DOI : 10.17577/IJERTV12IS060197
- Open Access
- Authors : Mansi Kanojia, Mitali Kanojia
- Paper ID : IJERTV12IS060197
- Volume & Issue : Volume 12, Issue 06 (June 2023)
- Published (First Online): 11-07-2023
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
Bio Climatic Design Strategies for Buildings in Varanasi, India
Mansi Kanojia
Student, School of Architecture and town Planning Lucknow, India
Mitali Kanojia UCG- NET Qualified
Lucknow, India
Abstract- the climate of Varanasi as that of India, is controlled by south-west monsoon with a seasonal rhythm of weather, characterized by moderate to extreme conditions. During the months of January and February the weather remain fine. But whenever, the snow fall occurs in the north- western part of Himalayas, the air blowing down in the Ganga Valley becomes substantially cold, temperature falling sometimes even below 4 degree C at Varanasi. However the severity of weather is broken by the incoming of western disturbance which cause some rainfall in these winter months. From the month of March the fast rise in temperature starts and attains more than 40 Deg. C in May. May and June are the hottest months in which scorching hot winds locally known as Loo blow from west and south-west during day hours raising temperature occasionally even more than 44 Deg. C. By the end of June, Varanasi comes under the grip of the SW monsoon which retreats by the end of September and sky becomes clear once again. However, the cool breeze of winter does not blow before November. Days are much warmer and nights are cooler. From November the temperature falls below 20 Deg. C accounting for fine dust free cool weather. The annual normal rainfall at Varanasi is 1009 mm. The rainfall of the wettest year (1971) and driest year (2009) were 1583 mm and 500 mm, respectively. More than 85 per cent of the annual rain is received during four rainy months from June to September."
Keyword- Bio-climatic design, Thermal comfort, Energy Efficiency, Sustainable development, Mahoney Table
-
INTRODUCTION
India is expected to achieve an urban population of about 50% by 2030. Reducing emission from urban energy consumption would be necessary to prevent potential adverse impacts of global warming especially in the present scenario of climate change. The worlds largest population without electricity lives in India and a very large number of people depend on inefficient sources of energy.
There is an urgent need to understand the complex relationship between factors driving urban household carbon emissions. We have studied the carbon from energy consumption of households in Varanasi city based on primary data in terms of socioeconomic classes, electricity, cooking and commuting activities.
Urban planning based on the identified factors influencing urban household carbon emissions would be necessary to formulate carbon mitigation policies. Inequality and lifestyle emissions at city level would strongly influence the development of Sustainable cities and societies.
-
CLIMATIC ZONE OF INDIA
As per IS 372-1978 Guide for Heat Insulation of Non- Industrial buildings, India has been divided into four climatic zones i.e. (1) Hot and Arid Zone (2) Hot and Humid Zone (3) Warm and Humid Zone (4) Cold Zone. Some discrepancies were reported later on in this zoning and Central Building Research Institute (CBRI), Roorkee was entrusted with the task of carry out research for new climatic classification. The research was primarily based on two climatic factors which mainly affect thermal comfort i.e. air temperature and humidity. The aim was to find out extremes of these two factors that are likely to cause discomfort. As per the recent studies carried out, India has been divided into four climatic zones.
i.e (1) Hot Dry(2)Warm Humid (3) Cold (4) Temperate and one sub- group i.e. Composite. A place has been assigned to one or other climatic zones if defined climatic conditions prevail there for more than six months, otherwise it has been placed under composite zone.
Table 1 shows recent climatic zones and its characteristics.
Climatic Zone
Mean Monthly Maximum Temperature (o C)
Mean Monthly Relative Humidity (%)
Hot Dry
Above 30
Below 55
Warm Humid
Above 30
Above 55
Above 25
Above 75
Temperate
Between 25-30
Below 75
Cold
Below 25
All Values
Each climatic zone does not have same climate throughout the year. If the climate of a particular place matches with the characteristics of a particular climatic zone for more than six months, the place may be assigned to that particular zone. Few cities like Banglore, Ahmedabad and Pune which present comfortable climate for greater part of the year conforms to temperate climatic zone, though it has been observed that there is no specific region under temperate climatic zone.
Fig 1 Shows The Climatic Zones Of India.
-
AN OVERVIEW OF VARANASI CLIMATE
Varanasi or Banaras is one of the oldest cities in the world. It is situated on the bank of river Ganga spreading over 1535 sq.km area in the state of Uttar Pradesh. It is located between the confluences of river Ganga and Varuna and river Ganga and Assi rivulet. the urban agglomeration is stretched between 82° 56E 83° 03E and 25° 14N 25° 23.5N. The Varanasi city is geographically located at 25000 to 25016 N Latitude and 82050 to 83010 E Longitude. The topography of the city is averaging between 50 feet (15 m) and 70 feet (21 m) above the river. The Ganga River flows from South to North having the world-famous Ghats on its left bank. averaging between 50 feet (15 m) and 70 feet (21 m) above the river. It is located at 25.282°N latitude 82.9563°E longitude.
Varanasi experiences a humid subtropical climate with large variations between summer and winter temperatures. The dry summer starts in April and lasts until June, followed by the monsoon season from July to October. The temperature ranges between 22 and 46 °C (72 and 115 °F) in the summers. Winters in Varanasi see very large diurnal variations, with warm days and downright cold nights
The annual average rainfall in the basin varies between 39 cm to 200 cm, with an average of 110 cm. Eighty percent of the rainfall occurs during the monsoon months i.e. from June to October. Because of large temporal variations in precipitation over the year, there is wide fluctuation in the flow characteristics of the river. In Varanasi monsoons normally begin from late June. The annual rainfall varies from 680 mm to 1,500 mm with large proportion of its occurring during the months of June to September. The month of October receives about 5 % of rainfall, and only 8 % of the rain occurs in remaining seven months from November to May.
The best time to visit Varanasi is during the winter months (November to February). Although it gets fairly cold during the winter, this is the best time when you can explore the holy city without getting tired. The average low temperature is around 5 degree C. the minimum temperature in Varanasi today is likely to hover around 33 degree Celsius, while the maximum temperature might reach 41 degree Celsius. The mercury level is expected to hover around 37 degree Celsius throughout the day, with the wind speed around 4.45.
The dry summer starts in April and lasts until June, followed by the monsoon season from July to October. The temperature ranges between 22 and 46 degree Celsius (72 and 115 degree F) in the summers variations with warm days and downright cold night.
<>Year/ months Temperature
Humidity (%)
Average
Rainfall (mm)
Mean Min (OC)
Mean Max (OC)
January
1.0
31.4
66
16.7
February
1.7
36.1
58
22.8
March
6.7
41.5
41
9.2
April
11.1
45.2
30
5.7
May
17.3
47.2
38
16.8
June
20.5
47.2
53
106.8
July
20.0
45.0
78
260.9
August
20.4
40.1
82
280.8
September
17.8
39.7
82
228.9
October
11.7
39.4
71
29.0
November
5.0
36.0
61
7.2
December
2.2
32.8
64
4.2
Table2 Climate Data Of Varanasi
-
THERMAL COMFORT ANALYSIS
Location
Varanasi
Longitude
82.9524 E
Latitude
25.3561 N
Altitude
82 meter (above sea level
-
Mahoney Tables
Mahoney table is a series of tables devised by C Mahoney which is a very good tool for the purpose of climatic data analysis. The initial part of the table records the location, longitude, latitude and altitude of the place. Table 3 shows the geographical location of Varanasi, India.
Monthly mean maximum temperature and monthly mean minimum temperature data from the metrological department of each month is
recorded in the respective line in the table 4. Monthly mean range is calculated by subtracting the monthly mean minimum values from monthly mean maximum values. The monthly mean range for each month is entered in the respective lines. Highest mean and lowest mean temperatures during the twelve months are entered on the right side of the table. Annual mean temperature (AMT) is calculated by
adding the highest mean temperature and lowest mean temperature values and dividing it by two. The same is entered in the respective box marked AMT. Annual mean range is calculated by subtracting the lowest mean minimum from highest mean maximum values and the same is entered in to the field marked AMR.
Table-4 Air temperature: °C
J
F
M
A
M
J
J
A
S
O
N
D
Monthly mean max.
22.3
26.4
32.7
38.6
39.7
37.3
32.2
31.5
31.5
30.7
28
23.8
Monthly mean min.
9.9
13.1
17.7
23.1
26.6
28
26.5
26
25
21
15.8
11.3
Monthly mean range
12.4
13.3
15
15.5
13
9.3
5.7
5.5
6.5
9.7
12.2
12.5
High
39.7
9.9
low
AMT
24.8
29.8
AM R
Table-5 Relative humidity %
Months
J
F
M
A
M
J
J
A
S
O
N
D
Monthly mean max. (A.M)
Monthly mean min. (P.M)
Average
66
58
41
30
38
53
78
82
82
71
61
64
Humidity group
3
3
2
2
2
3
4
4
4
4
3
3
Table-6 Rain & Wind
months
J
F
M
A
M
J
J
A
S
O
N
D
total
Rainfall, mm
16
19
9
6
10
137
305
254
173
40
6
7
982
Wind, prevailing
WNW
WNW
WNW
NW
NNE
NNE
E
ENE
ENE
NE
W
WNW
Wind secondary
WNW
WNW
WNW
NW
NNE
NNE
E
ENE
ENE
NE
W
WNW
Procedure for tabulating table 5 is as follows.
-
From metrological record, enter the monthly mean maximum (early morning reading) and monthly mean minimum (afternoon reading) of relative humidity in the respective lines.
-
ii. Calculate the average relative humidity and enter the values into third line.
-
iii. Establish the humidity group of each month (1, 2, 3 and 4) according to the following categories as defined in
Fig.2
Humidity group: 1
If average RH: BELOW 30%
2
30-50%
3
50-70%
4
Above 70%
Table- 7 Diagnosis
Months
J
F
M
A
M
J
J
A
S
O
N
D
AMT
Monthly mean max.
22.3
26.4
32.7
38.6
39.7
37.3
32.2
31.5
31.5
30.7
28
23.8
24.8
Dat comfort: upper
27
27
34
34
34
34
34
34
p>34 31
29
29
Lower
22
22
26
26
26
26
26
26
26
25
23
23
Monthly mean max.
9.9
13.1
17.7
23.1
26.6
28
26.5
26
25
21
15.8
11.3
Night comfort upper
21
21
25
25
25
25
25
25
25
24
23
23
Lower
17
17
17
17
17
17
17
17
17
17
17
17
Thermal stress: day
C
O
O
H
H
H
O
O
O
O
O
O
night
C
C
O
O
H
H
H
H
O
C
C
C
Fig 3
AMT over 20°C
AMT 15-20°C
AMT below 15°C
Comfort limits
Day
Night
Day
Night
Day
Night
1
26-34
17-25
23-32
14-23
21-30
12-21
2
25-31
17-24
22-30
14-22
20-27
12-20
Humidity group:
3
23-29
17-23
21-28
14-21
19-26
12-19
4
22-27
17-21
20-25
14-20
18-24
12-18
Table 7 is primarily used for the diagnosis of the climatic data. Procedure for tabulating table 7 is as follows.
-
Enter the monthly mean maximum temperature and monthly mean minimum temperature values from table 4.
-
ii. Find the upper and lower comfort limit for the day and night of each month on the basis of Fig 3, as defined by the annual mean temperature (AMT),
and humidity groups and enter these values in the lines 2, 3, 5 and 6 respectively.
-
iii. Compare the day comfort limits with mean maximum and night comfort limits with mean minimum and establish the nature of thermal stress by entering the following symbols in last two lines. H- Hot if mean is above limit O- (Comfort) if mean is within limit C-(Cold) if mean is below Limit
-
Table-7 Indicators
Indicators
J
F
M
A
M
J
J
A
S
O
N
D
Total
Humid: H1
2
H2
4
H3
2
Arid: A1
4
A2
1
A3
1
Fig. 4
Applicable when:
Thermal Stress
Rainfall
Humidity Group
Monthly mean range
Meaning
Indicator
Day
Night
Air movement essential
H1
H
4
2,3
Less than 10°C
Air movement Desirable
H2
OH
4
Rain protection necessary
H3
Over 200mm
Thermal capacity necessary
A1
H
1,2,3
More than 10°C
Out-door Sleeping desirable
A2
H
O
1,2
C
1,2
More than 10°C
Protection from cold
A3
Mahoney table defines six indicators in Fig.4. First three are humid indicators i.e. H1, H2 & H3 and next three are arid indicators A1, A2 &A3. Procedure for tabulating table 8 is as follows.
-
Check the monthly mean range, humidity group, rainfall from table (4, 5 & 6) and thermal stresses values from the table 7 and place a tick mark in the line of appropriate indicator.
-
In the last column, write the total number of ticks corresponding to a particular indicator.
Procedure for tabulating table 9 is as follows.
-
Transfer the indicators total from table 8 to the first line of table 9.
-
ii. Place a tick mark against the specification item in the same line corresponding to the indicator values
Indicator totals from table 2
H1
H2
H3
A1
A2
A3
2
4
2
4
1
1
Layout
0-10
1
Orientation north and south (long axis east-west)
11,12
5-12
0-4
2
Compact courtyard planning
Spacing
11,12
3
open spacing for breeze penetration
2-10
4
As 3, but protection from hot and cold wind
0,1
5
Compact lay-out of estates
Air Movement
3-12
6
Rooms single banked, permanent provision for air movement
0-5
1,2
6-12
7
Double banked rooms, temporary provision for air movement
2-12
0
0-1
8
No air movement requirement
Opening
0,1
0
9
Large openings, 40-80%
11,12
0,1
10
Very small openings, 10-20%
Any other conditions
11
Medium openings, 20-40%
3-12
12
Walls
0-2
13
Light walls, short time lag
3-12
14
Heavy external and internal walls
Roofs
0-5
15
Light, insulated roofs
6-12
16
Heavy roofs, over 8 h time-lag
Out- door sleeping
2-12
17
Space for out-door sleeping required
Rain protection
3-12
18
Protection from heavy rain necessary
Table-10 Detailed Recommendations
Indicator totals from table 2
H1
H2
H3
A1
A2
A3
2
4
2
4
1
1
Size of openings
0,1
0
1
Large: 40-80%
1-12
2
Medium: 25-40%
2-5
6-10
3
Small: 15-25%
11,12
0-3
4
Very small: 10-20%
4-12
5
Medium: 25-40%
Position of openings
3-12
6
In north and south walls at body height on windward side
1-2
0-5
7
As above, openings also in internal walls
6-12
0
2-12
Protection of openings
0-2
8
Exclude direct sunlight
2-12
9
Provide protection from rain
Walls and floors
0-2
10
Light, low thermal capacity
3-12
11
Heavy, over 8 h time-lag
roofs
10-12
0-2
12
Light, reflective surface, cavity
3-12
13
Light, well insulated
0-9
0-5
6-12
14
Heavy, over 8 h time-lag
External features
1-12
15
Space for out-door sleeping
1-12
16
Adequate rainwater drainage
The combined recommended specifications from table 9 & table-10 are tabulated in the table 11 which shows the design recommendation for energy efficient buildings in Delhi.
Table 11 design recommendation for Varanasi
Parameters
Recommendations
Layout
Building orientation north and south (long axis east west) to reduce solar radiation incident on the wall
Spacing
As 3, but protection from hot and cold wind
Air movement
Size of Openings
Very small openings, 10-20%
Position of openings
In north and south walls at body height on windward side
Protection of openings
Walls
Heavy, over 8 h time-lag
Roofs
Light, well insulated
Outdoor sleeping
Space for out-door sleeping required
External features
-
Rooms single banked, permanent provision for air movement
-
Double banked rooms, temporary provision for air movement
-
Exclude direct sunlight
-
Provide protection from rain
-
Space for out-door sleeping
-
Adequate rainwater drainage
-
-
-
CONCLUSIONS
In Delhi climate, buildings should be oriented in such a way that its longer axis should remain in east-west direction. In this orientation,
the walls will receive less solar radiation in summer and more solar radiation in winter in comparison to other orientations. This orientation minimizes the heat load in summer and is a very effective
passive cooling strategy. The walls should be thicker having time lag over 8 hours. Cavity walls or composite walls are also very helpful in controlling the heat transfer from outside to inside the building. When the air movement is necessary, the advantage of prevailing breeze should be taken by grouping the buildings in relation to the wind direction. Fenestrations should be made on the walls perpendicular to the wind direction. Direct sunlight must be excluded from the fenestration and window shades should be designed in such a way so that it cuts the summer sun but permits winter heat inside the building. Roofs should also be properly insulated so as to minimize heat transfer from the roof to the inside
of the building. Provision of adequate rainwater drainage is also essential in this climate.
VI. BIBLIOGRAPHY
-
Koenigsberger O.H, Ingersoll T.G., Alan Mayhew and Szokolay S.V. Climate Design: Manual of Tropical Housing and Building, Orient Longman Limited, 1975
-
Arvind Krishnan, Nick Baker, Yannas and Szokolay, S.V. Climate responsive Architecture, A dsign handbook for energy efficient buildings. Tata McGraw-Hill Education, 2001
-
Wind & weather statistics Varanasi Airport – Windfinder