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1. Quantifying the Urban Heat Island Effects and Energy Performance of Solar-Reflective Facades: A Simulation Study in a Dense Urban Context

   Chen, C. ; Duan, Q. ; Zhang, E. ; Wang, J. ( October 2023 , The 18th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES))

   Many researchers have studied the roles of building envelope materials on UHI, such as roofs, and walls, but few of them have explored the impacts of the emergence of the solar-reflective coatings, films, and panels but well-visible transmittance that is increasingly applied to glazed building facades, especially in hot climates, for outdoor thermal environments. The question then arises: Despite the positive effects of these strong solar-reflective facades on building heating and cooling energy savings, do they have the same positive effects on the adjacent outdoor area, especially in a dense urban context? This research aims to quantify the potential UHI effects of the solar-reflective facades relative to the non-reflective ones in a dense urban context, along with the heating and cooling energy performance analysis. As such, a simulation method in terms of a series of tools including LBNL Radiance, EnergyPlus, and WINDOW software was adopted in this work to analyze the solar radiation interactions between the façade surface and the surrounding urban structures and potential temperature rise under solar-reflective and non-reflective facades. The result shows that the annual cooling energy savings by using the solar-reflective facades are about 33.8% relative to the typical double-pane clear glazed façade because of the substantial reduction of U-factor and solar heat gains; But, this preliminary work also unveils the potential adverse effects of using such materials at the urban scale, leading nearly 2 times greater solar irradiation and UHI effects than the ones by the solar-non-reflective building surfaces in an urban area. Future optimization studies on the trade-off between the building cooling energy savings and UHI effects by the solar-reflective façades need to be conducted. 

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2. A Satellite-Based Model for Estimating Latent Heat Flux From Urban Vegetation

   https://doi.org/10.3389/fevo.2021.695995  

   Smith, Ian A. ; Winbourne, Joy B. ; Tieskens, Koen F. ; Jones, Taylor S. ; Bromley, Fern L. ; Li, Dan ; Hutyra, Lucy R. ( August 2021 , Frontiers in Ecology and Evolution)

   The impacts of extreme heat events are amplified in cities due to unique urban thermal properties. Urban greenspace mitigates high temperatures through evapotranspiration and shading; however, quantification of vegetative cooling potential in cities is often limited to simple remote sensing greenness indices or sparse, in situ measurements. Here, we develop a spatially explicit, high-resolution model of urban latent heat flux from vegetation. The model iterates through three core equations that consider urban climatological and physiological characteristics, producing estimates of latent heat flux at 30-m spatial resolution and hourly temporal resolution. We find strong agreement between field observations and model estimates of latent heat flux across a range of ecosystem types, including cities. This model introduces a valuable tool to quantify the spatial heterogeneity of vegetation cooling benefits across the complex landscape of cities at an adequate resolution to inform policies addressing the effects of extreme heat events. 

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3. Energy-saving potential of 3D printed concrete building with integrated living wall

   https://doi.org/https://doi.org/10.1016/j.enbuild.2020.110110  

   He Y, Zhang Y ( September 2020 , Energy and buildings)

   Large-scale concrete 3D printing and digital construction has brought enormous potential to expand the design space of building components (e.g., building envelope) for the integration of multiple architectural functionalities including energy saving. In this research, a modular 3D printed vertical concrete green wall system – namely the 3D-VtGW, was developed. The 3D-VtGW envelope was assembled with prefabricated (3D printed) multifunctional wall modular elements, which serves as the enclosure of the building as well as the backbone for a green wall system to improve building’s energy efficiency. Using this design concept and large-scale concrete 3D printing, a prototype commercial building was built in Nanjing, China. To quantify the energy-saving potential of the 3D-VtGW system, a thermal network model was developed to simulate the thermal behavior of buildings with 3D-VtGW system and for thermal comfort analysis. Whole-building energy simulation was carried out using Chinese Standard Weather Data (CSWD) o Nanjing, China. The simulation results indicate that the building with 3D-VtGW exhibited prominent potential for energy saving and improved thermal comfort. The integrated greenery system in 3D-VtGW largely reduces wall exterior surface temperature and through-wall heat flux via the combined effects of plant shading, evapotranspiration, and heat storage from soil. This study presents the immense opportunities brought by digital fabrication and construction to extend the design space and function integration in buildings. 

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4. Co-Simulation and Validation of Automated Shading Devices using EnergyPlus and Radiance to optimize Building Energy Use

   Vanage, Soham ; Kunwar, Niraj ; Malekpour, Diba ; Cetin, Kristen ( January 2022 , ASHRAE winter conference papers)

   Buildings in the U.S. are responsible for approximately 40% of energy and 70% of the electricity consumption. To address rising greenhouse gas emissions and climate changes, various studies have explored strategies to reduce energy consumption in buildings. One opportunity to improve the building envelope performance is through improvements to fenestrations, particularly complex multi-layer fenestration systems for exterior windows. Windows are the least thermally efficient of all components in a typical building envelope. Windows also permit solar radiation into a building, which significantly increases the building energy consumption during the summer season. Meanwhile, windows are necessary to provide occupants with natural light, a view to the outside, and to support productivity. Thus, there is a need to strike a balance between energy savings, and the thermal and visual comfort impacted by windows. Traditionally, shading devices are one method used to adjust the amount of heat and light entering an interior space. However, such shading devices are typically operated manually by occupants, and are seldom used effectively over time. Currently the building energy simulation program EnergyPlus, has limited capabilities to model shading devices, and more limited abilities to model dynamic fenestrations. In this study, thus, we propose to model and validate several types of automated multi-layer fenestration elements, using co-simulation of EnergyPlus and Radiance using laboratory-collected data. EnergyPlus was used to model energy consumption and thermal comfort while Radiance was used to model lighting levels. BCVTB was used to interface between EnergyPlus and Radiance to facilitate co-simulation. To validate the models, experimental data was collected from 5 illuminance sensors in an exterior office space located in a test facility in Ankeny, IA. This model methodology can be used to improve the flexibility and modeling capabilities of dynamic fenestration elements for building energy performance evaluation methods. 

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5. Contextualizing Thermal Effluent Impacts in Narragansett Bay Using Landsat-Derived Surface Temperature

   https://doi.org/10.3389/fmars.2021.705204  

   Benoit, Jonathan ; Fox-Kemper, Baylor ( September 2021 , Frontiers in Marine Science)

   This work utilizes remotely sensed thermal data to understand how the release of thermal pollution from the Brayton Point Power Station (BPPS) affected the temperature behavior of Narragansett Bay. Building upon previous work with Landsat 5, a multi-satellite analysis is conducted that incorporates 582 scenes from Landsat 5, Landsat 7, and Landsat 8 over 1984–2021 to explain seasonal variability in effluent impacts, contrast data after the effluent ceased in 2011, identify patterns in temperature before and after effluent ceased using unsupervised learning, and track how recent warming trends compare to the BPPS impact. Stopping the thermal effluent corresponds to an immediate cooling of 0.26 ± 0.1°C in the surface temperature of Mt. Hope Bay with respect to the rest of Narragansett Bay with greater cooling of 0.62 ± 0.2°C found near Brayton Point; though, cooling since the period of maximal impact (1993–2000) totals 0.53 ± 0.2°C in Mt. Hope Bay and 1.04 ± 0.2°C at Brayton Point. During seasons with lower solar radiation (winter) and lower mean river input (autumn and late summer), the BPPS effluent impact is more prominent. The seasonal differences between the high impact and low impact periods indicate that river input played an important role in the heat balance when emissions were lower, but surface fluxes dominated when emissions were higher. Putting the BPPS effluent in context, Landsat data indicates that Narragansett Bay warmed 0.5–1.2°C over the period of measurement at an average rate of 0.23 ± 0.1°C/decade and that net warming in Mt. Hope Bay is near zero. This trend implies that Narragansett Bay has experienced climatic warming over the past four decades on the scale of the temperature anomaly in Mt. Hope Bay caused by the BBPS effluent. 

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