Sunita

Narain

Director General of Centre for Science and Environment (CSE) and the Editor of Down To Earth magazine. She is an environmentalist who pushes for changes in policies, practices and mindsets

Green buildings: how to redesign

There is a buzz about green buildings

imageThere is a buzz about green buildings. But the question is: what does one mean by building green? And how does one design policies to make the green homes of our dreams?



Green is not about first building structures using lots of material and energy, and then fixing them so that they become a little more efficient. Building green is about optimizing on the local ecology, using local material as far as possible and, most importantly, building to cut the power, water and material requirements.

Take the glitzy airport building Delhi will soon get. Developers say it will come with a green tag. This is because the airport is investing in energy-efficient lighting, sewage disposal and rainwater harvesting. All these are important initiatives but the question remains: could the airport have been designed differently so that it used much less energy in the first place? For instance, the challenge before green airports today is to make them compact to reduce the time it takes from entering the building to entering the aircraft. This ‘frugal’ planning will make everything more efficient—take less building materials to build and less energy to cool and heat. But planners first think of building the biggest structures and then try sugarcoating them. I say this without even discussing the need for airports to give way to other modes of much more efficient transport like railways.

If one begins to think green in a locally appropriate way, one will realize that traditional architecture was green in many ways. Every part of India had its unique stamp of buildings. This is because creative and architectural diversity was built on biological diversity. So buildings in hot regions would ensure corridors directed the wind so that it naturally cooled the interiors. In wetter regions architects would build using the natural breeze and light. All in all, traditional architects knew how to optimize the use of elements.

Today, Indians have forgotten how to build for their environment. Instead, modern buildings are examples of monocultures—lifted from the building books of cold countries where glass facades are good to look at and appropriate for their climate. The same building in India is a nightmare; the glass traps the heat. The building cannot be naturally cooled because windows cannot be opened. It needs central air-conditioning and heating. In this situation, turning the building green means using very expensive glass to insulate better. Builders avoid this. So the only band-aid green measures left are to include a few token items like efficient lights and water-saving devices in the toilets.

Architects say God is in the details. In this case, the details are about both simplicity and diversity. In large parts of India, where the sun is both the source of light and heat, traditional architecture made use of a small but critical detail: the window shade. Modern facades are built without these shades because they don’t fit the image of the western building. Just raise your head and look at the glitzy building out there, you won’t find this simple but effective detail.

Clearly, the buildings of the green future have to be different. This will require setting the right policy so that practice can follow. The fact is even today we have no mandatory green standards for builders to follow. The National Building Code does not include energy, water or material efficiency standard. The only standard that exists is for energy—the Energy Conservation Building Code—and it is voluntary. The first and urgent step is to incorporate this voluntary energy code into the mandatory National Building Code. The second step is to ensure its implementation so that builders measure and reduce the energy usage of their construction.

But most importantly, the code must be developed so that it sets the mandatory benchmark for builders to follow—tough standards for energy usage for each square metre of built-up area. This will then allow architects and builders to do things differently. They can build for efficiency and cut costs rather than build for inefficiency and then spend money on making the building more efficient. This will bring back the knowledge and practice of building to maximize passive energy, natural light and wind, while keeping away the heat.

Simultaneously, the code needs to be expanded to include water and waste standards—to reduce water usage in toilets—and to ensure that institutions and large residential complexes recycle and reuse sewage. Similarly, these complexes must be provided space to compost kitchen waste. But priority should be segregating solid waste. Separate what can be composted or recycled and minimize what cannot be reused (like plastic).

This is only the beginning. Green buildings alone won’t make a city green. If green homes cannot be connected with public transport then the lives of the people living in them and the environment would still be brown and dirty.

—Sunita Narain

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  • Its most enlightning

    Its most enlightning contents..I simply got engrossed with..!

    Thank u,
    Manohar

    Posted by: Anonymous | 5 years ago | Reply
  • crisp and nicely put as usual

    crisp and nicely put as usual .

    Posted by: Anonymous | 4 years ago | Reply
  • Excellent article. The

    Excellent article.
    The traditional architecture needs to be revived.
    The Eastgate Centre is a shopping centre and office block in central Harare, Zimbabwe whose architect is Mick Pearce. Designed to be ventilated and cooled by entirely natural means, it was probably the first building in the world to use natural cooling to this level of sophistication. It opened in 1996 on Robert Mugabe Avenue and Second Street, and provides 5,600 m┬▓ of retail space, 26,000 m┬▓ of office space and parking for 450 cars.
    Designing for thermal control
    The Eastgate Centre's design is a deliberate move away from the "big glass block". Glass office blocks are typically expensive to maintain at a comfortable temperature, needing substantial heating in the winter and cooling in the summer. They tend to recycle air, in an attempt to keep the expensively conditioned atmosphere inside, leading to high levels of air pollution in the building. Artificial air-conditioning systems are high-maintenance, and Zimbabwe has the additional problem that the original system and most spare parts have to be imported, squandering foreign exchange reserves.
    Mick Pearce, the architect, therefore took an alternative approach. Because of its altitude, Harare has a temperate climate despite being in the tropics, and the typical daily temperature swing is 10 to 14 ┬░C. This makes a mechanical or passive cooling system a viable alternative to artificial air-conditioning.
    Passive cooling
    Passive cooling works by storing heat in the day and venting it at night as temperatures drop.
    ÔÇó Start of day: the building is cool.
    ÔÇó During day: machines and people generate heat, and the sun shines. Heat is absorbed by the fabric of the building, which has a high heat capacity, so that the temperature inside increases but not greatly.
    ÔÇó Evening: temperatures outside drop. The warm internal air is vented through chimneys, assisted by fans but also rising naturally because it is less dense, and drawing in denser cool air at the bottom of the building.
    ÔÇó Night: this process continues, cold air flowing through cavities in the floor slabs until the building's fabric has reached the ideal temperature to start the next day.
    Passively cooled, Eastgate uses only 10% of the energy needed by a similar conventionally cooled building.
    Eastgate is emulated by London's Portcullis House (2001), opposite the Palace of Westminster. The distinctive giant chimneys on which the system relies are clearly visible.
    Modern use of traditional solutions
    To work well, the building must be very carefully designed. After computer simulation and analysis, the engineering firm Ove Arup, gave Pearce a set of rules.
    They said that no direct sunlight must fall on the external walls at all and the north façade [direction of summer sun] window-to-wall area must not exceed 25%. They asked for a balance between artificial and external light to minimise energy consumption and heat gain. They said all windows must be sealed because of noise pollution and unpredictable wind pressures and temperatures, relying on ducted ventilation. Above all, windows must be light filters, controlling glare, noise and security.[3]
    To help with this last, the windows have adjustable blinds, but Pearce also used deep overhangs to keep direct sun off windows and walls. Deep eaves are a traditional solution in Africa, shading the walls completely from the high summer sun, while allowing the lower winter sun to warm the building in the morning.
    Further, passive cooling systems are particularly appropriate for this part of Africa because, long before humans thought of it, passive cooling was being used by the local termites. Termite mounds include flues which vent through the top and sides, and the mound itself is designed to catch the breeze. As the wind blows, hot air from the main chambers below ground is drawn out of the structure, helped by termites opening or blocking tunnels to control air flow.
    Pearce's practice is in Harare, and he specialises in buildings which are low cost, low maintenance, and have low environmental impact. His projects try to make best use of locally available resources, and include Harare International School Arts Centre, Harare Hindoo Temple and Chinhoyi Provincial Hospital, Zimbabwe. In 2003 Pearce was awarded the Prince Claus Award for culture and development, for his work on Eastgate.
    West spends more energy on heating while east on cooling. It was estimated Mumbai consumes 1000 MW daily for Air conditioning alone.
    Before air conditioning, in a bygone and surely less comfortable era, people employed all sorts of strategies for keeping cool in the heat. Houses were designed with airflow in mind -- more windows, higher ceilings..... In addition, many homes had porches where families could spend a hot day, and also sleeping porches with beds where they could ride out a hot night. Many home designs took passive solar design principles into account, even if they didn't name them as such.
    A lot of people run expensive air conditioning when it is actually pretty cool out- after the sun has been baking a California house all day it can be cool in the evening but the house is still holding a couple of hundred thousand BTUs of heat. In more temperate parts of the country, just moving the air and having good ventilation could eliminate the need for AC much of the time.
    There is a reason our ancestors built summer kitchens; those stoves put out a lot of heat and you didn't want them in your house in summer. Outside summer kitchens are all the rage in the luxury house/ mcmansion set as well. It really makes no sense to run a stove inside, just to then spend money to run air conditioning to remove the heat again. So get a gas barbecue and grill your vegetables, take advantage of farmers markets to get fresh stuff, and eat lots of salad.
    Cupolas are as functional as they are decorative. As warm air rises cupolas allow hot air to escape at the high points in the house while bringing up cooler air from below. They also create a steady air-flow even when there is no breeze outside. In some homes, cupolas provide soft, indirect sunlight that illuminates the home without bringing in the heat.
    Architect Manit Rastogi or Morphogenesis designed the Pearl Academy of Fashion in Jaipur using a number of old technologies to create "an environmentally responsive passive habitat."
    The exterior is clad in a perforated screen, described by the architect:
    The building is protected from the environment by a double skin which is derived from a traditional building element called the ÔÇÿJaaliÔÇÖ which is prevalent in Rajasthani architecture. The double skin acts as a thermal buffer between the building and the surroundings. The density of the perforated outer skin has been derived using computational shadow analysis based on orientation. The outer skin sits 4 feet away from the building and reduces the direct heat gain through fenestrations, yet allowing for diffused daylight. The jaali thus, serves the function of 3 filters- air, light, and privacy.
    A traditional way of cooling in India was the Stepwell, a pond dug into the ground or surrounded by walls above ground so that the air is cooled by evaporating water in an enclosed, shaded zone.
    "How did they think up something so elaborate and yet so simple in its basic philosophy? "How do you begin to think that you can dig into the ground and use the earth as a heat sink, have access to water, put a pavilion into it so that its comfortable through the year? It takes a lot of technology for us to think up something that simple now.( Architect Uses Ancient Techniques To Cool Modern Building in India, Lloyd Alter ,treehugger, February 29,2012).ÔÇØ
    Before air conditioning was invented, people living in hot climates developed many different strategies for coping with heat, many of which have been forgotten or ignored.
    Before refrigeration,people used to put milk in cans and dip them in Ganga river tying with a rope to adjacent pole in the evening and take out the milk cans in the morning. Ganga water is chill.
    MODERNISE THE TRADITIONAL ÔÇô TRADITIONALISE THE MODERN.
    Dr.A.Jagadeesh Nellore(AP),India

    Posted by: Anonymous | 4 years ago | Reply
  • "To reduce water usage in

    "To reduce water usage in toilets" is also just the beginning. It is much more rational and respectful to not create sewage, mixing our excrement with precious water to create a waste that is next to impossible to fully contain and treat, especially in cities with so many people so densely situated on the land.

    I invite you to read this 2-part interview on this subject. In fact, feel free to reprint it in DTE (with proper credits).
    http://www.chekhovskalashnikov.com/water-sanitation/
    http://www.chekhovskalashnikov.com/human-waste-disposal/

    I also invite you to read my (English/Spanish) blog, inodoroseco.blogspot.com
    and to read this book
    http://www.ecosanres.org/pdf_files/Ecological_Sanitation_2004.pdf

    Posted by: Anonymous | 4 years ago | Reply
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