Research Papers - Department of Mechanical Engineering

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    PublicationOpen Access
    Making Realistic Predictions on Building Energy Performance through Coupled Energy Simulation and Computational Fluid Dynamics
    (National Energy Symposium, 2015-11-20) Bandara, R. M. P. S; Attalage, R. A; Fernando, W. C. D. K
    Buildings account for nearly 40% of the global energy consumption and hence presently high emphasize is made on improving the energy performance of buildings. Energy Simulation (ES) is the most widely used method in predicting the energy performance of buildings during the conceptual stage. However, it is observed that Energy Simulation tools show certain inherent deficiencies in predicting the energy performance of buildings. The said tools do not have the capacity to model air circulation through the building space explicitly. Energy Simulation tools mainly rely on the simplifying assumption that air within a thermal zone of a building is well-mixed. Furthermore, convective heat transfer coefficients of building surfaces are calculated using set empirical correlations. Hence, ES tools often find it difficult to make realistic predictions on energy performance of buildings. The literature also reveals that most Energy Simulation tools under-predict energy consumption in buildings, especially under sunny conditions. On the other hand, Computational Fluid Dynamics (CFD) tools are capable of predicting the indoor flow field comprehensively. However, CFD simulations need to be provided with the corresponding boundary conditions of the computational domain, which are readily available in the Energy Simulation approach. On this basis, the paper explains how Energy Simulation can be coupled with Computational Fluid Dynamics in predicting the energy performance of an actual building design more accurately through complementary data exchange between the tools. The analysis uses EnergyPlus 8.0 and Ansys Fluent 6.3 as the tools for conducting Energy Simulation and Computational Fluid Dynamics respectively. MATLAB R2012a establishes the coupling platform. The study shows that the coupled scheme predicts considerably higher energy consumption for the building design compared to that given by the conventional Energy Simulation using EnergyPlus.
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    PublicationOpen Access
    Optimization Methodologies for Building Performance Modelling and Optimization
    (FACULTY OF ENGINEERING, UNIVERSITY OF MORATUWA, 2013) Bandara, R. M. P. S; Attalage, R. A
    Buildings account for approximately 40% of the global energy consumption and 36% of total carbon dioxide emissions. At present, high emphasis is given on the reduction of energy consumption and carbon footprint by optimizing the performance and resource utilization of buildings to achieve sustainable development. Building performance is analyzed in terms of energy performance, indoor environment for human comfort & health, environmental degradation and economic aspects. As for the energy performance analysis, this can be best modeled and optimized by a whole building energy simulation tool coupled with an appropriate optimization algorithm. Building performance optimization problems are inherently multivariate and multi-criteria. Optimization methodologies with different characteristics that are broadly classified as Adaptive, Non-adaptive and Pareto Algorithms can be applied in this regard. The paper discusses the applicability of the aforementioned optimization methodologies in building performance optimization for achieving realistic results.