Evaluating energy efficiency potential in high-rise buildings

Abstract

In light of the new requirements of the EU Energy Performance of Buildings Directive (EU) 2018/844, which stipulates that all new buildings must achieve nearly-zero energy status, this study sets out to investigate the best energy efficient methods for high-rise buildings after considering certain parameters that affect energy consumption such as height, weather, location and comfort criteria. Focus is mainly on the reduction of solar gains through the façade by researching different types of façades, glazing materials and shading devices, and how the same façade can be used for generation of renewable energy, using new technologies. Moreover, attention was also given to the improvement in energy efficiency of engineering services such as HVAC and water heating, to synergistically improve the building’s energy rating. In this work, a newly designed tower known as “Mercury Towers” located in St. Julian’s, Malta was investigated. The tower is in the transition phase between the design and the construction stages. An energy building information modelling (BIM) approach was adopted using Autodesk Revit. Design Builder software and its engine EnergyPlus were then used to simulate the energy consumption of the building at a very early stage. Various simulations were carried out and compared to the base model, to improve the overall energy rating of the building. The base model building envelope properties were set to follow the minimum local requirements. Sixteen case studies were carried out using different energy efficiency measures. From this study, it was found that the most effective measures for a high-rise building in Malta were those that reduce the overall space cooling and water heating demand, since they were the dominating energy consumption drivers. It was evident throughout the study that the glazing of tall buildings should be carefully selected, and that great importance should be given to shading in warm countries like Malta. The best option was to implement centralized water heating, together with external moveable window shading or BIPV glazing on the SE orientation, which reduced annual energy consumption by 50 percent. The use of photovoltaic façade walls yielded an added benefit of reducing the carbon footprint of this building by at least 7 percent, meaning that the energy consumption of the base model building can be significantly improved when all measures are taken collectively.