Urbanization diminishes and fragments greenspaces. Thus, it contributes to the degradation of the environment. Urbanization also contributes to the creation of urban heat islands. Housing schemes should have greenspaces that are capable of mitigating urban heat islands. Nowadays, a terraced housing neighbourhood is the major type of housing scheme in Malaysia. However, the measurable influence of greenspaces is hard to quantify. The aim of the research is to quantify the cooling effects of urbangreenspaces in a residential area in a tropical region. In consideration of a location, layout, landscape component and built year, Bukit Indah, Johor is chosen as a study area. The study focuses on the layout, land use coverage ratio, and cooling intensity of greenspaces by using the three-dimensional microclimate model ENVI-met. A review of the literature in this field identified basic information about urban heat islands and mitigation methods and tools. Three focus areas with a dimension of 240 x 240 metre are chosen for detail comparison analysis in a neighbourhood scale within the study area. Those three areas contain different types of green space layout and coverage ratio, specifically, neighbourhood park, play field, play lot, recreational yard, and road side plantings as a parameter. Through the comparative study based on the different combination of parameters, it is concluded that urbangreenspaces in the study area mitigate urban heat islands by 1 ◦ C. In this case, a better cooling effect is found with interconnected greenspaces,
The potential of Landsat 5 TM to monitor the land cover changes and to analyse the spatial distribution of land surface temperature are widely used. The results indicate five major classes of land covers; water bodies, high dense trees, vegetations, built-up area, and cleared land. Due to urban growth, the dramatic changes in land use between 1991 and 2009 are relatively different, where high dense trees land cover areas have relatively decreased about 17.48%. This area is transformed to built-up land cover and cleared land where the dramatic changes happened in 1991 and 2009. The results show that LST and thermal signal of built-up and cleared land have distributed to rise average radiant temperature. While vegetated area (high dense tree and other vegetation) and water body experiencing lower temperature. Although this study is not conclusive, initial findings have shown that there are significant increases in the built-up areas in the Shah Alam City over a period of 18 years which resulted in higher LST in built-up areas as compared to water bodies or the vegetated areas. There is strong negative correlation between LST and NDVI, which indicates vegetation helps to reduce the LST of an area. Comprehensive ground observations are needed to validate the results obtained from satellite images. As resulting, urbanization significantly increases the LST. However, the initiative taken by the Shah Alam City Council and Kelana Jaya City Council to plant more trees helps to mitigate the UHI effects within a developed urban area. A climatic factor must be considered as criteria to perform sustainable development as well as to mitigate UHI effects in the city centre and to provide better quality of live among urban population. In addition, landscaping vegetation in urban area will help to beautify the urban surroundings tend to modify hot and humid tropical microclimates cities in Malaysian and beneficial to urban resident as well.
Cities in the tropics, urban open greenspaces are of particular importance as they offer shading and cooling, to mitigate the urban heat island effect and with regard to air pollution (Gago, Roldan, Pacheco-Torres, & Ordóñez, 2013). Trees offer shade on hot days and in sunny climates (Carmona, Freeman, Rose, & Woolley, 2004) and generally, parks are cooler than the urbanareas that surround them (Skoulika et al., 2014). According to Bowler et al. (2010), temperature in a park reduces averagely by about 0.94°C in day time and 1.15°C at night. Park size also plays a positive role in estimating the cooling effect, helping to maximize the cooling effects of parks, tree vegetation canopy cover can be increased and the choice of species for greening should be optimized (Feyisa et al., 2014).
Boosting Attic Ventilation
If the attic is too hot, is more ventila- tion a good idea? Maybe, but maybe not. Increasing the roof’s passive air vents can reduce the cooling load, but it is usually one of the least effective options. The incoming ventilation air is hottest just when you need the cooling. In retrofit work, we have seen increased ventilation bring a 5% reduc- tion in building cooling loads. But in humid or coastal locations, it can also create problems: At night, the vents bring in moist outside air that may condense on duct systems.
The current studies on the relationship between the urban configuration, the urbanmicroclimate and thermal comfort are dominated by the investigation on urban canyon or urban street canyon. Linear space, which normally covers building row that forms the urban canyon, is mainly influenced by Height to Width (H/W) aspect ratio and Sky View Factor (SVF). Table 1.2 summarises the review on the development of studies on the relationship of urban configuration with climate. It shows that pioneer studies (1970 1990) covered lesser climate variables and climate region. The studies were also conducted mostly on urban canyon instead of other types of urban configurations. Later studies (1990 2010) were performed with more climate variables in various configuration or types of buildings. Latest studies conducted between 2010 and 2015 were done with more choices of configuration, climate feature and climate regions. However, the studies investigation were mostly focused on climate variable, while this study specifically investigates the impact of more option of urban configurations on the holistic climate features in the context of Kuala Lumpur.
lead to achieve thermal comfort for humans, especially in residentialareas in the Sudan as a developing country. Therefore, the study of wind pattern around a group of buildings in urbanareas is one of important factors that ensure the penetration of air and ventilation to each building in particular, the residentialareas. Knowing the behavior of air movement around a group of residential buildings will be one of the factors, which should be taken into consideration by both planners and architects during the planning process for any residential area, and during the architectural design process of residential units.
The motivation to pursue this research is that properly confronting the effects of global climate change is one of the most pressing problem facing the planet in the 21 st century. The Intergovernmental Panel on Climate Change warns that without additional mitigation efforts global “… warming is more likely than not to exceed 4 °C above pre- industrial levels by 2100. The risks associated with temperatures at or above 4 °C include substantial species extinction, global and regional food insecurity, consequential constraints on common human activities and limited potential for adaptation” (IPCC, 2014). One of the most viable and effective climate change mitigation strategies is demand-side energy
When tree roots encounter dense soil layers, they usually change direction, stop growing, or adapt by remaining unusually close to the surface. This superficial rooting makes urban trees more vulnerable to drought and can cause destructive pavement heaving (Randrup et al., 2003). The highly compacted soils commonly required for constructing pavements do not allow tree root penetration (Scholz, 2013). Viswanathan et al. (2011) undertook a research study concerned with the performance of Liquidambar styraciflua L. (American sweetgum) roots under permeable and impermeable pavements. Their results suggested that the standing live root lengths for the American sweetgum were longer in impermeable concrete than in permeable concrete for the first 0 to 20 cm of soil depth. Beyond this depth, the standing live roots were more abundant in permeable than in impermeable pavements. However, they came to the conclusion that pervious concrete does not give a quantifiable root production benefit in comparison to impervious concrete. Giuliani et al. (2015) used modelling tools to analyse tree growth in street pavements. The findings indicate the progressive reduction of deformations with the increase of the depth of root penetration. However, these studies require a lot of data for individual trees and sites.
Ecology in town planning manifests itself in such aspects as taking great care to ensure that a town can “breath”. Developed town areas are composed of different types of urban fabric in a grid of roads and streets, which can cause accumulation of exhaust fumes and generation of smog (Fig. 3). A good plan of the network of streets and how they developed can create conditions for their natural airing. This effect can be achieved by creating open spaces, where air can travel freely from innertown and suburban greenareas, for example forests, from which air is “pumped” into the centre of the town.
To quantitatively compare diverse urban textures, urban morphological parameters have been explored, developed and employed in studies of environmental performance, landscape, land use, atmospheric and wind environment (Xie et al, 2006; Adolphe, 2001 Esbah, 2009; Ng et al, 2011; Van de Voorde, 2011). The urban morphological parameters that might be related to birdsong distribution and view of green area have been selected and developed from the perspective of possible effects of urban morphology on outdoor sound propagation (e.g., distance and ground, barrier and canyon effects) and urban view block. The parameters can indicate the characteristics of plot and street pattern, ground and building surface condition and building (barrier) geometry (Kang, 2007; Raydan and Steemers, 2006; Stamps, 2001). Seven quantitative parameters were used in this study: Building Plan Area Fraction (BPAF), Complete Aspect Ratio (CAR), Building Surface Area to Plan Area Ratio (BSAPAR), First- row Building Frontal Length Index (FBFLI), Distance of First-row Building to Green Area (DFBGA), Green Area Perimeter (GAP), and Green Area Dispersion Index (GADI). The first three parameters are for 2D and 3D characterisations of buildings, the fourth and fifth characterize the relative locations between buildings and greenareas, and the last two parameters are for the 2D characteristics of greenareas based on the results of the pilot study.
humidclimates higher regeneration temperatures are required (Ge et al., 2014)(H. Li et al., 2011)(Gommed & Grossman, 2007)(Jani et al., 2016).
Assuming daytime operation, a PV/T collector coupled with an SDC system can provide air conditioning and electricity to partially offset the peak load on the grid (Fan et al., 2019). Among the liquid-based (water) and air-based solar PV/T technologies, the water-based technologies certainly have a significant advantage over the air in terms of heat transfer and thermal storage capacity. In contrast, the air-based technologies benefit from no leakage, lower weight of the entire assembly, lower initial costs, and lower maintenance costs and effort (Yang & Athienitis, 2016). It is expected that an air-based PVT collector will have to maintain a high outlet air temperature to drive an SDC system. However PV/T collectors optimized for increasing the outlet air temperature adversely affect the electrical performance and material integrity of the PV modules (Yang & Athienitis, 2016). As a result, an auxiliary heater (AH) is commonly employed to boost the outlet air temperature to the required level to support the SDC system’s operation; increasing the input power requirements of the integrated system. In such a case, a PVT collector can either provide higher electrical output by maintaining lower PV surface temperature or provide higher outlet air temperature resulting in lower electrical output. Although, the latter will greatly help in the operation of SDC system, prolonged operation with such high outlet air temperature will result in higher PV surface temperature as well, in turn, adversely affecting the material integrity of the PV modules.
Electricity is indisputably the fundamental energy resource for industrial, commercial and domestic activity in the modern world. Although a major oil producer and investor in the electricity sector, Nigeria holds a low 69 th place in per capita electricity
consumption globally (CIA World factbook, 2011). The country has large amounts of natural resources utilized for energy generation (both conventional and renewable sources); but yet experiences unexpected and long periods of power outage, or fluctuating currents (Adelaja et al., 2008; Uyigue et al., 2009). Ibitoye and Adenikinju (2007) estimate that up to 54% of the population (81 million) are unconnected to the national grid, especially those in remote areas. Political instability, mismanagement, limited funds, long period of return of investment and maintenance neglect all result in electricity generation deficit, poor utility performance, and weak transmission and distribution infrastructure. These factors all contribute to the electricity crisis in Nigeria. There are presently more than 150 million people living in Nigeria according to IEA, (2008), and the power sector is only capable of generating around 3,500 MW of electricity. This is well below all economic projections and the country’s consumer and business needs, despite government investment of around USD1 billion annually in the sector (Corporate Nigeria, 2011).
Lahore Fort, Pakistan is a citadel spread over approximately 50 acres and built by Mughal Emperor Jalaluddin Muhammad Akbar in 1575 and resumed by Shah Jahan in 1632. The Shish Mahal courtyard is located inside the quadrangle section at the northwest corner of Lahore Fort which served as the residence of the Empress. In this courtyard, water is used both as an integrated hydraulic system here and coupled with a series of thick masonry walls. The systems ventilators within these walls were designed to provide occupant coolness in public spaces such as open plaza and courtyards. Miniature ducts ran underneath the courtyard floor and constant flow of water kept the floor incessantly cool.
The thermal comfort survey showed occupants adaptability to high temperatures with a neutral and preferred temperature range of 28.2 C 29.6 C and 25.4 C 28.3 C respectively with most of the occupants in the naturally ventilated building experiencing higher temperatures compared to those in air conditioned buildings. The linear regression analysis to calculate neutral and preferred temperatures confirm the higher adaptation potential at Lugbe compared to the lower temperatures recorded in Dutse Alhaji. However, the difference in temperature between the air conditioned and naturally ventilated building was only about 2 C. Upon further investigation, it was clear that most of the occupants of air conditioned buildings did not use their air conditioners for cooling frequently owing to power cuts being very common in this area during the survey. Most of the occupants find their thermal conditions acceptable and more than 70% of the spaces monitored in all case studies recorded temperatures above the comfort range.
Typical envelope related findings include single pane casement windows with poor closure, low levels of attic insulation, missing plumbing access covers and other drywall holes causing high levels of air infiltration. The homes typically have old or missing appliances and few, if any, compact fluorescent light bulbs (CFLs). Split-system forced air mechanical systems are the norm. Heat pump and electric resistance configurations are both common in the central Florida homes with gas heating dominating in north Florida and Alabama. Mechanical systems in homes built prior to the 1990’s generally have poor air flow across the conditioning elements, building cavities used as return plenums which are poorly connected to the air handler, undersized return plenums, small air handler closets in the conditioned space but open to the attic, and leaky ducts typically located in the attic. In homes with crawl spaces, primarily in north Florida and Alabama, ducts were typically installed below the frame floor. Homes built after the 1990’s generally have tighter ducts sealed with mastic at the major joints, and more
on a variety of factors: the type of soil and content of organic compounds in it, especially of humus, play a crucial role, having been demonstrated a positive correlation between the two parameters (Rimmer, 2006). Other influencing factors are microbiological activity, and also the species of cultivated plant. In fact, through different chemical composition of root exudates, plants can stimulate or inhibit the development and activity of soil microflora, and thus the total antioxidant capacity of soils (Skwaryło-Bednarz & Krzepiłko, 2009). There are several classes of chemical compounds in plants which are potential antioxidants and which could be moved into the soil. For instance, polyphenols, tannins as well as flavonoids have antioxidant effects (Rice-Evans et al., 1996; Hagerman et al., 1998). These substances also seem to have an impact on soil management, as reported by Zibilske and Bradford (2007), who showed that the slowing of organic carbon mineralization and the consequent accumulation of soil organic matter could be stimulated by using cover crops with higher phenol content. Rimmer and Smith (2009) and Rimmer and Abbott (2011) demonstrated that the amounts of antioxidants vary according to soil type, reflecting soil water-soluble organic carbon and total organic C contents. Furthermore, it is known from pharmaceutical studies that microbial activity is inhibited by isoprenoid plant compounds like terpenoids (Dickson et al., 2007). In addition to this, all chemical compounds suspected to be antioxidative have already been detected in soils and in potential precursors of soil organic matter (Schlichting & Leinweber, 2009).
This paper still has some limitations, and future research is needed. As net zero energy buildings are still a new concept in many countries, only 34 cases are found in hot and humid climate regions. Moreover, not every case analyzed in this study has comprehensive design and performance data available. Thus, there is a great need to document NZEB best practices in a future study, and enhance data transparency. Comprehensive documentation of design, cost and performance data would make a case study of a successful experience more convincing when disseminated to an audience. Operational conditions should be documented side-by-side with building operation energy data to de- monstrate the effectiveness of advanced design and technology per- formance in the operation stage. Energy consumption data are needed in different time intervals, such as: yearly, monthly and typical day hourly data. For emerging economies in hot and humidclimates, doc- umenting best practices would be very helpful to demonstrate the ef- fectiveness of NZEBs and thus reduce knowledge barriers among sta- keholders. With more and more NZEBs built and data documented in the future, in-depth analysis with larger sample sizes can be conducted.
found to be (in both simulation and experimental work) 0.1 μm, 0.15μm and 0.4 μm, respectively. The glazing transmitted 78% of the visible light and reflected almost all the infrared radiation from the sun. The optical properties of the glazing hardly depended on the angle of incidence of solar radiation. This makes it ideal for all hours of the day. During the night, in winter, it could act as an in- sulator to reflect the heat back inside the room. It satisfies the conditions for comfort in both the hot days of summer and the cold nights of winter.
The use of green space domain gathered the most common deterrents for use of urbangreenspaces among participants’ responses. The most frequent theme within this domain, social factors, was one of the most common themes among all domains. One of the key dissuasive elements for use of greenspaces was antisocial behaviour, e.g., “Since it’s a small and more or less hidden place, they take advantage to drink beer or something and you find there the typical drunk. So instead of enjoying this place, you try to avoid going there” [P6: R100491] and “I had some negative experiences because some people bring their dogs to the park and train them to fight at night” [P14: R103515]. Another important use discouraging element related to social factors was use overlap, e.g., “They are somewhat saturated because there are a lot of people, you know? I mean, there are lots of people who use these places so they usually are a little bit crowded” [P8: R100860], which was often associated with themes from the urban design domain such as small size or small amount of greenspaces, e.g., “If it’s a small place, old men will say that children bother them, while the children’s parents will ask the man with the dog to go elsewhere and the man with the dog will say 'I can’t go nowhere'. So there will always be conflicts. On the other hand, if it’s a big place where everybody fits within, everybody can find its own place. Everybody can enjoy it” [P6: R100491]. Other frequent deterrents for use within this theme included littering, e.g., “The place is cleaned up every day but it’s still always dirty. Even on holiday it’s cleaned up, you know? So I'd blame on the people who live there rather than the public services who are in charge of its maintenance” [P8: R100860], and dog mess, e.g., “dogs are animals so they make it where they want to. The problem comes when their owners don't pick up the excrement” [P5: R100283]. The rest of the use discouraging elements related to social factors were
External solar shading devices can substantially reduce the cooling load of buildings and large energy savings can be achieved. Hence, intercepting the radiant heat wave before penetrating to the internal environment through envelope openings is the main criterion in designing solar shading. In hot and humid climate, one draw back of using shading devices is the risk to reduce daylight level thus increases in use of artificial lighting. Therefore it is important to understand the magnitude of energy consumption for cooling and lighting when shading devices are adapted in order to analyze optimum shading as energy conservation option in high-rise office buildings. In other words, little is known about the relationship between energy use and external horizontal shading device geometry. In an attempt to elucidate these complex relationships, a simple experiment of an office room is carried out using dynamic computer simulation program eQUEST- 3 (DOE 2.2). The study indicated depth of the external horizontal overhang can be manipulated to obtain an optimum energy use in high-rise buildings. The results showed that correlation between overhang depth and energy is an important aspect compared to correlation between overhang depth with building cooling loads and daylight level, especially in tropical climate conditions.