Sunlight availability and potential food and energy self-sufficiency in tropical generic residential districts Abel Tablada ⇑ , Xi Zhao Department of Architecture, School of Design and Environment, National University of Singapore, Singapore article info Article history: Received 17 May 2016 Received in revised form 23 August 2016 Accepted 22 October 2016 Available online 2 November 2016 Keywords: Solar access BIPV Urban farming Low-carbon neighbourhoods Urban resilience abstract A transition to a solar-based carbon neutral economy is crucial to reduce the overall ecological footprint and greenhouse gas (GHG) emissions while providing new housing for the growing urban population worldwide. One of the key measures to achieve such reductions as a way to mitigate and adapt to climate change is to increase food and energy self-sufficiency in residential areas. The objective of this study is to explore the potential self-sufficiency in terms of food and energy in generic residential districts in Singapore and Southeast Asia. Computational tools are employed to obtain quantifiable indicators based on sunlight availability. A series of building typologies and urban forms was created as abstractions from actual residential developments in Singapore (1.3°N). In total, 57 cases were assessed in terms of sunlight availability and the impact of three density and geometry parameters: plot ratio, site coverage and build- ing height were considered. Results from selected cases were compared to Hanoi’s conditions (21°N). The results show that the indicators having the higher impact on the food and energy self-sufficiency are plot ratio and building height. The cases with the lowest plot ratio (PR < 1.9) achieved food self- sufficiency when a hybrid higher-yield farming method was applied. Regarding energy harvesting, the cases with the lowest building height (<42 m) achieve energy self-sufficiency due to the maximum exposed area with PV per number of residents. In low-latitude regions, solar access is more evenly dis- tributed among all facade orientations than in higher latitudes, therefore providing all facade orientations with food and energy harvesting potential. Food and energy self-sufficiency in equatorial regions is more heavily influenced by the available farming and PV area in relation to the total population than by the reduction of sunlight availability due to building typology and morphology. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction According to UN Habitat, new housing should be provided for 2.25 billion people by 2030 (UN-Habitat, 2012). This includes the 1.43 billion people expected to migrate to urban areas and those living in precarious conditions who will need decent and affordable houses. A large percentage of this amount corresponds to tropical and subtropical regions. Only by an urgent but well-planned tran- sition from fossil fuels to a solar-based carbon neutral economy can these huge challenges be surmounted while reducing the over- all ecological footprint and greenhouse gas (GHG) emissions. The urbanisation process is accelerating along the tropical belt, especially in Southeast Asia (SEA). In Singapore, although all the population is already urbanised, the need to build higher density residential districts to accommodate the growing population in the land-scarce Estate-Island obliges the demolition of relatively old housing estates and the construction of new ones. In other tropical and subtropical regions, the land used to build new resi- dential districts is, most of the time, located in the peri-urban areas in which agricultural activities are foremost. This poses tremen- dous stress on food production and food availability. On the one hand, food demand is increased due to the growing population with higher income level and, on the other hand, fertile land around the cities is dramatically reduced. In the case of Singapore, new residential developments have already reduced the farming areas considerably, which has increased its food dependency and compromised future food security. It is estimated that the yield increase rate of the main crops will not be sufficient to cope with the growing demand by 2050 due to the increase of population, the dietary shift towards meat and dairy, especially in Asia, and biofuel consumption (Tilman et al., 2011; Ray et al., 2013). In addition, the increase of land for agricul- ture to cope with the growing demand could directly affect natural ecosystems like tropical forests. Therefore, using building http://dx.doi.org/10.1016/j.solener.2016.10.041 0038-092X/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Department of Architecture, School of Design and Environment, National University of Singapore, 4 Architecture Drive, Singapore 117 566, Singapore. E-mail addresses: abel@nus.edu.sg, abeltablada@yahoo.com (A. Tablada). Solar Energy 139 (2016) 757–769 Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener