Hashem Akbari

Hashem Akbari
Concordia University Montreal · Faculty of Engineering and Computer Science

High School Diploma

About

246
Publications
94,112
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
17,137
Citations
Citations since 2016
36 Research Items
9828 Citations
201620172018201920202021202205001,0001,500
201620172018201920202021202205001,0001,500
201620172018201920202021202205001,0001,500
201620172018201920202021202205001,0001,500
Additional affiliations
January 1926 - November 2016
Concordia University Montreal
Position
  • Secretary of the Heat Island Group (Hashem dot Akbari at Concordia dot ca)
January 1920 - present
Concordia University Montreal
Position
  • Professor (Full)
Description
  • My email is Hashem.Akbari 'at'' Concordia dot com

Publications

Publications (246)
Article
A single performance indicator, the solar transmittance factor (STF), has been proposed in previous works, together with the derived solar transmittance index (STI). It is aimed at evaluating the summer performance of the roofing system and allowing the selection of the most effective mix of surface and mass properties. It is easily calculated from...
Book
Full-text available
Global Urban Heat Island Mitigation: Trends, Impacts, Strategies, and Technologies provides a comprehensive picture of global UHI micro-thermal interaction in different built environments. It explains the physical principles and how to moderate the undesirable consequences of swift and haphazard urban development to create more sustainable and resi...
Article
Integrated implementation of spatial and climate information is important for urban thermal environmental optimization. Sky view factor (SVF) is an urban form evaluation index widely used to study the relationship between geometrical parameters and microclimate characteristics. This relationship depends on the climate condition and the time scale o...
Article
Full-text available
The summer behavior of an opaque building component subjected to the solar cycle depends on the combination of its thermal insulation, inertia, and solar reflectance. To rate the component dynamic behavior while an air conditioning system ensures a steady indoor temperature, a ‘solar transmittance index’ (STI) has been proposed. This is a component...
Article
Heat-related mortality (HRM) is increasing because of the climate change and urbanization leading to extreme heat events. This paper summarizes the results of the excess mortality attributed to excessive heat events in two largest cities in Canada, Toronto and Montreal, during the three heat wave periods. We present an application of a fine-resolut...
Article
The objective of this paper is to review the topics related to the optimized operation of intelligent buildings with respect to occupant comfort and energy consumption. To simultaneously optimize energy costs and indoor environmental quality, intelligent buildings should consider several continuously changing inputs including energy exchange proces...
Article
Full-text available
The online Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is used to simulate the effects of albedo enhancement on aerosol, radiation, and cloud interactions in the Greater Montreal Area during the 2011 heat wave period. We used a 2-way nested approach to capture the full impacts of meteorological and photochemical reactio...
Conference Paper
Heat-related mortality (HRM) is increasing as a result of climate change leading to extreme heat events. Increasing surface reflectivity is applied to mitigate the effects of heat island and high temperature in urban areas. The Weather Research and Forecasting model (WRF) is coupled with a multi-layer of the Urban Canopy Model (ML-UCM) to investiga...
Article
Full-text available
Tropical cities aremore susceptible to the suggested fall outs fromprojected globalwarming scenarios as they are located in the Torrid Zone and growing at rapid rates. Therefore, research on the mitigation of urban heat island (UHI) effects in tropical cities has attainedmuch significance and increased immensely over recent years. TheUHI mitigation...
Conference Paper
The weather research and forecasting model with chemistry (WRF-Chem) is coupled with a multi-layer of the urban canopy model (ML-UCM) to illustrate the effects of albedo enhancement on urban climate and air quality over North America, focusing on Sacramento, Houston, Chicago and Montreal, during the 2011 heat wave period. Simulations are conducted...
Article
In shared spaces, occupants may have varied thermal and visual preferences for the indoor environmental conditions. Moreover, an occupant's perception of the indoor environment, such as her thermal and visual sensations, depends on her position inside an enclosed space. There is a strong relationship between occupants’ comfort conditions and their...
Article
Heat-related mortality is increasing as the result of climate change, extreme heat events and higher ambient temperature because of urban heat island (UHI) phenomenon. We coupled the Weather Research and Forecasting model (WRFV3.6.1) with a multi-layer of the Urban Canopy Model (ML-UCM) to investigate the effects of UHI intensity during the 2005 an...
Conference Paper
Full-text available
Urban surfaces modification as increasing the albedo is a mitigation strategy to counter the effects of urban heat islands and thus decrease ambient temperature and photochemical reaction rates. Here, the effects of increasing surface reflectivity assessed applying a multi-layer urban canopy model coupled to Weather Research and Forecasting model w...
Article
Full-text available
Increasing surface reflectivity in urban areas can decrease ambient temperature, resulting in reducing photochemical reaction rates, reducing cooling energy demands and thus improving air quality and human health. The weather research and forecasting model with chemistry (WRF-Chem) is coupled with the multi-layer of the urban canopy model (ML-UCM)...
Article
Full-text available
The extraction of urban built-up areas is an important aspect of urban planning and understanding the complex drivers and biophysical mechanism of urban climate processes. However, built-up area extraction using Landsat data is a challenging task due to spatio-temporal dynamics and spatially intermixed nature of Land Use and Land Cover (LULC) in th...
Article
In mesoscale meteorological modeling, physical models (radiation, planetary boundary layer, microphysics, cumulus, and land-surface) are employed to calculate terms of governing equations. We evaluate the sensitivity of near surface air temperature, wind speed, relative humidity and precipitation to different physical models within Weather Research...
Conference Paper
Full-text available
The Weather Research and Forecasting model with Chemistry (WRF-Chem) used to investigate the effects of Aerosol-Radiation-Cloud (ARC) interactions on air quality. The direct and indirect effects of aerosols simulated over North America during 2011 heatwave period. Simulations were conducted with and without aerosol estimations, interactions and con...
Article
The extreme effects of urban heat island (UHI) on energy consumption, air quality, and human health are significantly detrimental. Increasing the albedo of urban surfaces has been proposed as a potentially efficient mitigation strategy. In this study the Weather Research and Forecasting (WRF) mesoscale model has been used to simulate the urban clim...
Article
There is a strong relationship between occupants’ comfort and their productivity. Indoor environmental conditions have impacts on the mental and physical well-being of occupants that subsequently, influence their productivity. Generally, occupants in a shared space have varied preferences for the thermal conditions of the indoor environment. For en...
Chapter
Full-text available
The increasing awareness of the urban heat island (UHI) effect has raised the attention for monitoring and evaluating the outdoor thermal comfort in cities worldwide. However, most of the UHI studies are carried out in hot climates. Urban climate change in cold-climate cities of Canada is also becoming an important consideration for global climate...
Article
The thermal behavior of an external opaque building element depends on the combination of several physical characteristics related to insulation level, thermal inertia, external radiative properties. Concerning the insulation level, parameters like the R-value and its inverse, the U-value or thermal transmittance, are commonly considered in buildin...
Article
Full-text available
The increasing awareness of the urban heat island (UHI) effect has raised the attention for evaluating the outdoor thermal comfort in cities worldwide. In this research, we use the simulation model ENVI-met and the statistical approach “Bootstrap Methods in Nonparametric Regression” to analyze data for providing an urban development policy for SVF...
Article
Although the urban heat island (UHI) phenomena phenomenon has was been documented over a century ago, the effect of the urban heat island on urban climate and environment during the summer have only been the focus of research over the last three decades. One main characteristics of the recent research has been to evaluate the summertime effects of...
Article
Observing the rapid urban expansions and numerous infrastructure developments in the East-Asian context, many cities are suffering the urban heat island (UHI) effect and its associated environmental and social challenges. Moreover, the lack of sufficient attention to the application of effective heat mitigation strategies in current urban developme...
Article
This paper intended to investigate spatio-temporal monotonic trend and shift in concentration of monsoon precipitation across West Bengal, India, by analysing the time series of monthly precipitation from 18 weather stations during the period from 1901 to 2002. In dealing with, the inhomogeneity in the precipitation series, RHtestsV4 software packa...
Conference Paper
Full-text available
The increasing awareness of the urban heat island (UHI) effect has raised the attention for monitoring and evaluating the outdoor thermal comfort in cities worldwide. Currently, in Canada, some municipalities have discussed UHI mitigation at strategy level, carried out literature review, revealed current status of UHI impacts in Canadian cities on...
Conference Paper
Full-text available
In a typical mesoscale meteorological modeling, physical models (including: radiation, planetary boundary layer, microphysics, cumulus, and land-surface) are used to calculate sink/source term of governing equations (i.e., conservation of mass, momentum, and energy). We evaluate the sensitivity of near surface air temperature, wind speed, and preci...
Conference Paper
Full-text available
The rapid growth in urbanization and human activities, with the increase of anthropogenic heat emission in urban areas, lead to urban heat island formation that cause the increase of air temperature and accelerate pollutants photochemical reaction rates in the atmosphere and thus threaten human health. The goal of this paper is to present the effec...
Article
The Cool Roof Rating Council recommends applying the Monte Carlo (MC) method to ASTM standard C1549 to estimate the mean solar reflectance (R) of a variegated roofing sample. For samples with high degree of variation in the solar reflectance, the MC approach is slow in convergence. Applying proper set point of low-discrepancy sequences on the varie...
Article
Increasing albedo is an effective strategy to mitigate urban air temperature in different climates. Using reflective urban surfaces decreases the air temperature, which potentially reduces the rate of generation of smog. However, for implementing the albedo enhancement, complicated interactions between air, moisture, aerosols, and other gaseous con...
Article
Full-text available
Increase of the ambient air temperature in cities caused by the urban heat island phenomenon has a seri- ous impact on the economic and social system of cities. to counterbalance the consequences of the increased urban temperatures important research has been carried out resulting in the development of efficient mitigation technologies. the present...
Article
The increasing awareness of the urban heat island (UHI) effect has raised the attention for monitoring and evaluating the outdoor thermal comfort in cities worldwide. The urban microclimate is an important factor for pedestrians' health, but it also affects the urban air quality, the energy use of buildings, citizen wellbeing, and urban sustainabil...
Article
A laboratory method to simulate natural exposure of roofing materials has been reported in a companion article. In the current article, we describe the results of an international, nine-participant interlaboratory study (ILS) conducted in accordance with ASTM Standard E691-09 to establish the precision and reproducibility of this protocol. The acce...
Article
In this paper, effect of increasing the urban albedo in Montreal (Canada), a cold climate region, on 2-m air temperature and energy consumption of HVAC systems is investigated. An algorithm is developed to select "monthly typical meteorological days" that represent the weather of each month in 2005. The Weather Research and Forecasting (WRF) model...
Conference Paper
Full-text available
The effects of climate change and urban heat island (UHI) phenomena have raised the attention for monitoring and evaluating the outdoor thermal comfort. The urban vegetation system is playing a significant role for UHI mitigation and adaption. In this paper, the common tree types and the size of trees in Montreal are investigated; and the effect of...
Conference Paper
Full-text available
Urban climate change is an important aspect for energy consumption, urban air quality, and citizens' comfort. Many Canadian cities have started to pay attention to climate change mitigation strategies, but they still often lack relevant data about the effects of possible efforts. In this research, we investigate how cool surfaces (on the roofs, the...
Article
We have developed an algorithm to optimise the fan flow rate by integrating DOE2 (building's energy simulation software) with MATLAB's genetic algorithm. In our developed algorithm, MATLAB can send desired values of optimisation variables for different hours to DOE2 to simulate building's energy use, and it can also receive building's energy consum...
Conference Paper
Full-text available
The Cool Roof Rating Council (CRRC) has developed a method to measure the solar reflectance of variegated roofing materials using ASTM standard C1549-09. The CRRC recommends using the Monte Carlo (MC) method to estimate the mean solar reflectance (R) of the variegated sample by measuring solar reflectance of some random spots on a roofing sample. T...
Article
An integrated approach was used to optimize energy use and expenditure of a RC-network model for five zones (four perimeters and one center zone) office building to control dimmable light, shade position, inside air temperature, and outside air flow rate. Parameters considered in this model were: (1) heat transfer, solar heat gain, and illuminance...
Conference Paper
Full-text available
Snow can play an important role in heat gain of building through the roof. As long as snow exists on the roof it changes the thermal conductivity and solar reflectance of the roof. It also may change the thermal storage and the wind speed on the roof surface and consequently convection part of heat transfer on the roof however, the latter effects a...
Article
Full-text available
The relationship between the sky view factor (SVF) and the urban heat island (UHI) effect in Montreal is explored, by assessing the effect of SVF on air temperature (T-a) and mean radiant temperature (MRT). The amount of energy consumed by indoor heating and air conditioning is affected by T-a. The value of MRT is the sum of all short-wave and long...
Article
Solar reflectance (R) of roofing materials is a function of irradiance magnitude and direction, and surface properties. Current methods of labeling the surface reflectance are applicable to homogeneous materials. However, reflectivity of recently developed directional reflective materials (DRM) has a strong dependence on the heterogeneity of the su...
Article
Utilizing a cool roof is an efficient way to reduce the cooling energy use of a building. Cool roofs, however, may increase heating energy use in winter. In cold climates, during winter the sun angle is low, days are short, the sky is cloudy, and most the heating occurs early in the morning or in the evening hours when the solar intensity is low. I...
Article
Highly reflective roofs can decrease the energy required for building air conditioning, help mitigate the urban heat island effect, and slow global warming. However, these benefits are diminished by soiling and weathering processes that reduce the solar reflectance of most roofing materials. Soiling results from the deposition of atmospheric partic...
Article
A validated computational fluid dynamics simulation tool is used to study the long-term performance of a centralized latent heat thermal energy storage system (LHTES). The LHTES system is integrated with a building mechanical ventilation system. Paraffin RT20 was used as a phase change material (PCM) and fins are used to enhance its performance. To...
Article
Full-text available
Urban heat island (UHI) phenomenon has been observed in many large cities located in cold regions (e.g. Montreal in Canada) during summer. One of the well-known strategies to mitigate the temperature rise of urban areas is increasing their albedo. Roofs cover about 25% of urban areas and increasing their reflectivity would have a significant effect...
Article
Centralized latent heat thermal energy storage (LHTES) system offers potential benefits in energy efficiency, in load shifting, and in emergency heating/cooling load systems. A three-dimensional heat transfer model of a LHTES is developed to investigate the quasi-steady state and transient heat transfer of phase change materials (PCMs). The predict...
Article
Installing roofs with high solar reflectance and high thermal emittance, known as “Cool roofs,” are becoming increasingly popular because of their cooling energy saving potentials, cost effectiveness and sustainability. Lower surface temperature of cool roofs may affect the hygrothermal performance of roofing systems and hence their performance sho...
Article
Reflective roofs can reduce demand for air conditioning and warming of the atmosphere. Roofs can also host photovoltaic (PV) modules that convert sunlight to electricity. In this study we assess the effects of installing a building integrated photovoltaic (BIPV) roof on an office building in Yuma, AZ. The system consists of thin film PV laminated t...
Article
The scope of the present chapter is to present the cool materials rating techniques as extracted and followed by specific technical standards. The methodology to measure solar reflectance and infrared emmitance are presented in detail.
Book
Energy is one of the most important factors that define the quality of urban life and the global environmental impact of cities. The urbanization process dramatically affects energy consumption.
Article
With increasing the solar reflectance of urban surfaces, the outflow of short-wave solar radiation increases, less solar heat energy is absorbed leading to lower surface temperatures and reduced outflow of thermal radiation into the atmosphere. This process of “negative radiative forcing” effectively counters global warming. Cool roofs also reduce...
Article
Many contaminants in the living space of a house, such as carbon monoxide, benzene, toluene, and ethylbenzene, originate from attached garage. As more airtight and energy-efficient houses are designed and constructed, these contaminants may be retained in indoor air for a longer period of time, jeopardizing the occupants' health. In this study, CON...
Article
Full-text available
Solar reflective urban surfaces (white rooftops and light-colored pavements) can increase the albedo of an urban area by about 0.1. Increasing the albedo of urban and human settlement areas can in turn decrease atmospheric temperature and could potentially offset some of the anticipated temperature increase caused by global warming. We have simulat...
Article
Exposed asphalt shingles undergo chemical and physical changes as they weather. Here we focus on the resulting changes in solar reflectance. Most roofing granules employing inorganic metal oxide pigments are very stable. Initial reflectance changes are therefore due to changes in the asphalt itself, and the loss of processing oils coating the granu...
Article
Cool roofs, cool pavements, and urban vegetation reduce cooling energy use in buildings, lower local air pollution, and decrease greenhouse gas (GHG) emissions from urban areas. To promote widespread and large-scale implementation of cool roofs to moderate urban heat-island phenomenon, more awareness and understanding of cool roof benefits at the l...
Article
Vehicle thermal loads and air conditioning ancillary loads are strongly influenced by the absorption of solar energy. The adoption of solar reflective coatings for opaque surfaces of the vehicle shell can decrease the “soak” temperature of the air in the cabin of a vehicle parked in the sun, potentially reducing the vehicle’s ancillary load and imp...
Article
Solar reflectance can vary with the spectral and angular distributions of incident sunlight, which in turn depend on surface orientation, solar position and atmospheric conditions. A widely used solar reflectance metric based on the ASTM Standard E891 beam-normal solar spectral irradiance underestimates the solar heat gain of a spectrally selective...
Article
A companion article explored how solar reflectance varies with surface orientation and solar position, and found that clear sky air mass 1 global horizontal (AM1GH) solar reflectance is a preferred quantity for estimating solar heat gain. In this study we show that AM1GH solar reflectance Rg,0 can be accurately measured with a pyranometer, a solar...
Article
The widespread use of solar-reflective roofing materials can save energy, mitigate urban heat islands and slow global warming by cooling the roughly 20% of the urban surface that is roofed. In this study we created prototype solar-reflective nonwhite concrete tile and asphalt shingle roofing materials using a two-layer spray coating process intende...
Article
Full-text available
Cool roofs—roofs that stay cool in the sun by minimizing solar absorption and maximizing thermal emission—lessen the flow of heat from the roof into the building, reducing the need for space cooling energy in conditioned buildings. Cool roofs may also increase the need for heating energy in cold climates. For a commercial building, the decrease in...