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The Metropolitan Jerusalem Master Plan
The Metropolitan Jerusalem Master Plan
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Of course, in order for this effect to take
place, the groups of trees need to be more
or less of similar volume as the burst of
hot air arriving.
Even now, the Jerusalem forest helps
break heat waves coming towards the
city from the west, and metropolitan
Jerusalem has a high potential for creating
a forest belt to protect the city from heat
wave conditions coming in from the
southeast. But a desert lies to the east
of Jerusalem – so how can we increase
the numbers of trees in such areas
where precipitation is never enough?
In such areas, the determining factor in
Sustainability in Jerusalem
Urban Heat Islands
Urban heat islands are a climate phenomenon that occurs when a
city affects the climate, causing substantial differences between
the city’s climate and the climate of the surrounding area.
Building a city causes changes, including tearing up
plants, creating stone and asphalt pockets, limiting
exposed topsoil, and putting up topographic
obstacles. Human activity in the city adds to this,
causing greater output of greenhouse gasses.
These changes create climate conditions different
to those in open areas around the city. The
phenomenon is usually expressed by a rise in city
temperatures and the creation of a hot layer above
it. The layer where this phenomenon can be sensed
most is the urban space – the layer of air trapped
between the ground level and building roof levels.
The urban heat island phenomenon can
cause temperature differences of up to 10-12
degrees between a big city and nearby rural
areas. Therefore, data on global warming reflect
microclimate changes in big cities more than
climate change worldwide.
The trend towards the creation of urban heat
islands exists in Jerusalem as well. Temperature
differences in the city center and further
neighborhoods can reach up to three degrees,
whereas twenty years ago it was two. Since the
change in policies regarding building height in
Jerusalem took place, the urban heat island trend
has taken on greater velocity. In light of the fact
that already today some half of all electricity
manufactured in Israel is used for air conditioning,
heating, and ventilating homes, this phenomenon
will definitely bring about an increase in energy
consumption, harm the environment, and lower
quality of life. This difference of just a few
degrees on a hot day can mean uncomfortable
temperatures for city residents, disruption of
tourists’ plans, dehydration and heat stroke.
Among the factors causing the formation of
urban heat islands are a lack of urban parks, the
construction of tall buildings, sealing off topsoil
with asphalt or concrete, and construction which
doesn’t incorporate full-grown trees close to
buildings. In order to minimize this phenomenon,
buildings higher than eight floors should not be
built, stretches of parks and forests should be
established equally and uniformly throughout
the metropolis, and full-grown trees should be
planted on every street.
whether flora is to develop is topography.
A concentration of runoff water increases
the amount of water seeping into the
soil much more than the amount of
precipitation coming in. Ancient Nabatean
agricultural methods in the Negev were
based on this concept. Runoff water must
be channeled so that it reaches the location
for forestation.
Further, there are types of trees which
are suited for planting in the desert and
can still give enough humidity to break dry
heat waves: tamarix aphylla, acacia raddiana,
Christ’s Thorn Jujube, eucalyptus and pine
Calabrian.
Kanfei Nesharim
Street today, and
simulated imagery of
its appearance after
making it usable for
pedestrians
Sustainability in Jerusalem