study of aspect ratio and thermal responsiveness in vernacular … · vernacular houses in...

International Journal of Engineering Technology, Management and Applied Sciences

www.ijetmas.com October 2016, Volume 4, Issue 10, ISSN 2349-4476

140 Swasti Sthapak and Dr Abir Bandyopadhyay

Study of Aspect Ratio and Thermal Responsiveness in

Vernacular Houses in Chhattisgarh: A Case- Study

Swasti Sthapak ˟ and Dr Abir Bandyopadhyay˟˟

˟ Associate professor, Department of Architecture NIT Raipur (CG)

˟˟ Professor, Department of Architecture NIT Raipur (CG)

Each community over the years develops a prototype that responds to local needs and carries it forward

through generations (Oliver, 2006). Vernacular architecture is built to meet specific needs, while

accommodating the values, economies, and ways of life of the cultures that produce them (Oliver, 1987).

Vernacular architecture is influenced by different aspects of environment and human behavior. This leads to

differing building forms for almost every different context. The family size, life style of building occupants,

their food habits social and cultural behavior has great influence on building forms. It responds to ambient

environmental conditions, and so, development of vernacular houses is a naturally evolving process. Each

community over the years develops a prototype that responds to local needs and carries it forward through

generations (Oliver, 2006). Thermal comfort in vernacular houses is found to be achieved through proper

layout and orientation of building, appropriate form, appropriate use of building materials, proper landscape

design, and use of shading devices, overhangs and external surface finish.

Raipur the present capital of Chhattisgarh state is situated between 22o 33' N to 21o14'N Latitude and 82o 6'

to 81o38'E Longitude. This place has a tropical wet and dry climate, temperatures remain moderate

throughout the year, except from March to June, when this region undergoes hot and dry period with very

high temperatures. The temperature in April–May sometimes rises above 48 °C (118 °F).These summer

months also have dry and hot winds. Winters last from November to January and are mild, although lows can

fall to 5 °C (41 °F).

The vernacular and traditional houses of Chhattisgarh are mostly courtyard houses. The basic plan form

consists of an open courtyard having verandahs and rooms on three or four sides. Courtyard and verandah

offer a wide range of thermal comfort and is used for different functions at different part of the day and year.

Site selection: To understand the relationship of aspect ratio and the thermal responsiveness in the vernacular

houses of Chhattisgarh, 3 houses ( with different Aspect Ratio) in the village Sondongri were selected which

is around 15 Kilometers from Raipur the capital city of state of Chhattisgarh. There are 30-35 houses in the

village, most of them are traditional houses with courtyard type planning. Though there are some pakka

houses built recently without courtyards.

Plan Form and configuration: The houses are having courtyard at center and verandahs and rooms around

them. Rooms are mostly rectangular in plan. All rooms are directly attached to courtyards through semi open

verandahs. Doors and windows openings of a room face towards the courtyard. There are no window

openings on outer walls. The main entrance is located in a manner that does not allow the outsider to directly

get view of the courtyard. The houses have pitched country tile roofs.

Materials: All three selected houses are made of stone which is locally available. Inner walls of rooms are

plastered with cement or mud whereas outer walls are not. Thickness of the walls is 40 or 50 cm and some

partition walls are 25 / 30 cm thick.

http://en.wikipedia.org/wiki/Tropical_wet_and_dry_climate




General observations: Major activities are performed in courtyard. According to season the cooking place is

shifted. Cooking is even done in open (i.e. courtyard) or semi-open spaces. In summer, at night sleeping

activity is also performed in courtyard.

Use of Courtyard: The inward form of the courtyard provides a sense of enclosure and privacy to the

residents of the house. The court in the heart of the house allows different functions to take place during

different parts of the day. The courtyard is used as an extension of the kitchen

during mornings or as an extension of the living room during evenings to entertain guests.

This also acts as a space for interaction for all family members. Privacy is ensured by screened or walled

entrances. The courtyard house absorbs the noise of the house within itself offering acoustical privacy. This

helps in providing a quieter and private outdoor space.

Data Collection: All the three houses were studied and data was collected thrice a day, two times in a week

for a period of four months I.E. January to April 2015. Onsite temperature and data was measured with the

help of handheld thermo hygrometer. Measurements were taken three times (i.e. morning 9:30 AM, afternoon

1:30 PM and evening 6:00 PM) twice in a week (i.e. on Sunday and Wednesday). Temperature of all the

rooms on east, west, north and south direction of the houses were taken.

House 1: House 1 is a rectangular house with a square courtyard with entrance on its west. There are two

story structures on its eastern and western sides, whereas a single story verandah on north and kitchen in

south. The courtyard measures 7.02 Mts X 6.79 Mts . A 2.5 meters verandah protects the western wing and a

3meters verandah protects the eastern wing.

Figure1: House 1 Plans




Eastern Wing Northern wing

The temperature data for different time of the day for a particular month is averaged and shown in figure 2, 3,

4 and 5. Simultaneous outdoor temperature variation is also shown in the same table.

Figure 2 Figure 3

Figure 4 Figure 5

In month of January and February the temperature in all the rooms is lowest at 9.30 AM (ranging between

23.4˚C -25.6˚C) and highest at 1.30 PM (ranging between 26.3˚C – 28.27˚C), showing some reduction in




temperature at 6.00PM (ranging between 25.2˚C - 26.3˚C). In months of March and April the pattern slightly

varies in eastern and western rooms, where the temperature at 6.00 PM (ranging between 25.9˚C - 27.9˚C) is

lower than the one recorded at 9.30 AM (ranging between 26.8˚C -28˚C). This clearly shows the effect of high

thermal mass of the house. The temperature in Northern and Southern wings are higher due to more exposure.

House 2:

House2 is rectangular in plan having a rectangular

courtyard measuring 8.5 Mts X 4.5 Mts. The

house has its entrance at west. It has rooms on

eastern and western sides. There is a small kitchen

in south and a small verandah in north. There are

boundary walls enclosing the rest of the courtyard

at its north and south. The western wing is

protected by 2 mts wide verandah at its east.

Figure 6: House 2 Plan

Eastern Wing Western Wing

The temperature data for different time of the day for a particular month is averaged and shown in figure 7, 8,

9 and 10. Simultaneous outdoor temperature variation is also shown in the same table.




Figure 7 Figure 8

Figure 9 Figure 10

In month of January and February the temperature in all the rooms is lowest at 9.30 AM (ranging between

23.2˚C -24.6˚C) and highest at 1.30 PM (ranging between 25.3˚C – 27.5 ˚C), showing some reduction in

temperature at 6.00PM (ranging between 23.8˚C - 25.1˚C). In months of March the pattern slightly varies in

eastern and western rooms, where the temperature at 6.00 PM (ranging between 24.6˚C - 27.8˚C) is lower than

the one recorded at 9.30 AM (ranging between 25.9 ˚C -27.9˚C). This clearly shows the effect of high thermal

mass of the house.

House 3: House 3 is rectangular in plan having central courtyard measuring 3.94 MtsX 4.12 Mts, with rooms

on three sides. There is staircase and boundary wall on north. Only western wing is double story.




Figure 11: House 3 Plans

Eastern Wing

Northern wall




The temperature data for different time of the day for a particular month is averaged and shown in figure

13,14,15 and 16. Simultaneous outdoor temperature variation is also shown in the same table.

In month of January and February and March, the temperature in all the rooms is lowest at 9.30 AM (ranging

between 19˚C -22.2 ˚C) and highest at 1.30 PM (ranging between 22.2˚C – 24.8 ˚C), showing some reduction

in temperature at 6.00PM (ranging between 21˚C - 23.3˚C). In months of April the pattern slightly varies in

southern, eastern and western rooms, where the temperature at 6.00 PM (ranging between 21.8˚C - 24.5˚C) is

lower than the one recorded at 9.30 AM (ranging between 22.1˚C -23.9˚C). This clearly shows the effect of

high thermal mass of the house.

Aspect Ratio: Aspect Ratio (AR) is calculated for all three houses as:

Area of the courtyard floor

Aspect ratio = --------------------------------------

(Average height of the surrounding walls)²

Figure13

Figure14

Figure15 Figure16




Aspect Ratio and Shape of the Courtyards in Three Houses

In House1 the courtyard is wide and shallow (high aspect ratio of 1.8), it performs as sun collector. On the

other hand, the narrow and deep courtyard (low aspect ratio) performs as a sun protector, in which orientation

has a weak effect on the house.

The Aspect ratio of courtyards in all three houses is calculated.

Time / Temperature Range 9.30 AM 1.30 PM 6.00 PM

House1 23.4 ˚C -25.6 ˚C 26.3 ˚C – 28.27˚C 25.2 ˚C - 26.3˚C

House2 23.2 ˚C -24.6˚C 25.3 ˚C – 27.5˚C 23.8 ˚C - 25.1˚C

House3 19 ˚C -22.2˚C 22.2 ˚C – 24.8˚C 21 ˚C - 23.3˚C

Conclusion: The houses are made of 40 or 50 cm thick locally available stone, plastered with cement or mud

in inner side. This gives benefits of high thermal mass and offers wide time-lag. The variation in temperature

ranges at all three times of the day i.e. 9.30 AM, 1.30 PM and 6.00 PM clearly shows a direct relationship

with Aspect Ratio of the courtyards.House3 with the least AR (deep Courtyard) shows lowest range of

temperatures, whereas House1 with highest AR (shallow courtyard) shows highest temperature ranges and

House2 remains in between. The temperature variation in different side rooms generates shift of functional

usage of those rooms. In all three houses the eastern and western wings keep cooler due to mutual shading of

neighboring houses and deep verandahs, and thus these are mostly used as sleeping areas. The courtyard

showing high temperatures during all parts of day dissipates the heat after sun set and offers most suitable

sleeping area during summer months.

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