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.

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.

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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.
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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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