Measurement serve the purpose of giving a qualitative understanding of how specific design features in an existing building respond to outdoor environment. Initially the precise measurement of the outdoor variables (Solar radiation, Wind Velocity and direction, Air temperature and R. H) and the resulting indoor conditions (Air temperature, M. R.T., Air Velocity and R. H.) are required over a period which should be two of three times the time taken by the building to respond to the external conditions.

Rather than attempting detailed measurements of one building, we thought it would be more fruitful to take limited measurement in all the different building types with the specific purpose of obtaining an overall view of the Indoor thermal environment in each case and to try to relate it to a standard outdoor environment (such as at meteorological observatory) instead of highly variable micro climate around the building Measurement of this type can;

i. Show the thermal behaviour of specific building elements.

ii. Provide a basis for comparing the Indoor thermal conditions existing in different areas of building.

iii. Provide a basis for comparing the overall performance of different buildings.

Experimental set up

For conducting the experiments two historical residential buildings were selected, one compactly planned and the other courtyard type, irrespective of their floor area but of same building form.

Experiments were conducted in the peak seasons in two buildings in the first week of January 1998 and last week of May 1998.

The experimental set-up was created by fixing up the Thermocouples on both the sides four walls of North, East, South, West oriented rooms in each building.

Parameters measured and the corresponding instruments used :

Climatic Parameters

Instruments used

1 a. Air temperature (deg. C)

b. Surface temperature c. Globe temperature

2. Air Humidity 3. Air Movement

Thermo Hygrometer Digital Thermal Indicator

Globe thermometer Thermo Hygrometer Kata Thermometer

SHAPE * MERGEFORMAT

Analysis Of The Data

The measured data was fed into the computer and the Graphs were plotted. The Graphs were then analysed on the basis of the following parameters:

* Air Temperatures

* Air Velocity

* Relative Humidity

* Time Lag

* Thermal Comfort Index (T. S.I.)

BUILDING — I ( Roshan — Ud — Duala Kothi — Fig. 2) PARAMETERS SUMMER READINGS WINTER READINGS AIR The room temp. were found to All the rooms were found to be TEMPERATURE be Slightly above the comfort in slightly cool zone with slight zone but within the acceptable limit. variation in temp. The temp. Fluctuation in the The outdoor temp. Fluctuation outdoors was in the order of Was In the order of 15-16 18-19deg. C where as the deg. C where as the indoor indoor fluctuation was of 5-6 deg. C. fluctuation was of 3-4 deg. C. The max. Indoor temp. was The max. Indoor temp. was 7-80C lower than the 3- 40 C higher than the corresponding outdoor temp. corresponding outdoor temp. AIR VELOCITY Ventilation fenestration were Ventilation fenestration are Normally kept open through kept out closed through out the day & the day and night which night so as to minimize heat increases the indoor air temp. But at the same time induces air movement which provides greater sensible comfort. loss. The central hall was found to Although the openings Have max. Air velocity remained between 0.8 — Closed but still due to infiltration 1.0 m/s the air velocity was between 0.05 — 0.3 m/s. RELATIVE The humidity varied between The humidity varied between HUMIDITY 31% — 52% which was within 42% — 72% which was within the the comfort zone comfort zone TIME LAG The exterior walls of the rooms had the Time lag of about 8 — 10 hours. —— do—— Both the surfaces of the interior walls reached its peak almost at the same time. —— do—— The difference in the peak The difference in the peak temp temp. of Both the surfaces of the of both the surfaces of the exterior walls is comparatively exterior wall was more (1.5 0C) less (0.5oC) . The T. S.I. was in the slightly The T. S.I. was in the slightly THERMAL Warm Zone i. e. 30 — 330C cool COMFORT which is within the acceptable limit of comfort zone. zone i. e. 16 — 200C The decrement factor was lowest of all (0.27) —— do——

PARAMETERS SUMMER READINGS WINTER READINGS AIR TEMPERATURE The room temp. were found to be slightly above the comfort zone but within the acceptable limit. The temp. Fluctuation in the outdoors was in the order of 18-19 deg. C where as the indoor fluctuation was of 6-7 deg. C. All the rooms were found to be in Varying between slightly cool zone to too cool limit. The outdoor temp. Fluctuation was in the order of 15-16 deg. C where as the indoor fluctuation was of 8-9 deg. C. The max. Indoor temp. was 7 — 80C lower than the corresponding outdoor temp. The max. Indoor temp. was 2-30 C higher than the corresponding outdoor temp. AIR VELOCITY The shaded courtyard (throughout the day induces cool air inside the semi opened rooms and ensures ventilation through the building even during the calm outdoor conditions. Due to the courtyard the interiors remains warm during the day time but in the evenings as the temp. drops and the rate of heat loss shoots high as the rooms are semi opened The courtyard was found to Have max. Air velocity between 0.9 — 1.0 m/s As all the rooms opened into the courtyard the air velocity was found to be same in all the spaces. RELATIVE HUMIDITY The humidity varied between 29% — 60% which was within the comfort zone. The humidity varied between 41% — 79% which was slightly above comfort zone. TIME LAG The exterior walls of the rooms had the time lag of about 7 — 8 hrs. —— do—— THERMAL COMFORT The T. S.I. was in the slightly warm zone i. e. 27 — 320C, which is within the acceptable limit of comfort zone. The T. S.I. was below the slightly cool zone i. e. 8 — 16.50C The decrement factor was slightly Higher than building I (0.34) The decrement factor was found to be very high (0.63)

BUILDING II —( Jannat — Ki — Khirki — Fig, 3)

Conclusion

The fact is that in heritage buildings some very ingenious solutions can be seen, to the architectural problems of resisting the weather and of maintaining comfortable conditions indoors when the climate is harsh outside. By necessity these solutions have worked with simple materials and through the manipulation of geometry of building form, through the relationship of one building to another so as to provide shading, windbreaks, control of cooling breezes and so on as well as through the relationship of buildings to topography,
and by the use of trees and plants. The result is an infinitely more subtle, economical, humane mode of design, one that is often formally and aesthetically very rich as a consequence; by contrast with the brute force technological solutions of today which work inspite of climate, rather than working with the elements, and which rely on ‘imported’ energy and mechanical services, rather than using local natural forces, deflected or diverted to achieve the facts desired.

The results of the experiments show that:

1. The thermal performance of the Building — I is found to be the most comfortable out of both the case studies. In this type of building, the amplitude of indoor air temperature was no more than 5-60C while the outdoor temperature fluctuation was of the order of 180C. The maximum indoor temperature was 8 0 C lower in summer and 3 -4 0C higher in winter than outdoor maximum.

2. Ventilation apertures which were kept open throughout the day caused the building to warm up during the day but the air movement provided greater thermal comfort.

3. A time lag 6 — 8 hours was observed in the historical buildings. The greater time lag is also accompanied by a smaller decrement factor, which reduces the heat flux entering the building.

4. The courtyard system ensured ventilation through the building even during the periods when the outdoor conditions were calm, provided the building temperature at such times was higher than the outdoor temperature and ventilation was desirable.

5. The areas of the building directly exposed to the sun reached temperature which were at times 150C higher than the corresponding ambient air temperature. The control of solar radiation in this type of climate is therefore paramount.

6. Orientation and layout played and important role in reducing energy load on heating and cooling appliances and allow maximum use of sun light for lighting purposes and minimum use of artificial heating and cooling

7. The heat storage capacity of thick walls and roofs tends to narrow the internal range tending to bring it to a level fairly close to the average external temp.

8. Form of the enclosure should be with minimum surface area exposed to solar radiation. Here the buildings were square in shape which not only reduces heat gains in summer but at the same time minimises heat loss in winters.

9. Vegetation cover to a building acts as a beautiful natural self regulatory system and thus improves performance of a passive system.

10. Use of building elements such as shading devices, buffer spaces like Courts, verandah etc. wind catchers screens, recessed openings, water Body, vegetation at appropriate places helps considerably in tempering the stress of the climate.

References

Books

1. Aronium J. E, Climate and Architecture, Reinhold publishing Corp. New York.

2. Givoni B, Man, Climate and Architecture. Applied Science Publishers London, UK, 1976.

3. Jarmul Seymour, The Architecture Guide to Energy Conservation Mc Graw Hill Book Comp. New York 1980.

4. Koenigsberger and others, Manual of tropical housing and building (Part I) : ClimaticDesign, Longman Press India 1975.

5. Kukreja C. P. Tropical Architecture, Tata Mc Graw Hill Publishing Company Ltd. New Delhi 1978.

6. Martin Evans, Housing Climate and Comfort, Architectural Press LTD, UK, 1980.

8. Olgay Victor, Design with Climate, Princeton University press, USA 1973.

9. Wagner W. F. Energy Efficient Buildings, Mc Graw Hill publishing Comp. New York1980.

10. Watson Donald, Climatic Design Mc Graw Hill Company new York 1983.

Journals/papers

1. Bhatia Gautam, The Architecture of Laurie baker, Inside Outside Oct./Nov. 1989.

2. Gandhi Nandini, Power Hungry : Switch to renewable energy resources, Indian Architect and Builder, April 1991

3. Gupta Vinod, Energy Conservation Indian myths and realities, Architecture + Design Vol. IX, No. 3 May June 1992.

4. Krishan Arvind, Agnihotri M. R. Bio-Climatic Architecture a fundamental approach to design, Architecture + Design Vol IX No 3 May June 1992.

5. Prakash Sanjay, Energy Conscious Architecture : an endless quest Architecture + Design Vol. IX No 3 May June 1992.