CONTRIBUTION OF VASTUSHASTRA TO THERMAL COMFORT: A CASE OF SHEKHAWATI HAVELIS

Abstract

In earliest times, heat and cold discomfort were the normal conditions for most people, when individuals relied upon clothing to maintain thermal equilibrium. Recent trends, however, depend upon the production of artificial interior climates. Achievement of indoor thermal comfort is considered to be one of the finest achievements of modern civilization. However creating a comfortable environment at a low price was possible during the late nineteenth and early twentieth centuries. However, with the energy crisis of the 1970's and today's fluctuating energy costs, this process became quite expensive, which led to the researches about providing a comfortable environment, saving energy and money. In the wake of energy crisis, there is a clear need to further develop the traditional systems based on natural resources. Before inventing or proposing new mechanical solutions, traditional solutions in vernacular architecture should be evaluated, and then adopted or modified and developed to make them compatible with modern requirements. This process should be based on modern developments in the physical and human sciences, including the fields of materials technology, physics, aerodynamics, thermodynamics, meteorology, and physiology. Before the advent of modern mechanical means for obtaining thermal comfort, people in the hot arid and warm humid zones were forced to devise ways to cool their houses with only natural sources of energy and physical phenomena. Generally, these solutions have been found to be much more energy efficient than modern means. Since it is most difficult to achieve thermal comfort in Hot-dry climates (because of unavailability of water and very high solar radiation resulting in high daytime temperatures), the challenge of designing comfortable buildings is also greatest. Yet the traditional buildings provide thermally comfortable environment without the use of

mechanical means. In Hot-dry region of India, traditional buildings (rural and urban both) are the finest examples of energy efficient architecture. Most of these traditional buildings were designed based upon the principles of Vaastushastra. Thus hot-dry region of India was selected for studying the effect of Vaastushastraon thermal comfort. Vaastushastras are books containing prescriptions regarding design and planning of buildings, settlements and furniture. They are derived from Sthapatya Veda which is an upaveda dealing with all the 64 fine arts of which architecture is one. The knowledge in Sthapatya Veda was understood by scholars from all regions of country. It was then rewritten in the form Vaastushastras which also took into account the local conditions (Social conditions, resource availability, physiological conditions etc.). Therefore even though the contents in all Vaastushastras procured from different parts of the country are similar but there are minor variations. Within the scope of current research, Vaastushastra poplar in western region of India was identified. It was identified as Rajvallabhmandanam which was created by Sthapati Sutradhar Mandan who was the chief architect of Maharaja Mokal of Mewar in Rajasthan. Its contents are similar to other Vaastushastras available in different parts of country. For analyzing the effect of Vaastushastra on thermal comfort, such traditional buildings were required which have not changed from their original design. Rajasthan has many such places where buildings are intact in their original form. However since Vaastushastra finds its applicability more in residential buildings and majority of buildings fall under this category; residential buildings were to be identified. Shekhawati region in Rajasthan is world famous for its frescos on the walls of residential buildings called Havelis. The streets here are lined with painted walls which give an effect of an open air art gallery. Beyond the painted facades, these Havelis are thermally comfortable inward looking residences which houseda multitude of functions inside.

Shekhawati Havelis were constructed by the rich Marwaris as a mark of their success in business. The lavish Havelis competed with the forts owned by rajput rulers in their extravagance. Marwaris were patrons of local art and these Havelis reflect that. All the Havelis essentially have courtyard in the centre of the house; rest of the spaces surrounded courtyard, courtyard not only served as the common space for celebrating occasions and day to day activities but it also regulated the climate as it brought all five elements of nature into the building. The Havelis have traditional construction made up of hand pressed bricks and lime mortar. The walls are exceptionally thick and lime mortar is used for laying of bricks, plastering, flooring and finishing. The typical features of traditional architecture such as chajja and jharokha are present in these Havelis. All these features help in maintaining thermally comfortable environment inside. It was sure that all these features help in achieving thermal comfort but whether prescriptions laid in vaastushastra help in achieving thermal comfort was to be established. 25 Shekhawati Havelis were documented and analysed within the scope of this research. To achieve this task of analyzing effect of Vaastu on thermal comfort in Shekhawati Havelis, both these parameters had to be quantified. Quantifying thermal comfort is easy as there are many quantities which could be used to represent thermal comfort. But quantifying Vaastu application was difficult as Vaastu is a qualitative subject. Therefore a quantity called Vaastu score was formulated. The prescriptions in Rajvallabhmandam which could be manifested in physical form were identified. A weightage was assigned to each prescription depending upon its importance as per Vaastu. Final score obtained as a total of scores obtained against each prescription was called Vaastu score. For quantifying thermal comfort, a new quantity called PUHos was devised. It was the 'percentage of uncomfortable hours inside against outside in summers'. This reflected the percentage of uncomfortable hours which were converted to comfortable with the help of building. But percentage of uncomfortable hours in summers only was considered because summer is the more problematic period in Shekhawati. For most part of the year it remains hot and the prime objective of buildings is to maintain a cooler environment inside. Therefore all passive techniques employed in Shekhawati Havelis lead towards cooling except heavy thermal mass. This reduces the heat gain in winters also thereby reducing comfort in winters. Also since it is possible to enhance thermal comfort by increasing clothing while it is not possible in summers, summer becomes more challenging in hot-dry regions. For calculating PUHos, all the case studies were simulated using Energy Plus and Design Builder Software. The output was obtained for all the habitable zones in each Haveli. Hourly data was obtained for Dry Bulb Temperature (DBT), Relative Humidity (RH) and Air velocity (v) for all habitable zones. Since thermal comfort is not dependant of any one of these quantities in isolation, thermal comfort index was used which took into account the effect of all these quantities. There are many comfort indices which have been developed. However most suited for the Indian subjects is Tropical Summer Index (TSI). From the hourly readings of DBT, RH and v, TSI was calculated as per the formula. The comfort range of TSI is between 25-30 TSI and the extended comfort range is 19-34 TSI. Extended comfort range was considered for calculation of PUHos. Once Vaastu score and PUHos were calculated for all the cases, regression analysis was carried out to establish the relation. The analysis revealed significant findings. It reported that PUHos is significantly affected by Vaastu score. Higher Vaastu score implied lesser PUHos which means enhanced thermal comfort. Relationship was also established between Vaastu score and percentage of uncomfortable hours in winter and for whole year but significant relationship was not established. Shekhawati Havelis were also analysed for quantifying the effect of passive design parameters on thermal

comfort. It was found that number of storeys affect the PUHos most significantly while other factors such as Width to height ratio of courtyard, width of courtyard as percentage of width of building etc. did not affect PUHos that significantly. However the nature of relationship was established which was exactly as per theoretical understanding. Individual prescriptions of Vaastushastra were also analysed to quantify the effect on PUHos. It was established that Vaastu prescriptions relating to Courtyard, Building elements, Orientation, Landscape, Construction and Spatial Planning affect thermal comfort significantly in Shekhawati Havelis. However it should be noted that the results are specific to Shekhawati Havelis and Vaastu prescriptions laid in Rajvallabhmandanam. It was also established that most of the passive design parameters prescribed for Hot-dry climate are followed in Vaastushastra also. This proves that Vaastu has a scientific rationale behind it which might be a result of prevalent socio-economic conditions. Although the language of Vaastu texts is religious, it has a scientific basis. Hence it can be concluded that- Vaastushastra contributes significantly towards achieving thermal comfort in Shekhawati Havelis in summers. In other words, Shekhawati Havelis following more Vaastu prescriptions remain more comfortable. So Vaastu prescriptions should be applied in modern residential buildings also to achieve similar results but the change in context makes it difficult. However with a little innovation, some of the Vaastu prescriptions can be easily applied in residential buildings in hot-dry climate. Efforts will also be needed at policy making level to implement reasonable Vaastu prescriptions. It is difficult but still possible in modern context. Thus Vaastushastra should not be discarded as a mythological and religious text. It may however be modified to suit the present context while keeping the essence intact.