Journal: Deliverable Technical Report / Cooling Singapore

Abbreviation

Publisher

Singapore-ETH Centre (SEC), Cooling Singapore (CS)

Journal Volumes

ISSN

Description

Filters

2019 - 201922020 - 202522
Reset filters

Search Results

Publications 1 - 10 of 24
  • Surface Urban Heat Island (S-UHI) investigations using remote sensing
    Item type: Report
    Philipp, Conrad H. (2019)
    Deliverable Technical Report / Cooling Singapore
    Roth (2013:145) defines and differentiates urban heat island (UHI) phenomena associated with air and surface temperatures: “The Canopy-Layer UHI (CL-UHI) and the Urban-Boundary Layer UHI (UBL-UHI) refer to a warming of the urban atmosphere whereas the Surface UHI (S-UHI) refers to a warming of the surface. The S-UHI … is a surface energy balance phenomenon and involves all urban facets (street, roofs, trees, etc.). Urban surface temperatures are sensitive to the relative orientation of the surface components to the sun by day and the sky at night, as well as to their thermal (e.g., heat capacity, thermal admittance) and radiative (e.g., reflectivity or albedo) properties. It is strongest during daytime when solar heating creates large differences between dry/wet and vegetated surfaces, horizontal surfaces such as roofs and pavements (industrial-commercial zones, especially those with large, flat-topped buildings or extensive open areas of pavement e.g., airport, shopping malls, and major highway intersections). At night, some of the processes are reduced, and urban-rural differences and intra-urban variability of surface temperature are smaller than during the day”. Within this study meso-scale Urban Heat Island (UHI) assessment through remote sensing will be carried out to support the following essential urban climate research tasks: • Calculation of the surface temperature for Singapore via satellite based remote sensing data to map temporal changes of the Surface UHI (S-UHI) over the last decades. • Provision of environmental input data, products and information that shape the exposure to urban heat such as land cover, street geometry, building volume, large floor area, aspect ratio, shading, land use and land surface to be directly integrated into climate models (e.g. Cosmo, WRF). • Providing data that help to support the validation of the meso-scale canopy-layer models (e.g. SingV, WRF). • Processed output data to be incorperated into Singapore Views for visualization purposes.
  • Outdoor Thermal Comfort and Cognitive Performance of Older Adults in Singapore: A field quasi-experiment
    Item type: Report
    Borzino, Natalia; Chng, Samuel; Chua, Rochelle; et al. (2020)
    Deliverable Technical Report / Cooling Singapore
    This field quasi-experiment with 109 older adults examined their cognitive performance in outdoor naturalistic environments and how it is potentially influenced by the Physiological Equivalent Temperature (PET) index (proxy for outdoor thermal comfort (OTC)) and individual climatic conditions (i.e. air temperature, relative humidity, mean radiant temperature and wind speed). Cognitive performance was evaluated when older adults performed physical and sedentary outdoor activities in residential and commercial areas at different times of the day (i.e. morning, afternoon and evening) using a Stroop game. Besides, we collected socio-economic and demographic characteristics and lifestyle data of the participants. Overall, our results show that a higher PET (could also be interpreted as a lower OTC) was negatively related to older adults’ cognitive performance. Wind speed improved cognitive performance while air temperature, relative humidity and mean radiant temperature have detrimental effects on their cognitive outcomes, however in dissimilar magnitude. Social isolation, the use of air-conditioning at home, low levels of educational attainment, poor self-rated health and the engagement in sedentary activities were also related to poorer cognitive performance. These findings suggest that older adults’ cognitive performance was poorer when OTC was lower and this effect might be exacerbated by lifestyle and demographic characteristics. Further investigation into the effects of the lower OTC on older adults’ cognitive performance in different areas of Singapore will be useful for the identification of potential mitigation and adaptation actions.
  • Anthropogenic Heat of Power Generation in Singapore: analyzing today and a future electromobility scenario
    Item type: Report
    Kayanan, David R.; Fonseca, Jimeno A.; Norford, Leslie K. (2020)
    Deliverable Technical Report / Cooling Singapore
    This report studies the anthropogenic heat emissions of Singapore’s power generation sector and evaluates the potential future emissions with electromobility across the island. We thus developed a power plant dispatch model to downscale the total heat released by the power sector in 2016. Taking electricity demand and fuel prices as inputs, the model was based on an energy-only model of the National Electricity Market of Singapore. Generation companies were assumed to bid at marginal cost and discount the value of cogeneration heat. This led to a higher correlation of electricity prices and demand than in reality, and sensitivity to fuel prices. The model is capable of calculating the dispatch, fuel consumption, cogeneration heat and waste heat streams of each plant. These heat profiles would then serve as inputs to a WRF mesoscale model of Singapore. The model was calibrated with the monthly fuel mix and annual fuel consumption in 2016 via hyperparameter optimization. An RMSE of 4.67 ktoe was achieved in the electricity produced per month and per fuel, and the total released heat was within 1.88% of the energy statistics. Simulation of the baseline electricity demand showed that CCGT PNG plants emit over half of the waste heat (1796 ktoe of 3282 ktoe), with the Senoko power plant releasing half of this. Cogeneration CCGT plants released about 882 ktoe of waste heat, while producing as much as 1813 ktoe of process heat. As much as 47% of the total waste heat is released into the air as sensible heat, and 27% as latent heat, with the rest released into the sea. Based on data from a previous study on the anthropogenic heat emissions in the transportation sector, we simulated a scenario wherein the road transportation in Singapore was fully electrified. This scenario could have an additional waste heat of 248 ktoe, and an additional electricity demand of 369 ktoe. This additional demand represents a reduction of vehicle heat on the roads by a factor of six, and more heat is emitted at far-away and efficient cogeneration plants. Overall, the estimated reduction in total anthropogenic heat is 1473 ktoe, or about 7% less than in 2016.
  • Modelling the Urban Heat Island in Singapore – state of the art WRF model technical details
    Item type: Report
    Mughal, Muhammad Omer (2020)
    Deliverable Technical Report / Cooling Singapore
    Though the technical details of the Weather Research and Forecasting (WRF) Model are well documented on the web, a technical summary is required for the partner agencies and the PIs to understand the technical workflow. This report covers the major aspects of WRF modelling with the WRF Multilayer Urban Canopy Model utilizing the Building Effect Parameterization and the Building Energy Model. This report will elaborate the procedure followed in performing the Urban Heat Island (UHI) analysis for Singapore specifically and code modifications
  • Towards a Digital Urban Climate Twin: Simulation-as-a-Service (SaaS) for Model Integration
    Item type: Report
    Aydt, Heiko (2020)
    Deliverable Technical Report / Cooling Singapore
    A Digital Urban Climate Twin (DUCT) is a set of specialised urban climate models and anthropogenic heat emission models needed to closely resemble the urban climate dynamics for a particular city of interest. It allows its users to experiment with a digital representation of the city, its urban climate and the various anthropogenic contributors to urban heat (e.g., industry, traffic, and buildings). The outcomes of such an experimentation can be used to support research as well as planning and decision making. Conducting simulation-based experiments and what-if analyses requires to carry out a number of use-case specific workflows involving many individual steps. These workflows also involve a variety of computational models. In order to facilitate interoperability between these models, a DUCT should be designed as a federation of loosely coupled models. In addition, the underlying middleware, that facilitates the federation of models, should be designed so its components can be deployed and operated in a distributed manner. This report introduces the Simulation-as-a-Service (SaaS) concept and discusses a SaaS middleware prototype as the foundation for the development of a DUCT for Singapore. Two case studies are discussed. The first demonstrates automated workflow execution. The second showcases the interoperability between SaaS components and an end-user decision support application. Based on our evaluation with the prototype as well as the demonstrators, we conclude that the SaaS concept presented here is suitable for realising a full-scale DUCT, including a federation of models and end-user applications. Future work will be concerned with extending the original SaaS concept further with features currently absent in the prototype. For example, this will include a dedicated data object repository as well as significantly enhanced operational security.
  • Microscale Assessment of the Anthropogenic Heat Mitigation Strategies
    Item type: Report
    Adelia, Ayu Sukma; Ivanchev, Jordan; Resende Santos, Luis G.; et al. (2020)
    Deliverable Technical Report / Cooling Singapore
    Anthropogenic heat could worsen air quality and amplify thermal stress, which in a long term could be detrimental to human health. One way to reduce the negative effects of anthropogenic heat emissions is by exploring the advantages of using the new technology. This report evaluates the energy and environmental benefits of potential technological scenarios for the future Singapore's Central Business District (CBD). The focus lies in technology scenarios for the buildings and transportation sectors. We analysed four scenarios for building cooling systems and six scenarios for transportation, including the Business-as-Usual (BAU) and the alternative active strategies, such as District Cooling System (DCS) and electrification of public and private vehicles. Then, we selected five scenarios to be simulated with Computational Fluid Dynamics (CFD) model to see the impacts of each strategy on microclimate. In this study we found that there is a linear decrease in both the total energy consumption and Greenhouse Gas (GHG) emission as we increase the proportion of District Cooling System (DCS) in buildings and electrification of vehicles. From the climatic perspective, as compared to the Business-as-Usual (BAU) scenario, both 100% DCS and electric vehicle scenarios show a negligible reduction (< 0.1oC) in terms of the averaged canopy layer temperature. For the outdoor thermal comfort (OTC), the maximum reduction of weighted averaged PET during the hottest hours is 1.01oC and 0.97oC with 100% DCS and 100% electric vehicles respectively. The key metrics presented in this report are also considered as part of the benefit metrics evaluation in the Cost-Benefit Analysis (CBA) done in the Cooling Singapore 1.5 project.
  • System Analysis of Mesoscale and Microscale Urban Climate Simulation Workflows
    Item type: Report
    Li, Shiying; Aydt, Heiko (2020)
    Deliverable Technical Report / Cooling Singapore
    The Cooling Singapore project studies the urban climate of Singapore and, in particular, evaluates measures to mitigate urban heat. For this purpose, Cooling Singapore utilises a variety of tools for modelling, simulation, data processing and analysis. Some of these tools are off-the-shelf software (e.g., MATLAB, ANSYS Fluent), while others are third-party open-source software modified to meet the needs of the project (e.g., WRF), or software that has been developed in-house specifically for the purpose of the project. The resulting ecosystem of tools is thus highly diverse, requiring a diverse set of skills and operating environments in order to perform integrated studies across multiple domains. At the moment, such integrated studies are carried out in a collaborative manner involving the contributions from various researchers. The ability to carry out integrated what-if scenario analysis is important to investigate the potential impact of mitigation measures on the urban climate. This ability is not only important for researchers but also for practitioners, such as urban planning authorities for example. Manual workflow execution, involving the contributions of several researchers, represents a significant constraint. Not only is this process time-consuming, it is also prone to human error. A better approach would be to clearly specify the individual steps needed to carry out a particular what-if scenario analysis and automate (as far as possible) the entire process. This would not only reduce the amount of manual work (thus freeing researchers’ time to focus on other things) but also vastly improve the reproducibility of results and reduce the likelihood of human error. The first steps towards automated workflow execution are to analyse the workflows to better understand the various steps that are needed in order to carry out integrated studies and what-if scenario analyses. This document represents a systematic analysis of the primary workflows and their principal components in the context of the Cooling Singapore project. In particular, this document provides an overview of all principal components, as well as their input and output data. The information provided in this document is not meant to be a detailed documentation for each of the various model components. Instead, it is a system-level analysis that focuses on the flow of data from one model to another. It should also be noted that the information provided here is valid as of the time of writing. However, as the project evolves, so will the workflows and the components of the system.
  • Analysis of climatic variables in different urban sites of Singapore and evaluation of strategies to improve the outdoor thermal environment
    Item type: Report
    Acero, Juan Angel; Koh, Elliot J.Y.; Tan, Yon Sun (2020)
    Deliverable Technical Report / Cooling Singapore
    This report presents the outcome of outdoor thermal comfort campaigns carried out in two different areas of Singapore (commercial and residential/park areas). The aim was to quantify the impact of different urban elements and strategies on the local climate variables and outdoor thermal comfort. In each area, sensors were deployed simultaneously in 4-5 sites to measure air temperature, wind speed and direction, relative humidity, and globe temperature. Evaluation of thermal comfort was done by means of the Physiological Equivalent Temperature heat stress index (PET). Continuous measurements were carried for 4 - 7 months at each site during years 2019 and 2020. The results revealed seasonal OTC differences that justify the necessity of evaluating OTC and its strategies throughout the year. Analysis of vegetation elements has shown a benefit in PET of 7-8°C during the midday/afternoon period. Also shadow from high-rise buildings can produce a decrease of 12°C. Orientation of streets, as well as type of development, have a significant effect on duration, intensity and timing of the diurnal PET peak. Inside each area, during night-time, sites in low-rise developments showed a lower air temperature (1.2-1.5°C) than high-rise areas in agreement with higher sky view factor and higher heat release. On the contrary, during the morning, high-rise street canyons presented a delay in the warming phase that turned into lower air temperature (~0.5°C) compared to low-rise developments. Finally, semi-outdoor spaces (e.g. elevated podiums) can register in the afternoon period up to 13-15°C (PET) lower than close by high-rise developments and 8-9°C (PET) lower than open urban areas, depending on the climatic season. Results provided grounded insights to OTC levels in different urban typologies that can influence decision-making in the context of improving OTC through adequate urban design.
  • Anthropogenic Heat Sources in Singapore
    Item type: Report
    Kayanan, David R.; Resende Santos, Luis G.; Ivanchev, Jordan; et al. (2019)
    Deliverable Technical Report / Cooling Singapore
    This report describes the sources of anthropogenic heat (AH) in Singapore for the year 2016. The objective of this report is two-fold: first, to deliver a Sankey diagram of the main sources of AH in Singapore; and second, to explain all the definitions, assumptions, methods and outstanding uncertainties. We also provide our definition of AH in the context of Cooling Singapore 1.5. This is important for both Cooling Singapore and its stakeholders, since our results serve as the cornerstone for 1) validating any mathematical or physical approximation of the AH contributions in Singapore, and 2) analyzing the impact of AH on the Urban Heat Island (UHI) effect and subsequently on Outdoor Thermal Comfort (OTC). As most of our energy usage spontaneously decays into heat, this report is largely based on the 2018 Singapore Energy Statistics of the Energy Market Authority. However, to get a more comprehensive understanding, an analysis of the country oil balance, supply of natural gas, power stations including cogeneration, and the industrial sector is done. We focus on the domestic use of energy as we are accounting the heat released within Singapore’s land territory. We identified four major sources of AH in Singapore. These are Power Plants (including the grid; together release 3118 ktoe of heat, or 15.3%); and the three end use sectors Industry (11906 ktoe or 58.5%), Buildings (2430 ktoe or 11.9%), and Transport (2328 ktoe or 11.4%). We also estimated the heat released by human metabolism, which contributes a minimal amount (579 ktoe or 2.8%). We also viewed the heat from power plants alternatively as indirect heat, and allocated this based on the demand of the end use sectors. The Sankey diagram of the energy system including the AH sources of Singapore in 2016 is shown in Annex A. The underlying calculations are shown in Annex B. Finally, two simple analyses of the Sankey diagram can be found in Annex C.
  • Building Anthropogenic heat flux in Singapore
    Item type: Report
    Santos, Luis Guilherme R.; Singh, Vivek Kumar; Mughal, Muhammad Omer; et al. (2020)
    Deliverable Technical Report / Cooling Singapore
    Buildings are amongst the biggest sources of anthropogenic heat in cities. In Singapore, buildings consume close to 28 TWh/year, which is eventually rejected as heat into the environment. It is believed that this amount may contribute to raising temperatures in the city state and thus urban warming. In order to provide a better understanding this phenomenon, this work characterizes the distribution of anthropogenic heat flux from buildings in Singapore. The focus lies in the analysis of the heat generated by different building morphologies and typologies throughout a typical year across the island. The methodology is divided into two parts. In the first part, we assess the energy consumption of over 13,000 buildings in Singapore across diverse building typologies (commercial, private housing and public housing [HDB]) and local climate zones. The result is the mean sampled energy use intensity for three main typologies: commercial buildings, public housing (HDB) and private housing. The mean sampled energy use intensity for each typology is validated against energy statistics. The second part combines this information with a Local Climate Zone (LCZ) - Land Use map, resulting in a map of Singapore’s building anthropogenic heat flux and an estimation of total anthropogenic heat released over one year, also validated against reported energy consumption. The analysis of Energy Use Intensity (EUI) revealed that commercial buildings (mean EUI of 267 kWh/m²/yr) can be four to five times more energy intensive than public (50 kWh/m²/yr) and private housing (72 kWh/m²/yr). The EUIs for each typology tend to remain nearly constant for different LCZs, which is expected, given that the effect of different morphologies is not evident when normalizing the energy of buildings per gross floor area. The EUI is converted into anthropogenic heat density (AH Density) with the use of the Floor Area Ratio (FAR) index, which is the ratio between gross floor area and site area. The AH density, expressed in annual heat per site area, is then converted into anthropogenic heat flux (AH Flux), assuming a constant distribution of power throughout the year. In terms of AH flux, the highest flux is generated in compact high-rise areas (LCZ1), with AH flux of commercial buildings (105 W/m²) being 6 to 7 times higher than private (18 W/m² ) and for public housing (15 W/m²). The lowest anthropogenic heat flux is observed in sparsely built regions (LCZ9), with AH flux ranging from 2 W/m² in residential buildings to 7 W/m² in commercial buildings. In Singapore, open lands (LCZ3, LCZ4 and LCZ5) comprises 70% of the built-up spaces, with 34% of the site area from buildings corresponding to high rises (LCZ4) and 27% to open mid-rises (LCZ5). In those regions, the average heat flux from commercial buildings (55 – 91 W/m²) is estimated to be 8 to 11 times higher than private housing (5-11W/m²) and 6 to 7 times higher than public housing (HDB) (9-13W/m²). The spatial distribution of AH flux presents a clearer distinction between commercial and residential areas. Commercial areas are, as expected, the most heat intensive areas, with a range of AH flux between 70 and 110 W/m² in business and retail areas such as Central Business District (CBD), Orchard Road, and the Mapletree Business City, but also with a significant amount (40-90 W/m²) in university campuses. Although residential buildings have an AH flux five to twenty times lower than the commercial sector (2-20 W/m²), residential buildings are distributed over an area three times larger than that of commercial buildings. Therefore, residential buildings are still significant, representing around 30% of the total AH emitted in Singapore. In terms of total anthropogenic heat, LCZ4 and LCZ5 present the highest share of aggregated heat released, due to their larger site area coverage. Up to 62% of the AH released coming from buildings is observed in those urban morphologies. From that, 65% is due to commercial (10.69 TWh/yr) and 35% is due to residential (5.80 TWh/yr), also indicating how much more intensive the commercial sector is in Singapore. Our results provide a visual representation of the direct contribution of buildings to anthropogenic heat emissions across Singapore, highlighting the hotspots across the island. It also establishes the basis for the evaluation of “what-if” scenarios, such as changes in the Master Plan or assessing the potential impact of new developments. Future work will explore the incorporation of building energy models in this framework, accounting for hourly variation throughout the day and a potential to explore a wider range of “what-if” scenarios related to building technology.
Publications 1 - 10 of 24