Thermal Performance

A prototype tool to assist architects during the early design stage of floor plans has been developed, consisting of an Evolutionary Program for the Space Allocation Problem (EPSAP), which generates sets of floor plan alternatives according to the architect's preferences; and a Floor Plan Performance Optimization Program (FPOP), which optimizes the selected solutions according to thermal performance criteria. The design

Power dissipation is expected to increase exponentially to 150-250 W per chip over the next decade. To manage this large heat output, it is necessary to minimize the thermal resistance between the chip and a heat dissipation unit that the device is attached to. It is therefore important to further improve the thermal performance of thermal interface materials (TIMs), which can be achieved through 1) improvement of the bulk thermal conductivity of TIMs; and/or 2) reduction of interfacial thermal resistances between the TIM and the device and/or TIM and the heat dissipation unit. The latter improvement may be obtained by enhanced physical properties of TIMs (e.g., viscosity or wetting ability) and/or surface modification of the heat dissipation unit or the inactive side of the device. Researchers have tried to take advantage of the high 1D thermal conductivities of graphite fibers, and more recently of carbon nanotubes (CNT), to reduce the thermal resistance between the chip and the h...

A technically accurate, credible, and cost-effective energy performance rating system aided by use of accurate simulation software has lead, over the last decade, to a transformation of the building fenestration market and industry in North America. A transformation continues to spread to other countries. These simulation tools provide the technical basis for fenestration design, rating, labeling, promotion, marketing and regulation (both voluntary and mandatory). In the United States, window thermal performance is rated under the auspices of the National Fenestration Rating Council (NFRC). NFRC’s rating system utilizes simulations of window energy performance, validated by a limited number of measurements, through administrative and technical procedures to produce fair, accurate and credible ratings of fenestration performance. It is through the use of both good science and credible certification procedures that industry and the marketplace put credence into a rating system that is...

Parabolic trough is a concentrating solar collector. It is there since many years, generating electricity in solar power plants. It has just been a bit too expensive to compete with fossil fuels. This paper was concerned with an experimental study of parabolic trough collector designed and manufactured. A parabolic trough solar collector uses three reflecting material stainless steel, aluminum foil and mirror glass strips affix on cloth in the shape of a parabolic cylinder to reflect and concentrate sun radiations towards an absorber tube located at the focus line of the parabolic cylinder. The receiver absorbs the incoming radiations and transforms them into thermal energy, the latter being transported and collected by a fluid medium circulating within the absorber tube. To improve performance and reduce costs direct steam generation in the collector has been proposed. The Designing and Fabrication of parabolic trough solar water heater for water heating was executed, the procedure employed includes design, construction and testing stages. The model which is made up of reflector surface, reflector support, absorber pipe and a stand with manual tracking arrangement was fabricated using locally sourced material for rural applications point of view. In this paper the efficiency of parabolic trough collectors is compared on the basis of different reflecting surfaces (current SEGS plants). The model is based on absorber fluid temperature so it can be used to predict the performance of the collector with any working fluid. We determined the performance of PTSC on the basis of different reflecting surfaces.

This paper addresses the thermal performance of the building housing the Faculty of Architecture and Urbanism of the University of São Paulo, FAU-USP. The interest generated in assessing the environmental performance of such a building is based on its iconic value and the unique architectural composition in which internal spaces were conceived to have physical and environmental features in response

Increased awareness on environmental issues, together with requirements imposed by implementation of energy efficiency codes, has generated the need for tools that evaluate thermal performance of buildings. Their objective is to ensure compliance and certification. However, existing computer models are still rudimentary with many limitations for use in early design stages of any architectural project. They require exact data in a stage when designers consider conceptual ideas from a range of options rather than precise details and numbers. Design tools that suggest solutions based on ideas are rare. This disadvantage can be seen in the planning of intelligent facades, where the number of possible configurations can be overwhelming and decisions made in early stages have profound effects on energy and comfort performance.This paper presents NewFacades, a model that helps pass from ideas to significant concepts in the design of intelligent facades. It uses energy and visual comfort strategies abstracted from a prescriptive energy code for hot climates to suggest a range of good starting solutions. Designers can have energy and visual comfort estimations to these alternatives through an advanced stage energy simulation program such as EnergyPlus, or explore them further with other tools.Methods used by the tool are presented here in the context of sample cases. By working on energy principles or relying on local existing energy standards, the model can be extended to all types of climates.

Rammed earth is an ancient construction technique that consists of unsaturated loose soil compacted inside a formwork. Through the analysis of a recent project that sees the application of this material in remote communities of Western Australia, this paper discusses the social, financial and environmental sustainability of rammed earth. It shows that its embodied energy is low when compared to other materials like steel or concrete. This work also argues the need of heating, ventilation and air conditioning (HVAC) units in rammed earth buildings to reduce the dependence on the energy required by these units, energy that is not always available in remote areas or in under-developed countries. In hot arid climatic zones, by simply applying some traditional design features it might be possible to create a comfortable living space without any artificial air conditioning devices.

This paper presents the preliminary findings of on going study intended to develop a cool house by introducing roofing materials with higher Solar Reflectance Index (SRI). SRI is a composed measure that accounts for surface's solar reflectance and emittance. It is ...

Different categories of solar cooker ranging from concentrator types, solar ovens, box type cookers with or without reflectors and indirect solar cookers have been designed and tested in Nigeria. The uses of different designs of solar cookers have not become acceptable in the rural areas due to number of reasons. It is either they are too expensive for individual family to afford or they are yet to be practically known. In view of these shortcomings, this paper presents thermal performance of low cost reflectors based solar box cooker implemented in Ile-Ife, Nigeria. The cooker was constructed with locally available materials. The thermal performance of the cooker in terms of figures of merits and cooker efficiency was evaluated based on Indian Standard (IS 13429:2000). Results of field evaluation show maximum insolation of 520 W/m 2 at 2.00 pm and minimum of 246 W/m 2 at 11.00 am. The average solar radiation and ambient temperature observed during the test periods were 403 W/m 2 an...

Self-heating effects in silicon-on-insulator (SOI) power devices have become a serious problem when the active silicon layer thickness is reduced and buried oxide thickness is increased. Hence, if the temperature of the active region rises, the device electrical characteristics can be seriously modified in steady state and transient modes. In order to alleviate the self heating, two novel techniques which lead to a better heat flow from active silicon layer to silicon substrate through the buried oxide layer in SOI power devices are proposed. No significant changes on device electrical characteristics are expected with the inclusion of the novel techniques. The electro-thermal performance of lateral power devices including the proposed techniques is also presented.

In this paper, the electrical and thermal performances of a single-crystalline submerged photovoltaic (PV) solar panel (SP2) is investigated. In particular, due to the presence of water, several phenomena occur such as the modification of solar-radiation spectrum and the reduction of the module operating temperature. These phenomena have different impacts on the global energy performance of the PV module, which depends on the environmental conditions, on the PV technology, and on the water depth. Energy performances of an SP2 module are measured using two different experimental setups in different environmental conditions, with an increase in power ranging from 10% to 15%.

India is a large subcontinent having many diverse regions, each having its own vernacular architecture tradition. These regions are as diverse as hills, desert, coastal area, hot and humid riverine plain, humid rainforests and many more. Similarly, the vernacular forms of architecture are diverse in their layout, form, building materials, methods of construction and structural systems. There is but one basic similarity – they are climatically and geographically most suited to their original regional location.

Indira Gandhi Rashtriya Manav Sangrahalaya (IGRMS), Bhopal is a museum that houses examples of these vernacular structures in full scale built by their original inhabitants in natural site. The city of Bhopal is capital of the state of Madhya Pradesh (literally translates as the Central Province, and justifies that name with its central position in India) is situated ‘Humid Sub-tropical’ region of India as per Koppen’s classification and offers a different context from the original site and climate  situation of these vernacular structure.

This paper thus aims at assessing whether and how vernacular architecture performs consistently in regions other than its own when transplanted. Thus, it has recorded and quantified climatological data for some of these vernacular huts belonging to diverse regions to compare and contrast their construction material, design and thermal performances on a iso-climatic framework. In the research, climatic data like ambient temperature, wind velocity, relative humidity have been collected for selected vernacular houses that are originally scattered within the huge geographical area of India, and which also belong to varied climatic regions. These houses vary in terms of  their layout, materials and methods of construction and so forth. These data have been compared and analysed to find their dependence on the different building features and components of these houses. The analysis of the collected database have also been used to assess the basic question of the research i.e., to assess and compare the relative performance of these houses brought together in a single place under the same climate.

External shading devices have been utilized very extensively in the residential buildings in the tropics to reduce the amount of solar radiation occurring in the buildings. It is now widely accepted that architects should encompass the environmental task of reducing fossil fuel energy consumption in response to climate change. The study focuses on the minimum depth required for the fixed horizontal shading device for optimum shading performance at south façade for commonly used opening sizes in the residential buildings in Dhaka city. Particular emphasis has been given on the opening size, depth of the shading device, vertical shadow angle during the warmest part of the day of warmest seasons and the thermal performance for using different depth of shading devices in various opening sizes. Two residential buildings are fundamentally chosen as topic for this study. The units having two different sizes of opening and shading systems are taken as the study element. Difference between maximum outdoor temperature and indoor temperature and the shadow patterns are taken into account during the warmest part of the day to identify the parameters for existing thermal performance due to shading devices. The field survey was conducted in a sunny day to measure the temperature difference between indoor and outdoor and the direct solar radiation in both study models. The shadow simulation of the case studies were conducted by the Sketch up v7.0 having location data and based on the dates and times of the warmest months. The simulation is more visual than analytic. This paper is an outcome of the study which encompasses the efficient shading device design strategy to reduce direct solar exposure on the openings at south façade along with the case studies in the context of Dhaka, Bangladesh and its effect on building performance in terms of thermal performance.