Passive Solar Hot Water

Solar hot-water panels at the PMK Bungalow

One of the cheapest and most effective ways to use solar energy is for heating water — replacing electric geysers with solar heaters can reduce your bills quite dramatically. These panels are quite different from the solar photo-voltaic (PV) panels which produce electricity in that they contain no electronic parts and are fairly easy to maintain.

There are two types of panels and their usage depends on budget and climatic factors.

In most tropical climates, the ordinary collectors work well. These collectors consist of copper fins that heat up rapidly and transfer this heat to copper pipes attached directly behind them. The pipes supply hot water to a storage tank by thermo-siphon and the whole assembly is put behind a glass pane for protection.

The other type of panel becomes necessary in places with extreme climates. Called Evacuated Vacuum Tube Collectors these are much more efficient but also more expensive. Here an outer tube of borosilicate glass has an absorptive layer and an inner tube to which the heat is transferred. Here too, the water rises by convection into a storage tank.

Tips

You will definitely need to have an insulated collection tank to store the hot water generated, especially if you want to use it before the sun comes up the next morning. Also make sure that the piping from the panel to the tank is properly insulated – this is something the installers often “forget”.

There are times of the year when heating won’t be very effective – due to cloud cover, for instance. For the monsoon and for early winter mornings, it might be useful to pipe the water though instant-type heaters in individual bathrooms to boost the temperature.

External Links

• http://www.energiesolar.com
• http://www.tatapowersolar.com/
• http://www.nrgtechnologists.com

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What is Sustainability?

“Nature has enough for everybody’s need; not for everybody’s greed.”
– Mahatma Gandhi

Quoting Mohandas Karamchand Gandhi may no longer be fashionable but these words are more relevant today than they’ve ever been.

Every material used in construction comes, eventually, from the earth. For any architect who cares about nature, that is a predicament to be faced every day. I know it is unrealistic to halt the production or extraction of such materials but we should, at the very least, try and minimise their usage.

A simple example: small structures in India are often built with reinforced cement concrete frames when ordinary load-bearing brickwork (which is about 25% cheaper by the way) would be more than satisfactory.

Nature-friendly Architecture & Design

Nature has an enormous ability to repair herself but when we exceed her capacity to do so, this cycle of restoration and renewal is broken.

Sustainable architecture and design takes into consideration all aspects of construction that affect the environment.

There are many factors that go into making a building nature-friendly:

Using Materials Sustainably

A large chunk of a construction’s carbon footprint is determined by the materials used. For small structures, reinforced concrete (RCC) framing is environmentally expensive and thoroughly unnecessary to boot! I’ve found that load-bearing work usually does a better job.
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Better Design & Construction Methods

Better design is not just about aesthetics. It holistically considers architectural design, landscape & plantation, sustainable systems & climatic conditions,. A well designed construction has minimal negative impact on the site and its surroundings.
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Saving Energy

During its life cycle, a building needs an enormous amount of energy for lighting, heating & cooling. A design that makes good use of naturally occurring sunlight & prevailing breezes goes a long way in saving associated costs.
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Saving Water

Economists have pointed out that future wars will be over water which makes this the most important factor in my estimation. Saving, harvesting and recycling water is far easier than it is made out to be and you often don’t need an expert to get it working.
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Waste Disposal

Disposal of solid waste might not be an architect’s area of expertise but we can play a proactive role by designing for composting pits etc.
[under construction]

Impediments

If you compare apples to oranges, you will invariably draw the wrong conclusion.

The biggest deterrent to making clients accept sustainable solutions is, usually, perceived cost. That’s because they almost always compare apples with oranges. For example, if a solar heating system is installed for a project, it will naturally raise the initial cost but, if you calculate how much it saves in the medium to long term, you will find that it doesn’t make sense not to fit it. Essentially, green buildings cost less in the long term.

Even as far as basic construction is concerned, green building costs can be made lower than for typical structures. This was amply demonstrated while building Kaya Kalp where, locally available, low-tech materials and labour were used.