CHAPTER 7 THERMAL PERFORMANCE STUDY AND ...shodhganga.inflibnet.ac.in/bitstream/10603/38625/12/12...128 CHAPTER 7 THERMAL PERFORMANCE STUDY AND ASSESSMENT OF VERNACULAR DWELLINGS 7.1

128

CHAPTER 7

THERMAL PERFORMANCE STUDY AND ASSESSMENT

OF VERNACULAR DWELLINGS

7.1 INTRODUCTION

The study of thermal comfort is very important because it is

correlated not only with occupants comfort, but also with energy

consumption. The thermal comfort is highly a subjective aspect which

majorly depends on the social conditions, acclimatization to geographic

locations, culture and psychological conditions of the inmates (Avinash

Gautam, 2008). Many researchers have defined thermal comfort for different

contexts under different conditions and came out with values for comfort zone

range. According to ASHRAE Standard 55-2004, the ideal range for thermal

comfort is 19.4°C (67°F) and 27.77°C (82°F).

Olgyay (1963) defined thermal comfort using the bioclimatic chart

devised by him. The chart combines temperature and relative humidity to

define the human comfort zone which lies is in the centre, with winter and

summer ranges indicated separately (taking seasonal adaptation into account),

and gives recommendations for points that lie within the defined boundary.

The chart also incorporates wind speed and radiant temperature.

The concept of the chart was based on the outdoor climatic

conditions. This resulted in some limitations in analyzing the physiological

requirements of the indoor environment of the building. Therefore the chart is

129

applicable to a hot humid climate since there is no high range fluctuation

between indoor and outdoor conditions.

Figure 7.1

A mathematical relationship between the comfort temperature (Tc) and

outdoor temperature (To) for a passive building was derived by Humphrey in

1981, who has done an extensive research on thermal comfort and collected

data from comfort surveys from all across the world (Monsingh D Devadas

2001). It is defined as:

Tc = 12.1 + 0.53 To

Nicol (2001) proposed a new theory of adaptive comfort in which

he states that, humans adapt themselves to the average indoor temperature. An

advantage of variable comfort temperature is that it changes with the outside

temperature and hence will require less energy to achieve than a fixed

comfortable temperature. In summer, the comfort temperature increases and

in winter, it decreases.

130

Nicol and others have continued similar researches and concluded

in 2001 with specific reference to Indian sub-continent, and it is defined as :

Tc = 17.0 + 0.38 To

For the summer, the comfort zone ranges from 27.870C to 32.880C

and for the winter, the comfort zone ranges from 24.30C to 28.740C (Nicol

2001).

Based on these available sources of information, the thermal

performance evaluation of the selected sample dwellings in the identified

settlements was carried out for a time span of one month in summer (1st May

31st May, 2013) and one month in winter (1st January to 31st January, 2013)

using ECOTECT 2011 software.

7.2 CLIMATIC PROFILE OF THANJAVUR REGION

The typical weather data of Thanjavur region over the course of an

average year is given below. It is based on the historical records from 2002 to

2012. Thanjavur region has a warm temperate climate with dry winters and

hot summers.

Table 7.1 Climate profile of Thanjavur

MONTH

TEMPERATURE

(0C) RH (%)

AVERAGE WIND

SPEED (mph)

MAX. MIN. MAX MIN MAX MIN

January 31 21 94 47 9 7

February 33 22 93 37 8 7

March 36 23 92 37 7 6

April 37 26 91 38 7 6

May 38 26 88 39 12 7

131

(Source: Weather data recorded at the Tiruchirapalli International Airport, (Tiruchirapalli (Trichy), India) weather station)

The selected sample dwellings were simulated using ECOTECT 2011

software and the values were recorded for critical month of the winter period

(January 2013) and critical month of the summer period (May 2013), and

analyzed.

7.3 THERMAL PERFORMANCE ANALYSIS

The measurement of temperature (corresponding to the prevailing

relative humidity, and wind speed) of different indoor spaces of the sample

dwellings that belong to different typologies of dwellings (typology 1,

typology 2 and typology 3) for the one month from 1st May

to 31st May 2013) during summer period and

from 1st January to 31st January 2013) during winter period were analyzed and

the results are discussed below.

which the outdoor ambient temperature reaches its maximum during the

which the outdoor ambient temperature reaches its minimum during the

winter period.

June 37 26 84 40 14 10

July 36 26 81 39 14 14

August 36 26 86 42 14 11

September 35 25 89 44 11 8

October 33 24 96 48 8 6

November 30 23 96 62 9 6

December 30 21 96 54 9 8

132

7.3.1 Thermal Performance Analysis of Typology-1 Dwellings

7.3.1.1 Critical month of the Summer period (May 2013)

i) Sample dwelling 1 at Vallam (T1-SD1-V)

It is a south facing structure consists of a small square courtyard at

the centre, two rooms at the front accessible from the thinnai, living space on

the western side of the courtyard, one room on the south west corner and three

rooms on the eastern side of the courtyard.

a. For the entire month of May, the indoor spaces of the house

maintain a stable temperature, ranges between 32.10C to 36.70C

irrespective of the temperature variation outside, ranging between

26.70C to 41.30C.

b. The maximum temperature of the indoor spaces for the critical

month of summer (1st May to 31st May 2013) is as follows:

35.90C for living space, i.e., 5.40C lower than the maximum

outdoor temperature, 36.70C for front room on the western side,

i.e.,4.60C lower than the maximum outdoor temperature, 36.60C for

front room on the eastern side, i.e.,4.70C lower than the maximum

outdoor temperature, and 36.10C for side rooms on the eastern side,

i.e.,5.20C lower than the maximum outdoor temperature.

c. The living space around the central courtyard and the private rooms on the eastern side maintains slightly a warm temperature ranging between 320C to 36.10C throughout the month with a diurnal variation of 3.90C and 2.90C respectively which shows a considerable difference from the outdoor temperature.

133

Figure 7.2 (a & b) Thermal performance analysis of sample dwelling 1

at Vallam during the critical month of Summer

period (1st and 12th May, 2013) calculated through

Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0

HOURLY TEMPERATURES ALL VISIBLE THERMAL ZONES Wednesday 1st May - Tiruchirapalli Ta IND, WMO# = 433440

0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0

HOURLY TEMPERATURES ALL VISIBLE THERMAL ZONES Sunday 12th May - Tiruchirapalli Ta IND, WMO# = 433440

0 2 4 6 8 10 12 14 16 18 20 22

134



period (24th and 31st May, 2013) calculated through

Ecotect Analysis.

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0

HOURLY TEMPERATURES ALL VISIBLE THERMAL ZONES Friday 24th May - Tiruchirapalli Ta IND, WMO# = 433440

0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0

HOURLY TEMPERATURES ALL VISIBLE THERMAL ZONES Friday 31st May - Tiruchirapalli Ta IND, WMO# = 433440

0 2 4 6 8 10 12 14 16 18 20 22

135

d. The minimum temperature of the indoor spaces for the critical month of summer period (1st May to 31st May 2013) is as follows:

320C for living space, i.e.,5.30C higher than the minimum outdoor temperature, 32.10C for front room on the western side, i.e.,5.40C higher than the minimum outdoor temperature, 32.80C for front room on the eastern side, i.e.,6.10C higher than the minimum outdoor temperature, and 33.20C for side rooms on the eastern side, i.e.,6.50C higher than the minimum outdoor temperature.

e. The temperature fluctuation for the indoor spaces is 3.80C on an average (3.90C for living, 4.60C for front room on the western side, 3.80C for front room on the eastern side and 2.90C for side room on the eastern side) whereas the temperature fluctuation for the external environment is 14.60C.

ii) Sample dwelling 2 at Melattur (T1-SD2-M)

It is a south facing dwelling consists of a large central courtyard

and two secondary courtyards. The living space is located on the west and

northern side of the main central court, private rooms at the front and kitchen

at the north-west corner with a kitchen courtyard. The north-east part consists

of the utility area with a service courtyard.

a. This multiple courtyard house shows that the indoor temperature was relatively stable, ranges between 320C to 350C, regardless of the fluctuation of outdoor temperature which varies between 26.70C to 41.30C.

b. The maximum temperature of the indoor spaces for the critical month of summer period (1st May to 31st May 2013) is as follows:

136

37.40C for rezhi , i.e., 3.90C lower than the maximum outdoor

temperature 36.20C for living space on the northern side, i.e.,5.10C

lower than the maximum outdoor temperature and 36.30C for living

on the western side, i.e.,50C lower than the maximum outdoor

temperature, 36.90C for front room, i.e.,4.40C lower than the

maximum outdoor temperature and 37.60C for kitchen, i.e.,3.70C

lower than the maximum outdoor temperature.

c. It is evident that the living space on the north and west side of the

central court maintains more or less the same temperature with a

diurnal variation of 1.70C and 1.90C respectively which shows a

considerable difference from the outdoor temperature.

d. The minimum temperature of the indoor spaces for the critical

month of summer period (1st May to 31st May 2013) is as follows:

33.40C for rezhi, i.e., 6.70C higher than the minimum outdoor

temperature 34.50C for living on the northern side, i.e.,7.80C higher

than the minimum outdoor temperature, 34.40C for living on the

western side, i.e.,7.70C higher than the minimum outdoor

temperature, 36.90C for front room, i.e.,7.10C higher than the

minimum outdoor temperature and 32.40C for kitchen, i.e.,5.70C

higher than the minimum outdoor temperature.

e. The temperature fluctuation for the indoor spaces is 3.20C on an

average (40C for zone 1, 1.70C for zone 4, 5.20C for zone 5 and

1.90C for zone 9) whereas the temperature fluctuation for the

external environment is 14.60C.

137


at Melattur during the critical month of Summer


Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

138




Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

139

iii) Sample dwelling 3 at Someshwarapuram (T1-SD3-S)

It is a south facing structure, consists of a large square courtyard at the centre, living space on the west and northern side and two private rooms on the eastern side of the courtyard.

a. Throughout the month, the average indoor temperature of the spaces ranges between 270C to 350C whereas the outdoor temperature varies between 26.70C to 41.30C.

b. During the peak hours (11 AM to 3PM), there is a considerable variation between the indoor and the outdoor temperature. However, the living space located around the courtyard shows slightly a higher temperature than the room spaces due to direct heat received through the courtyard.

c. The maximum temperature of the indoor spaces for the critical month of summer period (1st May to 31st May 2013) is as follows:

39.50C for living, i.e.,1.80C lower than the maximum outdoor temperature, 37.90C for front room, i.e., 3.40C lower than the maximum outdoor temperature and 37.70C for rear room, i.e.,3.60C lower than the maximum outdoor temperature.

d. The minimum temperature of the indoor spaces for the critical month of summer period (1st May to 31st May 2013) is as follows:

31.30C for living, i.e.,4.60C higher than the minimum outdoor temperature, 32.80C for front room, i.e., 6.10C higher than the minimum outdoor temperature and 330C for rear room, i.e.,6.30C higher than the minimum outdoor temperature.

e. The temperature fluctuation for the indoor spaces is 60C on an average (8.20C for living, 5.10C for front room and 4.70C for rear room) whereas the temperature fluctuation for the external environment is 14.60C.

140


at Someshwarapuram during the critical month of

Summer period (1st and 12th May, 2013) calculated

through Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

141


at Someshwarapuram during the critical month of

Summer period (24th and 31st May, 2013) calculated


W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

142

7.3.1.2 Critical month of the Winter Period (January 2013)

i) Sample dwelling 1 at Vallam (T1-SD1-V)

a. The internal temperature during the month of January ranges between 24.70C to 28.60C whereas the outdoor temperature ranges between 20.60C to 32.70C.

b. The maximum temperature of the indoor spaces for the critical month of Winter Period (1st January to 31st January 2013) is as follows:

28.60C for living space, i.e., 4.10C lower than the maximum outdoor temperature, 28.60C for front room on the western side, i.e., 4.10C lower than the maximum outdoor temperature, 28.60C for front room on the eastern side, i.e., 4.10C lower than the maximum outdoor temperature and 28.10C for side rooms on the eastern side, i.e., 4.60C lower than the maximum outdoor temperature.

c. All the internal spaces maintain more or less the same temperature with minor variations, but however, the private rooms located on the eastern side maintains a stable temperature throughout the month with a diurnal variation of 2.50C irrespective of the temperature variation exists outside.

d. The minimum temperature of the indoor spaces for the critical month of Winter Period (1st January to 31st January 2013) is as follows:

25.20C for living space, i.e.,4.60C higher than the minimum outdoor temperature, 24.70C for front room on the western side, i.e.,4.10C higher than the minimum outdoor temperature, 24.80C for front room on the eastern side, i.e.,4.20C higher than the minimum outdoor temperature, and 25.60C for side rooms on the eastern side, i.e.,50C higher than the minimum outdoor temperature.

143

e. The temperature fluctuation for the indoor spaces is 3.40C on an average (3.40C for living, 3.90C for front room on the western

Figure 7.8 (a & b) Thermal performance analysis of sample dwelling 1 at Vallam during the critical month of winter period (1st and 12th January, 2013) calculated through Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0

HOURLY TEMPERATURES ALL VISIBLE THERMAL ZONES Tuesday 1st January - Tiruchirapalli Ta IND, WMO# = 433440

0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0

HOURLY TEMPERATURES ALL VISIBLE THERMAL ZONES Saturday 12th January - Tiruchirapalli Ta IND, WMO# = 433440

0 2 4 6 8 10 12 14 16 18 20 22

144

side, 3.80C for room on the eastern side and 2.50C for side rooms on the eastern side) whereas the temperature fluctuation for the external environment is 12.10C.


at Vallam during the critical month of Winter period

(24th and 31st January, 2013) calculated through

Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0

HOURLY TEMPERATURES ALL VISIBLE THERMAL ZONES Thursday 24th January - Tiruchirapalli Ta IND, WMO# = 433440

0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k 1.2k 0.8k

0.4k

C

40

30

20

10

0

HOURLY TEMPERATURES ALL VISIBLE THERMAL ZONES Thursday 31st January - Tiruchirapalli Ta IND, WMO# = 433440

0 2 4 6 8 10 12 14 16 18 20 22

145


a. During the month of January, the indoor temperature of the house ranges between 24.50C to 30.40C whereas the outdoor temperature ranges between 20.60C to 32.70C..


29.70C for rezhi , i.e., 30C lower than the maximum outdoor temperature, 28.10C for living on both the north and southern side, i.e.,4.60C lower than the maximum outdoor temperature, 28.60C for front room, i.e.,4.10C lower than the maximum outdoor temperature and 30.40C for kitchen, i.e., 2.30C lower than the maximum outdoor temperature.

c. The living space on the north and west side of the central court shows a considerable temperature difference from the exterior temperature with a diurnal variation of 1.50C and 1.60C respectively.

d. The minimum temperature of the indoor spaces for the Winter Period (1st January to 31st January 2013) is as follows:

25.20C for rezhi, i.e., 4.60C higher than the minimum outdoor temperature, 26.60C for living on the northern side, i.e.,60C higher than the minimum outdoor temperature, 26.50C for living on the western side, i.e.,5.90C higher than the minimum outdoor temperature, 25.90C for front room, i.e.,5.30C higher than the minimum outdoor temperature and 24.50C for kitchen, i.e.,3.90C higher than the minimum outdoor temperature.

e. The temperature fluctuation for the indoor spaces is 3.240C on an average (4.50C for rezhi, 1.50C for living on the northern side, 1.60C for living on the western side, 2.70C for front room and 5.90C

146

for kitchen) whereas the temperature fluctuation for the external environment is 12.10C.

Figure 7.10 (a & b) Thermal performance analysis of sample

dwelling 2 at Melattur during the critical

month of Winter period (1st and 12th January,

2013) calculated through Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

147

Figure 7.11 (a & b) Thermal performance analysis of sample dwelling

2 at Melattur during the critical month of Winter

period (24th and 31st January, 2013) calculated


W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k 1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

148


a. The indoor temperature of all the spaces of this dwelling ranges between 23.10C to 31.70C whereas the outdoor temperature ranges between 20.60C to 32.70C.

b. The maximum temperature of the indoor spaces for the critical month of winter period (1st January to 31st January, 2013) is as follows:

31.70C for living, i.e.10C lower than the maximum outdoor temperature, 29.70C for front room, i.e., 30C lower than the maximum outdoor temperature and 29.50C for rear room, i.e.,3.20C lower than the maximum outdoor temperature.

c. The minimum temperature of the indoor spaces for the critical month of winter period (1st January to 31st January, 2013) is as follows:

23.10C for living, i.e.,2.50C higher than the minimum outdoor temperature, 24.60C for front room, i.e., 40C higher than the minimum outdoor temperature and 250C for rear room, i.e.,4.40C higher than the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 60C on an average (8.60C for living, 5.10C for front room and 4.50C for rear room) whereas the temperature fluctuation for the external environment is 12.10C.

149


3 at Someshwarapuram during the critical month

of Winter period (1st and 12th January, 2013)

calculated through Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

150



of Winter period (24th and 31st January, 2013)


W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k 1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

151

7.3.1.3 Comparative analysis

During the critical month of summer period (May 2013), the

sample dwelling 1 at Vallam shows a low internal temperature compared to

the sample dwelling 2 at Melattur and sample dwelling 3 at

Someshwarapuram mainly because of,

a. the size of the courtyard(2.9m x 3.0m) which is proportionate to the dwelling size (5 % to the plinth area of the dwelling) with 0.7m eaves projection provides better shading

b. alignment of the courtyard along the central axis induces good amount of ventilation and air movement

c. the location of the private rooms on the eastern side reduces direct heat gain by the walls, and

d. the high thermal mass of the structure with adequate time lag, (i.e., the thickness of the wall and composite construction made of flat bricks and laterite stone with lime mortar) provides better insulation.

The sample dwelling 2 at Melattur also shows a moderately low

temperature mainly due to the compact arrangement of spaces around the

central courtyard. The living spaces on the northern and western side

maintains a comparatively lower temperature than the other habitable spaces

in the house, mainly due to the presence of movement passage (thazhvaram)

around the court which acts as a buffer zone in between the courtyard and the

living space. Though the size of the courtyard (5.4m x 6.4m) is slightly big

(14% to the plinth area of the dwelling), the projected eaves prevents the entry

of direct heat into the living space. The openings aligned along the axis

facilitate air movement into the spaces. Also the depth of the courtyard (0.6m)

dissipates most of the incident heat thus facilitates low internal temperature.

152

The orientation of the habitable spaces in the house plays a major

role in reducing indoor temperature. The spaces located on the eastern and

northern side have lower temperature than the rooms located on the western

and southern side. Provision of smaller window openings to the rooms

induces the air movement and thus reduces the internal heat gain.

In sample dwelling 3 at Someshwarapuram, the living space around

the courtyard shows a higher temperature (39.50C) compared to the other

spaces of the dwelling, with a diurnal variation of 8.20C. The large courtyard

(4.5m x 3.9m) which is disproportionate to the size of the dwelling (8.6 % to

the plinth area), allows entry of direct heat into the living area which is

located on the western side. In addition, the house is exposed to direct solar

radiation, as it is a detached structure with open space all around.

The dwelling has only one window facing the south except which,

it is completely sealed without window openings. This results in lack of free

circulation of air and increased thermal conditions inside. However, the

materials (brick and mid mortar) and wall thickness (45cm) contributes to the

improved thermal performance of the dwelling to some extent.

During the hottest day of the critical month during the summer

period (12th May, 2013), the maximum and minimum internal temperatures

with diurnal variation of the sample dwellings, that belong to typology 1, is as

follows:

153

Table 7.2 Comparative Thermal Performance of the Sample Dwellings

(Typology 1) during the hottest day(12th May, 2013) of the

critical month of Summer period (May 2013)

Typology 1 dwellings Vallam Melattur Someshwara- -puram

Outdoor Temperature (in 0C) Max. 41.3

Min. 26.7

Indoor Temperature (in 0C) Max. 36.7 37.6 39.5

Min. 32.7 32.4 31.3

Diurnal variation ( in 0C) 4 5.2 8.2

Decrease in temperature (Max.) from exterior ( in 0C)

4.6 3.7 1.8

Increase in temperature (Min.) from exterior ( in 0C)

6 5.7 4.6

Figure 7.14 Comparative Analysis of the thermal performance of

different spaces of the sample dwellings of Typology 1,

during critical month of Summer period (May 2013)

154

During the critical month of winter period, both the sample

dwelling 1 (Vallam) and sample dwelling 2 (Melattur) maintains more or less

a stable internal temperature throughout the month, ranges from 24.70C to

28.60C and 24.50C to 30.40C respectively, which lies exactly within the

comfort zone.

The temperature fluctuation is high in sample dwelling

3(Someshwarapuram). The living space around the central court in sample 3

has a diurnal variation of 8.60C, with maximum temperature as 31.70C and

minimum temperature as 23.10C.

During the coldest day of the month during the winter period (31st

January, 2013), the maximum and minimum internal temperatures with

diurnal variation of the sample dwellings, that belong to typology 1, is as

follows:


(Typology 1) during the Coldest Day (31st January, 2013) of

the critical month of Winter Period (January 2013)

Typology 1 Dwellings Vallam Melattur Someshwara- -puram

Outdoor Temperature (in 0C)

Max. 32.7 Min. 20.6

Indoor Temperature (in 0C)

Max. 28.6 29.6 31.7 Min. 24.7 25.3 23.1

Diurnal variation ( in 0C) 3.9 4.3 8.6 Decrease in temperature (Max.) from exterior ( in 0C)

4.1 3.1 1


4.1 4.7 11.1

155



during critical month of Winter period (January, 2013)


7.3.2.1 Critical month of Summer period (May 2013)

(i) Sample Dwelling-4 at Vallam (T2-SD4-V)

It is a south facing structure, consists of a long and rectangular

courtyard on the western side with two living spaces on the northern and

southern side, connected by a narrow passageway and two private rooms

located on the eastern side of the courtyard.

a. Throughout the month of May, the average indoor temperature of the spaces ranges between 29.40C to 40.10C whereas the outdoor temperature varies between 26.70C to 41.30C.

156

b. The maximum temperature of the indoor spaces for the critical month of summer period (1st May, 2013 to 31st May, 2013), is as follows:

40.10C for the living space, i.e. 1.20C lower than the maximum outdoor temperature and 38.20C for the private rooms, i.e. 3.10C lower than the maximum outdoor temperature.

c. The minimum temperature of the indoor spaces for the critical month of summer period (1st May, 2013 to 31st May, 2013), is as follows:

29.40C for the living space, i.e. 2.70C higher than the minimum outdoor temperature, and 30.10C for the private rooms, i.e. 3.40C higher than the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 9.40C on an average (10.70C for living space and 8.10C for the private room), whereas the temperature fluctuation for the external environment is 14.60C.

157


dwelling 4 at Vallam during the critical month of

Summer period (1st and 12th May, 2013)


W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

158




Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

159

(ii) Sample Dwelling-5 at Melattur (T2-SD5-M)

It is a south facing house, consists of a linear rectangular inner courtyard on the eastern side with living space on the western side, a private room on the south west corner, a rezhi (transition space) on the southern side and a kitchen on the northern side of the courtyard with a small kitchen court (skylight).

a. The dwelling maintains an average internal temperature ranging from 28.70C to 410C whereas the outdoor temperature varies between 26.70C to 41.30C.

b. The rezhi (transition space) and the front room located on the south west corner maintains more or less a stable temperature compared to the living and the kitchen area.

c. The maximum temperature of the indoor spaces for the critical month of summer period (1st May, 2013 to 31st May, 2013), is as follows:

410C for the living space, i.e. 0.30C lower than the maximum outdoor temperature, 36.80C for the front room, i.e. 4.50C lower than the maximum outdoor temperature, 36.90C for the rezhi, i.e. 4.40C lower than the maximum outdoor temperature, and 39.60C for the kitchen, i.e. 1.70C lower than the maximum outdoor temperature.

d. The minimum temperature of the indoor spaces for the critical month of summer period (1st May, 2013 to 31st May, 2013), is as follows:

29.20C for the living space, i.e. 2.50C higher than the minimum outdoor temperature, 30.90C for the front room, i.e. 4.20C higher than the minimum outdoor temperature, 30.20C for the rezhi, i.e. 3.50C higher than the minimum outdoor temperature and 28.70C for the kitchen, i.e. 20C higher than the minimum outdoor temperature.

160

e. The temperature fluctuation for the indoor spaces is 8.80C on an

average (11.80C for living space, 6.70C for the front room, 5.90C


dwelling 5 at Melattur during the critical month of Summer period (1st and 12th May, 2013) calculated through Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

161

for the rezhi and 10.90C for the kitchen), whereas the temperature fluctuation for the external environment is 14.60C.




Ecotect Analysis

W/m2

2.0 k

1.6k 1.2k 0.8k 0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

162

(iii) Sample Dwelling-6 at Someshwarapuram (T2-SD6-S)

It is a south facing structure, consists of a linear rectangular inner

courtyard on the eastern side with a living space and two private rooms on the

western side of the courtyard, a rezhi (transition space) on the southern side

and a kitchen on the northern side of the courtyard.

a. The dwelling maintains an average internal temperature ranging from 30.10C to 40.40C whereas the outdoor temperature varies between 26.70C to 41.30C.

b. The living space has the maximum internal temperature (40.40C) during the peak hours (11AM to 3 PM), though it is protected by means of a movement passage (Thazhvaram).

c. The rear room located on the northern side of the courtyard maintains fairly a low temperature compared to the other rooms located on the western side of the courtyard.

d. The maximum temperature of the indoor spaces for the critical month of summer period (1st May, 2013 to 31st May, 2013), is as follows:

40.40C for the living space, i.e. 0.90C lower than the maximum outdoor temperature, 370C for the room located on the western side, i.e. 4.30C lower than the maximum outdoor temperature, 36.80C for the front room, i.e.4.50C lower than the maximum outdoor temperature, 37.60C for the rezhi, i.e. 3.70C lower than the maximum outdoor temperature and 34.50C for the kitchen (room on the northern side), i.e. 6.80C lower than the maximum outdoor temperature.

163

e. The minimum temperature of the indoor spaces for the critical month of summer period (1st May, 2013 to 31st May, 2013), is as follows:

30.10C for the living space, i.e. 3.40C higher than the minimum outdoor temperature, 31.30C for the room located on the western side, i.e. 4.60C higher than the minimum outdoor temperature, 30.80C for the front room, i.e. 4.10C higher than the minimum outdoor temperature, 30.10C for the rezhi, i.e. 3.40C higher than the minimum outdoor temperature, and 31.30C for the kitchen (room on the northern side), i.e. 4.60C higher than the minimum outdoor temperature.

f. The temperature fluctuation for the indoor spaces is 6.50C on an

average (10.30C for living space, 5.70C for the room located on

the western side, 6.80C for the front room, 6.70C for the rezhi

and 3.20C for the kitchen (room on the northern side), whereas

the temperature fluctuation for the external environment is

14.60C.

164



of Summer period (1st and 12th May, 2013)


W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

165



of Summer period (24th and 31st May, 2013)


W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

166

7.3.2.2 Critical Month of the Winter Period (January 2013)

(i) Sample Dwelling-4 at Vallam (T2-SD4-V)

a. The internal temperature during the month of January ranges between 22.40C to 32.30C whereas the outdoor temperature varies between 20.60C to 32.70C.


32.30C for living space, i.e., 0.40C lower than the maximum outdoor temperature, and 29.80C for the rooms on the western side, i.e., 2.90C lower than the maximum outdoor temperature.

c. The minimum temperature of the indoor spaces for the critical month of Winter Period (1st January to 31st January 2013) is as follows:

22.40C for living space, i.e.,1.80 C higher than the minimum outdoor temperature, and 23.60C for the rooms on the western side, i.e.,30C higher than the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 80C on an average (9.90C for living and 6.20C for rooms on the western side) whereas the temperature fluctuation for the external environment is 12.10C.

167


dwelling 4 at Vallam during the critical month

of Winter period (1st and 12th January, 2013)


W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

168


4 at Vallam during the critical month of Winter



W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k 1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

169


a. During the month of January, the indoor temperature of the dwelling ranges between 22.30C to 33.60C whereas the outdoor temperature varies between 20.60C to 32.70C.

b. The maximum temperature of the indoor spaces for the critical month of winter period (1st January to 31st January 2013) is as follows:

31.40C for living space, i.e.,1.30C lower than the maximum outdoor temperature, 29.80C for rezhi , i.e., 2.90C lower than the maximum outdoor temperature, 28.60C for front room, i.e.,4.10C lower than the maximum outdoor temperature and 33.60C for kitchen, i.e., 1.70C higher than the maximum outdoor temperature.

c. The minimum temperature of the indoor spaces for the critical month of Winter Period (1st January to 31st January 2013) is as follows:

23.60C for living space, i.e.,30C higher than the minimum outdoor temperature, 23.70C for rezhi, i.e., 3.10C higher than the minimum outdoor temperature, 24.60C for front room, i.e.,40C higher than the minimum outdoor temperature and 22.30C for kitchen, i.e.,1.70C higher than the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 7.30C on an average (7.80C for living space, 6.10C for rezhi, 40C for front room and 11.30C for kitchen) whereas the temperature fluctuation for the external environment is 12.10C.

170

Figure 7.24 (a & b) Thermal performance analysis of sample dwelling 5 at Melattur during the critical month of Winter period (1st and 12th January, 2013) calculated through Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

171


5 at Melattur during the critical month of Winter



W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k 1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

172


a. Indoor temperature of all the spaces of this house ranges between 22.80C to 34.80C whereas the outdoor temperature varies between 20.60C to 32.70C.


34.80C for living, i.e.2.10C higher than the maximum outdoor temperature, 28.70C for room on the western side, i.e., 40C lower than the maximum outdoor temperature, 28.80C for the front room, i.e. 3.90C lower than the maximum outdoor temperature, 29.80C for the rezhi (transition space), i.e. 2.90C lower than the maximum outdoor temperature, and 28.40C for rear room(kitchen), i.e.,4.30C lower than the maximum outdoor temperature.


22.80C for living space, i.e.,2.20C higher than the minimum outdoor temperature, 25.10C for room on the western side, i.e.,4.50C higher than the minimum outdoor temperature, 24.40C for front room, i.e., 3.80C higher than the minimum outdoor temperature, 23.60C for rezhi (transition space), i.e.,30C higher than the minimum outdoor temperature, and 250C for rear room, i.e.,4.40C higher than the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 5.90C on an average (120C for living, 3.60C for room on the western side, 4.40C for front room, 6.20C for the rezhi (transition space), and 3.40C for rear room) whereas the temperature fluctuation for the external environment is 12.10C.

173


dwelling 6 at Someshwarapuram during the critical month of Winter period (1st and 12th

January, 2013) calculated through Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

174


dwelling 6 at Someshwarapuram during the

critical month of Winter period (24th and 31st

January, 2013) calculated through Ecotect

Analysis

W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k 1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

175

7.3.2.3 Comparative Analysis

During the critical month of summer period (May 2013), all the

sample dwellings that belong to typology 2, show invariably a higher

temperature range, mainly because of

the size of the courtyard which is disproportionate to the size

of the dwelling

Orientation and geometry (shape and proportion) of the

courtyard

Orientation and geometry of the dwelling.

A high blank enclosure wall on one side of the court reflects

most of the incident heat directly into the dwelling,

especially to the living space.

Among the other internal spaces, the living space of all the samples have

more heat gain as they are located adjacent to the large, rectangular courtyard.

Sample dwelling 4 at Vallam shows a lower temperature in the

living space even though the courtyard (2.3m x 7.35m) is located on the

western side. in addition, materials used for construction, i.e. composite wall

made of flat bricks and laterite blocks also contributes to the lower heat gain

through walls. The openings aligned along the axis facilitate good amount of

air movement into the spaces which brings down the temperature to some

extent.

In Melattur, the living space on the western side of the courtyard in

Sample 5 shows a higher temperature compared to the other spaces of the

dwelling, with a diurnal variation of 11.80C. The large rectangular courtyard

(3m x 7.5m) allows entry of direct heat into the narrow living area. in

176

addition, the dwelling has a vacant land on its western side which makes the

western wall to get completely exposed to solar radiation, results in direct

heat gain. The kitchen shows a higher temperature comparatively, as it has a

small kitchen court which allows direct heat inside. At the same time,

washing and other activities related to cooking happen in the court which

keeps it wet and thus reduces the internal heat gain through the court

considerably.

Though the living space is located adjacent to the large rectangular

courtyard (8.6m x 3.1m) in sample 6 at Someshwarapuram, it is protected by

means of a deep passageway which results in slightly lower temperature

compared to sample 5 at Melattur.

During the hottest day of the month during the summer period (12th

May, 2013), the maximum and minimum internal temperatures with diurnal

variation of the sample dwellings, that belong to typology 2, is as follows:


(Typology 2) during the Hottest Day (12th May, 2013) of the

Summer Period

Typology 2 Dwellings Vallam Melattur Someshwara- -puram

Outdoor Temperature (in 0C) Max. 41.3

Min. 26.7

Indoor Temperature (in 0C) Max. 40.1 41 40.4

Min. 32 32 32.4

Diurnal variation ( in 0C) 8.1 9 8


1.2 0.3 0.9


5.3 5.3 5.7

177



during the critical month of Summer period (May, 2013)

These dwellings maintain a fairly comfortable thermal environment

during the winter season.

The temperature fluctuation is high in sample dwelling 6

(Someshwarapuram) compared to Vallam and Melattur. The living space on

the western side of the courtyard in sample 6 has a diurnal variation of 120C,

with maximum temperature as 34.80C and minimum temperature as 22.80C.

During the coldest day of the month during the winter period (30th



follows:

178

Table 7.5 Comparative Thermal performance of the Sample dwellings

(Typology 2) during the coldest day (31st January, 2013) of the

critical month of Winter period

Typology 2 Dwellings Vallam Melattur Someshwara- --puram

Outdoor Temperature

(in 0C)

Max. 32.7

Min. 20.6

Indoor Temperature

(in 0C)

Max. 32.3 30.4 34.8

Min. 23.8 24.5 22.8

Diurnal variation ( in 0C) 8.5 5.9 12


0.4 2.3 -2.1


3.2 3.9 3.2



during the critical month of Winter period (January, 2013)

179


Dwellings with a double height central space with clerestory

openings on all the sides form typology 3. As this typology of dwellings is

rare and found only in specific settlements, only two samples are selected viz.

one from Melattur and another one from Someshwarapuram.

7.3.3.1 Critical month of the Summer Period (May 2013)

(i) Sample dwelling 7 at Melattur (T3-SD7-M)

It is a two storied structure faces north, consists of a central living

space with a double height ceiling, a rezhi (transition space) in between the

thinnai and the living space, two private rooms on the northern side and a

room and a kitchen on the southern side of the central living space. The first

floor consists of a large dormitory above the front part and a terrace.

a. The individual spaces of the dwelling maintain a more or less

stable temperature throughout the month of May 2013 and the

internal temperature of the dwelling ranges between 30.50C and

390C whereas the external temperature varies between 26.70C to

41.30C.

b. The maximum temperature of the indoor spaces for the critical

month of summer period (1st May, 2013 to 31st May, 2013), is

as follows:

38.30C for the living space, i.e. 30C lower than the maximum

outdoor temperature, 38.90C for the front room, i.e.2.40C lower

than the maximum outdoor temperature, 390C for the rezhi, i.e.

2.30C lower than the maximum outdoor temperature, 38.90C for

the rear room, i.e. 2.40C lower than the maximum outdoor

180

temperature and 36.30C for the kitchen, i.e. 50C lower than the

maximum outdoor temperature.

c. The minimum temperature of the indoor spaces for the critical

month of summer period (1st May, 2013 to 31st May, 2013), is

as follows:

31.70C for the living space, i.e.50C higher than the minimum

outdoor temperature, 310C for the front room, i.e. 4.30C higher

than the minimum outdoor temperature, 30.50C for the rezhi, i.e.

3.80C higher than the minimum outdoor temperature, 31.60C for

the rear room, i.e. 4.90C higher than the minimum outdoor

temperature, and 31.20C for the kitchen, i.e. 4.50C higher than

the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 7.10C on an

average (6.60C for living space, 7.90C for the front room, 8.50C

for the rezhi, 7.30C for the rear room, and 5.10C for the kitchen,

whereas the temperature fluctuation for the external

environment is 14.60C.

181

Figure 7.30(a & b) Thermal performance analysis of sample dwelling 7



Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

182




Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

183

ii) Sample dwelling 8 at Someshwarapuram (T3-SD8-S)

It is a two storied structure faces west, consists of a large central hall with a double height ceiling, a rezhi (transition space) and a room in the front, and a kitchen and a room in the rear side. The first floor has a large front hall and terrace.

a. A huge fluctuation prevails in the internal temperature ranging from 290C to 40.10C whereas the external temperature varies between 26.70C to 41.30C.

b. The living space has higher temperature compared to the other internal spaces of the house. The maximum temperature of the indoor spaces for the critical month of summer period (1st May, 2013 to 31st May, 2013), is as follows:

40.10C for the living space, i.e. 1.20C lower than the maximum outdoor temperature, 37.80C for the front room, i.e.3.50C lower than the maximum outdoor temperature, 39.80C for the rezhi, i.e. 1.50C lower than the maximum outdoor temperature, 36.30C for the rear room, i.e. 50C lower than the maximum outdoor temperature and 38.50C for the kitchen, i.e. 2.80C lower than the maximum outdoor temperature.

c. The minimum temperature of the indoor spaces for the critical month of summer period (1st May, 2013 to 31st May, 2013), is as follows:

290C for the living space, i.e. 2.30C higher than the minimum outdoor temperature, 28.40C for the front room, i.e. 1.70C higher than the minimum outdoor temperature, 29.40C for the rezhi, i.e. 2.70C higher than the minimum outdoor temperature, 31.60C for the rear room, i.e. 4.90C higher than the minimum outdoor temperature, and 31.20C for the kitchen, i.e. 4.50C higher than the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 8.60C on an average (11.10C for living space, 9.40C for the front room,

184

10.40C for the rezhi, 4.70C for the rear room, and 7.30C for the kitchen, whereas the temperature fluctuation for the external environment is 14.60C.

Figure 7.32(a & b) Thermal performance analysis of sample dwelling 8 at Someshwarapuram during the critical month of Summer period (1st and 12th May, 2013) calculated through Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

185

Figure 7.33(a & b) Thermal performance analysis of sample dwelling


of Summer period (24th and 31st January,2013)


W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

186

7.3.3.2 Critical month of the Winter Period (January 2013)

(i) Sample dwelling 7 at Melattur (T3-SD7-M)

a. The indoor temperature of all the spaces of this dwelling ranges between 240C to 30.70C, whereas the outdoor temperature ranges between 20.60C to 32.70C.


29.90C for living space, i.e.2.80C higher than the maximum outdoor temperature, 30.40C for the front room, i.e. 2.30C lower than the maximum outdoor temperature, 30.70C for the rezhi (transition space), i.e. 20C lower than the maximum outdoor temperature, 30.60C for rear room, i.e.,2.10C lower than the maximum outdoor temperature, and 28.10C for kitchen, i.e.,4.60C lower than the maximum outdoor temperature.


25.40C for living space, i.e. 4.80C higher than the minimum outdoor temperature, 24.90C for front room, i.e., 4.30C higher than the minimum outdoor temperature, 240C for rezhi (transition space), i.e.,3.40C higher than the minimum outdoor temperature, and 25.50C for rear room, i.e.,4.90C higher than the minimum outdoor temperature and 24.90C for kitchen, i.e.,4.30C higher than the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 50C on an average (4.50C for living, 5.5 0C for front room, 6.70C for the rezhi (transition space), 5.10C for rear room, and 3.20C for

187

kitchen whereas the temperature fluctuation for the external environment is 12.10C.


7 at Melattur during critical month of Winter

period (1st and 12th January, 2013) calculated


W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

188


at Melattur during critical month of Winter period

(24th and 31st January, 2013) calculated through

Ecotect Analysis

W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k 1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

189

ii) Sample dwelling 8 at Someshwarapuram (T3-SD8-S)

a. The indoor temperature of all the spaces of this house ranges between 22.20C to 32.70C, whereas the outdoor temperature ranges between 20.60C to 32.70C.


33.20C for living space, i.e.0.50C lower than the maximum outdoor temperature, 310C for the front room, i.e. 1.70C lower than the maximum outdoor temperature, 32.70C for the rezhi (transition space), i.e. equal to the maximum outdoor temperature, 28.40C for rear room, i.e. 4.30C lower than the maximum outdoor temperature, and 30.20C for kitchen, i.e. 2.50C lower than the maximum outdoor temperature.


22.50C for living space, i.e. 1.90C higher than the minimum outdoor temperature, 220C for front room, i.e., 1.40C higher than the minimum outdoor temperature, 22.20C for rezhi (transition space), i.e.,1.60C higher than the minimum outdoor temperature, and 25.40C for rear room, i.e.,4.80C higher than the minimum outdoor temperature and 24.70C for kitchen, i.e.,4.10C higher than the minimum outdoor temperature.

d. The temperature fluctuation for the indoor spaces is 7.70C on an average (10.70C for living, 90C for front room, 10.50C for the rezhi (transition space), 30C for rear room, and 5.50C for kitchen whereas the temperature fluctuation for the external environment is 12.10C.

190


at Someshwarapuram during critical month of

Winter period (1st and 12th Janbg uary, 2013)


W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k

1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

191


8 at Someshwarapuram during critical month of

Winter period (24th and 31st January, 2013)


W/m2

2.0 k

1.6k

1.2k

0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

W/m2

2.0 k

1.6k 1.2k 0.8k

0.4k

C

40

30

20

10

0


0 2 4 6 8 10 12 14 16 18 20 22

192

7.3.3.3 Comparative Analysis

During the summer month (May 2013), both the sample dwellings that belong to typology 3, show a much higher temperature range compared to the other two typologies, which is above the thermal comfort zone as per ASHRAE Standard 55-2004. Minimum number of openings and orientation of the spaces are the main causes for the higher internal temperature.

In sample 7 at Melattur, living and kitchen spaces have lower temperatures compared to the other spaces of the dwelling. Though the heat gain through the western wall (which is exposed to direct solar radiation) is more, the movement passage provided continuously from the front to rear door opening aligned along the N-S axis, acts as a buffer space thus reduces internal temperature considerably. In addition, the clerestory openings above the living space induce air circulation by letting out the hot air and the cool air enters through door openings in north and south side. As the kitchen is located on the north east corner of the dwelling, it maintains a comfortable temperature (36.30C) inside with a diurnal variation of 5.10C. In addition, it has window openings on the northern wall, which induces air movement and thus reduces the internal heat.

In sample 8 at Someshwarapuram, the east-west orientation of the dwelling with western facade is the main reason for the higher internal temperature. The spaces such as front room, rear room and kitchen which are located on the northern part of the dwelling could maintain comparatively lower temperature than the other spaces. In addition, the less number of window openings minimizes the air movement result in thermal uncomfort.

During the hottest day of the critical month during the summer period (12th May, 2013), the maximum and minimum internal temperatures with diurnal variation of the sample dwellings 7and 8 that belong to typology 3 is as follows:

193


(Typology 3) during the hottest day (12th May, 2013) of the

critical month of Summer period

Typology 3 Dwellings Melattur Someshwarapuram


Max. 41.3 Min. 26.7


Max. 39 40.1 Min. 30.5 29

Diurnal variation ( in 0C) 8.5 11.1 Decrease in temperature (Max.) from exterior ( in 0C)

2.3 1.2


3.8 2.3



during critical month of Summer period (May, 2013)

194

The sample dwelling 7 at Melattur maintain fairly a comfortable

thermal environment during the winter season compared to the sample

dwelling 8 at Someshwarapuram which is slightly on the higher side, i.e.

22.50C to 33.20C with a diurnal variation of 10.70C.

During the coldest day of the month during the winter period (30th



follows:


(Typology 3) during the coldest day (31st January, 2013) of the

critical month of Winter period

Typology 3 Dwellings Melattur Someshwarapuram


Max. 32.7

Min. 20.6


Max. 30.7 33.2

Min. 24 22.2

Diurnal variation ( in 0C) 6.7 11


2 -0.5


3.4 1.6

195



during critical month of Winter period (January, 2013)

7.4 SUMMARY

The analysis, using interaction with the occupants, personal

observations during field study, and simulated results of the samples, that

belong to different typologies of dwellings in Thanjavur region, clearly

reveals that:

In hot humid climatic conditions, the court yard acts as the major

micro climatic modifier and the effect mainly depend on the location and the

geometry of the courtyard.

In row housing pattern, the orientation with either south or north

facing dwelling, facilitate free air movement as the openings are facing the

windward direction.

196

The buffer spaces such as raised platform in the front (thinnai) and

movement passage (thazhvaram) around the court yard protects the habitable

spaces from the direct entry of heat from exterior.

The construction techniques and the materials which are eco

friendly, locally available and require minimum energy for production and

usage, also play a major role in providing comfortable thermal environment in

the interior irrespective of the exterior temperature.

Typology 1 dwellings (with central courtyard) have indoor

temperature more or less closer to the comfort conditions and largely depend

on the size and proportion of the courtyard.

Among the sample dwellings that belong to Typology 1, sample 1

(dwelling at Vallam) has a better indoor thermal environment compared to

sample 2 (dwelling at Melattur and) and sample 3 (dwelling at

Someshwarapuram), mainly due to the proportionate size of the courtyard,

composite construction of the wall and the materials used for it.

Typology 2 dwellings (with side courtyard) have indoor

temperature range slightly above the comfort conditions, as per ASHRAE

standards and Nicol, due to the narrow width of the dwelling and the linear,

disproportionate size of the courtyard.

Among the sample dwellings that belong to Typology 2, sample 4

(dwelling at Vallam) has a better indoor thermal environment compared to

sample 5 (dwelling at Melattur and) and sample 6 (dwelling at

Someshwarapuram), mainly due to the high and blank enclosure wall on one

side of the courtyard which reflects the incident heat into the living and other

spaces. In sample 4, the wall faces the east whereas in sample 5 and sample 6,

the wall faces the west.

197

Typology 3 dwellings (double height central space with clerestory

openings above) have a higher temperature range, sometimes exceeds the

outside temperature. It is mainly because of the poor air circulation due to

minimum openings and location and orientation of the habitable spaces.

However, the occupants of these dwellings (except typology 3) feel

comfortable in those conditions and are highly satisfied with the temperatures

inside their dwellings. This is mainly because, comfort is the condition felt

by the users based on culture and the phenomenon of acclimatization

(Avinash Gautam 2008).

Documents

CHAPTER 7 THERMAL PERFORMANCE STUDY AND ...shodhganga.inflibnet.ac.in/bitstream/10603/38625/12/12...128 CHAPTER 7 THERMAL PERFORMANCE STUDY AND ASSESSMENT OF VERNACULAR DWELLINGS 7.1