Today is a hot, sticky day in Delhi, almost 90 F in the shade, and in my apartment, less than ten years old, I’m sweating as I type underneath the fan. In fact, I’m sweating even when I turn on my air conditioner. And yet, outside, in Delhi’s most beautiful park, Lodhi Gardens, I can sit outside in an open air tomb built almost five hundred years ago, and I feel cool.
If I were in Jaipur right now, in hot, dry western India, where it is more than 100 F, and yet feels like 70 inside the forts of the ancient Rajput kings. Admittedly, it may be hotter now than it was in the summer of 1734, when it was built, but these palaces were designed to keep their residents cool without electricity, conditioned air and refrigerants. How? By recognizing some fundamentals of heat and physics. If we want to design for the future, we need to learn from the past.We have known for hundreds of years that solids cool more than liquids which cool more than air. And yet, in US and in Indian corporate, we attempt to cool our spaces and ourselves with air. We also know that the human body loses its heat from radiation far more than from convection (moving air over your surface) or even perspiration (though, it sure feels like sweating is the only option, right now!). Yet, our air conditioning systems rely on convection – blowing cold air over all of us. Instead, we can design like the Rajputs.
In Rajasthan, ancient kings were masters of hydrology and thermodynamics; they captured rainwater across their territory and built hundreds of kilometres of pipes, eventually piping water underneath their floors. This cool water running underneath the floors creates a massive thermal mass, which both stores this coolness, and radiates it when you’re within the structures.
But this technology is not lost to the past. Rohan Parikh, head of Green Initiatives at Infosys, described today the incredible experiment current underway at Infosys. In one of the new office buildings in Hyderabad (one of the hottest cities in India), Infosys has divided the building perfectly in half. One half is conventionally cooled (with inefficient convection using inefficient air), and the other half using in-slab radiant cooling (piping cool water through the floors of each office). The metered measurements from this system will be launched in September, when the building becomes operational. Projections estimate that this building will use only 1/3 of the energy of a typical high-quality Infosys building!
As Rohan says, “We need to design for the future; the design — of a company, of a community, of a society — is its legacy.” Rajasthani kings have left a legacy of innovative thermal cooling; the traditional designs in Morocco use night-time radiation and thermal mass to keep buildings cool all day; and we’re on the path to leaving a legacy of consumption. But we can leave a legacy of energy innovation. But it may mean looking back before we move forward.