Detailed climatic study of GUWAHATI. Sun information. Winds. Surface to Volume ratio. Evolution of Architecture.

1. CLIMATOLOGY
ASSIGNMENT
1 & 2
CLIMATIC STUDY OF
GUWAHATI
MADHU SAGAR
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2BV14AT028
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CLIMATIC STUDY OF GUWAHATI
GUWAHATI
• COUNTRY – INDIA
• STATE – ASSAM
• REGION – LOWER ASSAM
• DISTRICT – KAMRUP METROPOLITAN
DISTRICT
• METROPOLIS AREA – 216 km2
• METRO AREA – 1,528 km2
• ELEVATION – 55.5 m
• TIMEZONE – IST (UTC+5.30)
• COORDINATES - 26°10′ North latitude
92°49′ East longitude
• CLIMATE – CWA (KOPPEN)
• Guwahati has a HUMID SUBTROPICAL
CLIMATE (Köppen climate
classification Cwa – Temperate Dry
Winter Hot Summer)
•The average annual temperature is
24.2 °C with extremes ranging from
40.6 °C (recorded on April 24, 2014)
to 3.0 °C (recorded in January,
1964).
CLIMATE
Climatically, whole year can be divided into 4
seasons
• WINTER SEASON
– December, January, February
- Foggy morning, Clear night, Sunny noon
- January is coldest
- Temperature – 24.6 to 10 degree Celsius
• PRE-MONSOON SEASON
– March to May
- Transition between hot summer and wet monsoon
- Temperature increases from March to May
- Local rain and thunderstorms are common feature.
- Atmosphere is dusty in March.
• MONSOON OR SUMMER SEASON
– June, July, August and first part of September.
- Heavy rainfall and hot summer.
- Average rainfall 300 – 400 mm
- August is hottest month.
- Average temperature is 33 degree Celsius.
• RETREATING MONSOON SEASON
- Last week of September and first week of
October.
- Temperature and rains fall down gradually.
- Weather is pleasant.
• Guwahati lies in seismic zone
5.
• Zone 5 covers the areas with
the highest risks zone that
suffers earthquakes of
intensity MSK IX or greater.
• The IS code assigns zone factor
of 0.36 for Zone 5.
• Structural designers use this
factor for earthquake resistant
design of structures in Zone 5.
•
• The zone factor of 0.36 is
indicative of effective (zero
period) level earthquake in this
zone.
• It is referred to as the Very
High Damage Risk Zone.
Cwa (KOPPEN CLASSIFICATION)
• Temperate, Dry Winter, Hot Summer.
• HUMID SUBTROPICAL CLIMATES OR WARM
TEMPERATURE
 They have a warm and wet flow from
the tropics that creates warm and
moist conditions in the summer
months.
 Summer is often the wettest season.
 The flow out of the subtropical
highs and the summer monsoon creates
southern flow from the tropics to
that brings warm and moist air to the
lower east sides of continents .
 This flow is often what brings the
frequent but short-lived summer
thunderstorms so typical of
subtropical east-coast climates.

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CLIMATIC STUDY OF GUWAHATI
WIND
• November to February – North-
East to South-West.
• April to mid-September – South-
west to North-east.
TEMPERATURE
• The maximum temperature ranges
from 33 degree Celsius to a
minimum of about 10 degree
Celsius during the year.
• December to February show the
low temperature.
• August is the hottest month.
• October, November are
comparatively cooler.
HUMIDITY
• Guwahati experiences high
relative humidity during the
whole year.
• The month of January, during
the morning, has the highest
humidity, above 80%.
RAINFALL
• Guwahati receives rainfall
mainly from South-west monsoon
wind.
• Highest rainfall occurs during
the month of June, July and
August.
• Medium rainfall occurs during
months of April and May.
• During monsoon, Guwahati
receives an average rainfall of
365 mm.
• The months from November to
March are generally dry.
• Rainfall is scanty during these
months.
• The annual rainfall is more
than Indian Average.
SUNRISE, SUNSET, DAWN, DUSK TIMES GRAPH
Sun path
Today
June solstice
December solstice
Annual variation
Equinox (March and
September)
Sunrise/sunset
Sunrise
Sunset
Time
00-02
03-05
06-08
09-11
12-14
15-17
18-20
21-23
SUN ALTITUDE ANGLE
• 11 am – 77.650
• 12 pm – 76.960
• 1 pm – 65.930
• 2 pm – 52.90
• 3 pm – 39.470
• 4 pm - 260
• Days are longer during May – July.
• May-July fall under Monsoon or Summer
season.
• June Solstice is the longest day in the year.

4. GUWAHATI, INDIA - SOLAR ENERGY AND SURFACE METEOROLOGY
These data were obtained from the NASA Langley Research Center Atmospheric Science
Data Center; New et al. 2002
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CLIMATIC STUDY OF GUWAHATI
MONTH MEAN VALUE OF
RELATIVE
HUMIDITY (%)
JANUARY 79
FEBRUARY 65
MARCH 57
APRIL 68
MAY 75
JUNE 81
JULY 83
AUGUST 82
SEPTEMBER 83
OCTOBER 82
NOVEMBER 82
DECEMBER 82
ANNUAL 77
RELATIVE HUMIDITY
BETWEEN 1971 AND 1990
MONTH MEAN DRY BULB
TEMPERATURE (0C)
JANUARY 17.1
FEBRUARY 19.0
MARCH 22.9
APRIL 25.3
MAY 26.7
JUNE 28.4
JULY 28.5
AUGUST 28.8
SEPTEMBER 27.9
OCTOBER 26.0
NOVEMBER 22.2
DECEMBER 18.1
ANNUAL 24.2
MEAN DRY BULB
TEMPERATURE BETWEEN 1971
AND 1990
Variable JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Insolation, kWh/
m²/day
4.02 4.81 5.48 5.36 5.08 4.40 4.18 4.21 4.06 4.39 4.33 3.93
Clearness, 0 - 1 0.62 0.63 0.60 0.52 0.46 0.39 0.38 0.40 0.43 0.54 0.64 0.64
Temperature, °C 12.01 14.47 18.39 20.29 21.76 23.00 23.19 23.22 22.09 19.70 16.12 13.08
Wind speed, m/s 4.08 3.84 4.02 3.62 3.19 3.07 2.99 2.79 2.74 3.09 3.74 4.03
Precipitation, m
m
12 17 55 158 274 358 361 273 197 99 19 8
Wet days, d 1.0 1.4 3.9 8.4 12.0 13.4 14.2 11.5 9.2 4.4 1.3 0.5
MONTH MEAN NO. OF
SUNSHINE HOURS
JANUARY 225.5
FEBRUARY 213.8
MARCH 220.1
APRIL 200.6
MAY 191.1
JUNE 133.1
JULY 123.7
AUGUST 161.6
SEPTEMBER 139.0
OCTOBER 205.8
NOVEMBER 230.9
DECEMBER 231.7
ANNUAL 2276.9
MEAN NO. OF SUNSHINE HOURS
BETWEEN 1971 AND 1990
PERIOD : 1971 - 2000
Months
Mean
Temperature
(oC)
Mean
Total
Rainfall
(mm)
Mean
Number
of Rainy
Days
Mean Number of days with
Daily
Minimum
Daily
Maximum
HAIL
Thunde
r
FOG
SQUAL
L
Jan 10.6 23.6 11.5 1.2 0.0 0.6 8.5 0.0
Feb 12.2 26.0 22.3 2.2 0.0 2.0 1.0 0.1
Mar 15.9 29.8 50.9 4.3 0.2 5.2 0.4 0.5
Apr 20.0 31.0 159.3 9.2 0.1 12.5 0.0 2.0
May 22.5 31.0 256.3 13.3 0.1 14.3 0.1 1.7
Jun 24.9 31.9 303.6 14.4 0.0 11.9 0.0 0.3
Jul 25.5 31.8 356.8 16.8 0.0 10.9 0.0 0.0
Aug 25.5 32.2 258.6 12.6 0.0 12.5 0.0 0.1
Sep 24.5 31.5 194.4 10.5 0.0 9.1 0.0 0.2
Oct 22.0 30.3 103.9 4.9 0.0 3.2 2.1 0.0
Nov 17.0 27.7 18.4 1.3 0.0 0.9 5.7 0.0
Dec 11.9 24.6 7.4 0.6 0.0 0.2 10.9 0.0
Annual 19.4 29.3 1743.4 91.3 0.4 83.2 28.6 4.9

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CLIMATIC STUDY OF GUWAHATI

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CLIMATIC STUDY OF GUWAHATI
DATA ANALYSIS
• For designing, considering May, June, July and August becomes
critical.
• These months experience two extremes of weather i.e., summer and
rainy.
• Characteristics are heavy rainfall and hot summer.
• These months experience high temperatures ranging from 22 to 32
degree Celsius.
• These months also experience high rainfall ranging from 255 to 360
mm.
• These months have moderate wind speed ranging from 2.7 to 3.2 m/s.
• Solar insolation ranges from 4.2 to 5.1 kWh/m2/day.
• Cloud cover is around 55% to 62%.
• During these months, it rains more than half a month.

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CLIMATIC STUDY OF GUWAHATI
GENERAL OBSERVATIONS
• The revenue villages around
Guwahati are mostly dominated by
houses for which bamboo
reinforced biomass was
traditionally used as cladding
material while thatch or
corrugated iron sheets were used
as roofing materials.
• The majority of houses in these
villages around the city of
Guwahati are of traditional
Assam-housing typology where the
roofing system consists of timber
/ bamboo trusses supporting
thatch or CGI sheets.
• The wall system is made of Ikra
and / or bamboo-reinforced
biomass cladding.
• However, a gradual shift towards
confined masonry hoouses (i.e.,
burnt brick masonry walls 6 x 6”
RC posts, RC bands at lintel
level, roof construction made of
timber or tubular steel trusses
supporting CGI sheet roofing) can
be observed.
• The various traditional
construction practices and
housing types that are prevailing
today in the different regions
have evolved based on technology
transfer one generation to the
next by word of mouth or by some
kind of documentation done by
practicing masons and end users.
• The construction schemes have
characteristics that address the
prevalent local conditions of
weather and other environmental
and natural hazards i.e.,
earthquakes, floods or cyclones.
NON‐ENGINEERED CONSTRUCTION TYPOLOGIES
•The variety of non‐engineered construction typologies is quite limited in the city
of Guwahati as well as surrounding sub‐urban and rural areas.
•In general, these building typologies are constricted to the traditional Assam‐
type house as well as both unreinforced and confined clay brick masonry houses.
•The Assam‐type (Ikra) house is a vernacular construction typology made of timber.
•Traditionally, it was the most common building type throughout Northeast India
which is located in the country’s most severe seismic zone, i.e. Zone V –
corresponding to a MSK‐intensity IX (9.0).
•The majority of these houses were and still are used for residential purposes
while the construction technology has been transferred traditionally from one
generation of local masons to the next.
•During the colonial era, the British made this type of construction popular by
preparing specifications and improving the construction technology.
•The advantage of this both lightweight and eco‐friendly construction was well
understood by the successive governments before and after India’s
independence.
•During this period of time, the practice was largely adopted for construction of
government offices and residences across the Northeast Indian states.
•The Assam Public Works Department (APWD) included specifications of this type of
housing in their building schedule.
• In rural areas, these houses are typically built with lightweight
locally available material like bamboo, wooden planks, thatch etc. and are
generally termed as ‘thatch house’.
• These housing types have traditional systems of bamboo posts in rural areas and
wooden posts in more urban areas.
•Bamboo posts are inserted into the ground to act as compression members and are
tied with horizontal bamboo/wooden girders with the help of coconut fibre ropes or
bamboo ropes to give a proper shape and framing action.
•Bamboo or seasoned wood has natural resistance to decay, which makes these houses
sustainable and low on maintenance. It was noted that the majority of houses s
urvived the recent big earthquakes in 1897 (Assam earthquake) and 1950 (Assam
Tibet earthquake).
•Ikra houses are generally single‐storied structures consisting of brick or stone
masonry walls up to about 1 m above the plinth.
•This masonry supports the walls consisting of bamboo woven together with a wooden
frame, and plastered with cement or mud plaster.
•Even though this building typology is more prevalent in rural areas, a
significant percentage of this type of housing can be also found in the cities of
the region.

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• Figure 2 –
Traditional
Assam-type
building in an
urban
residential
area.
• Figure 4 –
Timber truss
used in the
roofing o
Assam-type
building built
in 1950-1960 by
Assam PWD.
• Figure 5 –
Two-way slope
of the roofing
system, which
provides
efficient
bracing action
at the post
plate level
against out-of-
plane failure.
• Figure 6 – Typical half-wall in bricks above plinth,
which interface with the timber frame panels to contain
the upper part of the wall made of reed with cement
mortar plaster work. The timber posts are bolted to the
plinth. These kind of lighter and well-integrated wall
systems are now replaced with heavier brick work, which
are sometimes not well-integrated and thereby increasing
the falling hazards of walls during earthquakes.
• Figure 7 – Nowadays traditional Assamese houses coexist
along with RC constructions that have become more
popular.
CLIMATIC STUDY OF GUWAHATI

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• Guwahati’s building stock is dominated by 3 groups of building typologies
 traditional Assam-type houses,
 confined clay brick masonry houses, as well as,
 ductile and non-ductile RC frame structures.
• In the semi-urban and rural areas around the city, the traditional Assam-type houses had been and still are being
replaced by confined masonry houses while a wide range of variations (especially with respect to used building materials)
can be observed.
• However, these houses can also be found in large numbers in urban areas.
• The urban and sub-urban housing stock is dominated by reinforced concrete frame buildings (with clay brick masonry infill
walls) upto 8 stories high.
• There are a few commercial buildings with greater storey numbers.
• The observed construction technology and workmanship are considered to be fairly good
CLIMATIC STUDY OF GUWAHATI

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CLIMATIC STUDY OF GUWAHATI
JANUARY FEBRUARY MARCH
12 PM
2 PM
INFOR
MATIO
N
• WINTER SEASON
• COLDEST MONTH
• TEMPERATURE – 120 C – 230 C
• RAINFALL – 10 – 12mm
• CLOUD COVER – 38%
• RELATIVE HUMIDITY – 79%
• WIND DIRECTION – NE to SW
• WINTER SEASON
• TEMPERATURE – 120 C – 260 C
• RAINFALL – 17 – 22mm
• CLOUD COVER – 63%
• RELATIVE HUMIDITY – 35%
• WIND DIRECTION – NE to SW
• PRE-MONSOON SEASON
• ATMOSPHERE IS DUSTY
• TEMPERATURE – 160 C – 300 C
• RAINFALL – 50 – 55mm
• CLOUD COVER – 40%
• RELATIVE HUMIDITY – 57%
• WIND DIRECTION – NE to SW

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CLIMATIC STUDY OF GUWAHATI
APRIL MAY JUNE
12 PM
2 PM
INFOR
MATIO
N
•PRE-MONSOON SEASON
• TEMPERATURE – 200 C – 310 C
• RAINFALL – 155 – 160mm
• CLOUD COVER – 48%
• RELATIVE HUMIDITY – 68%
• WIND DIRECTION – SW TO NE
•PRE-MONSOON SEASON
• TEMPERATURE – 220 C – 310 C
• RAINFALL – 250 – 275mm
• CLOUD COVER – 54%
• RELATIVE HUMIDITY – 75%
• WIND DIRECTION – SW to NE
• MONSOON OR SUMMER SEASON
• TEMPERATURE – 250 C – 320 C
• RAINFALL – 300 – 360mm
• HIGH RAINFALL
• CLOUD COVER – 61%
• RELATIVE HUMIDITY – 81%
• WIND DIRECTION – SW to NE

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CLIMATIC STUDY OF GUWAHATI
JULY AUGUST SEPTEMBER
12 PM
2 PM
INFOR
MATIO
N
•MONSOON OR SUMMER SEASON
• TEMPERATURE – 250 C – 320 C
• RAINFALL – 355 – 360mm
• HIGH RAINFALL
• CLOUD COVER – 62%
• RELATIVE HUMIDITY – 83%
• WIND DIRECTION – SW to NE
•MONSOON OR SUMMER SEASON
• HOTTEST MONTH
• TEMPERATURE – 260 C – 320 C
• RAINFALL – 260 – 275mm
• CLOUD COVER – 60%
• RELATIVE HUMIDITY – 82%
• WIND DIRECTION – SW to NE
• FIRST WEEKS - MONSOON OR SUMMER SEASON
• LAST WEEKS – RETREATING MONSOON SEASON
• TEMPERATURE – 240 C – 310 C
• RAINFALL – 190 – 195mm
• CLOUD COVER – 57%
• RELATIVE HUMIDITY – 83%
• WIND DIRECTION – SW to NE
• Orientation along NW-SE is preferable because the orientation shades two of the sides and provides shadow for long
distance.
• The longest side along NW-SE.

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CLIMATIC STUDY OF GUWAHATI
OCTOBER NOVEMBER DECEMBER
12 PM
2 PM
INFOR
MATIO
N
• RETREATING MONSOON SEASON
• TEMPERATURE – 220 C – 300 C
• RAINFALL – 15 – 20mm
• CLOUD COVER – 46%
• RELATIVE HUMIDITY – 82%
• WIND DIRECTION – SW to NE
• WINTER SEASON
• TEMPERATURE – 170 C – 280 C
• RAINFALL – 190 – 195mm
• CLOUD COVER – 36%
• RELATIVE HUMIDITY – 82%
• WIND DIRECTION – NE to SW
• WINTER SEASON
• TEMPERATURE – 120 C – 250 C
• RAINFALL – 7 – 10mm
• CLOUD COVER – 36%
• RELATIVE HUMIDITY – 82%
• WIND DIRECTION – NE to SW

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CLIMATIC STUDY OF GUWAHATI
1 2 3 4
PERIMETER (2x10) + (2x5) = 30 m (2x10) + (2x5) = 30 m (4 x 7) = 28 m (4 x 7) = 28 m
HEIGHT 3 m 9 m 3 m 9
AREA (S) 30 x 3 = 90 m2 30 x 9 = 270 m2 28 x 3 = 84 m2 28 x 9 = 252 m2
VOLUME
(V)
10 x 5 x 3 = 150 m3 10 x 5 x 9 = 450 m3 7 x 7 x 3 = 147 m3 7 x 7 x 9 = 441 m3
S/V 90 / 150 = 0.6 270 / 450 = 0.6 84 / 147 = 0.57 252 / 441 = 0.57
5 6 7 8
PERIMETER (2x3)+(2x10) = 26 m (2x5) + (2x15) = 40 m 4 x 10 = 40 m 4 x 15 = 60 m
HEIGHT 3 m 3 m 3 m 3 m
AREA (S) 26 x 3 = 78 m2 40 x 3 = 120 m2 40 x 3 = 120 m2 60 x 3 = 180 m2
VOLUME
(V)
3 x 10 x 3 = 90 m3 5 x 15 x 3 = 225 m3 10 x 10 x 3 = 300 m3 15 x 15 x 3 = 675 m3
S/V 78 / 90 = 0.86 120 / 225 = 0.53 120 / 300 = 0.4 180 / 675 = 0.26
• Case 7 and Case 8 are preferable as the S/V ratio is less.
• This helps in reducing the heat gained by the interior of the building.

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CLIMATIC STUDY OF GUWAHATI
5 6 7
PERIMETER (2x7.75)+(2x15.5)=46.5m (2x6.3) + (2x18.9) = 50.4 m 4 x 10 = 40 m
HEIGHT 3 m 3 m 3 m
AREA (S) 7.75x15.5=120 m2 6.3 x 18.9 = 119 m2 40 x 3 = 120 m2
VOLUME
(V)
7.75 x 15.5 x 3 = 360.4 m3 6.3 x 18.9 x 3 = 357.2 m3 10 x 10 x 3 = 300 m3
S/V 120 / 360.4 = 0.33 119 / 357.2 = 0.33 120 / 300 = 0.4