The beginning of what may, in the present context, be described as ‘unsustainable architecture’ began at the end of 18th century with industrial revolution, as many new technologies and materials came into being. Thereafter the growth rate of urban population has become much faster. The extremely rapid urbanization has resulted in the dramatic increase in the size of urban agglomerations led by environmental, social, political, economic, demographic and cultural problems. “Till we were static we were nearer to nature, as we are moving towards technology our cities are becoming robotic,” said Prof Charanjit Shah, Founding Principal, Creative Group. The consumption of energy particularly, embodied energy consumed in transportation, infrastructure and building industries have led to an increase in carbon monoxide and ultimately the expansion of ozone layer which has caused environmental degradation wherein even the outside quality of air in most of the Indian cities with PM 2.5 and PM10 has gone beyond 400 which is very alarming for the human health as everyone has now become a passive smoker and smokes 40-50 cigarettes a day. Such consumptions have converted the cities into charcoal cities which we very proudly say as our global transformation.
Now when we talk about capacity buildings, the skyscrapers or large infrastructure campuses where the energy consumption is high in the services, maintenance and usage for creating suitable utilities and management services in the capacity buildings, the recent trends of global empowerment into the built form has practically made it a necessity for all the capacity buildings to be centrally air-conditioned along with various other automation systems controlled by intelligent building management systems.
Covid-19 is perhaps, the biggest shock to the entire world in terms of human behaviour and the technological bound human settlement which is far away from nature and the natural resources. Due to central HVAC systems most of the indoor air is by circulation and the content of fresh is reduced to minimum so as to make the HVAC system more cost-effective. This new virus, social distancing causing air borne diseases is a matter of great concern and need to be professionally understood wherein maximizing intake of fresh air and daylight in the capacity building is what needs to be redefined and rediscovered in creating humane architecture and human settlement of tomorrow. The active and passive ways of design strategies needs to be understood and the great heritage particularly in this sub-continent is to be relooked and be made the principals of new design evolution helping create sustainable capacity buildings avoiding air syndrome in the built form. The human comfort level in terms of the ambient temperature also needs to be realized to be comfortable and sustainable.
In the surge of following the global trend, tall skyscrapers and glass buildings adorned with air-conditioning units has replaced our indigenous art and architecture. Landscaped areas have become a blot outside the window and mechanical systems replaced our passive heating and cooling techniques. We have developed the same urban form which is only distinguished by status and not by context and climate of the particular region.
INDOOR AIR POLLUTION IN URBAN BUILDINGS
The indoor quality in most of the urban buildings is degraded by the concentration of harmful pollutants in the indoor environment. People residing in the urban areas prefer spending their time indoors and find their relief in the crisp breeze of an air-conditioner. But have we ever wondered how our health is affected by inhaling the same re-circulated air without an exposure to the fresh air.
Basically here, mostly the same air is re-circulated after every cycle. This is done to reduce the energy consumption needed in bringing the outdoor air to the desired temperature due to which the spread of infections and viruses is enhanced. Recently even the quality of air is a great concern in the metro trains wherein more than 30 percent of the fresh air is being introduced in the HVAC system to dilute the effect of corona virus on the travellers.
PASSIVE STRATEGIES USED IN TRADITIONAL BUILDINGS
India is divided into majorly eight climatic zones each having its diverse culture, tradition and vernacular style of architecture but instead of evolving the roots of our traditions we blindly started following the Western culture and the architecture which our ancestors has evolved after centuries of error and trial was abandoned.
Air Circulation and Sun Movement:
There are various passive strategies affecting the circulation of air and sun in the building:
Courtyard Planning: It is done to ensure the maximum wind circulation in the building particularly in hot and dry and hot and humid climates. The buildings are made comfortable by using glare-free north light, shaded south light and protecting the glared harsh west light by way of planning and layering the built form.
Here, the maximum intake of northern glare-free light is ensured by using various passive techniques towards respecting the site topography, orientation, wind directions and selection of appropriate materials and technology lead to sustainability. Maximising daylight and minimising heat gain in hot-dry and composite climate is one of the major concerns of planning. Conservation of water and energy by use of natural process of recycling, reuse and making the built environment off the grid is what perhaps net zero is. We need to look beyond net zero. The harsh sun prevented to come in by various techniques includes:
- Fenestrations and Openings: More openings should be placed towards the direction of the prevailing winds in humid climates.
- Carved Exposed Surfaces: Traditional design took the benefit of carved wall surfaces to increase surface area for radiative loss and also to self-shade the wall.
- Mutual Shading: Our traditional architecture evolved through centuries of trial and mutual shading is one of the efficient techniques which can be seen in the streets of Rajasthan.
- Layering the Building: Layering is an efficient passive strategy used in minimising the heat intake and maximising the air circulation in the building. The meticulously planned floor plates ensure that the maximum floor area avails of the natural light with a minimal dependence on artificial source of light in the daytime. A wholesome lighting could not have been possible without glazed openings. A combination of features like ST 120 grade of St Gobain glass, metal louvers and the adequately positioned overhangs check the solar glare and the heat intake in the building. Moreover, the pergolas used on the building exterior serve as an add-on for the elevation of the building. The sciographic art created as a result of the solar movement brings about a very different picture of the building with every passing hour
- Earth Air Tunnels: Earth air tunnel or earth air heat exchanger is a pre-cooling or pre-heating system which consists of a pipe or network of pipes buried at reasonable depth below the ground surface. The cardinal principal behind its operation lies in changing the temperature and thereby density of the air in and around the tower. The difference in density creates a draft, pulling air either upwards or downwards through the tower. Various mechanical systems like the air-conditioners are installed in the buildings to attain the desired environment indoors. Air-conditioned buildings often have sealed windows, because open windows would work against the system intended to maintain constant indoor air conditions. Outside, fresh air is generally drawn into the system by a vent into a mix air chamber for mixing with the space return air. Then the mixture air enters an indoor or outdoor heat exchanger section where the air is to be cooled down, then be guided to the space creating positive air pressure.
There are various types of filters used in an HVAC system:
- Fibreglass Filters: Fibreglass filters are the most common type of HVAC air filter available. Crafted from strands of fibreglass spun together, this type of filter traps large airborne particles, including dust.
- Pleated Filters: A step up from fibreglass filters, pleated filters prevent dust from entering your HVAC system while trapping airborne particles and allergens such as pet dander and dust mites.
- Electrostatic Filters: Electrostatic filters are even better at filtering allergens compared to pleated filters. An electrostatic filter uses small cotton and paper fibres to generate a static charge when in use. It can be concluded that the traditional passive strategies can be effectively adapted to modern design conditions and benefit the comfort conditions in dwellings. It will allow more effective and systematic flow of the wind reducing the spread of any kind of virus.
Prof Charanjit Singh Shah is a planner and infrastructure expert, art and architecture critic, founding principal-Creative Group, chairman-Smart Habitat Foundation, senior advisor-Assochem GEMS.