. The full-enclosed block with a lower sky view factor (SVF) had a higher thermal comfort condition in summer and winter. The linear block with higher buildings and wider south–north spacing had a higher thermal comfort condition in summer and winter. When the buildings on the south side were lower and the south–north spacing was wider, the thermal environment of the square was more comfortable in winter.

Overwhelming evidence shows that the harsh climate conditions are affecting urban residents who are living in severe cold areas of China in winter, particularly affecting the frequency and length of outdoor space usage of the elderly. This study aims (1) to establish the modified model which is suitable for the harsh climate region, (2) to verify whether the physiological equivalent temperature (PET) index can be evaluated for the outdoor thermal comfort of older adults in severe cold areas of China in winter, (3) to draw the thermal comfort map that is based on the former conclusions. In this study, the outdoor environments in typical residential areas for the elderly of Changchun, China, has been investigated by using field measurement, questionnaire survey, and Computational Fluid Dynamics (CFD) simulation. The results show that the wind direction is the important aspects of model modification and quite possibly one of the most neglected. In addition, it is convenient to evaluate outdoor thermal comfort of the elderly on the basis of the PET index and the neutral PET temperature of elderly people who live in severe cold areas of China in winter is −0.5 degrees Celsius. According to the thermal comfort map, the park green land of urban residential is the best area for the elderly.