Impact of urban block typology on building solar potential and energy use efficiency in tropical high-density city

This paper presents the results of an investigation on the relationship between urban block typology, solar energy harvesting potential and building energy use efficiency in the context of the tropical high-density city Singapore. Thirty generic urban block cases in six typologies that represent a diverse range of urban forms were examined through simulation-based studies under the same planning conditions and simulation assumptions so as to rule out the impact of non-design related factors. Several key planning and geometric parameters which capture the formal characteristics of the urban blocks were examined as independent variables, and the dependent variables include the performance indicators on solar energy harvesting potential and building net energy use intensity that capture the dual benefits of photovoltaic (PV) systems in reducing building cooling loads and offsetting local plug loads with electricity generated on site. The results indicate that, under the same planning conditions and design premises, differences in urban block typology could lead to up to 200% increase in solar energy harvesting potential and electricity generated from rooftop PV, twelve times higher rate of reduction in building cooling loads, tow times higher rate of reduction in net purchased electricity, and 25% lower building net energy use intensity. The courtyard and hybrid urban block typologies consistently outperform the other typologies, especially the commonly implemented tower and slab blocks, and they benefit the most from PV deployment in the tropics. The comparison between an existing residential precinct and a hypothetical alternative hybrid urban block further demonstrated the significant impact of urban design on efficiency of PV electricity generation and building energy use efficiency. In addition to the significant economic benefit in reduction in utility cost and environmental implication in terms of equivalent reduction in CO2 emissions on urban scale, this study highlights the crucial role that urban design plays in terms of maximising on-site renewable energy production such as solar energy. The significant planning and geometric parameters in relation to the performance indicators provide insight as reference for establishing solar energy friendly urban planning and architectural design guidelines. The methodology and technical workflow as developed can support reliable and efficient feasibility studies, especially in the early stage of urban planning and architectural design. Integrated with other performance evaluations, they can facilitate decision-making on implementation of renewable energy integrated green building technologies and passive design strategies.