Evolution of cool-roof standards in the United States

Roofs that have high solar reflectance and high thermal emittance stay cool in the sun. A roof with lower thermal emittance but exceptionally high solar reflectance can also stay cool in the sun. Substituting a cool roof for a noncool roof decreases cooling-electricity use, cooling-power demand, and cooling-equipment capacity requirements, while slightly increasing heating-energy consumption. Cool roofs can also lower citywide ambient air temperature in summer, slowing ozone formation and increasing human comfort. Provisions for cool roofs in energy-efficiency standards can promote the building- and climate-appropriate use of cool roofing technologies. Cool-roof requirements are designed to reduce building energy use, while energy-neutral cool-roof credits permit the use of less energy-efficient components (e.g., larger windows) in a building that has energy-saving cool roofs. Both types of measures can reduce the life-cycle cost of a building (initial cost plus lifetime energy cost). Since 1999, several widely used building energy-efficiency standards, including ASHRAE 90.1, ASHRAE 90.2, the International Energy Conservation Code, and California's Title 24 have adopted cool-roof credits or requirements. This paper reviews the technical development of cool-roof provisions in the ASHRAE 90.1, ASHRAE 90.2, and California Title 24 standards, and discusses the treatment of cool roofs in other standards and energy-efficiency programs. The techniques used to develop the ASHRAE and Title 24 cool-roof provisions can be used as models to address cool roofs in building energy-efficiency standards worldwide

Urban Surfaces and Heat Island Mitigation Potentials

Data on materials and surface types that comprise a city, i.e. urban fabric, are needed in order to estimate the effects of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city. We discuss the results of a semi-automatic statistical approach used to develop data on surface-type distribution and urban-fabric makeup using aerial color orthophotography, for four metropolitan areas of Chicago, IL, Houston, TX, Sacramento, CA, and Salt Lake City, UT. The digital high resolution (0.3 to 0.5-m) aerial photographs for each of these metropolitan areas covers representative urban areas ranging from 30 km{sup 2} to 52 km{sup 2}. Major land-use types examined included: commercial, residential, industrial, educational, and transportation. On average, for the metropolitan areas studied, vegetation covers about 29-41% of the area, roofs 19-25%, and paved surfaces 29-39%. For the most part, trees shade streets, parking lots, grass, and sidewalks. At ground level, i.e., view from below the tree canopies, vegetation covers about 20-37% of the area, roofs 20-25%, and paved surfaces 29-36%

The Urban Heat Island Effect in the City of Toronto

AbstractThe increasing awareness of theurban 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 sustainability. Issues related to the urban microclimate are becoming more acute in cities given the increasing rates of urban development and construction. In this paper, UHI mitigation strategies in the city of Toronto are assessed. This paper also compares different urban forms according to their orientations, height of wall enclosure, and use of vegetation. The effects of cool surfaces (on the roofs, on the street pavements, or by additional vegetation) are evaluated through numerical simulations using the software ENVI-met. After having obtained the surface temperature, outdoor air temperature, and mean radiant temperature, this study compares three urban areas according to the possible mitigation of net surface radiation and thermal radiative power. The results demonstrate that the duration of direct sun and the mean radiant temperature, which are strongly influenced by the urban form especially in denserareas of the city, play a significant role over the urban thermal comfort. This research supports a sustainable urban developmentin a cold climate, such as that of Toronto. The final scope of this paper isto suggest design strategies for a more resilient urban planning

Surface roughness effects on the solar reflectance of cool asphalt shingles

We analyze the solar reflectance of asphalt roofing shingles that are covered with pigmented mineral roofing granules. The reflecting surface is rough, with a total area approximately twice the nominal area. We introduce a simple analytical model that relates the 'micro-reflectance' of a small surface region to the 'macro-reflectance' of the shingle. This model uses a mean field approximation to account for multiple scattering effects. The model is then used to compute the reflectance of shingles with a mixture of different colored granules, when the reflectances of the corresponding mono-color shingles are known. Simple linear averaging works well, with small corrections to linear averaging derived for highly reflective materials. Reflective base granules and reflective surface coatings aid achievement of high solar reflectance. Other factors that influence the solar reflectance are the size distribution of the granules, coverage of the asphalt substrate, and orientation of the granules as affected by rollers during fabrication

The Effect of it Governance on the Relationship Between Corporate Social Responsibility and Performance in Iraqi Banks

Purpose: The purpose of this research is to understand the greater responsibility placed by various organizations on the social responsibilities of the organizations towards their stakeholders. It also aims to explore the Corporate Social Responsibility (CSR) for daily operations of organizations to fulfill their social responsibilities to society.   Theoretical Framework: The study made assumptions based on in-depth review to investigate variables in Iraqi context. One of the comprehensive measurement criteria provided by Liao (2019) covers the three dimensions of effectiveness, efficiency, and consistency.   Design/methodology/approach: The statistical population contains all listed companies on the Iraqi Stock Exchange between 2015 and 2021. The hypotheses were tested employing a multivariate regression model. The hypotheses of the study were tested using a sample of 168 observations from listed Iraqi banks from 2015 to 2021 and a multiple regression model based on the panel data technique of the random effects model.   Findings: The results showed a positive and statistically significant relationship between social responsibility and bank performance. Also, information technology governance (ITG) moderates this effect. Additional methods (t+1, fixed effects, ordinary least squares) were employed to test the validity of the research models.   Research, Practical & Social Implication: As this is the first study to investigate this issue in emerging markets, it provides users, analysts, and legal bodies with valuable information regarding CSR, which substantially impacts banks' performance.   Originality/value: The finding suggests several consequences of IT governances and its effects on corporate social responsibility which contributing to the development of knowledge

An Integrated Model for Position-based Productivity and Energy Costs Optimization in Offices

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 level of productivity, hence, improving the productivity of occupants in offices offers significant economic benefits. The main interest of this research is to propose a Multi-Objective Optimization (MOOP) method for position-based energy and comfort management in offices. The proposed method accounts for personalized thermal and visual preferences of occupants and their positions within an office space, and simultaneously optimizes energy consumption costs and collective productivity of office workers, by proposing Pareto optimal solutions for the automated control of the indoor environment. Occupants’ thermal and visual preferences and positions, their productivity rates, thermal and visual behavior, Indoor Air Quality (IAQ) of the space, energy exchanges processes across the building, indoor and outdoor environmental parameters, and energy prices, are considered in this optimization. Application of the proposed method under varied occupancy scenarios is analyzed by energy performance simulation of a multi-zone office building, located in Montreal, Canada. The proposed method (1) has the flexibility to account for the diversity among occupants’ environmental preferences, (2) manages the indoor environmental conditions based on office workers’ positions and preferences, and (3) simultaneously optimizes energy costs and office workers’ productivity

Radiative Forcing and Temperature Response to Changes in Urban Albedos and Associated CO2 Offsets

The two main forcings that can counteract to some extent the positive forcings from greenhouse gases from pre-industrial times to present-day are the aerosol and related aerosol-cloud forcings, and the radiative response to changes in surface albedo. Here, we quantify the change in radiative forcing and surface temperature that may be obtained by increasing the albedos of roofs and pavements in urban areas in temperate and tropical regions of the globe. Using the catchment land surface model (the land model coupled to the GEOS-5 Atmospheric General Circulation Model), we quantify the response of the total outgoing (outgoing shortwave+longwave) radiation to urban albedo changes. Globally, the total outgoing radiation increased by 0.5 W/square m and temperature decreased by -0.008 K for an average 0.003 increase in albedo. For the U.S. the total outgoing total radiation increased by 2.3 W/square meter, and temperature decreased by approximately 0.03 K for an average 0.01 increase in albedo. These values are for the boreal summer (Tune-July-August). Based on these forcings, the expected emitted CO2 offset for a plausible 0.25 and 0.15 increase in albedos of roofs and pavements, respectively, for all global urban areas, was found to be approximately 57 Gt CO2 . A more meaningful evaluation of the impacts of urban albedo increases on climate and the expected CO2 offsets would require simulations which better characterizes urban surfaces and represents the full annual cycle

The long-term effect of increasing the albedo of urban areas

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 simulated the long-term (decadal to centennial) effect of increasing urban surface albedos using a spatially explicit global climate model of intermediate complexity. We first carried out two sets of simulations in which we increased the albedo of all land areas between ±20° and ±45° latitude respectively. The results of these simulations indicate a long-term global cooling effect of 3 × 10−15 K for each 1 m2 of a surface with an albedo increase of 0.01. This temperature reduction corresponds to an equivalent CO2 emission reduction of about 7 kg, based on recent estimates of the amount of global warming per unit CO2 emission. In a series of additional simulations, we increased the albedo of urban locations only, on the basis of two independent estimates of the spatial extent of urban areas. In these simulations, global cooling ranged from 0.01 to 0.07 K, which corresponds to a CO2 equivalent emission reduction of 25–150 billion tonnes of CO2