Nader Chalfoun - Academia.edu (original) (raw)

Videos by Nader Chalfoun

This project is a virtual exchange between students at the University of Arizona, USA and the Ame... more This project is a virtual exchange between students at the University of Arizona, USA and the American University of Cairo, Egypt. The students and teachers are exchanging ideas and classroom experiences related to the teaching and research in sustainable architecture.

Papers by Nader Chalfoun

Vivienda y comunidades sustentables, 2020

, us. RESUMEN De entre las alternativas para proporcionar una adecuada calidad ambiental interior... more , us. RESUMEN De entre las alternativas para proporcionar una adecuada calidad ambiental interior en las viviendas del noroeste de México y suroeste de los Estados Unidos, los sistemas de ventilación mecánica son la fuente más utilizada para proveer aire fresco y control de temperatura. La innovación tecnológica en los sistemas de ventilación a menudo nos conduce a la disminución en el uso de la ventilación natural, aunque, durante selectos días del año, la libre circulación del flujo de aire puede contribuir a la salud humana y la conservación de la energía. Para este estudio se realizó una evaluación de riesgos sanitarios a un estudio de caso donde se comparan los tres sistemas regulación de temperatura por su función como suministro de aire: ventilación natural, refrigeración evaporativa y aire acondicionado, para con ello observar y medir acumulaciones de polvo y variación de temperatura en una vivienda unifamiliar ubicada en Tucson, Arizona. Este estudio tiene como objetivo entender si la cantidad y la ubicación de las acumulaciones de polvo en una casa están correlacionadas con el tipo de ventilación. En segundo término, este estudio prueba cómo la exposición al polvo es diferente en dependencia de la ubicación de la acumulación dentro de la casa. Por último, se reflexiona acerca de las lecturas de temperatura y su relación con la eficacia de los tipos de sistemas de ventilación para mitigar la acumulación de polvo.

International Journal of Design & Nature and Ecodynamics, Dec 12, 2018

This investigation describes improved outdoor Human Thermal Comfort levels, based on the effects ... more This investigation describes improved outdoor Human Thermal Comfort levels, based on the effects of integrating vegetated surfaces, such as those from Urban Agriculture systems, to architecture components of a building envelope within Tucson, Arizona, which can contribute on Urban Heat Island mitigation. Urban Agriculture comprises the integration of crop production with the built environment, it can contribute to improving buildings' performance, reducing air pollution, alleviating food scarcity, reducing stormwater runoff, decreasing fossil fuel use, and restoring Human Thermal Comfort. A methodology for outdoor Human Thermal Comfort assessment was applied. It involved the use of digital analysis of fish-eye lens photographs, and 'OUTDOOR', a computer software developed by Nader Chalfoun, Ph.D., at the University of Arizona, which is capable of calculating Human Thermal Comfort indices. Assumptions of this study include: access to water, soil, air, a building envelope, and the presence of vertical and horizontal arrangements of vegetated surfaces, produced in successfully developed Urban Agriculture systems around a selected building envelope in a hot-arid climate. Existing Human Thermal Comfort conditions were compared to those simulated with the integration of vegetated surfaces in order to evaluate the potential effects of Urban Agriculture, and to reach restored Human Thermal Comfort levels.

Ecology and the Environment, Jun 20, 2018

Faculty and students of the House Energy Doctor (HED) Master of Science program at the University... more Faculty and students of the House Energy Doctor (HED) Master of Science program at the University of Arizona's College of Architecture, Planning, and Landscape Architecture are currently engaged in a multi-year effort towards accomplishing a vision that would preserve the heritage of the Organ Pipe Cactus National Monument (OPNM) buildings while transforming its status into the first net-zero park in the United States. The project is a collaboration with experts in heritage architecture from the park and students and faculty of HED. During the years, 2015 and 2016, of the project, two major park-built areas have been redeveloped; the Visitor Center and the Residential loop. While the work on the visitor center was documented and published in WIT STREMAH 2017, Alicante, Spain, this paper presents the recent work performed in 2016 on the one-mile residential loop. Three major tasks have been accomplished in this built area and focused on transforming the existing 13 residences into net-zero operation. The first accomplishment is the energy efficiency achieved through the use of energy performance simulation and integration of advanced environmental systems. The second, is the economic impact through the alternative designs developed in Studio 601 that focused on regional sustainable energy efficient high-performance buildings using latest environmental technologies for indoor and outdoor spaces. Development of the residential loop conformed to Mission 66 standards while added an important education trail component to the complex. Finally, all environmental strategies used in the design development were verified by empirical research and experimentation in the House Energy Doctor laboratory. This paper demonstrates the methods of intervention used on the residential loop to achieve the net-zero status and three redesign schemes as well as the energy performance predictions and verifications. These valuable findings could then be transformed to the design profession to facilitate future net-zero performance buildings.

... Stu-dents also designed forms and used them on site to record the collected data, as well as ... more ... Stu-dents also designed forms and used them on site to record the collected data, as well as their personal response to the thermal condi-tion of the different locations. ... To demonstrate theapplication of the method, I present a thermal analysis of one location from the ...

WIT Transactions on the Built Environment, Jun 27, 2016

Urbanization is no longer a gradual population shift, the world is undergoing major development a... more Urbanization is no longer a gradual population shift, the world is undergoing major development and is utilizing technology and energy to increase the rate of construction. With changes in today's society and culture, people are rapidly shifting from living in rural areas to urbanized environments. The world's demand for energy and water has increased. Energy and water are fundamental components of life, they can no longer be considered separated. The building sector is changing the future of energy, accounting for almost 40% of energy consumption in the World. In addition, access to sufficient quantities of acceptable water quality is a basic need for human beings and a prerequisite to sustain development and welfare. Human activities and consumption are also major contributors to climate change. Scientists have predicted that these effects will cause a rise in sea levels, more frequent floods, and droughts, which in return affects our initial water sources. The loss of water support below ground due to urban growth is becoming a geologic hazard, which may lead to land subsidence and Earth fissures being steadily encroached upon. Hence, mitigation through governmental decisions and policies as well as new technology and education will have the greatest impact on the building sector. This paper describes the development of innovative urban water efficiency systems and a four-legged education curriculum addressing: (1) water reduction, (2) water harvesting, (3) water reuse, and (4) water energy generation technologies. Focusing on the effective use of water to practice a more

Integrated cavity-wall systems are typically designed to shade the exterior of buildings. They ca... more Integrated cavity-wall systems are typically designed to shade the exterior of buildings. They can also eradicate daytime heat absorption by thermal convection. The combined heat loss through the natural nighttime sky radiation, the cavity wall shading effect, and the thermal convective loop results in a significantly improved building envelope performance. This paper outlines the design, construction, and monitoring of a south-facing cavity wall system integrated into a single-family residence in Southern Arizona. Implemented as a 'heat transfer regulator', the cavity wall functioned as a thermal break between the external and internal thermal forces through the south wall of the building envelope. The outside "Sol-air" surface temperatures of the cavity walls were found to be consistently lower than the standard non-cavity walls during extreme summer conditions. This was due to the combined effect of shading as well as stack-ventilation heat loss triggered by solar radiation received by the south cavity walls. Results from the field data monitoring and computer simulated results yielded a minimized operation of mechanical system, reduction in energy consumption, and optimized human thermal comfort.

... The University of Arizona “Arts Oasis” site is a 1.8 acre central open space surrounded by th... more ... The University of Arizona “Arts Oasis” site is a 1.8 acre central open space surrounded by the Colleges of Fine Arts from the west and south, the College of Architecture, Planning and Landscape Architecture (CAPLA), and the Center for Creative Photography (CCP) from the ...

A process of developing recommendations to the City of Tucson and to Pima County officials to dev... more A process of developing recommendations to the City of Tucson and to Pima County officials to develop the first code for Net-Zero capable buildings in the state of Arizona is described. The proposed code will have a tremendous impact on reducing the state energy consumption through both a prescriptive and performance compliance paths. Implementation of this voluntary standard will also encourage the use of energy simulation software to achieve code compliance. The process is divided into four major steps that lead into the establishment of the pre Net-Zero energy efficiency levels for each building prototype. Full Net-Zero status is then achieved through sizing appropriate PV system based to be installed on the roof or parking structures of buildings. Preliminary results demonstrate one residential prototype achieved the Net-Zero status by a reduced annual cost from 3,350to3,350 to 3,350to885 (73.6% savings) and a reduced consumption from 48.83 to 11.91 kBtu/ft!.yr (74.47% savings) compared to a basecase that originally complied with the 2006 International Energy Conservation Code (IECC2006). This paper strongly emphasizes on how energy simulation can influence and inform the design process of buildings.

Ecology and the Environment, Apr 23, 2014

Building envelopes play a major role in improving the overall energy efficiency as well as in pro... more Building envelopes play a major role in improving the overall energy efficiency as well as in providing a healthy indoor air quality for occupants in office buildings. The notion of this research is to develop an integrated façade technology that interacts and adapts with the changing climatic conditions, in hot arid regions, in order to improve occupants' thermal comfort in mixed mode office buildings through the use of natural ventilation and evaporative cooling techniques, thereby reducing mechanical cooling energy loads. In this research, façade design decisions were based on two main computer simulation results; thermal comfort levels and the reduction in energy consumption. The authors propose a double skin façade system that consists of an external skin which works on multiple operating modes. This skin integrates passive cooling strategies with the building envelope depending on the data collected by external and internal sensors. My previous investigations showed that shading, natural ventilation and evaporative cooling are the most effective passive cooling strategies for hot and arid regions In conclusion, this research will contribute in reducing energy consumption in commercial buildings, and help provide a productive work environment.

Procedia environmental sciences, 2014

This paper describes a method of greening university campus buildings that normally contribute to... more This paper describes a method of greening university campus buildings that normally contribute to a large amount of energy and water consumption, air pollution, and resource depletions. The University of Arizona became engaged in the American College and University Presidents Climate Commitment emphasizing those university campuses must exercise leadership in their communities and throughout society by modeling ways to minimize global warming emissions, and by providing their graduates the knowledge and education to achieve climate neutrality. The "House Energy Doctor" (HED) program is an education, research, and community outreach program at the University of Arizona's (UA) College of Architecture, planning and Landscape Architecture (CAPLA). During the last three years, and through a multiyear agreement between HED and the UA, Level III energy audits have been conducted on nine major campus buildings to identify energy efficiency opportunities that will contribute to the greening of campus. Some important findings focused on inefficient windows, external insulation, shading of critical building elements, energy-saving light fixtures, and envelope solar reflectance in summer. Strategies for mechanical systems propose changes to current thermostat set points, run periods, replacement of old components with higher efficiency units, and water harvesting of condensates for landscape use. The first three years of the "Greening of Campus" project demonstrated that the nine buildings total area of 1,081,512 ft² consumed an annual average 75,970,411 KBtu (70.2 KBtu/ft²) at the cost of 2,186,264peryear.TheimplementationoftheHouseEnergyDoctorrecommendationsfortheninebuildingswillyieldanannualenergysavingsof9,542,106KBtuandoperatingcostsavingof2,186,264 per year. The implementation of the House Energy Doctor recommendations for the nine buildings will yield an annual energy savings of 9,542,106 KBtu and operating cost saving of 2,186,264peryear.TheimplementationoftheHouseEnergyDoctorrecommendationsfortheninebuildingswillyieldanannualenergysavingsof9,542,106KBtuandoperatingcostsavingof265,318 (12.1%). This energy saving will help the environment by a reduction of 2,915 Metric tons of CO2 emission. The campus will also be saving 10.9 million gallons of water. In addition, two of nine buildings "Arizona-Sonora" and "La Aldea" have been successfully certified for Energy Star Designation. The method can be replicated in different units around campus and as a model for implementation in other university campuses around the world.

Programming Sensor Networks currently is a subtle task not because of enormous amount of code but... more Programming Sensor Networks currently is a subtle task not because of enormous amount of code but due to inherent limitations of embedded hardware like the power, memory, network bandwidth and clock speed. In addition, there are very few programming abstractions and standards available which lead to close coupling between the application code and the embedded OS requiring understanding of low-level primitives during implementation. A Middleware can provide glue code between the applications and the heterogeneity of devices by providing optimized set of services for autonomously managing the resources and functionality of wireless nodes in a distributed wireless sensor network. This paper presents an autonomous middleware framework for low power distributed wireless sensor networks that support adaptive sensor functionality, context aware communications, clustering, quality of service and faulttolerance. Finally an application on how to use the autonomous middleware is illustrated on the Envelope System Research Apparatus (ESRA).

This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolut... more This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at repository@u.library.arizona.edu

Energy Conversion and Management, Nov 1, 1994

In relatively arid regions, natural draft evaporative coolers can be used for cooling residential... more In relatively arid regions, natural draft evaporative coolers can be used for cooling residential and commercial buildings, as well as outdoor areas, however, their design can be time consuming. Several approximations are presented here to simplify the computations. Density calculations are eliminated using a correction term with wet and dry-bulb temperatures. Under calm conditions, iterative calculations involving the pad air velocity and efficiency can be eliminated with a logarithmic approximation.

This project is a virtual exchange between students at the University of Arizona, USA and the Ame... more This project is a virtual exchange between students at the University of Arizona, USA and the American University of Cairo, Egypt. The students and teachers are exchanging ideas and classroom experiences related to the teaching and research in sustainable architecture.

Vivienda y comunidades sustentables, 2020

, us. RESUMEN De entre las alternativas para proporcionar una adecuada calidad ambiental interior... more , us. RESUMEN De entre las alternativas para proporcionar una adecuada calidad ambiental interior en las viviendas del noroeste de México y suroeste de los Estados Unidos, los sistemas de ventilación mecánica son la fuente más utilizada para proveer aire fresco y control de temperatura. La innovación tecnológica en los sistemas de ventilación a menudo nos conduce a la disminución en el uso de la ventilación natural, aunque, durante selectos días del año, la libre circulación del flujo de aire puede contribuir a la salud humana y la conservación de la energía. Para este estudio se realizó una evaluación de riesgos sanitarios a un estudio de caso donde se comparan los tres sistemas regulación de temperatura por su función como suministro de aire: ventilación natural, refrigeración evaporativa y aire acondicionado, para con ello observar y medir acumulaciones de polvo y variación de temperatura en una vivienda unifamiliar ubicada en Tucson, Arizona. Este estudio tiene como objetivo entender si la cantidad y la ubicación de las acumulaciones de polvo en una casa están correlacionadas con el tipo de ventilación. En segundo término, este estudio prueba cómo la exposición al polvo es diferente en dependencia de la ubicación de la acumulación dentro de la casa. Por último, se reflexiona acerca de las lecturas de temperatura y su relación con la eficacia de los tipos de sistemas de ventilación para mitigar la acumulación de polvo.

International Journal of Design & Nature and Ecodynamics, Dec 12, 2018

This investigation describes improved outdoor Human Thermal Comfort levels, based on the effects ... more This investigation describes improved outdoor Human Thermal Comfort levels, based on the effects of integrating vegetated surfaces, such as those from Urban Agriculture systems, to architecture components of a building envelope within Tucson, Arizona, which can contribute on Urban Heat Island mitigation. Urban Agriculture comprises the integration of crop production with the built environment, it can contribute to improving buildings' performance, reducing air pollution, alleviating food scarcity, reducing stormwater runoff, decreasing fossil fuel use, and restoring Human Thermal Comfort. A methodology for outdoor Human Thermal Comfort assessment was applied. It involved the use of digital analysis of fish-eye lens photographs, and 'OUTDOOR', a computer software developed by Nader Chalfoun, Ph.D., at the University of Arizona, which is capable of calculating Human Thermal Comfort indices. Assumptions of this study include: access to water, soil, air, a building envelope, and the presence of vertical and horizontal arrangements of vegetated surfaces, produced in successfully developed Urban Agriculture systems around a selected building envelope in a hot-arid climate. Existing Human Thermal Comfort conditions were compared to those simulated with the integration of vegetated surfaces in order to evaluate the potential effects of Urban Agriculture, and to reach restored Human Thermal Comfort levels.

Ecology and the Environment, Jun 20, 2018

Faculty and students of the House Energy Doctor (HED) Master of Science program at the University... more Faculty and students of the House Energy Doctor (HED) Master of Science program at the University of Arizona's College of Architecture, Planning, and Landscape Architecture are currently engaged in a multi-year effort towards accomplishing a vision that would preserve the heritage of the Organ Pipe Cactus National Monument (OPNM) buildings while transforming its status into the first net-zero park in the United States. The project is a collaboration with experts in heritage architecture from the park and students and faculty of HED. During the years, 2015 and 2016, of the project, two major park-built areas have been redeveloped; the Visitor Center and the Residential loop. While the work on the visitor center was documented and published in WIT STREMAH 2017, Alicante, Spain, this paper presents the recent work performed in 2016 on the one-mile residential loop. Three major tasks have been accomplished in this built area and focused on transforming the existing 13 residences into net-zero operation. The first accomplishment is the energy efficiency achieved through the use of energy performance simulation and integration of advanced environmental systems. The second, is the economic impact through the alternative designs developed in Studio 601 that focused on regional sustainable energy efficient high-performance buildings using latest environmental technologies for indoor and outdoor spaces. Development of the residential loop conformed to Mission 66 standards while added an important education trail component to the complex. Finally, all environmental strategies used in the design development were verified by empirical research and experimentation in the House Energy Doctor laboratory. This paper demonstrates the methods of intervention used on the residential loop to achieve the net-zero status and three redesign schemes as well as the energy performance predictions and verifications. These valuable findings could then be transformed to the design profession to facilitate future net-zero performance buildings.

... Stu-dents also designed forms and used them on site to record the collected data, as well as ... more ... Stu-dents also designed forms and used them on site to record the collected data, as well as their personal response to the thermal condi-tion of the different locations. ... To demonstrate theapplication of the method, I present a thermal analysis of one location from the ...

WIT Transactions on the Built Environment, Jun 27, 2016

Urbanization is no longer a gradual population shift, the world is undergoing major development a... more Urbanization is no longer a gradual population shift, the world is undergoing major development and is utilizing technology and energy to increase the rate of construction. With changes in today's society and culture, people are rapidly shifting from living in rural areas to urbanized environments. The world's demand for energy and water has increased. Energy and water are fundamental components of life, they can no longer be considered separated. The building sector is changing the future of energy, accounting for almost 40% of energy consumption in the World. In addition, access to sufficient quantities of acceptable water quality is a basic need for human beings and a prerequisite to sustain development and welfare. Human activities and consumption are also major contributors to climate change. Scientists have predicted that these effects will cause a rise in sea levels, more frequent floods, and droughts, which in return affects our initial water sources. The loss of water support below ground due to urban growth is becoming a geologic hazard, which may lead to land subsidence and Earth fissures being steadily encroached upon. Hence, mitigation through governmental decisions and policies as well as new technology and education will have the greatest impact on the building sector. This paper describes the development of innovative urban water efficiency systems and a four-legged education curriculum addressing: (1) water reduction, (2) water harvesting, (3) water reuse, and (4) water energy generation technologies. Focusing on the effective use of water to practice a more

Integrated cavity-wall systems are typically designed to shade the exterior of buildings. They ca... more Integrated cavity-wall systems are typically designed to shade the exterior of buildings. They can also eradicate daytime heat absorption by thermal convection. The combined heat loss through the natural nighttime sky radiation, the cavity wall shading effect, and the thermal convective loop results in a significantly improved building envelope performance. This paper outlines the design, construction, and monitoring of a south-facing cavity wall system integrated into a single-family residence in Southern Arizona. Implemented as a 'heat transfer regulator', the cavity wall functioned as a thermal break between the external and internal thermal forces through the south wall of the building envelope. The outside "Sol-air" surface temperatures of the cavity walls were found to be consistently lower than the standard non-cavity walls during extreme summer conditions. This was due to the combined effect of shading as well as stack-ventilation heat loss triggered by solar radiation received by the south cavity walls. Results from the field data monitoring and computer simulated results yielded a minimized operation of mechanical system, reduction in energy consumption, and optimized human thermal comfort.

... The University of Arizona “Arts Oasis” site is a 1.8 acre central open space surrounded by th... more ... The University of Arizona “Arts Oasis” site is a 1.8 acre central open space surrounded by the Colleges of Fine Arts from the west and south, the College of Architecture, Planning and Landscape Architecture (CAPLA), and the Center for Creative Photography (CCP) from the ...

A process of developing recommendations to the City of Tucson and to Pima County officials to dev... more A process of developing recommendations to the City of Tucson and to Pima County officials to develop the first code for Net-Zero capable buildings in the state of Arizona is described. The proposed code will have a tremendous impact on reducing the state energy consumption through both a prescriptive and performance compliance paths. Implementation of this voluntary standard will also encourage the use of energy simulation software to achieve code compliance. The process is divided into four major steps that lead into the establishment of the pre Net-Zero energy efficiency levels for each building prototype. Full Net-Zero status is then achieved through sizing appropriate PV system based to be installed on the roof or parking structures of buildings. Preliminary results demonstrate one residential prototype achieved the Net-Zero status by a reduced annual cost from 3,350to3,350 to 3,350to885 (73.6% savings) and a reduced consumption from 48.83 to 11.91 kBtu/ft!.yr (74.47% savings) compared to a basecase that originally complied with the 2006 International Energy Conservation Code (IECC2006). This paper strongly emphasizes on how energy simulation can influence and inform the design process of buildings.

Ecology and the Environment, Apr 23, 2014

Building envelopes play a major role in improving the overall energy efficiency as well as in pro... more Building envelopes play a major role in improving the overall energy efficiency as well as in providing a healthy indoor air quality for occupants in office buildings. The notion of this research is to develop an integrated façade technology that interacts and adapts with the changing climatic conditions, in hot arid regions, in order to improve occupants' thermal comfort in mixed mode office buildings through the use of natural ventilation and evaporative cooling techniques, thereby reducing mechanical cooling energy loads. In this research, façade design decisions were based on two main computer simulation results; thermal comfort levels and the reduction in energy consumption. The authors propose a double skin façade system that consists of an external skin which works on multiple operating modes. This skin integrates passive cooling strategies with the building envelope depending on the data collected by external and internal sensors. My previous investigations showed that shading, natural ventilation and evaporative cooling are the most effective passive cooling strategies for hot and arid regions In conclusion, this research will contribute in reducing energy consumption in commercial buildings, and help provide a productive work environment.

Procedia environmental sciences, 2014

This paper describes a method of greening university campus buildings that normally contribute to... more This paper describes a method of greening university campus buildings that normally contribute to a large amount of energy and water consumption, air pollution, and resource depletions. The University of Arizona became engaged in the American College and University Presidents Climate Commitment emphasizing those university campuses must exercise leadership in their communities and throughout society by modeling ways to minimize global warming emissions, and by providing their graduates the knowledge and education to achieve climate neutrality. The "House Energy Doctor" (HED) program is an education, research, and community outreach program at the University of Arizona's (UA) College of Architecture, planning and Landscape Architecture (CAPLA). During the last three years, and through a multiyear agreement between HED and the UA, Level III energy audits have been conducted on nine major campus buildings to identify energy efficiency opportunities that will contribute to the greening of campus. Some important findings focused on inefficient windows, external insulation, shading of critical building elements, energy-saving light fixtures, and envelope solar reflectance in summer. Strategies for mechanical systems propose changes to current thermostat set points, run periods, replacement of old components with higher efficiency units, and water harvesting of condensates for landscape use. The first three years of the "Greening of Campus" project demonstrated that the nine buildings total area of 1,081,512 ft² consumed an annual average 75,970,411 KBtu (70.2 KBtu/ft²) at the cost of 2,186,264peryear.TheimplementationoftheHouseEnergyDoctorrecommendationsfortheninebuildingswillyieldanannualenergysavingsof9,542,106KBtuandoperatingcostsavingof2,186,264 per year. The implementation of the House Energy Doctor recommendations for the nine buildings will yield an annual energy savings of 9,542,106 KBtu and operating cost saving of 2,186,264peryear.TheimplementationoftheHouseEnergyDoctorrecommendationsfortheninebuildingswillyieldanannualenergysavingsof9,542,106KBtuandoperatingcostsavingof265,318 (12.1%). This energy saving will help the environment by a reduction of 2,915 Metric tons of CO2 emission. The campus will also be saving 10.9 million gallons of water. In addition, two of nine buildings "Arizona-Sonora" and "La Aldea" have been successfully certified for Energy Star Designation. The method can be replicated in different units around campus and as a model for implementation in other university campuses around the world.

Programming Sensor Networks currently is a subtle task not because of enormous amount of code but... more Programming Sensor Networks currently is a subtle task not because of enormous amount of code but due to inherent limitations of embedded hardware like the power, memory, network bandwidth and clock speed. In addition, there are very few programming abstractions and standards available which lead to close coupling between the application code and the embedded OS requiring understanding of low-level primitives during implementation. A Middleware can provide glue code between the applications and the heterogeneity of devices by providing optimized set of services for autonomously managing the resources and functionality of wireless nodes in a distributed wireless sensor network. This paper presents an autonomous middleware framework for low power distributed wireless sensor networks that support adaptive sensor functionality, context aware communications, clustering, quality of service and faulttolerance. Finally an application on how to use the autonomous middleware is illustrated on the Envelope System Research Apparatus (ESRA).

This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolut... more This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at repository@u.library.arizona.edu

Energy Conversion and Management, Nov 1, 1994

In relatively arid regions, natural draft evaporative coolers can be used for cooling residential... more In relatively arid regions, natural draft evaporative coolers can be used for cooling residential and commercial buildings, as well as outdoor areas, however, their design can be time consuming. Several approximations are presented here to simplify the computations. Density calculations are eliminated using a correction term with wet and dry-bulb temperatures. Under calm conditions, iterative calculations involving the pad air velocity and efficiency can be eliminated with a logarithmic approximation.

Bogota, Colombia, is the third highest capital in South America, its location near the equator as... more Bogota, Colombia, is the third highest capital in South America, its location near the equator assures high altitudes over the horizon and almost 5 hours of daily mean sunshine. Since 1981, efforts for using natural energy instead of nonrenewable fuel have been targeted to Colombia`s residential construction industry. This paper focuses on a computer aided design process for passive solar low-income row housing in Bogota. Thermal comfort for this tropical climate has been achieved through employing ``Guadua,`` a strong bamboo specie,as an alternative wall system to the traditional brick, adobe, or concrete structures. Through computer analysis, several energy conservation and passive solar strategies have been optimized for a case study row housing type common to the region. The load savings compared to a 6 inch CMU house totaled 72%, while the operating cost has been reduced by 71%. Furthermore, this lightweight and inexpensive ``Guadua`` material has reduced the construction cost by 30%.