ARCHITECTURE

1. The microclimate is a local atmospheric zone where the climate differs from the surrounding
area. The term may refer to areas as small as a few square feet (for example a garden bed)
or as large as many square miles. Microclimates exist, for example, near bodies of water
which may cool the local atmosphere, or in heavily urban areas where brick, concrete, and
asphalt absorb the sun's energy, heat up, and reradiate that heat to the ambient air: the
resulting urban heat island is a kind of microclimate. Microclimates can be found in most
places.
Another contributing factor to microclimate is the slope or aspect of an area. South-facing
slopes in the Northern Hemisphere and north-facing slopes in the Southern Hemisphere are
exposed to more direct sunlight than opposite slopes and are therefore warmer for longer.
The area in a developed industrial park may vary greatly from a wooded park nearby, as
natural flora in parks absorb light and heat in leaves, that a building roof or parking lot just
radiates back into the air. Advocates of solar energy argue that widespread use of solar
collection can mitigate overheating of urban environments by absorbing sunlight and putting it
to work instead of heating the foreign surface objects.[
citation needed]
A microclimate can offer an opportunity as a small growing region for crops that cannot thrive
in the broader area; this concept is often used in permaculture practiced in northern
temperate climates. Microclimates can be used to the advantage of gardeners who carefully
choose and position their plants. Cities often raise the average temperature by zoning, and a
sheltered position can reduce the severity of winter. Roof gardening, however, exposes
plants to more extreme temperatures in both summer and winter.
Tall buildings create their own microclimate, both by overshadowing large areas and by
channeling strong winds to ground level. Wind effects around tall buildings are assessed as
part of a microclimate study.
Microclimates can also refer to purpose made environments, such as those in a room or other
enclosure. Microclimates are commonly created and carefully maintained in museum display
and storage environments. This can be done using passive methods, such as silica gel, or
with active microclimate control devices.
Soil types[edit]
The type of soil found in an area can also affect microclimates. For example, soils heavy in
clay can act like pavement, moderating the near ground temperature. On the other hand; if
soil has many air pockets, then the heat could be trapped underneath the topsoil, resulting in
the increased possibility of frost at ground level [5]
Cities and regions known for microclimates[edit]
San Francisco is a city with microclimates and submicroclimates. Due to the city's varied

2. topography and influence from the prevailing summer marine layer, weather conditions can
vary by as much as 9°F (5°C) from block to block.[1]
The region as a whole, known as the San Francisco Bay area can have a wide range of
extremes in temperature. In the basins and valleys adjoining the coast, climate is subject to
wide variations within short distances as a result of the influence of topography on the
circulation of marine air. The San Francisco Bay Area offers many varieties of climate within a
few miles. In the Bay Area, for example, the average maximum temperature in July is about
64 °F (18 °C) at Half Moon Bay on the coast, 87 °F (31 °C) at Walnut Creek only 25 miles
(40 km) inland, and 95 °F (35 °C) at Tracy, just 50 miles (80 km) inland.[2]
The Los Angeles and San Diego areas are also subject to phenomena-typical of a
microclimate. As such, the temperatures can vary as much as 18°F (10°C) between inland
areas and the coast, with a temperature gradient of over one degree per mile (1.6 km) from
the coast inland. Southern California has also a weather phenomenon called "June Gloom or
May Grey", which sometimes gives overcast or foggy skies in the morning at the coast, but
usually gives sunny skies by noon, during late spring and early summer.
Calgary, Alberta, is also known for its microclimates. Especially notable are the differences
between the downtown and river valley/flood plain regions and the areas to the west and
north. This is largely due to an elevation difference within the city's boundaries of over
1,000 ft (300 m), but can also be attributed somewhat, to the effects of the seasonal
Chinooks.[3]
Halifax, Nova Scotia, also has numerous microclimates. Coastal temperatures and weather
conditions can differ considerably from areas located just 5–15 km inland. This is true in all
seasons. Varying elevations are common throughout the city, and it is even possible to
experience several microclimates while travelling on a single highway due to these changing
elevations.
Santiago, Chile, and Villa de Merlo, Argentina, are also subject to microclimates.
Known for its wines, the Ticino region in Switzerland benefits from a microclimate in which
palm trees and banana trees grow.
Gran Canaria is called "Miniature Continent" for its rich variety of microclimates.
Biddulph Grange is very rich with microclimates as a result of the large dips and variety of
very large trees alongside a large amount of water.
Mascot, located in New South Wales, Australia, is also noted as a microclimate.
Leeds, located in England is known to have a number of microclimates because of the
number of valleys surrounding the city centre.
Amman, Jordan has extreme examples of microclimate, and almost every neighbourhood
exhibits its own weather.[4] It is known among locals that some boroughs such as the
northern and western suburbs are among the coldest in the city, and can be experiencing
frost or snow whilst other warmer districts such as the city centre can be at much warmer

3. temperatures at the same time.
Climate
The climate of the earth consists of a series of interlinked physical
systems powered by the sun.
In the built environment we are generally concerned with local
climatic systems in particular:
·Macro-climate the climate of a larger area such as a region or a
country
·Micro-climate the variations in localised climate around a
building
The macro and micro climate has a very important effect on both
the energy performance and environmental performance of
buildings, both in the heating season and in summer.
The site and design of a building can have a profound effect upon the interaction
between a building and its environment.
The building site affects exposure to the prevailing wind, the solar
radiation the building receives, pollution levels, temperatures and
rain penetration.
Site and macro climate
The orientation of the building affects solar gains and exposure to
the prevailing wind (ventilation).
The location of neighbouring trees and buildings affects the solar

4. gains (shading) and wind patterns.
Neighbouring trees and buildings also protect the building from driving rain.
Macro Climate
The macro climate around a building cannot be affected by any
design changes, however the building design can be developed
with a knowledge of the macro climate in which the building is
located. General climatic data give an idea of the local climatic
severity:
·Seasonal accumulated temperature difference (degree day) are a
measure of the outside air temperature, though do not acount for
available solar
·Typical wind speeds and direction
·Annual totals of Global Horizontal Solar Radiation
·The driving rain index (DRI) relates to the amount of moisture
contained in exposed surfaces and will affect thermal conductivity
of external surfaces.
This Metereological data gives a general impression of the climate at the site of a
building and the building design can be planned accordingly. However the building
itself and surrounding geography will affect the local climate.
Micro-Climate
The site of a building may have a many micro climates caused by
the presence of hills valleys, slopes, streams and other buildings.
Micro Climate – Effect of Local Terrain
Surrounding slopes have important effects on air movement,
especially at the bottom of a hollow. In hollows air warmed by the
rises upwards due to buoyancy effects (anabatic flow), to be
replaced by cooler air drifting down the slope (katabatic flow).
The result is that valey floors are significantly colder than locations part way up the
slope. Katabatic flows often result in frosts persisting for longer in low lying
locations. The most favourable location in a valley is known as the thermal belt,
lying just above the level to which pools of cold air build up, but below the height

5. at which exposure to wind increases.
The crests of hills and ridges have unfavourable wind velocity profiles, the wind
flow is compressed (as happens with an aerofoil) leading to high wind velocities.
Micro-Climate – Effects of Buildings
Buildings themselves create further micro-climates by shading the ground,
changing wind flow patterns.
One example of how buildings affect the local climate is the heat island effect in
large cities where the average temperature is higher than the surrounding area:
Solar energy absorbed and re-emitted from building surfaces, pavements roads
etc. creates a warming effect on the surrounding air. Also the large quantities of
buildings break up the wind flow, reducing wind speeds and causing the warm
air to remain stagnant in the city. This also causes increased pollution as well

6. as temperatures
The presence of local high rise buildings can degrade the local
climate as wind speed at ground level can be significantly
increased, while extensive shadows block access to sunlight for
long periods, increasing space heating costs in surrounding
buildings.
Improving Micro Climate through Design
The aims of enhancing Micro-Climate around Buildings:
·Reduce costs of winter heating
·Reduce summer overheating and the need for cooling
·Maximise outdoor comfort in summer and winter
Also:
·Improve durability of building material (reduced rain
penetration)
·Provide a better visual environment in spaces around buildings
·Encourage growth of plants
·Discourage growth of mosses and algae
·Facilitate open air drying of clothes
Means of enhancing the micro climate around a building include:
Solar Access:
Allow maximum daylight into space and buildings
Allow maximum solar radiation into space and buildings
Shade space and windows from prolonged exposure to summer sun
Protect space and windows from glare
Wind Protection
Protect space and buildings from prevailing winds and cold (e.g.
North/East) winds.
Prevent buildings and terrain features from generating turbulence
Protect spaces and buildings from driving rain and snow
Protect space and buildings from katabatic flows, while retaining
enough air movement to disperse pollutants.

7. Features
Provide thermal mass to moderate extreme
temperatures
Use vegetation for sun shading and wind
protection (transpiration helps moderate
high temperatures).
Provide surfaces that drain readily.
Provide water for cooling be evaporation
(pools and fountains)
Factors Affecting Micro Climate
Outside Designers Control Within Designer’s Remit
Area and local climate Spacing and orientation of buildings
Site surroundings Location of open spaces
Site shape Form and height of buildings
Topographic features Fenestration
Surrounding Buildings Tree cover
Ground profiling
Wind breaks
Surrounding surfaces (paving grass etc)
Two main possibilities for influencing
Micro Climate are Solar Access and Wind
Control
Solar Access
Solar access to a site is often a case of
minimising solar overheating in summer
while maximising solar access during the
winter.
Buildings with a heating requirement
should be orientated north south with
maximum glazing on the south face.
Deciduous trees offer an excellent means
of site shading, with shading being reduced
in winter when the trees lose their leaves.
The colour of surrounding surfaces will
have a pronounced effect on the solar

8. radiation available to the building. Light
coloured paving will increase the radiation
reflected from the ground into the building.
Paving stones will also provide external
thermal mass, moderating temperature
swings immediately adjacent to the
building.
Grass planted outside a building will
reduce the ground reflected solar.
Use of courtyards and water can also
moderate the effects of high temperatures
on summer.
Wind Control
The form of the building can have a great
effect on the impact of the wind:
·Avoidance of the building flank facing
the wind
·Avoidance of funnel-like gaps between
buildings
·Avoidance of flat roofed buildings and
cubical forms
·Avoid piercing buildings at ground level
·Avoid abrupt changes in building heights
·Orientate long axis of the building

9. parallel to the direction of the wind
·Use podium to limit down draught at
ground level
·Use pitched rather than flat roofs and
stepped forms for higher buildings
·Groups of buildings can be arranged
inirregular patterns to avoid wind
tunneling.
Coniferous trees and fencing and other
landscape features such as mounds of earth
and hedges can also reduce the impact of
wind and driving rain on the building
structure.
Enhanced Micro Climate and Energy
Saving
Increased external air temperature leading
to reduced space heating reduction:
increase solar access to site, wind
protection, external thermal mass, quick
drying surfaces.
Reduced Air Change Rate, internal air
movement and decreased external surface
connective heat transfer: reduced pressure
driven ventilation by wind protection.
Reduced moisture effects on fabric: less
wetting of fabric and energy loss due to
evaporation from wet surfaces by
protecting from driving rain and providing
adequate surface drainage.