Taj Mahal Trick Helps India Cool Buildings Smartly

By Vandana Gombar

India’s old palaces and forts used water channels to cool the air inside. A modern version of those water channels could slash the energy cost for cooling buildings by up to 35%.

“It is a bit of an unbelievable number, but we have the data to prove it,” said Guruprakash Sastry, regional head of infrastructure and green initiatives at Infosys Ltd., Asia’s second-largest provider of information technology services, and one of the largest users of the so-called radiant cooling technology.

Infosys constructed two identical office buildings in the South Indian city of Hyderabad in 2010-11, using conventional air-conditioning in one, and radiant cooling in the other to prove its point. There is a certain crispiness to the air inside the building using radiant cooling. It feels fresher as one walks in, and the transition from the heat outside to the cool inside was smoother, and less of a body shock.

“Radiant cooling cuts cost for cooling buildings by 35%, when compared to best-efficiency air-conditioning systems. We have close to 4 million square feet of radiant-cooled buildings at Infosys, and we intend to use it in all our new buildings as well,” added Sastry. The company is also looking at retrofits of old buildings with this cooling technology, where possible.

There are likely to be many new buildings, as the company grows and headcount increases. In the last financial year, it added about 24,000 employees, to take the total to over 228,000.

Infosys is not the only company taking to radiant cooling.

The upcoming 2,500-seat office building of automaker Mahindra & Mahindra Ltd. in Pune will also use “energy-saving radiant cooling with 119 kilometers of pipes embedded in slabs. Will save 35% energy,” managing director Pawan Goenka tweeted in June.

The pipes embedded in the concrete slab of buildings run chilled water to provide cooling. The water, sourced from the local municipal body, is chilled and circulated in a continuous cycle. This water is replaced once every two-to-three years. Updated versions seen at the Infosys site run chilled water through panels suspended from the ceiling, referred to as radiant baffles. Not only is this kind of cooling lower-cost and greener, it also rates higher on what is called thermal comfort. The Taj Mahal, and many Indian palaces across the country, also used water channels integrated in the complex for cooling.

Infosys has been hosting national and international visitors to the site from companies keen to look at alternative cooling options: for most buildings, air conditioning is the largest component of energy consumption.

Power demand for cooling is expected to jump sharply in Asia, where hot days are getting even hotter due to global warming. India is projected to see the biggest volume increase in electricity demand for cooling over the next 32 years, to 2050, followed by China and Indonesia. It could end up with the world’s largest power demand for air-conditioning post 2050 if air-conditioner ownership mimics that of the developed economies, according to BloombergNEF’s New Energy Outlook 2019.

New Energy Outlook 2019 Read excerpts from the report here.

The zero aspiration

Some of this power demand can be curbed by initiatives like radiant cooling. Meanwhile, a more ambitious idea – of net-zero buildings – has taken hold. Net-zero on energy.

Globally, the World Green Building Council aims for all buildings to be highly energy-efficient and fully powered by on-site or off-site renewable energy by 2050. It refers to these as net-zero-carbon buildings. As many as 23 cities, including New York, London, Tokyo and San Jose, have taken the Council’s Net Zero Carbon Buildings Commitment, as have 23 businesses and organizations, and six states, including California in the U.S., and Catalonia in Spain.

The Bureau of Energy Efficiency or BEE is tasked with setting energy-efficient building standards, and has seen a rising uptake of its latest Energy Conservation Building Code in various states. It expects the code to be implemented in most of the states by the end of the year.

“If the building codes are fully implemented, it will change things substantially. Anywhere from 25-50% of energy per building can be saved,” said Abhay Bakre, Director General at BEE, “with not a single penny of additional cost.” This is possible because the overall air conditioning load requirement is slashed, which helps save on capital costs.

Since India is yet to construct most of its buildings, it has a chance to build smartly. The government is committed to ensure housing for all its billion-plus people by 2022 – which means construction of millions of new houses. It is also building out commercial spaces, industrial units, data centers and various other kind of buildings as it aims for a $5 trillion economy by 2025.

Radiant cooling would make a pitch for net-zero easier, but it is not being pushed throughout India since it faces the challenge of condensation in high-humidity environments.

Energy service companies like Bhavana Chittawar’s See-Tech Solutions invest upfront to make an existing building energy-efficient, and get paid from the savings on electricity bills. “We see huge demand in the market,” Chittawar said.

No red bricks in the wall 

The use of the right building material is critical to ensure energy efficiency. The ubiquitous red bricks seen in India are not ideal for preventing ingress of heat or leakage of cool air.

A Center-of-Excellence for Sustainable Habitats set up by Mahindra Lifespace Developers Ltd. and a think tank, The Energy and Resources Institute or TERI, aims to recommend building materials and technologies that are energy-efficient. It has looked at the thermal conductivity of bricks and found that red bricks are not the best option for construction in India.

The Center is currently seeking building materials for testing their thermal properties – at no charge.

Various organizations are working on a materials directory to help builders opt for the most efficient building materials in the market.

“For green buildings, cost is a non-issue in my opinion. It is the market which needs to be created, with sufficient supply – and suppliers – of appropriate construction materials and technology, as well as a sustainable demand for them,” said Smita Chandiwala, an architect whose firm, Energe-se, provides policy advice on green buildings.

Air conditioning load can also be reduced by not opting for super-chilled buildings. “We are running a campaign to encourage people to keep the air conditioning at 24 degrees or above,” said Saurabh Diddi, director at BEE. “It will have health benefits, and be economical too.”

TERI showcased another energy-efficient cooling option – earth air – at its campus on the outskirts of Delhi. A fan in a tunnel a few meters below the ground pumps the cool earth air to vents opening into rooms, which look deceptively similar to air-conditioning vents.

How green is my building?

Less than 5% of India’s stock of buildings are energy-efficient, according to widely accepted industry estimates. Some officials interpret this to mean that less than 5% of buildings in India are green, though the concept of green buildings is much wider, taking into account water usage and waste-to-landfill, among other things.

“About 7 billion square feet of built area is going green with Indian Green Building Council or IGBC. That is the third-largest stock in the world, after the U.S. and China,” said Sundaresan Raghupathy, deputy director general at the Confederation of Indian Industry, and the head of the IGBC. He expects India to be in the second spot soon. “The scope is very high. Awareness has picked up significantly,” he said.

IGBC is one of the green building rating bodies in India.

The U.S. Green Building Council provides LEED (Leadership in Energy and Environment Design) ratings. It announced in June that India had become “the fourth-largest market in the world for LEED with more than 2,900 registered and certified commercial projects participating, totaling more than 1.39 billion square feet.”

Griha, or Green Rating for Integrated Habitat Assessment, is run jointly by the renewable energy ministry and TERI. “I would want this market to transform completely, with all buildings in the country rated on how green they are. That is only the first step though,” said Sanjay Seth, chief executive officer of the Griha Council, and senior director at TERI. “We need to keep monitoring the buildings – even conduct an audit every five years – to ensure that they continue to operate efficiently.”

While some activists would prefer the government to mandate that all new buildings that come up are green, there are many who prefer economic incentives to nudge builders. “Allowing a bigger floor area on a parcel of land for buildings which are green, or offering other incentives like lower permit fee, would go a long way in pushing architects and builders towards green buildings,” Raghupathy said.

Many states already offer such incentives, says Seth of Griha. The southern state of Andhra Pradesh offers a subsidy on capital investment for Griha-rated projects, while some other states offer tax rebates. “India’s green building market is estimated to double by 2022, driven by increasing awareness levels, environmental benefits and fiscal incentives,” asserted Seth.

As India’s skyline changes, not choosing well would mean being saddled with a stock of energy-guzzling buildings, and more and more instances of productivity-sapping sick building syndrome. “Our buildings used to be part of nature. We will go back to that,” said an optimistic Raghupathy.

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