Extract

INTRODUCTION:
High rise residential buildings are becoming a significant portion of the Australia housing mix. Data from the 2016 census confirmed that the share of high-rise living has increased to 38% of all apartment dwellings as compared to only 18% reported for the 2006 census. Owing to their high energy use intensity per square meter of land area, an increase in the supply of high-rise residential buildings has significant implications on Australia’s existing energy supply infrastructure, including the 2050 Net zero emission targets recently committed to at the ongoing COP26 in Glasgow. Various publications, including the recent stringency proposals documented in the ABCB’s “NCC 2022 and beyond trajectory” suggests the need to transition Australia’s building performance to Net zero energy (NZE) levels. However, due to unique challenges such as high energy consumption from central and communal facilities, limited roof space for the application of rooftop renewable energy technologies, increased potential for overshadowing in high-density neighbourhoods, challenges of shared ownership and absence of a regulatory framework and significant capital cost increase, dissenting opinions exist in the research community as to the possibility of achieving the performance goal for high-rise residential buildings. To investigate the feasibility of such performance target in Australia, a research on design strategies that could lead to NZE performance for high-rise residential buildings was conducted, this paper presents the result of the investigation.

METHODS:
A mixed methods approach involving the use of a questionnaire survey and indoor environment monitoring via data loggers were employed for collecting data on a selected 26 storey high-rise residential building as case study. This was then followed by design intervention studies by means of building energy simulation using the DesignBuilder software version 6.1. To demonstrate the feasibility across different climates and density, weather data from five major Australian cities representing different climate zones and two density scenarios were simulated in the study.

RESULTS:
Findings suggest that the combination of various passive and active design strategies could deliver up to 60% improvement in performance over the baseline, with strategies focused on envelope optimisation being some of the most promising approaches. Results also confirm that the current provisions for minimum insulation levels and infiltration/ air tightness are inadequate for NZE performance. Shading from neighbouring building and nearby objects constitutes the largest impediment to the attainment of NZE performance in all the locations studied, leading to as much as 15% drop in energy production via PV panels on the façade.

CONCLUSIONS:
The investigation revealed that NZE performance is achievable in all climates in Australia with the right building performance approach and selection of technologies during the early stages of design decision-making, location and density considerations are also equally important. While the tropical, subtropical and cold temperate climates appear to be more challenging, proper design and optimisation of the envelope proved to be an effective solution to overcome the challenges imposed by the more demanding climates. Findings suggest that the attainment of NZE standards for high-rise residential buildings must look beyond the building level but also at the immediate environment at an urban scale.

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