OPEN ACCESS
Compensating area, which refers to off-site land being used if the energy demand cannot be met due to the urban arrangement of buildings, is required in a carbon-free city because the energy demand, including thermal energy (heating, cooling and hot water), power (ventilation and artificial light) in buildings and transport, need to be covered by the renewables gained on site or in the surrounding area outside of the town. This paper aims to develop a method to explore the urban density that could deliver an energy saving, land saving, and human-scaled urban situation. Various scenarios of urban densities in the cities in different climate zones were created to emphasize the comparison and the relative difference in the required compensating area. It is found that, although transportation energy consumption can be reduced by increasing number of storeys, the rate of decrease slows down as the number of storeys increases. Also, building energy consumption increases with the number of storeys because the artificial light will reach saturation (100% of hours of use) with the increased number of storey. In terms of the comparison between climate zones, the optimal scenario would be 4 to 6 storeys in cold or moderate climates. And the optimal choice would be 6 to 8 storeys in the hot and humid climates. With regard to the consideration of human scale, not only do these optimal ranges of the number of storeys provide good daylight access, but they also fall into the range of human scale.
carbon-free city, compensating measure, energy demand, land-use requirement, urban densities, Zero Energy Building
[1] Ratti, C., Bakerb, N. & Steemers, K., Energy consumption and urban texture. Energy and Buildings, 35(7), pp. 762–776, 2005. doi:10.1016/j. enbuild.2004.10.010
[2] Salat, S., Energy loads, CO2 emissions and building stocks: morphologies, typologies, energy systems and behaviour. Building Research and Information, 37(5–6), pp. 598– 609, 2009. doi:10.1080/09613210903162126
[3] Salat, S., Cities and Forms: On Sustainable Urbanism. Paris: CSTB Urban Morphology Laboratory, 2011.
[4] MacKay, D., Sustainable Energy – without the hot air. Tratto da UIT Cambridge, 2009, available at www.withouthotair.com
[5] Chen, H.-H. & Dietrich, U., Land-use planning for Zero-Energy-Buildings: comparison of 4 high-density cities. Sustainable City 2017- 2th International Conference on Urban Regeneration and Sustainability. Seville, Spain, 2017.
[6] Chen, H.-H. & Dietrich, U., Potential and risk for (nearly)-Zero-Energy-Buildings under defined urban densities: The case of Singapore. Hamburg: SBE 16-International Conference on Sustainable Built Environment, 2016.
[7] PRIMERO-COMFORT, Retrieved from PC-program developed by HCU Hamburg, promoted by Rud. Otto Meyer-Umwelt-Stiftung, 2009, available at www.primerosoftware.de
[8] Newman, P. & Kenworthy, J., Sustainability and Cities: Overcoming Automobile Dependence. Washington DC: Island, 1999.