Rethinking Infrastructure Design - Rethinking Infrastructure Design for Multi-Use Water Services - page 13

Fig. 13 Examples of harvested roof water and grey water recycling

issue was dealt with by interacting with other ecosystem services. By solving one
problem, MUS solutions are designed to provide co-bene

ts. In the case of puri-

fication of water, vegetation plays an important role in the treatment process. The
advantage of this decentralised biological treatment system is that they do not
produce sludge or require chemicals. In addition, the level of energy consumption is
much lower and the operating and management cost are lower as well. Showcases
of such systems have been developed in Amsterdam for separate sewer system,
which showed not only cheaper but also cleaner ef uent.

There are companies that have started producing and marketing simple grey
water recycling products.

4.4 Urban Heat Island

As urban areas developed, the landscape changed greatly. As common constructed
materials replaced natural ones, more sun energy is absorbed in urban areas.
Impermeable and dry areas instead of permeable and moist ones with urban street
canyon effect are one of the reasons to contribute to the positive thermal balance of
urban areas

Urban Heat Island phenomenon. In climate areas where the population
has not developed resilience to heat waves, large-scale fatalities can occur (Fig. 14 ).
What are the differences between a vegetated scenario and non-vegetated sce-
nario? Two main reasons heat islands are formed are: impermeable and watertight
materials, widely used for urban building construction, which directly leads to
insuf

—

'

cient moisture available to dissipate the sun s heat; dark materials and urban

canyon effect of buildings and pavement ' block the radiation from surfaces to cool

sky (Fig. 15 ).

Trees and vegetation besides shading can lower the surface temperature through
shade and evapotranspiration (evaporative cooling). As in rural areas, trees and
vegetation dominate the landscape; urban areas are commonly covered by dry,

'