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Title

OPTIMIZING THE PERFORMANCE OF BUILDING ENVELOPE FOR ENERGY EFFICIENCY CONSIDERING ADAPTIVE THERMAL COMFORT: A CASE OF TROPICAL CLIMATE IN DHAKA

Creator

Rahman, Anisur

Date

2014, 2014-05

Description

As demand for fossil fuel increases and availability decreases, energy consumption reduction in building becomes critical component of a city...
Show moreAs demand for fossil fuel increases and availability decreases, energy consumption reduction in building becomes critical component of a city’s comprehensive energy strategy. The performance of a building’s envelope is pivotal to the energy consumption of office buildings and it must mediate between external climate conditions and people’s comfort. By optimizing a buildings envelope, the heat gain or loss of a building can be manipulated and it can reduce energy consumption. In Dhaka, a widespread desire for office building with glazing areas far greater than the percentage required achieving comfortable thermal and light levels, with high solar transmittance, is directly at odds with the need to curb cooling-related energy use. When addressing energy efficiency in a building, it is necessary to account for local climate first and foremost to define the thermal comfort condition. This determines the energy demand and consumption. Passive cooling and natural ventilation, when combined with appropriate window ratios and sun shading strategies, can reduce mechanical system energy demands significantly. This research presents a workflow that integrates adaptive thermal comfort, natural ventilation and envelope optimization to develop a pre-policy statement as a guideline for energy efficient office buildings in Dhaka, Bangladesh. First, a common practice baseline model was developed from data collected from energy audits to gain a clear understanding of the energy consumption in typical existing office buildings in Dhaka. Adaptive Comfort Algorithms from EN15251 and ASHRAE 55 were used to calculate variable set-points related to running mean and monthly mean xv of the outdoor temperature respectively. Variable set-points have been used in EnergyPlus AirflowNetwork to determine the potential energy saving of adaptive comfort control strategy of HVAC equipment and for encouraging natural ventilation envelope strategies to create comfortable indoor environment in the local climatic context of Dhaka. A method of envelope optimization was developed by combining an optimization tool with a building energy simulation tool to determine the optimum solution for improving building envelope performance. GenOpt, a generic optimization program, has been coupled with EnergyPlus for this optimization. Then, the values of envelope and glazing parameters for optimum energy performance were determined using this automatic optimization method. The reduction of a building’s energy consumption was also addressed with regards to capital and operational costs. An economic analysis was performed to establish a correlation between energy saving and capital cost increase associated with the energy-efficient envelope measures. This research shows that significant reductions in energy consumption are possible with the application of fundamental, but not complicated, changes to local building codes and establishment of a comprehensive energy conservation code. This reduction could be even greater if inhabitant behavior can be changed, if users start to take more responsibility for their interaction directly with a building’s envelope and systems to have some degree of control over daily comfort. Technology and design innovations should be utilized for adaptive threshold of appropriate, responsive architecture.
PH.D in Architecture, May 2014
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