scholarly journals Revising the definition of anthropogenic heat flux from buildings: role of human activities and building storage heat flux

2021 ◽  
Author(s):  
Yiqing Liu ◽  
Zhiwen Luo ◽  
Sue Grimmond
Keyword(s):  
Heat Flux ◽  
Energy Consumption ◽  
Energy Balance ◽  
Human Activities ◽  
Building Energy ◽  
Heat Emission ◽  
Heat Fluxes ◽  
Anthropogenic Heat ◽  
Anthropogenic Heat Flux ◽  
The Difference

Abstract. Buildings are a major source of anthropogenic heat emissions, impacting energy use and human health in cities. The difference between building energy consumption and building anthropogenic heat emission magnitudes and time lag and are poorly quantified. Energy consumption (QEC) is a widely used proxy for the anthropogenic heat flux from buildings (QF,B). Here we revisit the latter’s definition. If QF,B is the heat emission to the outdoor environment from human activities within buildings, we can derive it from the changes in energy balance fluxes between occupied and unoccupied buildings. Our derivation shows the difference between QEC and QF,B is attributable to a change in the storage heat flux induced by human activities (∆So-uo) (i.e., QF,B = QEC − ∆So-uo). Using building energy simulations (EnergyPlus) we calculate the energy balance fluxes for a simplified isolated building (obtaining QF,B, QEC, ∆So-uo) with different occupancy states. The non-negligible differences in diurnal patterns between QF,B and QEC caused by thermal storage (e.g. hourly QF,B to QEC ratios vary between −2.72 and 5.13 within a year in Beijing, China). Negative QF,B can occur as human activities can reduce heat emission from building but are associated with a large storage heat flux. Building operations (e.g., open windows, use of HVAC system) modify the QF,B by affecting not only QEC but also the ∆So-uo diurnal profile. Air temperature and solar radiation are critical meteorological factors explaining day-to-day variability of QF,B. Our new approach could be used to provide data for future parameterisations of both anthropogenic heat flux and storage heat fluxes from buildings. It is evident that storage heat fluxes in cities may also be impacted by occupant behaviour.

scholarly journals On the Assessment of a Cooling Tower Scheme for High-Resolution Numerical Weather Modeling for Urban Areas

2019 ◽  
Vol 58 (6) ◽  
pp. 1399-1415 ◽  
Author(s):  
Miao Yu ◽  
Jorge González ◽  
Shiguang Miao ◽  
Prathap Ramamurthy
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Urban Areas ◽  
Cooling Tower ◽  
Absolute Humidity ◽  
Heat Fluxes ◽  
Anthropogenic Heat ◽  
Near Surface ◽  
Anthropogenic Heat Flux ◽  
Temperature Errors

AbstractA cooling tower scheme that quantifies the sensible and latent anthropogenic heat fluxes released from buildings was coupled to an operational forecasting system [Rapid Refresh Multiscale Analysis and Prediction of the Beijing Urban Meteorological Institute (RMAPS-Urban)] and was evaluated in the context of the megacity of Beijing, China, during summer months. The objective of this scheme is to correct for underestimations of surface latent heat fluxes in regional climate modeling and weather forecasts in urban areas. The performance for surface heat fluxes by the modified RMAPS-Urban is greatly improved when compared with a suite of observations in Beijing. The cooling tower scheme increases the anthropogenic latent heat partition by 90% of the total anthropogenic heat flux release. Averaged surface latent heat flux in urban areas increases to about 64.3 W m−2 with a peak of 150 W m−2 on dry summer days and 40.35 W m−2 with a peak of 150 W m−2 on wet summer days. The model performance of near-surface temperature and humidity is also improved. Average 2-m temperature errors are reduced by 1°C, and maximum and minimum temperature errors are improved by 2°–3°C; absolute humidity is increased by 5%.

scholarly journals Anthropogenic Heat Flux Estimation Based on Luojia 1-01 New Nighttime Light Data: A Case Study of Jiangsu Province, China

2020 ◽  
Vol 12 (22) ◽  
pp. 3707
Author(s):  
Zhongli Lin ◽  
Hanqiu Xu
Keyword(s):  
Heat Flux ◽  
Energy Consumption ◽  
Urban Climate ◽  
Power Estimation ◽  
Anthropogenic Heat ◽  
Economic Activities ◽  
Estimation Model ◽  
Nighttime Light Data ◽  
Anthropogenic Heat Flux ◽  
Nighttime Light

With the rapid process of urbanization, anthropogenic heat generated by human activities has become an important factor that drives the changes in urban climate and regional environmental quality. The nighttime light (NTL) data can aptly reflect the spatial distribution of social-economic activities and energy consumption, and quantitatively estimate the anthropogenic heat flux (AHF) distribution. However, the commonly used DMSP/OLS and Suomi-NPP/VIIRS NTL data are restricted by their coarse spatial resolution and, therefore, cannot exhibit the spatial details of AHF at city scale. The 130 m high-resolution NTL data obtained by Luojia 1-01 satellite launched in June 2018 shows a promise to solve this problem. In this paper, the gridded AHF spatial estimation is achieved with a resolution of 130 m using Luojia 1-01 NTL data based on three indexes, NTLnor (Normalized Nighttime Light Data), HSI (Human Settlement Index), and VANUI (Vegetation Adjusted NTL Urban Index). We chose Jiangsu, a fast-developing province in China, as an example to determine the best AHF estimation model among the three indexes. The AHF of 96 county-level cities of the province was first calculated using energy-consumption statistics data and then correlated with the corresponding data of three indexes. The results show that based on a 5-fold cross-validation approach, the VANUI power estimation model achieves the highest R2 of 0.8444 along with the smallest RMSE of 4.8277 W·m−2 and therefore has the highest accuracy among the three indexes. According to the VANUI power estimation model, the annual mean AHF of Jiangsu in 2018 was 2.91 W·m−2. Of the 96 cities, Suzhou has the highest annual mean AHF of 7.41 W·m−2, followed by Wuxi, Nanjing, Changzhou and Zhenjiang, with the annual mean of 3.80–5.97 W·m−2, while the figures of Suqian, Yancheng, Lianyungang, and Huaian, the cities in northern Jiangsu, are relatively low, ranging from 1.41 to 1.59 W·m−2. This study has shown that the AHF estimation model developed by Luojia 1-01 NTL data can achieve higher accuracy at city-scale and discriminate the spatial detail of AHF effectively.

scholarly journals Evaluation of the Town Energy Balance Model in Cold and Snowy Conditions during the Montreal Urban Snow Experiment 2005

2010 ◽  
Vol 49 (3) ◽  
pp. 346-362 ◽  
Author(s):  
A. Lemonsu ◽  
S. Bélair ◽  
J. Mailhot ◽  
S. Leroyer
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Transition Period ◽  
Sensible Heat Flux ◽  
Heat Fluxes ◽  
Surface Radiation ◽  
Anthropogenic Heat ◽  
Balance Model ◽  
Spatial And Temporal Variability ◽  
The Town

Abstract Using the Montreal Urban Snow Experiment (MUSE) 2005 database, surface radiation and energy exchanges are simulated in offline mode with the Town Energy Balance (TEB) and the Interactions between Soil, Biosphere, and Atmosphere (ISBA) parameterizations over a heavily populated residential area of Montreal, Quebec, Canada, during the winter–spring transition period (from March to April 2005). The comparison of simulations with flux measurements indicates that the system performs well when roads and alleys are snow covered. In contrast, the storage heat flux is largely underestimated in favor of the sensible heat flux at the end of the period when snow is melted. An evaluation and an improvement of TEB’s snow parameterization have also been conducted by using snow property measurements taken during intensive observational periods. Snow density, depth, and albedo are correctly simulated by TEB for alleys where snow cover is relatively homogeneous. Results are not as good for the evolution of snow on roads, which is more challenging because of spatial and temporal variability related to human activity. An analysis of the residual term of the energy budget—including contributions of snowmelt, heat storage, and anthropogenic heat—is performed by using modeling results and observations. It is found that snowmelt and anthropogenic heat fluxes are reasonably well represented by TEB–ISBA, whereas storage heat flux is underestimated.

Observing the surface radiation and energy balance, carbon dioxide and methane fluxes over the city centre of Amsterdam

2020 ◽  
Author(s):  
Gert-Jan Steeneveld ◽  
Sophie van der Horst ◽  
Bert Heusinkveld
Keyword(s):  
Carbon Dioxide ◽  
Heat Flux ◽  
Energy Balance ◽  
Surface Radiation ◽  
Anthropogenic Heat ◽  
City Centre ◽  
Gas Fluxes ◽  
Anthropogenic Heat Flux ◽  
Greenhouse Gas Fluxes ◽  
The City

<p>Cities largely affect boundary-layer climates due to complex surface structures, pollutant emissions, and anthropogenic heat release. As urban populations are expanding worldwide, insight is required into the urban surface radiation and energy balance and urban greenhouse gas fluxes. However, little long-term flux measurement records are available for dense city centres. We present one year (June 2018 - May 2019) of flux observations taken at a 40-meters tower in the city centre of Amsterdam. We analyse the diurnal and seasonal variation of the turbulent and greenhouse gas fluxes, and we estimate the flux footprint to gain insight in flux variation with wind direction. Also, anthropogenic heat flux and storage fluxes are estimated from emission inventories and the objective hysteresis model respectively. This analysis shows that, especially during the winter, the sum of the sensible and latent heat flux exceeds the net radiation. Thus, the storage flux and anthropogenic heat flux are significant energy providers. Also, we find a surprisingly good surface energy balance closure, especially during summer. To achieve annual energy closure, the sensible heat and latent heat flux require an increase of 13%. Moreover, we find that the measured carbon dioxide flux (45 kg CO<sub>2</sub> m<sup>-2</sup> y<sup>-1</sup>) is close to bottom-up source quantification (47 kg CO<sub>2</sub> m<sup>-2</sup> y<sup>-1</sup>). For some wind directions, the agreement is better than for others. In addition, we show that the annual methane emission is slightly higher than the emission found in Florence and London. Yet the methane source partitioning in Amsterdam remains open for more research.</p>

scholarly journals Energy balance measurements over a banana orchard in the Semiarid region in the Northeast of Brazil

2009 ◽  
Vol 44 (11) ◽  
pp. 1365-1373 ◽  
Author(s):  
Carlos Antonio Costa dos Santos ◽  
Bernardo Barbosa da Silva ◽  
Tantravahi Venkata Ramana Rao ◽  
Christopher Michael Usher Neale
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Eddy Covariance ◽  
Heat Fluxes ◽  
Irrigation District ◽  
Semiarid Region ◽  
Energy Balance Closure ◽  
Wet Season ◽  
Growing Seasons ◽  
Eddy Covariance System

The objective of this work was to evaluate the reliability of eddy covariance measurements, analyzing the energy balance components, evapotranspiration and energy balance closure in dry and wet growing seasons, in a banana orchard. The experiment was carried out at a farm located within the irrigation district of Quixeré, in the Lower Jaguaribe basin, in Ceará state, Brazil. An eddy covariance system was used to measure the turbulent flux. An automatic weather station was installed in a grass field to obtain the reference evapotranspiration (ET0) from the combined FAO-Penman-Monteith method. Wind speed and vapor pressure deficit are the most important variables on the evaporative process in both growing seasons. In the dry season, the heat fluxes have a similar order of magnitude, and during the wet season the latent heat flux is the largest. The eddy covariance system had acceptable reliability in measuring heat flux, with actual evapotranspiration results comparing well with those obtained by using the water balance method. The energy balance closure had good results for the study area, with mean values of 0.93 and 0.86 for the dry and wet growing seasons respectively.

scholarly journals Estimating evaporation with thermal UAV data and two-source energy balance models

2016 ◽  
Vol 20 (2) ◽  
pp. 697-713 ◽  
Author(s):  
H. Hoffmann ◽  
H. Nieto ◽  
R. Jensen ◽  
R. Guzinski ◽  
P. Zarco-Tejada ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
High Resolution ◽  
Eddy Covariance ◽  
Land Surface ◽  
Weather Conditions ◽  
Heat Fluxes ◽  
Thermal Camera ◽  
Model Input ◽  
Eddy Covariance Measurements

Abstract. Estimating evaporation is important when managing water resources and cultivating crops. Evaporation can be estimated using land surface heat flux models and remotely sensed land surface temperatures (LST), which have recently become obtainable in very high resolution using lightweight thermal cameras and Unmanned Aerial Vehicles (UAVs). In this study a thermal camera was mounted on a UAV and applied into the field of heat fluxes and hydrology by concatenating thermal images into mosaics of LST and using these as input for the two-source energy balance (TSEB) modelling scheme. Thermal images are obtained with a fixed-wing UAV overflying a barley field in western Denmark during the growing season of 2014 and a spatial resolution of 0.20 m is obtained in final LST mosaics. Two models are used: the original TSEB model (TSEB-PT) and a dual-temperature-difference (DTD) model. In contrast to the TSEB-PT model, the DTD model accounts for the bias that is likely present in remotely sensed LST. TSEB-PT and DTD have already been well tested, however only during sunny weather conditions and with satellite images serving as thermal input. The aim of this study is to assess whether a lightweight thermal camera mounted on a UAV is able to provide data of sufficient quality to constitute as model input and thus attain accurate and high spatial and temporal resolution surface energy heat fluxes, with special focus on latent heat flux (evaporation). Furthermore, this study evaluates the performance of the TSEB scheme during cloudy and overcast weather conditions, which is feasible due to the low data retrieval altitude (due to low UAV flying altitude) compared to satellite thermal data that are only available during clear-sky conditions. TSEB-PT and DTD fluxes are compared and validated against eddy covariance measurements and the comparison shows that both TSEB-PT and DTD simulations are in good agreement with eddy covariance measurements, with DTD obtaining the best results. The DTD model provides results comparable to studies estimating evaporation with similar experimental setups, but with LST retrieved from satellites instead of a UAV. Further, systematic irrigation patterns on the barley field provide confidence in the veracity of the spatially distributed evaporation revealed by model output maps. Lastly, this study outlines and discusses the thermal UAV image processing that results in mosaics suited for model input. This study shows that the UAV platform and the lightweight thermal camera provide high spatial and temporal resolution data valid for model input and for other potential applications requiring high-resolution and consistent LST.

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