Welcome to bT Square Peg

Based in Bombay (Mumbai) bT Square Peg has been creating sustainable designs in architecture & interiors since 1993.  The primary intention is to seamlessly blend practicality & timeless aesthetics with sustainability — the resources on this planet are not limitless.

design principle:
to seamlessly blend practicality, aesthetics & sustainability

Many designers care more about how the job will look in a magazine article—preferably the cover feature—than it does in reality. This often leads to homes and offices that look very dramatic in photographs but don’t necessarily work in practice. Equally, there are clients who fall into the trap of wanting to showcase the latest rage. Both approaches are wrong in my opinion.

The principle here is to keep in touch with current trends and materials without becoming a slave to transient fashions. Ultimately the objective is to create spaces that are—both physically and aesthetically—appealing to the inhabitants.

Featured Projects

[ShKo] Bungalow

Nasrapur, Karjat [2012-2015]

Courtyard and swimming tank seen through a brick jaliWith rooms arranged around an open court that has a swimming tank, this bungalow is the weekday home of a couple who come into the city mostly on weekends.

Instead of a typical compact layout, this house was designed as a series of spaces with clear public and private zones. When seen from a nearby hill, it looks like a cluster of three houses rather than just a single one.

Satya Health Resort

Vanjarwadi, Karjat [1999-2001]

Entrance aangan to a cottageNestled in a valley between the Matheran and Bhimashankar ranges, on a 50 acre (20 Hectares) piece of land, this is a resort with a difference. It was designed to have the look and feel of a typical Indian village.

The layout reflects the variable contours, with groups of ground-hugging cottages following the gradients. Some units are arranged in a cluster around a central courtyard, while others have individual aangans from which one enters them. Including the unpaved, covered, otlas behind them, each room has almost as much outdoor space as it does within.

Handloom Training Centre

Maheshwar, MP [1994-1996]

Entrance to Kaya KalpBuilt in the historical fort of Maheshwar — old capital of the Holkar kingdom is this training centre for handloom weavers. It was built using only locally available materials and labour, which brought the cost of construction down to a surprising Rs. 1,125/m² (about Rs. 105/square foot). Today that figure sounds almost unreal but, even at that time, it had worked out to approximately one-third of what a similar, concurrent project in the same town had cost.

The walls were made entirely of load-bearing brick with no reinforced concrete whatsoever, and the mortar used was a mixture of lime and cement.

Energy-Efficient Lighting

The incandescent bulb is the most common – and one of the least energy-efficient lighting options for brightening a space. Today we have numerous fluorescent type fittings; both, the old tubelight and modern compacts which retro-fit into incandescent holders. Light Emitting Diodes – LEDs – are rapidly getting cheaper and have now reached a level of affordability. The ways of lighting an interior or exterior space are numerous. We’ll touch on a few common ones here and see how they compare.


Apart from being free, studies have shown that natural light improves productivity and has significant health benefits compared to artificial light. Getting natural light into your home or office is not difficult to do – all it takes is a little planning by the architect at the design stage. It is necessary, of course, that the designer take care of glare and solar heat-gain but, once these factors are accounted for, there’s nothing better than sunshine to light up your life.

Unlike in Europe and North America, in peninsular India, light from the north-east is the best because it is glare-free. In fact, that’s why vastu stipulates that you put your study in that very corner of your house. Conversely, the south-west is where the glare is the worst, so it’s better to have shade giving trees to protect you on that side. If you are living in the extreme north of our country, however, where it is really cold in winter, you’d want to open out your southern side and achieve some heat gain. For the rest of us, reflected and indirect light is the best.

The mechanics of day lighting are more complicated and will, time-willing, have a page of their own but suffice to say that every architect should try to achieve adequate lighting without building up heat inside the building.

Tube Lights

Tubelights have been around for a while and, because of the harsh light they gave off in their early days, there are numerous people who detest their very existence. But tubelights are efficient and their colour temperature has improved dramatically in recent times which makes them as comfortable to use, if not more so, than an ordinary bulb.

Tubelights have a long life and their drawback, if any, it is that they require a bit of extra energy to start up. Newer electronic chokes have reduced this surge but it’s still often better to leave a tubeliight on than to turn it off and then re-start it within a few minutes.

Compact Fluorescent Lights (CFLs)

CFLs are the new tubelights – they have been squeezed and twisted so that they can replace ordinary bulbs. And they should! CFLs consume just 25% of the energy that a bulb does and are available in “soft white” which is easy on the eyes. Granted, they cost more, but the energy saved is more than paid back during its life which is 10 times as long as a bulb.


LEDs or Light Emitting Diodes are extremely energy efficient and should last for at least 10 years of continuous usage. They are becoming cheaper as production ramps up and the technology improves. They are still expensive when compared to the other forms of lighting but, as the comparison shows, that cost is more than paid back in the long term.

Efficiency Shootout

Here is a comparison that tells you approximately how much you benefit by installing fluorescent fittings or LEDs in place of incandescent ones. Note that the figures are approximate and likely to change as time goes by.

Cost Comparison over 10,000 hrs Usage Bulb CFL Tube LED
(a) Life of single bulb/tube (hrs) 1,000 10,000 2,000 25,000
(b) Number of bulbs/tubes required Nos. 10 1 5 1
(c) Cost of each bulb/tube (₹) 10 200 100 350
(d) Total cost of bulbs/tubes [(b) x (c)] (₹) 100 200 500 350
(e) Light Output [lumens per watt] (lm/W) 15 60 75 90
(f) Power requirement [equivalent to 100W bulb] (W) 100 25 20 15
(g) Electricity consumed (kWh) 1,000 250 200 150
(h) Running Cost [@ Rs. 5/kWh] (₹) 5,000 1,250 1,000 750
(i) Overall Cost [(d) + (h)] (₹) 5,100 1,450 1,200 1100
(j) Saving compared to ordinary bulb (₹) NA 3,650 3,900 4,000

As you can see, we can no longer say that the ordinary tubelight is still king. LEDs have a rated life of 25,000 hours although the drivers (transformers) will only last for half as long.  Like the new fluorescent fittings, they are usually available at colour temperatures that closely resembles daylight.

External Links

Philips India Lighting
Osram India
Havells Lighting
GE Asia Pacific


If you are the manufacturer/dealer of any product that you feel is appropriate for this page, please fill this form stating clearly what exactly makes your product green/sustainable.

Please note that Greenwashing will not get you anywhere and inclusion of the product is not guaranteed and is entirely at our discretion.

Glass Curtain Walls


Glass curtain walls and façades, seen as signs of modernity & progress, are inappropriate for our tropical climate.

Unfortunately, there is a strong trend in India these days towards designing building with glass curtain walls. These are seen as making a break from the bad old days when we were perennially short of power and couldn’t afford to run air-conditioning to keep ourselves cool. Well, I have some news for people with this view — we’re still perennially short of power and cannot afford to run so much air-conditioning.

Our country has a huge shortfall of electric power and that’s not going to change any time soon — at least not unless we suddenly manage to generate power from cold-fusion. In the meanwhile, huge quantities of fossil fuel will continue to be burned thereby exacerbating climate change and making things even worse for everybody and their pet dog.

Glass curtain-wall buildings are inappropriate for our climate for two reasons:

  1. Having a glass skin means that the inside is subjected to an enhanced greenhouse effect. Glass easily allows short wavelength light to pass through. Once this light has reflected off objects in the room, is of a longer wavelength which glass blocks. As a result, the internal temperature of the building builds up because the heat has now been trapped.
  2. This trapped heat has, somehow, to be expelled and – since there is never any significant natural ventilation in a glass building – this calls for massive (and environmentally expensive) air-conditioning. Let us not also forget that living and working in permanently enclosed spaces leads what is known as “sick building syndrome”.

Heat-reducing glass is like a pick-pocket returning your empty wallet.

Glass manufacturers will claim that their specialised products reduce heat build-up by 30%-40%. What they don’t tell you that not having a glass wall in the first place will reduce your heat-gain by twice that amount!

Another specious argument put forth is that using glass walls reduces the usage of electricity for lighting. Again, this is half-truth. Let us, for a moment, leave aside the amount of glare that people working inside such buildings have to put up with.

Consider a 10m² space.  Under normal circumstances, the air-conditioning load would be about 3,500W (or 2,500kW if you’re using a highly efficient HVAC system).  Lighting the space needs less than 100W if you’re using fluorescent lights and even less if you’re using LED fittings.

Now, the maximum saving you can achieve in lighting is 100W. On the other hand, your HVAC energy requirements will increase exponentially.  Even if expensive special glass is used, I’m afraid no amount of mathematical spin can bury this simple fact.

There are other aspects too, although unrelated to energy consumption. Migratory birds get confused by the glass and often die or sustain critical injuries when they slam against the huge transparent panes.

Further, if you happen to be in a glass building during a fire, there is no scope for ventilation so you asphyxiate–unless the glass curtain wall shatters, thereby endangering both, you and your rescuers from the fire department.


We can easily save energy and reduce our energy consumption by taking a few simple steps. Most are not too expensive and they pay back fairly quickly.

Solar Hot Water

It’s one of the cheapest and simplest ways to save a huge amount of energy and the payback period is pretty short. The panels to be installed are basic and require very little maintenance. Essentially, the technology consists of nothing but copper pipes which zigzag behind a glass pane and heat the water that runs through them. This water is stored in an insulated tank so that if you wake up at the crack of dawn and try to have a bath, there’ll probably be some warm water for you to use. That’s if you didn’t use it up the previous night.
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Passive Cooling in Tropical Climates

For centuries, until the invention of electricity, architects simply had to take into account the ways of the weather so that the interior of a home or workplace was comfortable for its tenants. In India, it led to the development of the Vastu Shastras – an ancient science that has now been obfuscated into a first class superstition… But that’s another story.
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Energy-Efficient Lighting

The incandescent bulb is the most common – and one of the most wasteful – ways of lighting a space. Today we have numerous fluorescent type fittings; both, the old tubelight as well as modern compacts which retro-fit into incandescent holders. Light Emitting Diodes – LEDs are rapidly getting cheaper and have now reached a level of affordability.
Continue Reading →

Star Rated Equipment

India’s Bureau of Energy Efficiency (BEE) has created a system of energy rating for a large range of appliances, equipment and light fixtures. Air-conditioners are, of course, the biggest guzzlers here and, while the initial expense is high if you choose, say, an inverter type, consistent use over time will more than offset the cost. BEE has created an interactive Energy Calculator to tell you how much you would save for different ratings of air conditioners.

Glass Façades in Tropical Climates

In our country today, glass-walled buildings are looked upon as indicative of progress and modernity and an international aesthetic. But the fallout of using such climatically inappropriate designs, is soaring energy consumption and sick-building syndrome.
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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]


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.

Energy Calculator for Air-Conditioners in India

More and more people are installing air-conditioners in their homes these days thanks in large part to the concrete hot-boxes being constructed in our cities and the heat-island effect. Added to that is the fact that many commercial buildings have senseless glass façades – which makes them even-hotter-boxes. Net result: the amount of energy being consumed in urban areas is rising at an alarming rate.  The archaically-named Bureau of Energy Efficiency or BEE has been more proactive than many other government agencies in trying to make a change in this regard.  They’ve created mandatory star ratings for refrigerators, fluorescent lamps and air-conditioners and voluntary ratings for other appliances like fans and geysers.

They’ve also created an associated site with a great energy calculator that you can use to check how much money you would save by using air-conditioners with higher star ratings.  I’ve seen similar calculators on the net that cater to the USA or Europe but it’s great to have one that is valid for us in India. It basically tells you how many rupees you would save based on your usage and on city you live in. At this time, there are 17 major Indian cities in the list and, if you can’t find your own, look for one that has a similar climate and temperature range.  You must remember that such calculators make lots of assumptions so while they should give you a fairly accurate idea, don’t expect that figures to be 100% accurate.

The site also has some basic tips on saving energy and I feel that BEE should make calculators for other appliances as well – especially light fittings and fans.

Now if only they’d remove that asinine piggy-bank mascot…

“Windancer” Windmills Have Some Great Features

With their windmills starting rotation in breeze as light as 1m/s, Wind Simplicity’s designs would be great for many parts of India that are not on the conventional wind-map. They are built to withstand snow and ice – not problems we face every day in our tropical climate!  Now if only some Indian manufacturer would tie up with them to make these in India…

Edit: The website <http://www.windsimplicity.ca/> doesn’t seem to be working any longer but here is the archived page in case you’re still interested.

Solar Powered Air Conditioners Released

This is the ideal air conditioner – the hotter the sun gets the better the a/c works. Still, there have been drawbacks that made such machines non-viable. Now, a company called GreenCore Air has released a hybrid unit that claims to have solved the inefficiency problem.

Go to :: GreenCore The website has been squatted upon.  Try this company instead.
via :: MetaEfficient

World’s Largest (proposed) Solar Energy Project

The Clinton Foundation is talking to the Gujarat Government to set up a “solar city” project that will eventually generate 5 gigawatts of power. Talks are also on with the Andhra Pradesh and Rajasthan for setting up solar energy projects.

Now we can only hope that the Great Indian Bureaucracy doesn’t kill this initiative…

Full Article :: Business Standard via :: TreeHugger

Fiber Optics for Accent Lighting

C|NET reports that a company based in Ohio, USA has created interior lighting systems that consume just one-third the energy compared to the average fluorescent system. In addition, it is said to emit neither heat nor UV light and won’t leak mercury if broken. Although the systems are expensive at the moment, they are expected to become affordable in the near future.

Okay, let’s be clear about how it works. What the system does is that it takes light from a conventional source – say an incandescent or a metal halide and distributes it via flexible plastic cables with optical fibre inside. This light is transferred to numerous “bulbs” which are naturally highly efficient given that there is no emission of heat at all.

Edit [27.09.2015]
The site <http://www.fiberstarspoolandspa.com> seems to have disappeared. Here’s a link to the most recently cached version of the site on Wayback Machine.