Interactions Between Building Integrated Photovoltaics and Microclimate in Urban Environments

Solar Energy ◽  
2005 ◽  
Author(s):  
Yiping Wang ◽  
Wei Tian ◽  
Li Zhu ◽  
Jianbo Ren ◽  
Yonghui Liu ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
City Planning ◽  
Fossil Fuel ◽  
Urban Environments ◽  
Anthropogenic Heat ◽  
Partial Replacement ◽  
Radiation Balance ◽  
Cooling Load ◽  
Urban Microclimate ◽  
Building Integrated Photovoltaics

BIPV (Building Integrated Photovoltaics) has progressed in the past years and become an element to be considered in city planning. BIPV has influence on microclimate in urban environments and the performance of BIPV is also affected by urban climate. The effect of BIPV on urban microclimate can be summarized under the following four aspects. The change of absorptivity and emissivity from original building surface to PV will change urban radiation balance. After installation of PV, building cooling load will be reduced because of PV shading effect, so urban anthropogenic heat also decreases to some extent. Because PV can reduce carbon dioxide emissions which is one of the reasons for urban heat island, BIPV is useful to mitigate this phenomena. The anthropogenic heat will alter after using BIPV, because partial replacement of fossil fuel means to change sensible heat from fossil fuel to solar energy. Different urban microclimate may have various effects on BIPV performance that can be analyzed from two perspectives. Firstly, BIPV performance may decline with the increase of air temperature in densely built areas because many factors in urban areas cause higher temperature than that of the surrounding countryside. Secondly, the change of solar irradiance at the ground level under urban air pollution will lead to the variation of BIPV performance because total solar irradiance usually is reduced and each solar cell has a different spectral response characteristic. The thermal model and performance model of ventilated BIPV according to actual meteorologic data in Tianjin (China) are combined to predict PV temperature and power output in the city of Tianjin. Then, using dynamic building energy model, cooling load is calculated after BIPV installation. The calculation made based in Tianjin shows that it is necessary to pay attention to and further analyze interactions between them to decrease urban pollution, improve BIPV performance and reduce cooling load.

Interactions between Building Integrated Photovoltaics and Microclimate in Urban Environments

2005 ◽  
Vol 128 (2) ◽  
pp. 168-172 ◽  
Author(s):  
Yiping Wang ◽  
Wei Tian ◽  
Li Zhu ◽  
Jianbo Ren ◽  
Yonghui Liu ◽  
...  
Keyword(s):  
Urban Areas ◽  
City Planning ◽  
Urban Climate ◽  
Urban Environments ◽  
Performance Model ◽  
Electrical Performance ◽  
Cooling Load ◽  
Canopy Layer ◽  
Building Integrated Photovoltaics ◽  
Building Cooling

BIPV (building integrated photovoltaics) has progressed in the past years and become an element to be considered in city planning. BIPV has significant influence on microclimate in urban environments and the performance of BIPV is also affected by urban climate. The thermal model and electrical performance model of ventilated BIPV are combined to predict PV temperature and PV power output in Tianjin, China. Then, by using dynamic building energy model, the building cooling load for installing BIPV is calculated. A multi-layer model AUSSSM of urban canopy layer is used to assess the effect of BIPV on the Urban Heat Island (UHI). The simulation results show that in comparison with the conventional roof, the total building cooling load with ventilation PV roof may be decreased by 10%. The UHI effect after using BIPV relies on the surface absorptivity of original building. In this case, the daily total PV electricity output in urban areas may be reduced by 13% compared with the suburban areas due to UHI and solar radiation attenuation because of urban air pollution. The calculation results reveal that it is necessary to pay attention to and further analyze interactions between BIPV and microclimate in urban environments to decrease urban pollution, improve BIPV performance and reduce cooling load.

Solar irradiance, air pollution and temperature changes in the Arctic

1995 ◽  
Vol 352 (1699) ◽  
pp. 247-258 ◽  
Keyword(s):  
Air Pollution ◽  
Spatial Distribution ◽  
Solar Irradiance ◽  
Early Spring ◽  
Surface Radiation ◽  
The Arctic ◽  
Radiation Balance ◽  
Temperature Changes ◽  
Global Irradiance ◽  
Arctic Haze

A highly significant decrease in the annual sums of global irradiance reaching the surface of the Arctic, averaging 0.36 W m -2 per year, was derived from an analysis of 389 complete years of measurement, beginning in 1950, at 22 pyranometer stations within the Arctic Circle. The smaller data base of radiation balance measurements available showed a much smaller and statistically non-significant change. Reductions in global irradiance were most frequent in the early spring months and in the western sectors of the Arctic, coinciding with the seasonal and spatial distribution of the incursions of polluted air which give rise to the Arctic Haze. Irradiance measured in Antarctica during the same period showed a similar and more widespread decline despite the lower concentrations of pollutants. A marked increase in the surface radiation balance was recorded. Possible reasons for these interpolar anomalies and their consequences for temperature change are discussed.

scholarly journals Urban Microclimate Canopy: Design, Manufacture, Installation, and Growth Simulation of a Living Architecture Prototype

2020 ◽  
Vol 12 (15) ◽  
pp. 6004
Author(s):  
Qiguan Shu ◽  
Wilfrid Middleton ◽  
Moritz Dörstelmann ◽  
Daniele Santucci ◽  
Ferdinand Ludwig
Keyword(s):  
Parametric Design ◽  
Glass Structure ◽  
Iterative Solution ◽  
Hybrid Structure ◽  
Urban Environments ◽  
Urban Microclimate ◽  
Master's Students ◽  
Climbing Plants ◽  
Technical Structure ◽  
External Stimuli

Urban Microclimate Canopy is a digitally fabricated fiber glass structure supporting climbing plants in order to explore new ways of integrating vegetation in densely built urban environments. A prototype was designed and manufactured in the context of an interdisciplinary studio with master’s students following an approach of research by design. Varying the assembly of winding frames and fiber weaving syntax generates diverse geometric shape and structural performance. For two short-term exhibitions, ivy plants were temporarily installed in the structure. This first step was followed with a reflection of systematic integration of the growth processes of climbing plants and parametric design. An iterative solution is given, consisting of a feedback loop linking the design of the technical structure, the simulation of plant growth, and the simulation of the environmental effects of the hybrid structure. To achieve this a novel framework for simulating twining plant’s growth on network-like structures is presented: external stimuli define a cone-shaped circumnutation space (searching space model) which results in a climbing path (climbing steps model). The framework is constructed to integrate improved individual functions (such as stimuli of circumnutation) for better simulation results. To acquire more knowledge about interactions between the plants and the fiber structure, the prototype was installed permanently and planted with three different climbing plants, representing different climbing mechanisms.

scholarly journals City-Scale Building Anthropogenic Heating during Heat Waves

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1206
Author(s):  
Xuan Luo ◽  
Pouya Vahmani ◽  
Tianzhen Hong ◽  
Andrew Jones
Keyword(s):  
Urban Environment ◽  
Heat Waves ◽  
Waste Heat ◽  
Heat Emission ◽  
Urban Land Use ◽  
Anthropogenic Heat ◽  
Urban Microclimate ◽  
Energy Models ◽  
Wave Event ◽  
Building Heat

More frequent and longer duration heat waves have been observed worldwide and are recognized as a serious threat to human health and the stability of electrical grids. Past studies have identified a positive feedback between heat waves and urban heat island effects. Anthropogenic heat emissions from buildings have a crucial impact on the urban environment, and hence it is critical to understand the interactive effects of urban microclimate and building heat emissions in terms of the urban energy balance. Here we developed a coupled-simulation approach to quantify these effects, mapping urban environmental data generated by the mesoscale Weather Research and Forecasting (WRF) coupled to Urban Canopy Model (UCM) to urban building energy models (UBEM). We conducted a case study in the city of Los Angeles, California, during a five-day heat wave event in September 2009. We analyzed the surge in city-scale building heat emission and energy use during the extreme heat event. We first simulated the urban microclimate at a high resolution (500 m by 500 m) using WRF-UCM. We then generated grid-level building heat emission profiles and aggregated them using prototype building energy models informed by spatially disaggregated urban land use and urban building density data. The spatial patterns of anthropogenic heat discharge from the building sector were analyzed, and the quantitative relationship with weather conditions and urban land-use dynamics were assessed at the grid level. The simulation results indicate that the dispersion of anthropogenic heat from urban buildings to the urban environment increases by up to 20% on average and varies significantly, both in time and space, during the heat wave event. The heat dispersion from the air-conditioning heat rejection contributes most (86.5%) of the total waste heat from the buildings to the urban environment. We also found that the waste heat discharge in inland, dense urban districts is more sensitive to extreme events than it is in coastal or suburban areas. The generated anthropogenic heat profiles can be used in urban microclimate models to provide a more accurate estimation of urban air temperature rises during heat waves.

Prediction of Building Integrated Photovoltaic Cell Temperatures*

2001 ◽  
Vol 123 (3) ◽  
pp. 200-210 ◽  
Author(s):  
Mark W. Davis ◽  
A. Hunter Fanney ◽  
Brian P. Dougherty
Keyword(s):  
Heat Transfer ◽  
Environmental Conditions ◽  
Solar Irradiance ◽  
Operating Temperature ◽  
Predictive Performance ◽  
Transfer Model ◽  
Cell Temperature ◽  
Widespread Application ◽  
Building Integrated Photovoltaics ◽  
Building Integrated Photovoltaic

A barrier to the widespread application of building integrated photovoltaics (BIPV) is the lack of validated predictive performance tools. Architects and building owners need these tools in order to determine if the potential energy savings realized from building integrated photovoltaics justifies the additional capital expenditure. The National Institute of Standards and Technology (NIST) seeks to provide high quality experimental data that can be used to develop and validate these predictive performance tools. The temperature of a photovoltaic module affects its electrical output characteristics and efficiency. Traditionally, the temperature of solar cells has been characterized using the nominal operating cell temperature (NOCT), which can be used in conjunction with a calculation procedure to predict the module’s temperature for various environmental conditions. The NOCT procedure provides a representative prediction of the cell temperature, specifically for the ubiquitous rack-mounted installation. The procedure estimates the cell temperature based on the ambient temperature and the solar irradiance. It makes the approximation that the overall heat loss coefficient is constant. In other words, the temperature difference between the panel and the environment is linearly related to the heat flux on the panels (solar irradiance). The heat transfer characteristics of a rack-mounted PV module and a BIPV module can be quite different. The manner in which the module is installed within the building envelope influences the cell’s operating temperature. Unlike rack-mounted modules, the two sides of the modules may be subjected to significantly different environmental conditions. This paper presents a new technique to compute the operating temperature of cells within building integrated photovoltaic modules using a one-dimensional transient heat transfer model. The resulting predictions are compared to measured BIPV cell temperatures for two single crystalline BIPV panels (one insulated panel and one uninsulated panel). Finally, the results are compared to predictions using the NOCT technique.

scholarly journals Liquid Desiccants Applications in Cooling and Dehumidification – An Overview

2019 ◽  
pp. 1-17
Keyword(s):  
Air Conditioning ◽  
Power Plants ◽  
Fossil Fuel ◽  
Electrical Energy ◽  
Cooling Load ◽  
Vapor Compression ◽  
Vapor Compression System ◽  
Industrial Use ◽  
Optimum Cost ◽  
Effective Use

Potential option to replace the traditionally used vapor compression system with desiccant based dehumidification and cooling to overcome the problems in VCR use like as substantial consumption of high grade electrical energy and to eliminate the use of the CFC based refrigerants which are responsible for the depletion of ozone layer. The desiccant cooling can be proved to be an efficient in highly moist atmosphere to handles the latent cooling load of the conditioned space. The present overview explains about the detailed ideas for making use of various chemicals as the desiccant solution for their optimum cost and characteristics. The desiccant cooling can handle both humidity and temperature separately and effectively to produce necessary thermal comfort within the conditioned space. The desiccant cooling can find optimum use of renewable solar energy in air conditioning by applying them for desiccant regeneration to lower the consumption of electricity which produced mostly by fossil fuel based power plants which leads to problem of pollution subsequently. The present review provides the direction for effective use of the desiccant based cooling for separable control over temperature and humidity in case of both residential and industrial use to ameliorate the dual - energy and cost saving.

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