Planting for Nature

The lives of birds and insects are so closely intertwined that you’re unlikely to have one without the other and both are extremely dependent on plants for shelter and sustenance. In nature, nothing works in isolation so, if you want to attract what are generally considered “beautiful creatures” to your garden, you have to be willing to accept the less popular ones. If you want butterflies, you will also have caterpillars and if you want birds you have to be willing to accept all manner of insects – some of which will attack your plants.

Despite that, it is extremely important to avoid chemical pesticides and fertilisers that will either kill them or drive them away. Unlike plants that are able to selectively repel certain types of creatures, man-made chemicals are less discriminating. Instead, if you want to keep the caterpillars (and other plant-eating insects) in check, make sure your garden also attracts birds. Butterflies and their caterpillars are themselves food for many birds and if the garden isn’t attractive to birds, the caterpillars will eat everything in sight. It’s just part of the balance of nature.

This page gives a list of trees and shrubs that you could plant to attract both, birds and butterflies. I have not given separate lists because the two of them pretty much sail and sink together.

Ways to Attract Butterflies

Creating a garden that consistently attracts butterflies is not all that difficult. You don’t necessarily need a lot of space – although that naturally helps – but you will need to learn a bit about these beautiful creatures before you begin. What this page will give you, is only a primer to start you off because the species of butterflies found in different parts of our country vary quite dramatically.

The first thing you need to provide if you want to attract these beautiful creatures to your garden, is a habitat they can be comfortable with. This means planting everything from dense shrubs that shelter them from predators and rain to tall trees (which some of the larger butterflies frequent in an activity known as “tree-topping”) while also leaving open space for them to bask close to the ground. Being cold-blooded insects, they need to warm their wings in the sun before they can take flight in the morning.

The second thing you need to do is bribe them outright! Many (though by no means all) adult butterflies feed on the nectar of flowers. In doing so, they act as couriers for the pollen grains that stick to their bodies, thereby helping in pollination making it a symbiotic relationship. By and large, butterflies prefer to visit multiple small florets as opposed to single large flowers so you might want to look for plants that have these characteristics. It is helpful to have a variety of plants so that their different flowering seasons ensure availability of nectar through the year.

The third important thing that most people don’t realise is that it is not enough to merely attract the adults; if you want their continued presence, you must provide for their young as well. Caterpillars (and here’s something you might not know) are very specific about the plant they feed on. Caterpillars of any given butterfly species will only feed on a single plant species or sometimes a bunch of related plant species. For instance, many of the smaller lycanid caterpillars will only feed on grasses while, say, a tiger butterfly will hunt for a certain milkweed (Calotropis) on which to lay her eggs – and a Red Pierrot caterpillar will restrict itself to the fleshy leaf of Bryophyllum. Put the red pierrot caterpillar on a tree full of juicy green leaves and it will simply die of starvation.

One more thing that is easily provided and will attract a lot of male butterflies during the dry months is a patch of damp earth. Males flock to such patches for “mud-puddling” wherein they get salts and other nutrients from the soil which they need to be considered eligible by the females. And if you really start getting addicted to butterflies, you can also bait some species with rotten and fermenting fruit; the little alcoholics will simply love you!

How to Attract Birds

Like butterflies, birds also require a variety of plant types to make them visit your garden. Some birds like thrushes and babblers prefer to forage in the shade, Sunbirds go to nectar-rich flowers while parakeets and Barbets want to get at fruits and seeds that are usually found in the larger trees like the fig. One therefore needs to plant a tiered garden with patches of sunlight on the one hand and dense shade on the other. Also, birds usually prefer local vegetation so keep that in mind when you do your plantation.

Install a bird-bath. It’s not very difficult to make and as long as you don’t have cats as pets (or neighbours), the birds will give you hours of enjoyment. There are numerous pages on the internet that explain how to make a birdbath. Just one thing to remember is that if you leave the water stagnant, you will be breeding mosquitoes – not a pleasant thing.

The trees you plant should be dense and shade-giving. These will give great shelter for roosting or even nesting. And if they happen to be fruit-bearing, that is even better. Bushes, especially flowering ones, should be planted around the trees in clusters instead of scattered all over the place.

As with any nature-friendly place, you should avoid (or at least minimise) the use of chemical fertilisers and pesticides. Pesticides will eliminate a broad range of insects and spiders some of which you may not be very keen on but which are extremely attractive to our feathered friends. A garden devoid of insects will get very few birds visiting especially during the nesting season when they’re foraging for their young. Nothing exists in isolation in nature and if you want to look at pretty creatures, you’ll have to learn to look at and enjoy the ones that aren’t as popular.

Appropriate Plantation

There is a raging debate among naturalists about the desirability of cultivating exotic plant species and there are no easy answers. My own view is that we should try our best to avoid introducing any new species into an existing ecosystem but there is no need to get worked into a froth if a species has naturalised over a substantial period of time. Yes, there are places where exotic species have become very invasive at the cost of the local varieties and there may be a case for culling them – but such a discussion is beyond the scope of this article. Instead, we are going to focus on the use of exotic and native species in the context of what is appropriate landscape architecture in a predominantly hot country like India.

Improving Comfort Levels

Trees are often the first line of defence when it comes to passive cooling of a bungalow or other low-rise structure. They provide shade which prevents the build-up of heat not only on the ground but also on the walls of the building. Shade on the ground means the breeze coming in through your window is cooler and shade on the walls means less heat gets transferred indoors. Aside from shading, trees also cool by transpiration to the extent that they can, if properly located, reduce ambient temperatures by as much as 5° compared to the surroundings.

So what kind of trees should we plant, and where?

While the finer details vary across different parts of the country, broadly it is safe to say that the hottest sides are the South and West so, if you can concentrate on protecting these directions with dense evergreens, you’re good to go. On the East, you might want to have high-branching trees that won’t block your early morning sun and on the North – depending on whether you get direct sunlight penetration or not – you could grow colourful, possibly deciduous trees. You have to be careful during plantation that you leave enough distance between the tree and your foundation because many of the large trees have strong spreading roots.

Trees, even in urban areas (albeit to a lesser extent), are part of an ecosystem and need to treated at as such. If they are native, they will invariably be well integrated into that ecosystem along with the local fauna like the birds and butterflies. An introduced plant is unlikely to be so well assimilated and may therefore not contribute in a positive way. There are plants that have been naturalised over a long period of time but I’m referring to those that have been introduced because they are ornamental or because they grow rapidly. Usually the ornamental ones are fragile and drop their branches on your head at the beginning of the monsoon and the fast-growing varieties with their short life-spans often sap the soil so severely that nothing else grows there for years after they’re gone.

Usage of Water

This is a very important factor to take into consideration especially if you’re thinking of sustainable landscaping. Many ornamental trees and bushes are extremely high-maintenance and don’t even get me started on lawns. They may look very pleasing to the eye but, with few exceptions, they guzzle frightening amounts of water and are often heavily sprayed with chemical pesticides — which naturally leech into the groundwater.

Here, a very important argument for using native species is that they will, by default, survive with the naturally available moisture and precipitation. Of course they may need some amount of watering when they are saplings as also during the hot summer months but, in general, their water requirements are a small when compared to exotic ornamentals.

Rational Vastu 2.0

This book is free to read, download & shareAs an Architect, I have often been confronted by my clients’ blind faith in the Vastu Shastras — the ancient building code of India. At first, I dismissed it out of hand; but the trend refused to die. Finally, I decided to take a closer look at this phenomenon, hoping to gather enough evidence against it.

To my surprise, I found that when seen in totality, it conflicted very little with my professional training. The Vastu Shastras are, basically, rules for holistic architecture. However, that is only the good news.


Icon
Rational Vastu 2.0 | The Science of Sustainability

The scientific basis of the Vastu Shastras has been reduced to mere superstition by self-styled experts

The bad news is that it has been turned into a monster of superstition by a number of so-called experts. They have crawled out of the woodwork to make a very fast buck by preying on people’s insecurities.

This booklet was written because the non-professional has no way of understanding the first thing about these ancient texts. It explains in simple terms, the origins and meaning of the Vastu Shastras.

While this book is not intended to be a comprehensive encyclopaedia on the subject, a thinking person will quickly learn to differentiate between the genuine code and outright superstition.


CC | BY-NC-NDThis book is distributed under a Creative Commons License v.3.0 and you may distribute it freely provided that it is non-commercial, unmodified, and attributed to the author.

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.


Recycling Water

Apart from saving fresh water there are also some ways of reusing and recycling water so as to reduce our requirement. The technology for this could be hi-tech, like a filtration plant, for example but we will concentrate on basic low-cost solutions here.

Grey Water for Flushing

When we bathe, wash our hands, wash our clothes or get the house swabbed, the discharge that goes into the drain is known as ‘grey’ water (as opposed to ‘black’ water from the toilet). Grey water is sometimes soapy and sometimes contains large amounts of dirt. On occasion, it may have a slight smell but, on the whole, it harbours no harmful pathogens.

This grey water requires only a minimal amount of treatment before it is good enough to use again. You may not want to drink it or even bathe with it but, in fact, you don’t have to come in contact with it at all. You can simply reuse it for flushing.

Apart from reducing your water consumption by almost 50%, if you have a septic tank, re-using grey water has an additional side-benefit that the black water no longer gets diluted by the grey water and, as a result, decomposes more efficiently. Even if you don’t want to build a separate treatment section for grey water, the least you can do is put it into your plants.

Reuse Water for Landscaping

The discharge from your kitchen, bath and washing machine is not harmful to plants so, if you have your own garden, you can always release this water almost directly. In case the food you eat is relatively oily, it might be necessary to install a small grease-trap to take first remove grease from the kitchen waste.

I know someone in the city of Pune who, for years, has released grey water from the kitchen and bathrooms of his bungalow straight into a clump of lush Papaya trees. I asked him pointedly about the chemicals in the soap etc. and he just laughed. He is, by the way, an graduate in agriculture so I guess he knows what he’s laughing about.

The explanation is this: chemicals in detergents and cleaning agents are considered bad because they promote the growth of algae. In fresh water, algae deplete the oxygen which, in turn, kills the fish and other fauna there. But these same chemicals – among them phosphates – also act as growth promoters for trees and are, therefore, excellent for landscaping.

Sewage Treatment

Section to be added…

External Links

To be Added


More

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.

Saving Water

There are literally thousands of sites on the internet which will show you ways of saving water. Some boast of having the 100 best tips while others give you five; but almost all of them are useless to us here in India. We don’t clean our cars with a hosepipe (we pay a cleaning ‘boy’ who uses a tiny bucket with a mop) and we don’t water our lawns every week – we don’t usually have lawns to water in the first place. So, on this page, let us not go on about obvious things like “don’t keep the tap running when you brush your teeth”. Let us look at systemic solutions instead, this is an architectural website, after all.

Low-flow Taps and Showers

From an average shower head, the flow averages 8 to 10 litres each minute. So for every 10 minutes of showering, you use between 80 and 100 litres of water. With a bucket, on the other hand, you are likely to average around 15 litres. That is a huge difference and for people who dislike using a bucket, a huge weight on their conscience – or so I would like to believe.

Similarly, though on a smaller scale, when we run a tap, we tend to use more than we really need; but fiddling with a mug while you’re rushing to shave in the morning can be difficult. So we have to look for some other solution to this problem.

If you are willing to, you can simply change the shower-heads and taps to ones that allow a lot less water through. They are classified as ‘low-flow’ and are still quite a rarity in India. They have a design that aerates the water so that although it feels like a good flow, a lot less water is actually consumed. At the same time, the apertures through which the water passes are kept tiny so that the water is forced through and hits you with the same force as a full-flow shower or tap.

Low-flow showers use about 3-5 litres/minute so a 10 minute shower now costs you 35 litres instead of, the average 90 – a saving of 55 litres. Low-flow taps (don’t forget the kitchen sink!) save at least 15 litres per person each day.

If you think that is not much, remember that you save over 25,000 litres every year. Per person! For a family of 4, that’s more than one lakh litres! And if you’re willing to go the bucket and mug route for your bath, you – as an individual – will save almost 30,000 litres per annum.

For the record a lot of people absolutely hate low-flow fittings. In fact there are people who complain that even normal showers flow too slowly for their liking and they actually install on-line pumps to increase the water pressure. If you are one of these people, I know you are going to say that just one person makes no difference. Ummm… Twenty Five Thousand Litres is no difference? Really?

Dual Flushes

Another major way to save water is by changing your flushing system. A normal flush uses 10 litres each time – regardless of whether the bowl contains 100ml of urine or the sum and substance of your latest bout of diarrhoea. On an average day, a person goes for a big job a couple of times and urinates about eight times. With a normal flush, that means you send 100 litres down the drain in 24 hours.

Dual flush systems allow you to choose whether you want a full flush (usually ~5 litres) or just half (~2.5 litres).

Eight urinations + two big jobs:
Grand total for the day : (5×2)+(2.5×8) = 30 litres
That is a saving of a whopping 70 litres which totals 25,550 litres each year. Knock off the 550 litres for all those times when your spouse/parent/teenage offspring complains that “it did not flush properly the first time” and round off the figure to 25k. Not bad, what?

It is a common misconception that such flushes don’t do a good job with the big job. What determines whether the stuff goes away quietly is not so much the amount of water as the design of the toilet bowl itself. Attaching a low-flow cistern to a potty that was designed for twice as much water is not necessarily going to give you good results.

Almost all the major sanitary ware companies make dual flush tanks with matching WCs. Also, recent municipal rules, at least in Bombay (Mumbai), insist that only dual-flush cisterns may be used in all new construction. Some manufacturer links are at the bottom of the page.

Stop that Leak!

Little drops of water make the mighty oceans. If you let all your taps leak all day long for the rest of your life, you would still be unable to fill the Pacific. But you could, very well, fill a large lake. A tap that leaks just a single drop every second, wastes almost 12,000 litres each year. That means throwing away approximately half as much water as you could save by changing your flush tank or by installing low-flow taps and showers.

Do you have a dripping tap? Try the American Water Works Association’s drip calculator to see how much you’re really wasting.

Not getting leaky taps fixed is usually nothing more than laziness on our part because we don’t realise the extent of the problem. That excuse no longer washes, so if you are not handy with a wrench, go call that plumber. And place a bucket under the tap while you wait for his highness.

Choose your Appliances Wisely

Washing machines and dishwashers consume water that would otherwise be used to manually clean your clothes and dishes. While the latter are still relatively uncommon in India, the former are found in most urban homes. So what should you look for when you go to buy one? Aesthetics?

A friend recently wanted a new washing machine that consumed the least possible water. We went to a reputable store that has branches all over town. After looking around, it boiled down to two front-loading machines – let us call them ‘E’ (for a famous European brand) and ‘A’ (an equally famous East Asian company). Front-loaders, by the way, are far more water efficient than top-loaders.

Anyway, we naturally asked the salesperson which model used less water. He hesitated just a fraction and then told us that ‘E’ used 90 litres on a full load while ‘A’ used only 60 litres. This I found surprising because I already had an ‘E’ that used only 49 litres and I mentioned this to the salesman. The latter was adamant and it led to a bit of an argument until we asked him to bring us the technical specifications for both models.

It turned out that ‘E’ does use 49 litres on a full load and ‘A’ uses around 55 litres for the same full load. The point I am trying to make here is that salespeople are usually not trained to answer questions like water consumption and most are not trained to say “I don’t know but let me find out” either. So do not believe what you are told – ask for the printed specifications.

So, Will You?

You can see that the overall saving for a normal user can be anything between 25,000 and 50,000 litres each year. Of course, it will cost you a few thousand rupees and, because water is subsidised in India, you may not recover the financial investment for quite a while. But think of the environmental benefits. You must be concerned; you would not be reading this page otherwise. Fifty Thousand Litres. And that’s just from one person. Go ahead. Make the change. You won’t regret it.

Oh, and if you are seriously thinking of water harvesting then this will actually translate into a lot of money because the cost of storage tanks will immediately drop by almost half.

External Links

Cera Sanitaryware, India
Hindustan Sanitaryware, India
Kohler Sanitaryware, India
Water-saving showerheads. US site
Drip Calculator


More

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.

Water

In the future, wars will be fought over water, not oil.

Many eminent thinkers have predicted that future wars will be fought not over oil but, over water because our access to clean, potable water is threatened by industrialisation, pollution and our own profligacy. Most of us, especially urban folk, just don’t seem to value it enough; after all, it just takes the twist of a tap to turn it on. For the rural woman who spends a major part of her day trying to get a few pots of water for her family’s drinking, bathing and cooking requirements, it is very precious commodity indeed.

There are many, many things we can do to alleviate this situation and, if we don’t act on it immediately, all the doomsday predictions may very well be fulfilled. It may look like we have a mountain to climb, but if we take it one step at a time, it’s not that hard.

Saving Water

There are many ways to skin a cat. The Internet will give you a thousand ways to save water – some practical, some not so. Here are a few from an architectural point of view.
Continue Reading →

Recycling Water

It’s not just enough to reduce our consumption of this precious resource. What we do use, can – to a large extent – be recycled very easily.
Continue Reading →

Harvesting Rainwater

We have a mountain to climb, but if we take it one step at a time, it’s really not that hard.

A lot of people are thoroughly confused after reading half-baked media articles on Rainwater Harvesting (RWH) and most, as a consequence, dismiss it as an impractical fantasy. Not true. RWH will soon prove to be the only way forward in most cities.
Continue Reading →

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.

Daylight

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

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


More

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_Façade

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.

Passive Cooling in Tropical Climates

Passive cooling In tropical climates can be achieved by intelligent architectural design.In tropical climates, it’s important to keep the interior of a building cool and it is known as “passive cooling” because the reliance on “active” or mechanical means (air-conditioning) is kept to a minimum. In most parts of India, it is wise to keep direct sun away from the interiors of the building especially during the hot months. Allowing direct egress and glare leads to a build-up of heat and discomfort. This can be avoided by having deep roof overhangs and chajjas. Other methods of passive cooling depend on the local climatic factors.

Thermal Mass

In extreme climates which are usually also dry, you want to insulate yourself from the elements. For example in parts of Madhya Pradesh and Rajasthan, a hot and sand-laden wind (known as loo) is common in May. Under such circumstances, cross ventilation is something that you desperately want to avoid. In places like this, the openings are kept small and the walls are made so thick that by the time the heat manages to penetrate, the day is more or less over. Also, if you look at the local architecture, you will notice that all the structures are huddled together as if protecting each other from their harsh surroundings; which is, in fact, exactly what they’re doing.

Sun Studies

Sun Study

With the advent of computers and advanced software, what was once a tedious and error-prone manual procedure can now be completed by pressing a button. Sun studies help immensely in determining where and when sunlight enters a building, allowing the architect to accurately design awnings, verandahs and roof overhangs and even help in the placement of large trees which can provide shade.

The animation above was created using ArchiCAD – a parametric architectural package which is excellent, not only because one can design directly in 3D but, also, because it automatically calculates shadows for a given structure at any chosen date and time.

Cross Ventilation

In humid places like the coastal areas of our country, comfort is achieved by having air flowing over your skin; evaporating the sweat and cooling your body. For this, it is advisable to have large openings in the building’s envelope. However, deep overhangs need to be used to minimise direct entry of sunlight (read: heat) otherwise you’ll have hot air blowing over you, which pretty much defeats the purpose of the exercise, doesn’t it?

Clerestory windows help hot air escape

High-level clerestory windows help hot air escape

In addition, openings can be strategically placed to allow the heat to escape. In a single-storey house, high-level or clerestory windows allow hot air to escape and thus generate circulation even when there is very little natural breeze.

Another way to set up a stack effect is to install a wind-driven roof vent. They need no electricity to run and spin based on the difference between outside and inside temperature – the hotter it is outside, the faster they go. They can be purchased from:

Wind Vent :: Tamil Nadu
FlexiTuff Industries :: Maharashtra


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