Computational assessment of building system performance: Improved energy efficiency and thermal comfortability for the future

Energy expenditure is one of the significant overheads in the lifespan of multistoreyed buildings. Reliable and proficient functions of Heating, Ventilation and Air Conditioning (HVAC) systems are further imperative as a result of the climbing price of electricity. This research recommends that the compounded energy utilisation to meet the demand from high humidity and temperature could be minimised by adopting the alternative high-performance building envelope and low emission cooling method along with the optimised control of additional operational parameters. The core purpose of this research is to computationally evaluate the performance of various alternative building envelopes and low energy cooling methods to determine the best performing envelop and cooling method to enhance the energy efficacy and human comfort in buildings in a subtropical climate in Australia. Firstly, a detailed energy assessment of the current building systems is undertaken on a selected case study building in Rockhampton, Central Queensland. Then, a comprehensive energy simulation model is developed, employing a building energy simulation algorithm. The modelled energy and comfort data of the building systems are validated by means of on-site recorded data. The substantiated model is then expanded to evaluate the efficacy of several alternative building envelopes such as bio-phase change material (BioPCM), cavity wall, Trombe wall, building integrated photovoltaic (BIPV) and low emission cooling methods such as, cooled Beam, ground source heat pump, variable air volume, variable refrigerant flow system to secure better comfort and energy savings in both summer and winter months. Furthermore, an extensive multicriteria based optimisation is undertaken to determine combined alternative envelope and cooling method for retrofitting of the existing systems that will meet the requisite of the present and the future depending on the potential climate change scenario. This study found that both cooled beam and ground source heat pump as low energy high-performance cooling alternatives, and BioPCM as high-performance building envelope have the higher potential for energy conservation and better thermal comfort based on the present and future weather conditions. Through multi-criteria optimisation, the study found that BioPCM and Cooled Beam as an integrated mechanism can be successfully incorporated into buildings in subtropical climate to improve the energy efficiency by 30% and human comfort which have not been evaluated in any other studies in the past. Furthermore, the use of the combined optimised approach, i.e. integration of BioPCM and Cooled Beam, produces significantly less emission (21%) per year at the same time ensures the comfortability of the occupants which is the utmost consideration in the study. Finally, the study offered a net positive energy operating method to ensure that carbon footprint is minimised considering the present and future weather conditions. Overall, a practical thermal simulation orientated optimisation framework is developed and executed that unites the objective of minimising energy consumption of building systems as well as maintaining superior comfort of the people based on the present and future weather conditions.