Despite inter-building longwave radiative exchanges playing an important role in determining buil... more Despite inter-building longwave radiative exchanges playing an important role in determining building energy and environmental performance, simulation tools (e.g. EnergyPlus) simplify this by assuming the surface temperature of surrounding buildings to be equal to the air temperature, and therefore cause bias. Here we propose a ‘spin-up’ approach to update building external surface temperature using either air or the isolated building temperatures. Neighbourhoods with different plan area fraction of buildings (λP) are analysed to assess the impact on building external surface temperatures, cooling and heating energy demand as well as indoor overheating degree hours. Using the default EnergyPlus method causes a large bias in all metrics in a dense urban area (λP = 0.6) and climates assessed (cf. the new method): external wall temperature (3 °C less, midday median), annual energy demand for cooling (17.1% less) and heating (6.2% higher), annual overheating degree hours during the day (> 28 °C, 24.5% less) and night (> 26 °C, 60.1% less). These biases are larger at lower latitudes. Thus, neglecting the surroundings influence on inter-building longwave radiation impacts critical design considerations of building energy and thermal performance in dense urban areas
Journal of Applied Meteorology and Climatology, 2021
Urban heat island (UHI) and sea–land-breeze systems are well-known and important characteristics ... more Urban heat island (UHI) and sea–land-breeze systems are well-known and important characteristics of the climate of coastal cities. To model these, the accurate estimation of the surface energy balance (SEB) is a key factor needed to improve local-scale simulations of thermodynamic and dynamic boundary circulations. The Weather Research and Forecasting Model with a single-layer urban canopy model (WRF/SLUCM), with parameters derived from MODIS and local GIS information, is used to investigate the UHI and sea-breeze circulations (SBC) in the megacity of Shanghai. The WRF/SLUCM can reproduce observed urban radiation and SEB fluxes, near-surface meteorological variables, and the evolution of the UHI and SBC. Simulations for an August period show the maximum UHI tends to drift northwest in the afternoon, driven by the prevailing southeast wind. The sea breeze lasts for about 4 h and is strongest between 1200 and 1400 local time (UTC + 8 h). The interaction between UHI and SBC is evident ...
Despite inter-building longwave radiative exchanges playing an important role in determining buil... more Despite inter-building longwave radiative exchanges playing an important role in determining building energy and environmental performance, simulation tools (e.g. EnergyPlus) simplify this by assuming the surface temperature of surrounding buildings to be equal to the air temperature, and therefore cause bias. Here we propose a ‘spin-up’ approach to update building external surface temperature using either air or the isolated building temperatures. Neighbourhoods with different plan area fraction of buildings (λP) are analysed to assess the impact on building external surface temperatures, cooling and heating energy demand as well as indoor overheating degree hours. Using the default EnergyPlus method causes a large bias in all metrics in a dense urban area (λP = 0.6) and climates assessed (cf. the new method): external wall temperature (3 °C less, midday median), annual energy demand for cooling (17.1% less) and heating (6.2% higher), annual overheating degree hours during the day (> 28 °C, 24.5% less) and night (> 26 °C, 60.1% less). These biases are larger at lower latitudes. Thus, neglecting the surroundings influence on inter-building longwave radiation impacts critical design considerations of building energy and thermal performance in dense urban areas
Journal of Applied Meteorology and Climatology, 2021
Urban heat island (UHI) and sea–land-breeze systems are well-known and important characteristics ... more Urban heat island (UHI) and sea–land-breeze systems are well-known and important characteristics of the climate of coastal cities. To model these, the accurate estimation of the surface energy balance (SEB) is a key factor needed to improve local-scale simulations of thermodynamic and dynamic boundary circulations. The Weather Research and Forecasting Model with a single-layer urban canopy model (WRF/SLUCM), with parameters derived from MODIS and local GIS information, is used to investigate the UHI and sea-breeze circulations (SBC) in the megacity of Shanghai. The WRF/SLUCM can reproduce observed urban radiation and SEB fluxes, near-surface meteorological variables, and the evolution of the UHI and SBC. Simulations for an August period show the maximum UHI tends to drift northwest in the afternoon, driven by the prevailing southeast wind. The sea breeze lasts for about 4 h and is strongest between 1200 and 1400 local time (UTC + 8 h). The interaction between UHI and SBC is evident ...
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Papers by Sue Grimmond