Urban Green Areas – their functions under a changing lifestyle of ...

37). As yet sustainability generally includes the three classical dimensions: the ecological,
the economic and the social which of course clash in some areas and complement in others.
Due to the orientation of urban planning towards sustainability on the one hand and the
similarity of functions of parks, on the other hand, sustainability will be discussed here to
begin with in terms of the benefits to be derived from parks. Parks provide three types of
benefits as MARCOTULLIO (2001) demonstrated that “the economic, environmental and
social health of the city”. TZOULAS et al. (2007) all derive benefits from parks in terms of
their positive contributions to physical, mental and social well-being.
In this thesis, the term “function” will be taken to subsume both “sustainability” and also
“benefit” of parks and gardens.
2.4.1 Ecological benefits
Many studies show the positive ecological benefits of green spaces in cities (see
SUKOPP/WITTIG 1993).
Urban settlements emit substantially more green house gases than do rural settlements. And
thus has a higher pollutant density. UGAs help to reduce the pollution by influence in
almost all the aspect positively (SIMM 2012: 218).
It is also indicated that UGAs have positive effects on the micro-climate. Indeed,
SIMMS/CONISBEE (2012: 8) argue that “Greening the urban environment will also help
to ‘calm’ the brow of a warming world.” It has been demonstrated by a Japanese
measurements that urban green areas reduce 2 degrees K in an inclosing area 100m wide
(WITTIG 1993 in KUTTLER et al. 1993: 344). Furthermore, CHEN/EDWARD (2012)
affirm that UGAs are benefits for urban microclimate, creating comfort feeling for outdoor
activities.
THUY (1985) argues that a park changes the micro-climate also by altering wind speeds.
For example, a 30-ha-plantation has the ability to alter wind speed by 1m/s/ha. It is reported
by TOAN (1976: 99 ff.) that trees have the ability to raise air humidity. During hot days in
large parks, which have many trees, air humidity rises about 20 % compared with bare
ground. When the humidity rise 15 % so the air temperature reduces by 3.5 degree Celsius.
Furthermore, human thermal comfort is at a maximum when wind speed is between 0.5-
3 m/s. In hot weather, slight wind makes people feel more comfortable. Thermal comfort
and urban comfort will be considered in more detail in Section 2.4.
In addition, parks and gardens often include lake or pond. These kinds of water
bodies have effects on cooling off the air until 20 meter height, (FETZER 1995:
144f.). By evaporate process, it does not only cool off the water, but also the air
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