Modeling impacts of roof reflectivity, integrated photovoltaic panels and green roof systems on sensible heat flux into the urban environment

Scherba, Adam; Sailor, David J.; Rosenstiel, Todd N.; Wamser, Carl C.

doi:10.1016/j.buildenv.2011.06.012

Cited by 184 publications

(85 citation statements)

References 23 publications

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“…Figure S1 reduced the near-surface air temperature up to 0.5 • C for some central areas of Phoenix and Tucson. However, during the night, the cooling was less significant and typically ranged from 0.1 to 0.2 • C. These results concur with those presented in Scherba et al (2011) and recent high-resolution modelling simulations for California (Georgescu 2015) reporting that typical black and white roofs have similar skin temperature during the night but extremely different during the day (black roofs are warmer). Figure S1 (e-h) shows the mean impacts on near-surface air temperature for a high largescale deployment scenario of rooftop solar photovoltaic panels T 2 (FPV0.75) − T 2 (CTRL).…”

Section: Regional Impacts On Near-surface Air Temperaturesupporting

confidence: 90%

“…The remaining 11 WRF model sensitivity experiments correspond to different coverage rates of both roofing technologies, considered individually or jointly (Table 1 contains the complete list of WRF model experiments). For example, the WRF model experiment hereafter denoted as ALB0.75 represents a hypothetical situation where 75 % of each roof is covered with highly reflective membranes [we characterized highly reflective surfaces with an albedo equal to 0.8 (Oleson et al 2010;Scherba et al 2011)]. Similarly, the WRF model simulation denoted as FPV0.5 describes a hypothetical situation where 50 % of each roof is covered with solar photovoltaic panels.…”

Section: Numerical Experimentsmentioning

confidence: 99%

“…For instance, Scherba et al (2011), using a sophisticated building energy model forced with weather-based datasets, reported that solar photovoltaic arrays (deployed on the top of black roofs) can reduce (on average) the daily sensible heat flux into the urban environment by 11 %. On the other hand, Masson et al (2014), by means of an offline urban canopy model, demonstrated that rooftop solar panels can reduce the near-surface air temperature of Paris, France up to 0.2 • C during the day, and the UHI intensity (i.e., the 2-m air temperature difference between the warmest urban zone and its surrounding rural neighbourhoods) up to 0.3 • C during the night under the assumption of a practical deployment scenario (in this hypothetical situation approximately 50 % of each roof was covered with solar panels).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Citywide Impacts of Cool Roof and Rooftop Solar Photovoltaic Deployment on Near-Surface Air Temperature and Cooling Energy Demand

Salamanca

Georgescu

Mahalov

et al. 2016

Boundary-Layer Meteorol

110

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Assessment of mitigation strategies that combat global warming, urban heat islands (UHIs), and urban energy demand can be crucial for urban planners and energy providers, especially for hot, semi-arid urban environments where summertime cooling demands are excessive. Within this context, summertime regional impacts of cool roof and rooftop solar photovoltaic deployment on near-surface air temperature and cooling energy demand are examined for the two major USA cities of Arizona: Phoenix and Tucson. A detailed physics-based parametrization of solar photovoltaic panels is developed and implemented in a multilayer building energy model that is fully coupled to the Weather Research and Forecasting mesoscale numerical model. We conduct a suite of sensitivity experiments (with different coverage rates of cool roof and rooftop solar photovoltaic deployment) for a 10-day clear-sky extreme heat period over the Phoenix and Tucson metropolitan areas at high spatial resolution (1-km horizontal grid spacing). Results show that deployment of cool roofs and rooftop solar photovoltaic panels reduce near-surface air temperature across the diurnal cycle and decrease daily citywide cooling energy demand. During the day, cool roofs are more effective at cooling than rooftop solar photovoltaic systems, but during the night, solar panels are more efficient at reducing the UHI effect. For the maximum coverage rate deployment, cool roofs reduced daily citywide cooling energy demand by 13-14 %, while rooftop solar photovoltaic panels by 8-11 % (without considering the additional savings derived from their electricity production). The results presented here demonstrate that deployment of both roofing technologies have multiple benefits for the urban environment, while solar photovoltaic panels add additional value because they reduce the dependence on fossil fuel consumption for electricity generation. Keywords

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Section: Regional Impacts On Near-surface Air Temperaturesupporting

confidence: 90%

Section: Numerical Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Citywide Impacts of Cool Roof and Rooftop Solar Photovoltaic Deployment on Near-Surface Air Temperature and Cooling Energy Demand

Salamanca

Georgescu

Mahalov

et al. 2016

Boundary-Layer Meteorol

110

View full text Add to dashboard Cite

show abstract

“…Simulation by Scherba et al [116] showed that peak sensible heat flux could reduce by about 70% after replacing a black roof with a white roof during the summer, and Instead of modifying the surface albedo, they increased the planetary albedo of clouds over land by 1.9% as an idealized case. It was shown that albedo enhancement caused a large residual sinking motion over land, leading to a significant decrease of 13.3% and 22.3% in global land-mean precipitation and runoff, respectively.…”

Section: Environmental Impact At Large: City and Regional Hydroclimatesmentioning

confidence: 99%

Environmental impacts of reflective materials: Is high albedo a ‘silver bullet’ for mitigating urban heat island?

Yang

Wang

Kaloush

2015

Renewable and Sustainable Energy Reviews

204

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Studies on urban heat island (UHI) have been more than a century after the phenomenon was first discovered in the early 1800s. UHI emerges as the source of many urban environmental problems and exacerbates the living environment in cities. Under the challenges of increasing urbanization and future climate changes, there is a pressing need for sustainable adaptation/mitigation strategies for UHI effects, one popular option being the use of reflective materials. While it is introduced as one effective method to reduce temperature and energy consumption in cities, its impacts on multi-dimensional environmental sustainability and large-scale non-local effect are inadequately explored. This paper provides a synthetic overview of potential environmental impacts of reflective materials at a variety of scales, ranging from energy load on a single building to regional hydroclimate. The review shows that mitigation potential of reflective materials depends on a portfolio of factors, including building characteristics, urban environment, meteorological and geographical conditions, to name a few.Precaution needs to be exercised by city planners and policy makers for large-scale deployment of reflective materials before their environmental impacts, especially on regional hydroclimates, are better understood. In general, it is recommended that optimal strategy for UHI needs to be determined on a city-by-city basis, rather than adopting a "one-solution-fits-all" strategy.

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“…Roofs can provide security and protection to users; however, these also have sustainability functions such as renewable energy by PV panels and thermal isolation by green roofs [1]. The implementation of these technologies are increasing mostly because their application is recognized by the LEED standard [2].…”

Section: Introductionmentioning

confidence: 99%

The impact of height installation on the performance of PV panels integrated into a green roof in tropical conditions

Osma

Ordóñez

Hernández

et al. 2016

WIT Transactions on Ecology and the Environment

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This paper presents a study on the effect of the height installation of PV panels in a green roof integrated photovoltaic system (GRIPV) considering warm and humid climate conditions. According to recent work, there is mutual benefit between these two applications in temperate conditions. However, it is necessary to study this interaction in tropical conditions and to establish the significance of height as a factor of installation. Therefore, an experiment was designed using three PV panels of 250 W in portrait configuration with 10° of inclination; each PV panel uses a micro-inverter. The monitoring system can gather data such as ambient temperature, PV panel temperatures, solar radiation and electrical variables. The green roof used (440 m 2 ) is located on the Electrical Engineering Building of Universidad Industrial de Santander (Colombia), where the latitude is +7.1° and the ambient temperature varies between 24°C and 30°C during daily sun-time (6 am and 6 pm), while the relative humidity fluctuates between 60% and 90%. The experiment considers two height installations (50 cm and 75 cm) for both types of roof -black and green -for three weeks. According to the results, the lower height installation and the green roof increases the power output by 2.0% and 1.0%, respectively and the combined effect is nearly 2.8%.

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Modeling impacts of roof reflectivity, integrated photovoltaic panels and green roof systems on sensible heat flux into the urban environment

Cited by 184 publications

References 23 publications

Citywide Impacts of Cool Roof and Rooftop Solar Photovoltaic Deployment on Near-Surface Air Temperature and Cooling Energy Demand

Citywide Impacts of Cool Roof and Rooftop Solar Photovoltaic Deployment on Near-Surface Air Temperature and Cooling Energy Demand

Environmental impacts of reflective materials: Is high albedo a ‘silver bullet’ for mitigating urban heat island?

The impact of height installation on the performance of PV panels integrated into a green roof in tropical conditions

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