Monthly Archives: February 2014

How to preserve the environment

Just as we ensure there is money in our bank account, we need to balance our account with the earth.

As the Green Sense series touches the magical number 200 with this essay, we have two choices – take it as a time for celebration or take it as a moment of introspection. We need to choose the second.

There is no rosy picture around us, nor is there a ray of hope for future, however optimistic we wish to be. Carbon dioxide in the atmosphere has crossed the mythical level of 400 parts per million, possibly leading to faster climate change.

At this rate, global increase in temperature between 1900 and 2100 A.D. could be around 2.0 degrees Celsius or even more. The 21{+s}{+t}century could witness a rise in global mean sea level up to 0. 98 metres. The decade from 2001 to 2010 has been the warmest ever since 1850, possibly making it the hottest since modern human civilisation came to stay.

The 19{+t}{+h}U.N. climate change conference held recently at Warsaw has not evolved any safe road map for the future of the world.

Grim facts

These grim facts may appear far fetched at the global level, making us feel they do not impact our daily life. On the contrary, it’s our daily life which has cumulatively resulted in the above scenario.

How do we ensure there is money in our bank accounts? It sounds like a silly question, for the simple answer any school kid can give would refer to depositing more money than what we withdraw. Every elderly family member advices the young ones not to take credit over drafts or loans that could be difficult to repay. To save the earth, we need to follow the same formula. We need to balance our account with the earth.

We should give back all that we take from Earth and if possible, give more than what we take – individually. Every person may not be able to do it every time, like the younger generation may consume more resources but as we age, we can live with less.

There is one whole life time to balance our resource and energy account with the Earth, finally to ensure we leave this place with eco-balance for our next generations and not loss.


The problems have reached such mega scale now that many are sceptic about what an individual can do. We can act in small ways, but a million immediately doable small actions can achieve more than one mega action, which often is not easy to implement.

We can plant trees, support animals, use less water, go low tech, donate money, do not invest surplus income for more returns, spend for societal causes, manage with basic gadgets, educate the young, live in villages, do volunteer service, do not buy the unwanted, refuse what we can live without, earn just enough for living, avoid luxuries, decline incentives – this list can go on with as many ideas as we can individually live with.

Sunlight ‘yes’, heat ‘no’

There are many ideas like tilting the building to best orientation, using materials with thermal mass or designing the type of opening which helps in mitigating heat due to solar radiation.

15HAB-greensens_15_1757152eIn climatology, heat and light are intrinsically linked. Blind belief in looks and sometimes in light has led people to have big windows, resulting in heated-up interiors. Incidentally, one major shift in Indian buildings has been from small wooden windows to large sheet glass windows, without considering why small openings were provided for centuries, nearly all over India.

In south India, light invariably brings in heat, due to its geographical location on the surface of Earth. The reference to region is very important, for it also dictates lifestyle, as in Europe requiring more indoor warmth than south India. Here sun moves along lower altitudes in winter, penetrating deeper into the buildings through the windows, letting in more direct light. The indoor temperature also rises which is welcome during winters. In contrast, during summer, we need to keep indoors cooler, and ensure that least direct light penetration happens into the indoors. The fact that sun moves at higher altitudes during summer helps in this direction. Incidentally, there are locations when sunlight and heat are undesirable round the year, for the winters are also pretty hot.

On an average, from 10 a.m. to 3 p.m., there is maximum heat gain through roof conduction and oblique light penetration through the windows. During other times, light and heat enter through wall openings more directly. Appropriate shading of openings using chajjas , staggered walls, fins, roof overhangs and such others need to be employed. On a daily calculation, maximum heat gain comes from the roof; hence it should be properly designed and treated.

Right direction

Northern light is both minimum and least heat, hence an ideal direction for openings. The eastern wall is comparatively safe though as day advances, light and heat may build up, but this heat dissipates during the day time. Properly designed sunshades can resolve majority of solar heat problems. The south orientation faces much of solar radiation; hence simple window top chajjas may not be sufficient.

Verandahs, vegetation, designed roof overhangs and such others are necessary. Among the problem fronts is the western façade, which receives solar energy during afternoon hours, heats up, conducts it inside and makes the indoor warm during the evening and night, just when we need to use them most.

There are many ideas like tilting the building to best orientation, using materials with thermal mass or designing the type of opening which help in mitigating heat due to solar radiation.


In urban contexts, it may be easier to employ skylights with adequate hot air vents. However, among the best to get light without heat is the idea of internal courtyard with minimal openings to outside – no glare, equal distribution of light and cross ventilation, all together. No wonder, our forefathers realised this and lived in courtyard houses. We need to modernise this concept for application today.

Get light, not the glare

Theoretically, direct sunlight on outside wall surface penetrates into the room up to 20 ft., adequate enough for normal reading and such room activities.

08HAB-greensens_08_1748209eSunlight has been such a commonly studied aspect of building design that much before Autodesk launched its software programme Ecotect or many free download applications got introduced, people judged it by common sense. While those with access to computers may study the impact of sun in a tech savvy way, the rest need to continue with traditional wisdom. Incidentally, this wisdom continues to be very valid.

The challenges of designing for sunlight in South India are not all that simple, for the best light angle may bring in worst heat or bright glare. The starting point is to keep the longer face of the building to face north and south, wherein north lets in soft diffused light and south invites ample direct light which may have to be adequately shaded. Trees, verandah, projected walls and such others help in softening the south light. The shorter elevation facing east invites much needed morning light and the shorter west facing wall gets angular afternoon light which is not very harsh.

This orientation also invites glare, especially the evening one that can be troubling. To reduce it, the windows can be slightly angled, vertical sunshades can be introduced or simply the openings can be avoided. The morning glare may not be so harsh and after 9 a.m., once the sun moves up, the glare can be managed with normal sunshade atop the window or minimal windows. The afternoon sun can brighten up the south sky so much, we may have to keep the curtains pulled, yet adequate diffused light may filter in.

Theoretically, direct sunlight on the outside wall surface penetrates into the room up to 20 ft., adequate enough for normal reading and such room activities. If the room has to be wider, say up to 40’, we need windows on both side walls to ensure good day light factor. Big and square plans should be avoided with preference for rectangular plans. However, there could be low light during cloudy days or when the sun is totally on one side. To help with more light, we can keep the total window area around 25 per cent of floor area, much higher than the suggested 15 per cent. Also, making the windows tall, taking them up to the roof, helps by letting deeper sunlight penetration.

Generally, bedrooms in the northern half, especially to east and west, are best to sleep — neither too bright light nor excessive heat. South-west provides good lighting for evening study, family interaction, home games and such others. It gets heated up to act as a heat sink during night hours. South-east gets good direct light during morning half and diffused light during the afternoons, making it suited for varied activities.

In compact city sites, it is not always possible to design for best light, for neighbouring buildings tend to shade each other. Also, designing for light may contradict the criteria for heat, rain or wind. As such, the better option is to accept some compromise, but get the better of all criteria.

Salute the sun, and build

Orientation of structures to bring in natural light and avoid glare and heat is crucial.

01bgp-greensens_01_1740129eAsk any elderly person from any village – what is among the most important criteria to be followed in locating a building? How would they decide the location of specific rooms? How are the windows positioned? We can ask many more questions, but to get one single answer – respect the directions of the sun.

Commonly termed as orientation, humans learnt the importance of effective orientations towards a good home possibly as the nomadic way of life gave way to settled life! Among the earliest principles of eco-friendly buildings to be discovered, orientation continues to be valid even today, helping those who follow the sun and punishing those who disregard it.

The exact location of the sun varies depending on the place and time of the year. Also, the height to which it rises and the angle it creates in comparison to the position of the earth is a matter of great implication.

All these data have now been precisely documented under solar charts, altitudes, azimuths, shadow angles and such others for each location on earth. We know that the sun not only brings in light, but also heat and glare; as such, solar heat gains, sky glare and other factors affecting their impacts on our buildings have been quantified to precision.

Technology helps

During the last few decades they were available in printed version, but now with the advent of computer applications varied kinds of softwares are available which assist in applying our knowledge of orientation to design better buildings.

From mere data for design incorporation to real time simulation exercises, today a building can be pre-checked for natural air, day light, window protection, shading patterns, sky glare, heat gain and such others.

Such advanced applications would of course demand guidance by experts with high-end equipment, which all of us cannot afford to have. Incidentally, IGBC, TERI, BEE and such institutions with all their knowledge of research and data also suggest orientation as a safe starting point for design.

Keeping such technological skills aside, there are many common sense approaches that could be applied on an everyday basis. Our past generations have been a large repository of time-tested knowledge systems which can take care of a majority of basic design sensibilities.

Stating this is not to negate the relevance or importance of modern research-based data, but only to admit that we can manage basic climate confirming designs just by being sensible to our contexts.