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Urban Developments

Renewable energy vision. As the energy-efficiency of building improve the renewable energy sources become more appealing. Passive houses offer a possibility: By saving 75% of a buildings energy demand and doubling the use of renewable energy, only 5% of energy is nonrenewable.
Efficient solar energy utilization in Ekoviikki, Finland’s first ecological neighborhood.

Optimization
Urban comfort and energy-efficiency set requirements to neighborhood planning that are sometimes quite difficult to achieve. The buildings and public spaces should receive sunshine and daylight even in mid-December, they should be protected from dominant winds, but they should have natural protection from overheating in summer. The urban structure should allow for cool breezes in summer, but shelter from winter winds. It should not create wind corridors but still enable air exchange in the middle of the structure. Urban comfort and optimised and compact urban structure can conflict, and thus trade-offs are necessary despite of loosing some energy benefit.

Passive houses perform the best in optimised urban structures that enable efficient use of energy-saving technologies. Both passive solar heating and passive cooling should be included, since high solar irradiation in winter and low irradiation in summer contribute for a building’s low energy demand. This also defines the extent to which the concept can be applied in various settlements.

Density
Density of the urban development is crucial for a Passive House settlement. A rule of thumb is that a house should not over-cloud its neighbouring houses more than 50% of the south-facing façade on December 21 at 14:00. The houses should then have appropriate distances, or the building height should increase towards North.

Flat areas and gentle south-facing slopes are the most prominent design areas for passive houses. However, Passive House concept should be used especially on north facing slopes. On a slope the distances of equally high buildings can be shorter than on flatlands. Slope analysis gives preliminary information on settlement density and building sites that serve for overall energy performance of the neighbourhood. The steepness and orientation of slopes affect the length and direction of shadows on that slope. Appropriate site selection should generally aim at development on low slopes