Urban warming and future air-conditioning use in an Asian megacity: importance of positive feedback

The impact of feedback between urban warming and air-conditioning (AC) use on temperatures in future urban climates is explored in this study. Pseudo global warming projections are dynamically downscaled to 1 km using a regional climate model (RCM) coupled to urban canopy and building energy models for current and six future global warming (ΔTGW) climates based on IPCC RCP8.5. Anthropogenic heat emissions from AC use is projected to increase almost linearly with ΔTGW, causing additional urban warming. This feedback on urban warming reaches 20% of ΔTGW in residential areas. This further uncertainty in future projections is comparable in size to that associated with: a selection of emission scenarios, RCMs and urban planning scenarios. Thus, this feedback should not be neglected in future urban climate projections, especially in hot cities with large AC use. The impact of the feedback during the July 2018 Japanese heat waves is calculated to be 0.11ºC

A model for detailed evaluation of fossil-energy saving by utilizing unused but possible energy-sources on a city scale

There is growing interest in the utilization of unused, but possible, energy sources to reduce carbon-dioxide emissions and fossil-energy consumption, and especially to comply with the Kyoto Protocol which came into effect in 2005. Detailed considerations of plant location, land use and life cycle analysis, however, have not yet been fully estimated with a view to confirming the advantages of the new energy-source usage. A model for heat energy from river water and treated sewage water, and waste-heat energy from municipal solid-waste incineration plants was built and applied to the Tokyo urban area in Japan, considering the spatial and time-related distribution of demands and supplies, the shapes of buildings in the demand area, and life-cycle analysis. The model selected areas were those which should use these energies without prejudice, and sometimes the areas were far from the energy-source point. The reduction of carbon-dioxide emissions resulting from new energy-sources was about 8% of the reduction target for Tokyo in 1990. The model was able to precisely evaluate the new energy-usage, using data from both supply and demand sides.Kyoto Protocol Carbon dioxide emissions Fossil-energy consumption

Impacts of city-block-scale countermeasures against urban heat-island phenomena upon a building's energy-consumption for air-conditioning

This study quantifies the possible impacts of urban heat-island countermeasures upon buildings' energy use during summer in Tokyo metropolis. Considering the dependency of the buildings air temperature upon the local urban canopy structure, Tokyo urban canopies were classified in the city-block-scale using the sky-view factor (svf). Then, a multi-scale model system describing the interaction between buildings' energy use and urban meteorological conditions was applied to each classified canopy. In terms of urban warming alleviation and cooling energy saving, simulations suggested that the reduction in the air-conditioning anthropogenic heat could be the most effective measure in office buildings' canopies, and that vegetative fraction increase on the side walls of buildings in residential canopies. Both measures indicated daily and spatially averaged decreases in near-ground summer air temperature of 0.2-1.2 °C. The simulations also suggested these temperature decreases could result in the buildings' cooling energy-savings of 4-40%, indicating remarkable savings in residential canopies. These temperature drops and energy savings tended to increase with the decrease of the svf of urban canopies.Urban heat-island Mitigation measures Urban canopy model Building energy-simulation Urban energy conservation

Development of a numerical simulation system toward comprehensive assessments of urban warming countermeasures including their impacts upon the urban buildings' energy-demands

One of the detrimental effects caused by the urban warming phenomena is the increase of energy consumption due to the artificial air-conditioning of buildings in summer. In greater Tokyo, the temperature sensitivity of the peak electricity demand reaches up to 3%/°C in recent years, and about 1.5 GW of new demand is required as the daily maximum temperature increases by 1.0 °C. This huge demand for summer electricity is considered to be one of the common characteristics of big cities in Asian countries. In order to simulate this increase in cooling energy demands and to evaluate urban warming countermeasures from the viewpoint of buildings' energy savings, a numerical simulation system was developed adopting a new one-dimensional urban canopy meteorological model coupled with a simple sub-model for the building energy analysis. Then, the system was applied to the Ootemachi area, a central business district in Tokyo. Preliminary verification of the simulation system using observational data on the outdoor and indoor thermal conditions showed good results. Simulations also indicated that the cut-off of the anthropogenic heat from air-conditioning facilities could produce a cooling energy saving up to 6% with the outdoor air-temperature decrease by more than 1 °C in the summer urban canopy over Ootemachi area.Urban warming countermeasure Anthropogenic heat Urban canopy layer Cooling energy conservation

Changes in year-round air temperature and annual energy consumption in office building areas by urban heat-island countermeasures and energy-saving measures

This paper describes the effects of the installation of various countermeasures against urban heat-island (UHI) and energy-saving measures on UHI and global warming. A UHI and energy-consumption simulation model was developed by combining the one-dimensional meteorological canopy and building energy use models; further, the proposed model was expanded to evaluate the year-round air temperature and annual energy consumption. The simulation results showed that the humidification and albedo increase at building-wall surfaces reduced the total number of hours for which the air temperature was more than 30 °C during the daytime by more than 60 (h) per year. The UHI countermeasures reduced the annual energy-consumption despite causing a small increase during the winter period. However, they may result in certain unfavorable conditions for pedestrians. Energy-saving measures, on the other hand, reduce the total number of hours for which the air temperature is more than 30 °C by only a few hours per year. Thus, we demonstrate the effectiveness of the UHI countermeasures and measures against global warming by extending the calculation period from summer to an entire year.Canopy model Building energy model Urban heat-island Building energy-consumption

Associated results of Phase 1 of the Urban-PLUMBER model evaluation project

Archive of: https://urban-plumber.github.io/AU-Preston/plots/ Files in this folder are associated with the manuscript: “Evaluation of 30 urban land surface models in the Urban-PLUMBER project: Phase 1 results” Files are an archive of the website https://urban-plumber.github.io/AU-Preston/plots/ as of 2nd December 2022. Use of any data must give credit through citation of the above manuscript, the data repository, and other site references as appropriate. Corresponding author: Mathew Lipson ([email protected]) Usage Load the "index.html" to navigate through plots and results subpages Description These files include results from Phase 1 of the Urban-PLUMBER model evaluation project for urban areas. Data includes: - individual model results (error metrics) and submission metadata - individual model plots (timeseries, subsets, energy closure, distributions) - collective timeseries for every submitted output in the baseline experiment - collective timeseries for every submitted output in the detailed experiment - supplementary material for the manuscript - variable definitions Authors Mathew Lipson, Sue Grimmond, Martin Best, Gab Abramowitz, Andrew Coutts, Nigel Tapper, Jong-Jin Baik, Meiring Beyers, Lewis Blunn, Souhail Boussetta, Elie Bou-Zeid, Martin G. De Kauwe, Cécile de Munck, Matthias Demuzere, Simone Fatichi, Krzysztof Fortuniak, Beom-Soon Han, Maggie Hendry, Yukihiro Kikegawa, Hiroaki Kondo, Doo-Il Lee, Sang-Hyun Lee, Aude Lemonsu, Tiago Machado, Gabriele Manoli, Alberto Martilli, Valéry Masson, Joe McNorton, Naika Meili, David Meyer, Kerry A. Nice, Keith W. Oleson, Seung-Bu Park32, Michael Roth33, Robert Schoetter34, Andres Simon35, Gert-Jan Steeneveld, Ting Sun, Yuya Takane, Marcus Thatcher, Aristofanis Tsiringakis, Mikhail Varentsov, Chenghao Wang, Zhi-Hua Wan