scholarly journals Comparative Thermal Analysis of Different Cool Roof Materials for Minimizing Building Energy Consumption

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Y. Anand ◽  
A. Gupta ◽  
A. Maini ◽  
Avi Gupta ◽  
A. Sharma ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Urban Areas ◽  
Electricity Consumption ◽  
Building Envelope ◽  
Comfort Level ◽  
Urban Heat Islands ◽  
Heat Islands ◽  
Cool Roof ◽  
Cool Roofs ◽  
The Impact

The roof and walls in the urban areas contribute to major share in the absorption of solar radiations and also retard the outflow of the absorbed radiation from the building envelope, thereby increasing the global warming by inducing the heat island effect. The impact of using cool roof technologies on the thermal comfort of the office buildings has been estimated. Cool roofs reduce electricity consumption for maintaining the temperature of the air-conditioned buildings in the comfort level and also increase comfort in buildings merely not relying completely on cooling equipment. The cool roofs and cool pavements, however, can mitigate summer urban heat islands by improving indoor air quality and comfort. The thermal analysis of different materials has been carried out to analyze the impact of the rate of heat transfer on the building envelope and the results obtained indicate that different cool roof techniques are beneficial in maintaining the comfort level of the building which purely depends on the ambient temperature conditions.

Synergistic Interactions between Urban Heat Islands and Heat Waves: The Impact in Cities Is Larger than the Sum of Its Parts

2013 ◽  
Vol 52 (9) ◽  
pp. 2051-2064 ◽  
Author(s):  
Dan Li ◽  
Elie Bou-Zeid
Keyword(s):  
Urban Heat Island ◽  
Rural Areas ◽  
Urban Areas ◽  
Heat Waves ◽  
Mitigation Strategies ◽  
Urban Heat Islands ◽  
Heat Island ◽  
Heat Islands ◽  
Urban Heat ◽  
The Impact

AbstractCities are well known to be hotter than the rural areas that surround them; this phenomenon is called the urban heat island. Heat waves are excessively hot periods during which the air temperatures of both urban and rural areas increase significantly. However, whether urban and rural temperatures respond in the same way to heat waves remains a critical unanswered question. In this study, a combination of observational and modeling analyses indicates synergies between urban heat islands and heat waves. That is, not only do heat waves increase the ambient temperatures, but they also intensify the difference between urban and rural temperatures. As a result, the added heat stress in cities will be even higher than the sum of the background urban heat island effect and the heat wave effect. Results presented here also attribute this added impact of heat waves on urban areas to the lack of surface moisture in urban areas and the low wind speed associated with heat waves. Given that heat waves are projected to become more frequent and that urban populations are substantially increasing, these findings underline the serious heat-related health risks facing urban residents in the twenty-first century. Adaptation and mitigation strategies will require joint efforts to reinvent the city, allowing for more green spaces and lesser disruption of the natural water cycle.

scholarly journals Thermal Comfort Level Assessment in Urban Area of Petrolina-PE County, Brazil

2017 ◽  
Vol 32 (4) ◽  
pp. 555-563 ◽  
Author(s):  
Pedro Vieira de Azevedo ◽  
Péricles Tadeu da Costa Bezerra ◽  
Mario de Miranda Vilas Boas Ramos Leitão ◽  
Carlos Antonio Costa dos Santos
Keyword(s):  
Thermal Comfort ◽  
Urban Area ◽  
Rural Areas ◽  
Urban Areas ◽  
Thermal Conditions ◽  
Comfort Level ◽  
Urban Heat Islands ◽  
Thermal Discomfort ◽  
Heat Islands ◽  
Urban And Rural Areas

Abstract This study evaluated the thermal conditions of urban areas in Petrolina-PE, from continuous data collected in urban and rural areas for the year of 2012. The results characterized urban heat islands (UHI) with varying intensity in urban areas, especially UHI = 5.3 °C (high intensity) occurred on April 28, 2012. It was evident that the constituent elements of urban areas contribute to the formation and expansion of UHI bringing thermal discomfort for its inhabitants. An adaptation to Thom’s equation for calculating the Thermal Discomfort Index (DIT), was used to obtain the maximum (DITx) and minimum (DITm) thermal discomfort. In the urban area, the DITm indicated thermal comfort in 23.0% of the days and partial comfort in 77.0% of days surveyed. Already, the DITx characterized 71.6% of days with partial comfort and 28.4% of days with thermal discomfort. In the rural area, The DITm indicated that 41.5% of days were thermally comfortable and 58.5% of days had partial comfort. However, the DITx pointed 87.7% of the days of this environment with partial thermal comfort and 12.3% of thermally uncomfortable days. Finally, the results showed that afforestation of urban area constitutes to an effective and efficient way to mitigate thermal discomfort.

scholarly journals The Effect of Cool Roofs on the Achieving of Energy Conservation with the Administrative Building Spaces

2020 ◽  
Vol 27 (3) ◽  
pp. 112-124
Author(s):  
Duaa Faal Niama ◽  
Ghada Mohammed Kammou
Keyword(s):  
Energy Conservation ◽  
Urban Environment ◽  
Thermal Performance ◽  
Fossil Fuels ◽  
Research Problem ◽  
Building Envelope ◽  
Conservation Of Energy ◽  
Cool Roof ◽  
Cool Roofs ◽  
The Impact

The world has gone beyond the realization that fossil fuels are a depleted energy source, that the earth is going through a global warming phase, and that it is important to find the necessary energy alternatives, with the least environmental impact, and to address energy consumption in the building sector in particular. Passive systems and their use, or combined with effective systems. due to the dependence of the Iraqi urban environment on the electricitySignificantly and the source of fossil fuel, it is important to find suitable solutions, especially in the summer because of high temperatures and increased drought, by taking advantage of the experiences of countries within this scope, and applied to buildings , Because the roof is the main source of thermal gain inside the buildings it is necessary to take the systems of cool roofs, which is a passive system in the roofing of buildings, contribute to improving the internal environment and achieve the thermal comfort of the occupants, the research problem was:"There is no clear conception of the possibility of applying cool roof systems in the local administrative buildings" and The objective of the research is to" clarify the importance of achieving the concept of conservation of energy and improve thermal performance through the application of cool roof systems in the administrative buildings in the urban environment of Iraq with a hot- dry climate, "and then ensure the research Two aspects,first one:The concept of thermal performance and conservation of energy in administrative buildings and the way of achieving energy conservation using cool roofs, while the practical side included: the handling of several global experiences of sustainable administrative buildings used cool roofs and indicate the impact of this system on the efficiency of thermal performance, The research concluded that it is possible to apply cool roofs in claimte of  Iraq (hot-dry) because the cool roof has the ability to reflect a large amount of solar radiation falling on the surface of the roof, thereby reducing the thermal gain of the building and improve the thermal performance of the administrative building envelope, and as a result achieved Save energy within its spaces

scholarly journals The Impact of Green Roofs on the Parameters of the Environment in Urban Areas—Review

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 792 ◽  
Author(s):  
Dariusz Suszanowicz ◽  
Alicja Kolasa Więcek
Keyword(s):  
Urban Areas ◽  
Central And Eastern Europe ◽  
Single Case ◽  
Green Roofs ◽  
Urban Heat Islands ◽  
Heat Islands ◽  
Urban Heat ◽  
The Impact ◽  
The City

This study presents the results of a review of publications conducted by researchers in a variety of climates on the implementation of ‘green roofs’ and their impact on the urban environment. Features of green roofs in urban areas have been characterized by a particular emphasis on: Filtration of air pollutants and oxygen production, reduction of rainwater volume discharged from roof surfaces, reduction of so-called ‘urban heat islands’, as well as improvements to roof surface insulation (including noise reduction properties). The review of the publications confirmed the necessity to conduct research to determine the coefficients of the impact of green roofs on the environment in the city centers of Central and Eastern Europe. The results presented by different authors (most often based on a single case study) differ significantly from each other, which does not allow us to choose universal coefficients for all the parameters of the green roof’s impact on the environment. The work also includes analysis of structural recommendations for the future model green roof study, which will enable pilot research into the influence of green roofs on the environment in urban agglomerations and proposes different kinds of plants for different kinds of roofs, respectively.

scholarly journals Domestic Electricity Consumption in Mexican Metropolitan Areas under Climate Change Scenarios

2021 ◽  
Author(s):  
Adalberto Tejeda Martínez ◽  
Irving Rafael Méndez Pérez ◽  
Daniela Alejandra Cruz Pastrana
Keyword(s):  
Climate Change ◽  
Urban Areas ◽  
Metropolitan Areas ◽  
Electricity Consumption ◽  
The United States ◽  
Urban Heat Islands ◽  
Climate Change Scenarios ◽  
Heat Islands ◽  
Residential Electricity ◽  
Bioclimatic Conditions

The following estimates analyse human bioclimatic conditions due to climate change in three time horizons, as suggested by Article 2 of the Paris Agreement. Each scenario corresponds to an increase in the global average temperature (∆T) of 1 ºC, 1.5 ºC and 2 ºC, respectively. The measurements of residential electricity consumption for air conditioning were made in 30 metropolitan areas of Mexico with at least half a million inhabitants in 2010. Bioclimatic conditions also included estimates of the effects of urban heat islands (UHI). Use of heating will decrease and, in some cases, disappear, while the need for cooling will increase. Electricity consumption due to cooling is expected to increase in Mexicali, Reynosa-Río Bravo (on the border with the United States), Cancún, Villahermosa, and Veracruz (on the shores of the Caribbean Sea and the Gulf of Mexico). Urban areas like Toluca, Pachuca, Xalapa, San Luis Potosí, and Puebla-Tlaxcala used little or no energy for cooling in the second decade of the 21st century but will need to do so halfway through the century.

scholarly journals Evaluation of the Impact of the Envelope System on Thermal Energy Demand in Hospital Buildings

Buildings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 250
Author(s):  
Katia Jiménez Mejía ◽  
María del Mar Barbero-Barrera ◽  
Manuel Rodríguez Pérez
Keyword(s):  
Energy Demand ◽  
Construction Materials ◽  
Building Envelope ◽  
Urban Heat Islands ◽  
Heat Islands ◽  
Average Value ◽  
The Hours ◽  
Energy Simulations ◽  
Glass Surfaces ◽  
The Impact

Construction materials and systems for the thermal building envelope have played a key role in the improvement of energy efficiency in buildings. Urban heat islands together with the upcoming rising global temperature demand construction solutions that are adapted to the specific microclimate conditions. These circumstances are even more dramatic in the case of healthcare buildings where the need to preserve constant indoor temperatures is a priority for the proper recovery of patients. A new neonatal hospital, located in Madrid (Spain), has been monitored, and building energy simulations were performed to evaluate the effect of the building envelope on the energy demand. Based on the simulation results, the design of the building envelope was found to be insufficiently optimised to properly protect the building from the external heat flow. This is supported by the monitored results of the indoor temperatures, which went over the standard limit for about 50% of the hours, achieving up to 27 °C in June and July, and 28 °C in August. The results showed, on one hand, that solar radiation gains transmitted through the façade have an important impact on the indoor temperature in the analysed rooms. Heat gains through the opaque envelope showed an average of 8.37 kWh/day, followed by heat gains through the glazing with an average value of 5.29 kWh/day; while heat gains from lighting and occupancy were 5.21 kWh/day and 4.47 kWh/day, respectively. Moreover, it was shown that a design of the envelope characterised by large glass surfaces and without solar protection systems, resulted in excessive internal thermal loads that the conditioning system was not able to overcome.

scholarly journals Urban Heat Islands and Thermal Comfort: A Case Study of Zorrotzaurre Island in Bilbao

2021 ◽  
Vol 13 (11) ◽  
pp. 6106
Author(s):  
Irantzu Alvarez ◽  
Laura Quesada-Ganuza ◽  
Estibaliz Briz ◽  
Leire Garmendia
Keyword(s):  
Thermal Comfort ◽  
Heat Waves ◽  
Urban Environments ◽  
Urban Heat Islands ◽  
Extreme Weather Events ◽  
Climate Index ◽  
Physiological Equivalent Temperature ◽  
Heat Islands ◽  
The North ◽  
The Impact

This study assesses the impact of a heat wave on the thermal comfort of an unconstructed area: the North Zone of the Island of Zorrotzaurre (Bilbao, Spain). In this study, the impact of urban planning as proposed in the master plan on thermal comfort is modeled using the ENVI-met program. Likewise, the question of whether the urbanistic proposals are designed to create more resilient urban environments is analyzed in the face of increasingly frequent extreme weather events, especially heat waves. The study is centered on the analysis of temperature variables (air temperature and average radiant temperature) as well as wind speed and relative humidity. This was completed with the parameters of thermal comfort, the physiological equivalent temperature (PET) and the Universal Temperature Climate Index (UTCI) for the hours of the maximum and minimum daily temperatures. The results demonstrated the viability of analyzing thermal comfort through simulations with the ENVI-met program in order to analyze the behavior of urban spaces in various climate scenarios.

scholarly journals Green roofs and cool materials as retrofitting strategies for urban heat island mitigation: Case study in Belgrade, Serbia

2018 ◽  
Vol 22 (6 Part A) ◽  
pp. 2309-2324
Author(s):  
Marija Lalosevic ◽  
Mirko Komatina ◽  
Marko Milos ◽  
Nedzad Rudonja
Keyword(s):  
Green Roofs ◽  
Urban Heat Islands ◽  
Temperature Changes ◽  
Heat Islands ◽  
Air Temperatures ◽  
Urban Heat ◽  
Microclimatic Conditions ◽  
Typical Summer ◽  
Planning And Construction ◽  
The Impact

The effect of extensive and intensive green roofs on improving outdoor microclimate parameters of urban built environments is currently a worldwide focus of research. Due to the lack of reliable data for Belgrade, the impact of extensive and intensive green roof systems on mitigating the effects of urban heat islands and improving microclimatic conditions by utilizing high albedo materials in public spaces were studied. Research was conducted on four chosen urban units within existing residential blocks in the city that were representative of typical urban planning and construction within the Belgrade metropolitan area. Five different models (baseline model and four potential models of retrofitting) were designed, for which the temperature changes at pedestrian and roof levels at 07:00, 13:00, 19:00 h, on a typical summer day, and at 01:00 h, the following night in Belgrade were investigated. The ENVI-met software was used to model the simulations. The results of numerical modeling showed that utilizing green roofs in the Belgrade climatic area could reduce air temperatures in the surroundings up to 0.47, 1.51, 1.60, 1.80 ?C at pedestrian level and up to 0.53, 1.45, 0.90, 1.45 ?C at roof level for four potential retrofitting strategies, respectively.

scholarly journals Sensitivity Analysis of Occupant Preferences on Energy Usage in Residential Buildings

2021 ◽  
Author(s):  
Kaleb Pattawi ◽  
Prateek Munankarmi ◽  
Michael Blonsky ◽  
Jeff Maguire ◽  
Sivasathya Pradha Balamurugan ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Thermal Comfort ◽  
Residential Buildings ◽  
Electricity Consumption ◽  
Cost Savings ◽  
The United States ◽  
Comfort Level ◽  
Electrical Grid ◽  
Home Energy Management ◽  
The Impact

Abstract Residential buildings, accounting for 37% of the total electricity consumption in the United States, are suitable for demand response (DR) programs to support effective and economical operation of the power system. A home energy management system (HEMS) enables residential buildings to participate in such programs, but it is also important for HEMS to account for occupant preferences to ensure occupant satisfaction. For example, people who prefer a higher thermal comfort level are likely to consume more energy. In this study, we used foresee™, a HEMS developed by the National Renewable Energy Lab (NREL), to perform a sensitivity analysis of occupant preferences with the following objectives: minimize utility cost, minimize carbon footprint, and maximize thermal comfort. To incorporate the preferences into the HEMS, the SMARTER method was used to derive a set of weighting factors for each objective. We performed week-long building energy simulations using a model of a home in Fort Collins, Colorado, where there is mandatory time-of-use electricity rate structure. The foresee™ HEMS was used to control the home with six different sets of occupant preferences. The study shows that occupant preferences can have a significant impact on energy consumption and is important to consider when modeling residential buildings. Results show that the HEMS could achieve energy reduction ranging from 3% to 21%, cost savings ranging from 5% to 24%, and carbon emission reduction ranging from 3% to 21%, while also maintaining a low thermal discomfort level ranging from 0.78 K-hour to 6.47 K-hour in a one-week period during winter. These outcomes quantify the impact of varying occupant preferences and will be useful in controlling the electrical grid and developing HEMS solutions.

Should Cities Embrace Their Heat Islands as Shields from Extreme Cold?

2018 ◽  
Vol 57 (6) ◽  
pp. 1309-1320 ◽  
Author(s):  
Jiachuan Yang ◽  
Elie Bou-Zeid
Keyword(s):  
Urban Areas ◽  
Heat Waves ◽  
Anthropogenic Heat ◽  
Mitigation Measures ◽  
Cold Wave ◽  
Cold Waves ◽  
Heat Islands ◽  
Extreme Cold ◽  
Anthropogenic Modifications ◽  
Cool Roofs

AbstractThe higher temperature in cities relative to their rural surroundings, known as the urban heat island (UHI), is one of the most well documented and severe anthropogenic modifications of the environment. Heat islands are hazardous to residents and the sustainability of cities during summertime and heat waves; on the other hand, they provide considerable benefits in wintertime. Yet, the evolution of UHIs during cold waves has not yet been explored. In this study, ground-based observations from 12 U.S. cities and high-resolution weather simulations show that UHIs not only warm urban areas in the winter but also further intensify during cold waves by up to 1.32° ± 0.78°C (mean ± standard deviation) at night relative to precedent and subsequent periods. Anthropogenic heat released from building heating is found to contribute more than 30% of the UHI intensification. UHIs thus serve as shelters against extreme-cold events and provide benefits that include mitigating cold hazard and reducing heating demand. More important, simulations indicate that standard UHI mitigation measures such as green or cool roofs reduce these cold-wave benefits to different extents. Cities, particularly in cool and cold temperate climates, should hence revisit their policies to favor (existing) mitigation approaches that are effective only during hot periods.

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