The study deals with investigation of acoustical characteristics of a hybrid silencer made up of a dissipative silencer and a quarter wave tube resonator. The theoretical and experimental analyses are performed to define acoustic characteristics of a simple expansion chamber and reactive perforated silencer, while the numerical and experimental solutions are presented for dissipative perforated silencer. Furthermore, the experiments and numerical solutions are extended to the hybrid silencer to find the effect of quarter wave tube resonator on the silencer performance. The experimental results of dissipative silencer are verified with theoretical solutions. The empirical expressions for acoustic impedance of perforation and filling material are presented in this study for use in a three-dimensional boundary element method (BEM). Besides, an experimental setup is also established to find the characteristic impedance and wavenumber of absorbing material to import BEM solution when the empirical expression cannot be used. The results found with BEM are compared by analytical and experimental results favorably.

The aim of this study was developing an energy benchmarking method for urban quarters in order to design or manage the energy efficiently at urban scale. Rational implementation of energy efficiency strategies for the urban settlements can be possible with the comprehensive building stock models which have the ability to estimate and evaluate the energy demand of the building stock together with surrounding urban structures. The research initially focused to determine the factors which have an influence on the urban energy performance and rating, labeling, benchmarking systems used for evaluation of the energy performance. The field of study has narrow down to residential urban quarters which is approximately 70 % of the building stock. It has been considered surrounding attributes, building properties and occupant behavior. The results of the measurements from casestudy area were evaluated with regresional analysis in order to understand which factors have influence on energy performance. Artificial representative residential settlements were configured in that some of the factors were not possible to consider or evaluate with casestudy data. These representative residential settlements were evaluated with EnergyPlus simulation program and the results were compared with each other for forming a benchmarking method. The simulation results shows that density of the area and building envelope properties have significant effect on the urban energy performance. In order to use these benchmarking results, simulations were applied to the web tool. This urban energy benchmarking method provide the quantified energy performance of the different settlement types for urban designers and urban energy planners enabling them to estimate the urban energy requirement without socio economic context.