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Building energy simulation has become a useful tool for predicting cooling, heating and electrical loads for facilities. Simulation models have been validated throughout the years by comparing simulation results to actual measured values. The simulations have become more accurate as approaches were changed to be more comprehensive in their ability to model building features. These simulation models tend to require considerable experience in determining input parameters and large amounts of time to construct the models. As a result of the large number of man-hours required, simplified models have been sought and used. Simplified models are particularly useful for conducting preliminary assessments of energy conservation measures. These simplified models often use linear relationships in order to estimate conditions such as infiltration, energy usage, and temperature gradients. Studies have been performed in order to validate popular models such as ASHRAE's Bin or Modified Bin methods. A useful measure would be to determine the accuracy of a simplified model to establish error bounds. Having a simplified model and establishing its error bounds, technical estimations from such models could be used in selected applications with more confidence. The error bound relative to DOE-2 predictions, for a proposed simplified model denoted IEC, for estimating a commercial building's cooling load are presented along with two actual-building test cases for validation purposes. The sensitivity of the error to various building parameters such as minimum make-up air, cooling capacity oversize, and internal equipment load was investigated. The error bound was determined to be within ±15 per cent for both cases and almost all variations. / Master of Science

Shading devices have the potential to reduce peak cooling load and annual energy consumption because they can be used to control solar gain. Thus, the need to model shading devices in a glazing system analysis is important. This thesis deals with various measurement techniques and model development related to solar optics in windows with shading devices. It also considers longwave radiative properties of shading devices via model development and experimentation. The different shading devices examined were roller blinds, insect screens, pleated drapes and venetian blinds. The energy performance of windows with shading devices was modeled using a two step procedure. Solar radiation was considered in the first step by developing a multi-layer solar optical model for glazing/shading systems. This newly developed model is an extension of an existing model for systems of specular glazing layers and includes the effect of layers that create scattered, specifically diffuse, radiation in reflection and/or transmission. Spatially-averaged (effective) optical properties were used to characterise shading layers, including their beam-diffuse split. The multi-layer solar optical model estimates the system solar transmission and absorbed solar components. The absorbed solar components appear as energy source terms in the second step – the heat transfer analysis. The heat transfer analysis involves the formulation of energy balance equations and requires both effective longwave properties and convective heat transfer coefficients as input. The simultaneous solution of the energy balance equations yields the temperature as well as the convective and radiative fluxes. The effective solar optical properties of flat materials like drapery fabrics, roller blinds and insect screens were obtained by developing a new measurement technique. Special sample holders were designed and fabricated to facilitate measurements using an integrating sphere installed in a commercially available spectrophotometer. Semi-empirical models were then developed to quantify the variation of solar optical properties with respect to incidence angle. In turn, effective layer properties of venetian blinds and pleated drapes were modeled using a more fundamental net radiation scheme. The effective longwave properties of flat materials were obtained by taking measurements with an infrared reflectometer using two backing surfaces. The results enabled simple models to be developed relating emittance and longwave transmittance to openness, emittance and longwave transmittance of the structure. In turn, effective longwave properties of venetian blinds and pleated drapes were modeled using a net radiation scheme. Convective heat transfer correlations were readily available. Finally, the newly developed models were validated by measuring the solar gain through various shading devices attached to a double glazed window using the National Solar Test Facility (NSTF) solar simulator and solar calorimeter. Solar gain results were also obtained from simulation software that incorporated the models. There was good agreement between the measured and the simulated results thus strengthening confidence in the newly developed models.

Shading devices have the potential to reduce peak cooling load and annual energy consumption because they can be used to control solar gain. Thus, the need to model shading devices in a glazing system analysis is important. This thesis deals with various measurement techniques and model development related to solar optics in windows with shading devices. It also considers longwave radiative properties of shading devices via model development and experimentation. The different shading devices examined were roller blinds, insect screens, pleated drapes and venetian blinds. The energy performance of windows with shading devices was modeled using a two step procedure. Solar radiation was considered in the first step by developing a multi-layer solar optical model for glazing/shading systems. This newly developed model is an extension of an existing model for systems of specular glazing layers and includes the effect of layers that create scattered, specifically diffuse, radiation in reflection and/or transmission. Spatially-averaged (effective) optical properties were used to characterise shading layers, including their beam-diffuse split. The multi-layer solar optical model estimates the system solar transmission and absorbed solar components. The absorbed solar components appear as energy source terms in the second step – the heat transfer analysis. The heat transfer analysis involves the formulation of energy balance equations and requires both effective longwave properties and convective heat transfer coefficients as input. The simultaneous solution of the energy balance equations yields the temperature as well as the convective and radiative fluxes. The effective solar optical properties of flat materials like drapery fabrics, roller blinds and insect screens were obtained by developing a new measurement technique. Special sample holders were designed and fabricated to facilitate measurements using an integrating sphere installed in a commercially available spectrophotometer. Semi-empirical models were then developed to quantify the variation of solar optical properties with respect to incidence angle. In turn, effective layer properties of venetian blinds and pleated drapes were modeled using a more fundamental net radiation scheme. The effective longwave properties of flat materials were obtained by taking measurements with an infrared reflectometer using two backing surfaces. The results enabled simple models to be developed relating emittance and longwave transmittance to openness, emittance and longwave transmittance of the structure. In turn, effective longwave properties of venetian blinds and pleated drapes were modeled using a net radiation scheme. Convective heat transfer correlations were readily available. Finally, the newly developed models were validated by measuring the solar gain through various shading devices attached to a double glazed window using the National Solar Test Facility (NSTF) solar simulator and solar calorimeter. Solar gain results were also obtained from simulation software that incorporated the models. There was good agreement between the measured and the simulated results thus strengthening confidence in the newly developed models.

The following report investigates district cooling systems. This form of technology provides an alternative means of providing cooling. In a traditional cooling system each building would include cooling equipment to serve only that building. District cooling differs in that water is chilled at one location and pumped to two or more buildings. District cooling has many benefits over traditional cooling systems. This report, however, aims to determine the economic benefits (if any) of district cooling systems. The location chosen as a model for this study was the University of Natal (Durban) campus. This campus currently operates a district cooling system serving six buildings. This study is hypothetical in nature, as the cooling system is already finalized and operational. The aim of this dissertation is to answer the question of which would be the more attractive alternative if the University were in a position of having to install a completely cooling system. One of the most important steps in this process is the calculation of cooling loads. The cooling load was estimated for each of the buildings associated with the district cooling system. The LOADEST software package was used to derive these cooling loads. The accuracy of LOADEST software was also validated in this study. The bulk of this report is composed of the preliminary work required to obtain capital and operating costs for cooling systems, including validation of cooling load calculation software. It was felt that this prelimiinary work justified inclusion in the final report to provide accurate representation of the steps taken before any economic evaluation could be reached. The capital and operating costs of the district cooling system and a more traditional system were compared. It was found that the district cooling system reduces operating costs significantly, although it's capital cost is higher than the traditional system against which it was compared. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

Thesis (Master)--İzmir Institute Of Technology, İzmir, 2005. / Keywords: Artificial neural networks, fuzzy logic, modeling, cooling load, prediction. Includes bibliographical references (leaves. 44-45).

The energy consumption rate of non-OECD countries rises about 2.3 percent per year as compared to the energy consumption rate of OECD countries which is 0.6 percent. If developing countries use energy efficient technology and integrate renewable energy systems in the new building their carbon dioxide emission rate reduces by 25 to 44 percent.  However, even now, renewable energy integrated buildings are hardly considered while constructing them.   This thesis work focuses on the study of solar cooling system options for residential house in Bahir Dar city. To meet the demand of housing in the city, different type of apartments and villa houses are under construction.  Case study was made focusing on two types of residential houses (condominium apartment and Impact Real-estate Villa house) to determine the cooling load and to select cooling system.   Simulation results of IDA ICE software show that the average operative temperatures and cooling loads for condominium apartment and Real-estate Vila are 31.8oC and 30.7oC, 5.53 kW and 5.73 kW respectively. Most of the residences are not satisfied at this operating temperature.   There are different types of solar cooling systems.  Solar Sorption cooling systems are commonly used which can also be classified in to absorption, adsorption and desiccant cooling systems.  Solar adsorption cooling systems are easy to manufacture locally as compared to solar absorption cooling systems. They do not have moving parts. Some of the working medium pairs used in adsorption cooling system are: Activated Carbon/Ammonia, Silica gel/ water, Zeolite/water. Adsorption chillier with Silica gel/ water as a working pair was selected since it can operate at regeneration/desorption temperature as low as 45oC coming from flat plate collectors.  At 75oC regeneration temperature, the system delivers 9oC chilled water temperature.   The selected solar adsorption chiller has been compared with kerosene based adsorption cooling system using HOMER software.  In this project, the optimization was limited on cost comparison between the two energy sources.  The solar based cooling system has lower working cost.   From cooling load simulation result direct solar irradiation is the highest source of cooling load for both houses. This gives an opportunity for passive solar cooling technology.

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Industrial and military vehicles, including trucks, tanks and others, employ cooling systems that address passenger cooling and auxiliary cooling loads ranging from a few Watts to 50 kW or more. Such systems are typically powered using vapor-compression cooling systems that either directly supply cold air to the various locations, or cool an intermediate single-phase coolant closed loop, which in turn serves as the coolant for the passenger cabins and auxiliary loads such as electronics modules. Efforts are underway to enhance the performance of such systems, and also to develop more light weight and compact systems that would remove high heat fluxes. The distributed cooling configuration offers the advantage of a smaller refrigerant system package. The heat transfer between the intermediate fluid and air or with the auxiliary heat loads can be fine tuned through the control of flow rates and component sizes and controls to maintain tight tolerances on the cooling performance. Because of the additional loop involved in such a configuration, there is a temperature penalty between the refrigerant and the ultimate heat sink or source, but in some configurations, this may be counteracted through judicious design of the phase change-to-liquid coupled heat exchangers. Such heat exchangers are inherently smaller due to the high heat transfer coefficients in phase change and single-phase liquid flow compared to air flow. The additional loop also requires a pump to circulate the fluid, which adds pumping power requirements. However, a direct refrigerant-to-heat load coupling system might in fact be suboptimal if the heat loads are distributed across large distances. This is because of the significantly higher pressure drops (and saturation temperature drops) incurred in transporting vapor or two-phase fluids through refrigerant lines across long plumbing elements. An optimal system can be developed for any candidate application by assessing the tradeoffs in cooling capacity, heat exchanger sizes and configurations, and compression, pumping and fan power. In this study, a versatile simulation platform for a wide variety of direct and indirectly coupled cooling systems was developed to enable comparison of different component geometries and system configurations based on operating requirements and applicable design constraints. Components are modeled at increasing levels of complexity ranging from specified closest approach temperatures for key components to models based on detailed heat transfer and pressure drop models. These components of varying complexity can be incorporated into the system model as desired and trade-off analyses on system configurations performed. Employing this platform as a screening, comparison, and optimization tool, a number of conventional vapor-compression and distributed cooling systems were analyzed to determine the efficacy of the distributed cooling scheme in mobile cooling applications. Four systems serving approximately a 6 kW cooling duty, two with air-coupled evaporators and two with liquid-coupled evaporators, were analyzed for ambient conditions of 37.78°C and 40% relative humidity. Though the condensers and evaporators are smaller in liquid-coupled systems, the total mass of the heat exchangers in the liquid-coupled systems is larger due to the additional air-to-liquid heat exchangers that the configuration requires. Additionally, for the cooling applications considered, the additional compressor power necessitated by the liquid-coupled configuration and the additional power consumed by the liquid-loop pumps result in the coefficient of performance being lower for liquid-coupled systems than for air-coupled systems. However, the use of liquid-coupling in a system does meet the primary goal of decreasing the system refrigerant inventory by enabling the use of smaller condensers and evaporators and by eliminating long refrigerant carrying hoses.