Urban design • Impact of energy-related aspects on the urban design • Design principles of compact and solar building • Model urban design guidelines • Reference projects • Completed Passive House developments
Impact of energy-related aspects on the urban design Today catchwords, such as “solar city” or “energy-efficient urban development”, are being used to highlight the increasing significance of energy-related issues with new model and design concepts in town planning schemes. More often than not in these cases the space/energy-related interdependencies are given priority and demanded as design principles without taking into consideration the effects of their unilateral application on an urban and social level. In response to these conflicts and the complex nature of the interdependencies, many “traditional” town planners are trying to keep energyrelated issues out of the urban design process. The aim of the following contents is to bring together the two perspectives in such a way that the energy-related issues become an essential component of the urban design without dominating the process in a one-sided manner. A variety of studies and already completed residential housing estates have shown that the Passive House concept is capable of offering suitable and practical solutions in this respect.
Influencing factors of energy-efficient urban planning The factors influencing energy-efficient urban planning are extremely diverse, and complex in the way they correlate. It is for this reason that there are many publications containing statements and requirements which appear contradictory. For urban design, it is therefore absolutely essential to be able to differentiate between important and less important parameters while at the same time keeping an eye on the energy-related and spatial conditions. The results of the author’s [1, 2, 3] systematic studies on the interdependencies of town planning and energy-related issues can be summarised as follows (figs. 6.1 to 6.6): • The choice of the buildings’ energy performance is the most important and overriding factor concerning the energy demand of a residential housing estate. • Alongside the energy performance of buildings, the building services concept is mainly responsible for the level of the primary energy demand and the greenhouse gas emissions of the estate. • The density of housing is the most important space/energy design param-
direct radiation
eter in town planning. This factor is also extremely significant in terms of economic efficiency. • The location and positioning of structural elements in town planning schemes has an impact on the sunlight situation. The orientation of main facades and roofs, in particular, as well as the overshadowing produced by topography, neighbouring buildings and vegetation have an impact on the effective amount of solar heat gain. • In summer as in winter, thermal comfort is better in buildings where the main facades face south. However, southfacing windows require some kind of shading device in summer. • The overshadowing of facades is more pronounced on lower floors and in inner corners. Careful attention should be paid to these areas in terms of capturing sufficient sun and daylight. • The regional climate – even a distinctive climate of a small-scale area – is an important influencing factor on space heat demand and even more so on thermal comfort in indoor and outdoor spaces in summer. • A number of principles that have been regarded as very important in the past, such as wind protection, preventing the
diffuse radiation
reflected radiation infrared radiation overshadowing by vegetation
overshadowing by topography
b
c
d
overshadowing by neighbouring buildings 6.1
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a
6.2