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Master Planning

Solar design at www.suntool.net
Evaluation of South and North facing slopes.
Ecocity in Tübingen, Germany aims at very low neighborhood level energy consumption. Passive houses are one of the energy saving strategies.

General
Master planning and design of an energy efficient neighbourhood is a process of trade-offs between planning and building design choices and planning and design parameters. There are priorities and conflicts that have to be addressed in the process.

Master planning of an energy-efficient Passive House neighbourhood includes the basic master planning procedures as any master plan: site analysis, climatic analysis, topography, and slope analysis. The primary focus of the master plan is to ensure that the land is used efficiently and that the buildings fit appropriately into the service infrastructure.

Urban neighbourhoods are comprised of many urban features: buildings, roads and other infrastructure. The urban structure influences the local microclimate that may contribute significantly to both thermal and electrical loads of buildings in terms their demand for heating, cooling and artificial lighting. There are differences in temperature between a rural meteorological station and an urban street that can be attributed to background (heat island) and local (street canyon) thermal processes. The urban skyline influences both the direct and diffuse solar radiation incident on a façade.

Site layout

  • Use of southern orientation of buildings for passive solar heating. Optimum locations are sunny southern sides of valleys where the temperature balance can become positive helping for reduced heat consumption of buildings.
  • Avoidance of placing buildings in valleys because they can gather cold air during nights and the mean temperature will thus decrease.
  • Avoidance of creating cold air pockets with long or even curved buildings placed unconsidered on slopes.
  • Avoidance of placing buildings on shady places like northern slopes or the north side of dense forests or high buildings close to them.
  • Utilization of sunshine also for increasing the pleasantness of yards and public urban spaces.

Optimised urban structures do not reduce the energy requirement or the emissions directly; they provide good conditions for effective and economical applications of energy conservation techniques. A Passive House can utilize solar energy efficiently. Climatic analysis of a site shows the planner to what extent air temperature, solar radiation, air movement and relative humidity affect on buildings’ energy demand.

Energy consumption
In the northern hemisphere, south facing facades receive the greatest amount of solar radiation. South facing design areas should contain the greatest number of dwellings and the smallest lots. The location of buildings on south facing slopes increases the number of buildings that can utilise solar energy, but it is as important to take care of solar protection to avoid overheating during summer.

  • Compactness of the area (gross floor area/design area): reduced district heating network losses
  • Compactness of the structure (ratio volume-surface factor): tall apartment building (V/A 0,3) compared to houses in a row allows for approximately 20% less consumption for heating.
  • Optimized orientation of buildings towards south: approximately 15% less consumption for heating possible
  • Optimized solar irradiation: no shading vs. shading houses in a row; estimated 10% less consumption possible
  • Roofs for active solar use by optimum south facing solar panels: estimated 10% to 15% less consumption for hot water possible
  • Decision about building standard: Passive Houses compared to the national building code allows for at least 75% less space heating consumption.