Monthly Archives: December 2012

Design with the sun in mind

The building plan must work with the sunlight, and locate spaces accordingly.

29bgpgreensense_29_1314171eRecently the Jantar Mantar, a solar and astronomical observatory at Jaipur built by Sawai Man Singh, made news by getting into the UNESCO World Heritage Sites list. Many parts of the ancient world boast of historic structures designed to calculate climatic data, wherein the sun dial finds a place. Even today, some science students prepare sun dials for annual school exhibitions. The elderly in a village predict the time of the day nearly correct without any wrist watch. Local and vernacular houses never opened a window to certain directions, and where possible the village streets followed specific orientations to ensure that the majority of houses faced fewer directions.

We are discussing a traditional knowledge system, centred around the Sun – a system which resulted in mind-boggling applications ranging from rituals to rhythms; cosmic studies to cultivation; design matters to social philosophy. There are many temples where sunlight is brought into the core of the structure on certain days of the year, calculated so precisely hundreds of years ago. People realised how to understand sunlight, and invite it or avoid it accordingly. With no mechanical or artificial modes, they evolved shelters which stayed cool during summers and warm during winters.

Well, the point here is not to simply praise our past, but to wonder where we have lost that knowledge. With a wealth of buildings behind us, why are we building such that we get roasted inside during the summers? The answer is simple – we have ignored designing with the Sun.

India being a tropical country gets a great share of sunlight, which can be directed judiciously into the building to get all the daylight we require. Nowadays there are many computer softwares like ‘ecotect’ that advice about sunlights and shades, while in the past there were climatic data tables with sun chart diagrams and solar angles. One can apply the simple formulae using the solar positions called as altitudes and azimuths to know the direct solar incidence on a window. According to such computerised or manual calculations, one can decide the location and type of shading required.

Our elders have already researched about summer solstice of June 21 and winter solstice of December 21 to enumerate how one fixed window or shading device does not work best round the year. As such the challenge is to ensure the building plan works with the sunlight, i.e. locating spaces accordingly. Rooms requiring light face the solar directions, while those which need less light are kept away. Also, rooms that can block the heat gain are placed to cut the unwanted solar light.

However, planning alone cannot provide all solutions of letting in light without heat. Shading becomes an essential mode of designing for sunlight, a mode that demands more of our attention.

Tackling sunlight

Eco-friendly architecture and green buildings depend largely on elevation design, and specifically window design.

22bgIt is a paradox. Without consumption of sunlight we cannot live; equally well, without protection from sunlight we cannot live. In a modern context, this apparent contradiction needs to be resolved by the design of windows, hence eco-friendly architecture and green buildings depend largely upon the elevation design in general, also called as façade treatment, and specifically window design.

Three parameters

If we search for the essentials of architecture as shelter making, we end with up three parameters. Shelter from heavy rain, protection from cold wind and shade from harsh sunlight. The first is served by the roof; the second by the walls; and the last by both roof and walls. Of course it would be a dark box if only roof and walls exist. As such, to let the required air and light, windows were installed by the early human settlers. They were small, being built into the building volume, hence naturally protected. Contrastingly, today windows are large, placed at the open edge of the wall, exposed to vagaries of nature, demanding adequate measures not to let rain in and stop direct sun into the building.

The chajja

Traditionally, most regions of India did not have the projection, nowadays called as concrete chajja. The sloping roof overhang was so deep, it would cover up the wall and window opening. Alternately, there would be a wooden bracket supporting the sloping sunshade over the windows. In case of flat roofs in hot arid regions, small stone slabs or sometimes an ornate window design as a box can be seen. The formal concrete slab projection as chajja appears to be a post-independence phenomena, further popularised by PWD norms. Irrespective of cardinal directions, sun movement patterns, degree of shading required, type of building or any such criteria, we have been adding this concrete slab over the window everywhere. Most often, we do not know how effective this shading device has been.

Incidentally, in dense urban housing areas, the chajja may also do more harm than benefit. With neighbouring building standing tall, the whole wall of a building can be shaded, ruling out the need of chajja shades. With narrow setbacks between two houses where no direct sunlight reaches the windows, the chajja would further reduce the incoming indirect light, making the houses darker. When a chajja faces the direct sun, the air around it heats up, which trends to enter the house, increasing the interior heat gain. There have been numerous cases where chajja becomes a point of water ingress.

All these above notes are not to negate the need for chajja; they are also needed for stopping rain, add elevation attraction or protect the wall from rain water flow along the surface.

The point is about designing studied and properly reasoned solutions for shading a building, without losing out on indoor light or air. Incidentally, all such climate responsive buildings have also to be attractive and culturally appropriate.

Don’t ignore the small details

We can do our small bit towards reducing material consumption and wastage and take baby steps towards eco-sensitivity.

15bgpgreensense_15_1299663eClimate is changing possibly faster than we change mobile phones; data on Green House Gas (GHG) emission is outnumbering population numbers; seminars and published papers on ecological themes could be doubling every six months and carbon is going to outwit politics as the common talk everywhere. All these phenomena express our growing tensions, where consumption is turning into concern.

However, not all of the concerns have turned into action, partly because majority of the talk focuses on mega solutions involving international policies, federal governments, large public initiatives and such others, where implementing is as Herculean a task as is achieving consensus. As if individuals cannot do much about the carbon emission.

Of course, as individuals we can also do our small bit towards reducing carbon, consumption and wastage, be it refusing plastic containers or simple alternatives of carrying our own needs. In the construction sector too, there can be many baby steps towards eco-sensitivity, however small they may appear. While major items like wall, floor or roof would make a major difference, small items too matter.

Spacing

Window grills can be a good case in point. There was a time when 10 mm diameter m.s. rods were welded six inches apart, a spacing evolved from the minimum gap needed for anyone, including a child, to slip through and this gap was safe enough. The rods were also felt to be strong enough. Slowly, the spacing became lesser, as if five inch is safer than six inch, where both the spacing are narrow enough anyway. Today it is common to see up to three inch spacing!

Simultaneously, the thickness of steel rod also increased from 10 to 12 mm, and the costlier hexagon shape started to replace the round and square. Logically if a thief can cut the 10 mm rod, cutting off an additional two mm will pose no major hurdles, given all the latest melting acids and cutting machines. Yet, we feel safer with thicker rods; as such we believe that they make better guard bars.

More consumption

The net effect is the traditional 10 mm rods at six inch spacing has now led to 12 mm rods at four inch spacing, nearly doubling the steel consumption, with only marginal increase in security. Breaking into houses by cutting the window rods simply continues.

The above narration should not be misunderstood as neglecting security, but as a case of non-judicious increase in material, possibly advocated by players in the fabrication and construction industry, to jack up the total budget. For a determined thief, grill is no deterrent. So, we need alternative security measures, not pumping more steel into the windows, turning the house into a cage.

A little time spent thinking about the logic of window grills and keeping it judicious, however small the action is, has its contribution. And so with all the design issues, if deeply thought over.

Off with the terrace room

Designing every area of the house correctly is a challenge.

dec8How does a good sense towards design evolve? What method facilitates the selection of most appropriate choice? This question should be baffling all of us, the designers, owners and the builders. The fact that we can change the design on the drawing sheet and cannot once it is built instill greater responsibility in us to decide what kind of buildings should get built on Earth. Both the question and the critical responsibility together should make us think over this overarching issue.

There could be varied approaches to achieve a saner end, but avoiding blind repetition of what our elders did could be the starting point. It does not mean we do whatever comes in a mindless way, but be in a position to look at the design challenge deeply, understand the context, analyse the options and then evolve an idea most suited. The issue of internal steps of a house reaching up to the terrace and having a staircase room there could be a case in point.

If we live in a tall building or own a house high up in the city, it is pretty sure that we take our guests up for a “view from the terrace”. But if there are no guests, let us count how often we walk up to the terrace.

For the majority, there is no regular use of the terrace with going there being an occasional activity, may be for checking the overhead tank or clean the rain water pipes. Yet we need to spend much money on the room; finish the walls and floors; provide a door and electrical connections. The invisible terrace door could also mean insecurity, where a thief can work on forcing open the door with no resident being aware of it. What if we could reach the terrace by other means?

External steel staircase

Let us imagine having a properly fabricated external steel staircase from any balcony or common family space of the last floor. It may cost one-fifth of the internal stairs and room; avoids the need for a security door; saves more space for internal activities; leaves the terrace open for gardening, partying or water harvesting and may enable having a skylight over the stairs, lighting up the whole house.

Of course, there are flip sides – need an umbrella to use the stairs when it rains; need alterations to add another floor with internal access etc., which upon little thinking do not appear to be major hurdles at all.

What about those who dry clothes on terrace or use it for some other regular purposes? The external stairs could be walked up by anyone at anytime, hence makes no difference.

Alternatively, following the analysis of the above kind, one may stay put with the conventional internal stairs and the room on the terrace!

Green Sense is not only about building materials and construction technology, but equally about common sense design.

For a low-cost seamless floor

While contemporary styles can make old-world flooring options disappear, mosaic tiles possibly continue to be worth the money, Mosaic floors are easy to repair and can be re-polished.

dec1Much before the world got globalised as we define it today, innumerable ideas were actually travelling across to many nations, in the true sense of becoming universal. Often one would forget where the concept and technology originated from, possibly an ideal state where something local becomes global, yet becomes local again wherever it went.

Mosaic floor is an ideal illustration for such a societal phenomena, which could be claimed as a routine practice by Chennai as well as China.

How it is done

It can be laid in situ , with a mix of cement, marble powder and stone chips. First a thin layer of the mix is spread to about an inch thickness, semi-cured and then the floor area is subdivided into 2’x2’ squares with glass strips.

The top surface, about half-inch thick, is laid with finer chips or coloured ones to the level of glass strips, which prevent possible cracks. Very thin mosaic floor cracks, while doing the total depth at one stretch does not enable adequate curing. The flooring is polished many times, to get the necessary shine and smoothness.

Pros and cons

Casting mosaic at site helps in getting a seamless finish, levels as needed and cleanly defined edges. But it is vulnerable to defects by workmanship, besides a few other problems like retention of micro pores or inadequate curing.

As such, factories started to produce pre-cast tiles with pouring, pressing, grinding and polishing to fixed standards. Good compaction by machines ensured long-lasting wear and tear quality; epoxies ensured tiles without internal pores; and multiple patterning became possible. Factories also produced tiles for specific applications such as staircase, light industrial use or restoration of heritage structures.

Tiles are heavy and require transportation, but can be laid to thin concealed joints at site with polishing as usual. While pre-polished glazed tiles are possible, in situ polishing is required to get proper levels where the slurry produced during polishing is a nuisance.

Longer life

Mosaic floors are easy to repair, by replacing the tiles. If faded over time, they can be re-polished to get a fresh appearance again. Tiles come with much higher compressive and impact strength compared to ceramic or vitrified, and guarantee longer life.

While localising mosaic production had an advantage, it led to lack of standardisation with many manufacturers ignoring quality of raw materials and hastening the production as a cost-cutting measure. No wonder, tiles were not taking good polish or chips were coming off too soon. However, many reputed companies in every city continue to produce good tiles.

In a big market setback, multi-storeyed buildings preferred the new age, light-weight, pre-finished options to reduce dead load, save on structural design and save on finishing time at site.

With multiple options for flooring today, mosaic may not be the best option in every context. Possibly as the flooring option in maximum demand until recently, mosaic tiles continue to be worth the money. Also, as a material with negligible wastage or pollution, it is worthy for ecological reasons.