THE IMPACT OF THE URBAN FORM ON HEATING, COOLING AND LIGHTING DEMAND OF CITIES Aysegül Tereci, Dilay Kesten, Ursula Eicker Research Centre Sustainable Energy Technologies zafh.net, University of Applied Sciences Stuttgart Schellingstr.24, 70174 Stuttgart, Germany ursula.eicker@hft-stuttgart.de ABSTRACT The impact of the urban form on the energy demand of buildings is difficult to quantify. Only very few software tools are available that calculate the influence of mutual shading of buildings and topography on the energy demand. Some dynamic building simulation tools consider shading situations, but are limited to calculations of a specified window surface area with a given horizon line and cannot be used to simulate an urban area. If lighting electrical energy is also considered, the simulations become more complex, as the sky models need to be realistically represented. As a result there is not much information available, how the total primary energy demand is affected by the specific urban form. In this work, generic urban forms have been classified with regard to their overall energy performance. For selected forms detailed simulations of heating, cooling and daylighting were carried out on a floor by floor level to consider precisely the shading situation from neighbouring buildings. The parameters chosen for the urban form variation include the site coverage (i.e. density), settlement and building typology (block structures, row houses, multi-family houses, high rise etc.), building age and thermal standard. To validate the different simulation tools used, a case study was carried out on the urban area Scharnhauser Park near Stuttgart, Germany, where energy consumption data are available for the whole settlement of 10,000 inhabitants. For a given urban situation detailed energy simulations were carried out and compared with measured consumption data. The models were then simplified to represent a more abstract generic form. Using the geometrically simplified model, parameter variations were carried out, for example on site coverage, to calculate the impact of the urban form on the total energy demand. About 20% difference in energy demand was obtained for the same building typology, but higher surface coverage for a middle European climate with dominance of heating energy consumption. In the paper the different energy performance of urban forms will be compared for different climates with varying heating, cooling and daylighting situations. KEYWORDS Urban form, urban energy performance, heating, cooling, lighting. INTRODUCTION Energy efficiency and sustainable environments for cities have become a key topic of the recent studies. In order to evaluate the effects on urban energy performance, it is important to quantify relationships between wide ranges of urban factors. Urban design has a significant influence on energy performance of cities and it is irrespective of the socio economic context (Rohinton, 2005). To quantify the effect of this factor would be the first step for understanding the energy requirements of the cities and associated problems on environment and human health. Urban spatial structures together with urban forms shape the urban structure design. According to climatic conditions the structure of the urban quarters and their surface properties may have a positive or negative influence on the lighting, heating and cooling energy demand of the buildings. In the different research studies daylighting or thermal performance were investigated for urban areas related to urban forms. To understand which urban form gives the best land-use according to daylighting availability was evaluated in the late sixties by Leslie Martin and Lionel March in Cambridge. They classified the urban forms according to their daylighting performance as pavilions, slabs, terraces, terrace-courts, pavilion-courts and courts. A range of studies according to the Martin and March classification on urban forms were made by Gupta 1987, Blowers 1993, and Steemers et al.1997. Their works only considered the irradiance on the facade and does not include the work related with Published in: ICSU Proceedings of the 1 st International Conference on Substainable Urbanisation, Hong Kong, China, 15-17 September 2010.