9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 1/10

Posted by rajeshkav

Sathya Consultants

Blog Archives

For thermal comfort

JAN 5

Knowing daylight and shadow patterns round the year is helpful, and common sense observation can bethe starting point for understanding light and shade balance in buildings.

Often we see design ideas going through a paradigm shift, nearly to the opposite ends. To realisethis phenomena, look at this — from the past practice of building for shade inside the

(http://sathyaconsultants.files.wordpress.com/2013/01/jan5.jpg)house and outside on the walls,today we are seeing buildings washed with light everywhere. Accordingly, windows on the wallshave become larger, external walls are exposed to direct sunlight and skylights have beenintroduced.

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 2/10

Leave a Comment

While the theory of light is desirable, the resultant heat built-up is a nuisance no one can live with,hence the need for ideas to shade the building. From an eco-friendly perspective, the more shadedthe building, the more cool would be the inside space. In case of air-conditioned structures, thiswould reduce energy needs; and if not, we achieve more effective passive cooling.

Emergence of chajjas

During the early years of modern architecture in India, simple projected chajjas were introduced.Most people think they are mainly for rain, which is not true. As shading devices, though withoutspecific considerations of direction, depth of projection and materiality, they continue to be popularin India.

Thinking architects like Le Corbusier experimented with alternative forms, and came out withspecially inclined concrete walls outside the window, often called as Brise Soleil. Much before him,the Golconda building at Pondicherry had a series of horizontal concrete fins. Such external skinsplaced closely to the walls allow wind movement and let in diffused light from the bright tropicalsun but prevent direct solar radiation into indoor spaces.

Indian traditional designs did not use an external skin, but provided deep overhangs like atFatehpur Sikri or built external walls as perforated jaalis to reduce heat built-up as found inJaisalmer. Or positioned wooden louver-based features as walls as seen in the PadmanabhapuramPalace. Of course these are among the best examples we get, with thousands of variations with lessereffect commonly found all over our country.

Solar charts

While all the above measures are valid and much needed, our data base for ensuring shade hasdrastically improved over the years. For every region now there are solar charts – specificallylocating the sun in technical terms like altitude and azimuth for any given minute of the year.

It is possible today to calculate the exact pattern of shade for any given time using manual formulaeor computer simulated software driven programmes. These measures assist in designing the shadingdevice to derive increased shade in summer and increased sunlight penetration in winter. Indiabeing in the southern hemisphere with high summer sun and low winter sun is a difficult place todesign for, considering our vast geographical extent and regional diversities.

No single solution can serve year-round needs; hence we need to think judiciously to derivemaximum benefits across the seasons. While computer software can help, common senseobservation and following the right kind of precedence can be the starting point towards a buildingwhere light and shade are balanced.

Posted in designs, fundamentals

Tags: chajja, design, light

Tackling sunlight

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 3/10

Posted by rajeshkavDEC 22

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

(http://sathyaconsultants.wordpress.com/2012/12/22/tackling-sunlight/22bg/)It is a paradox.Without consumption of sunlight we cannot live; equally well, without protection from sunlight wecannot live. In a modern context, this apparent contradiction needs to be resolved by the design ofwindows, hence eco-friendly architecture and green buildings depend largely upon the elevationdesign 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 isserved by the roof; the second by the walls; and the last by both roof and walls. Of course it wouldbe a dark box if only roof and walls exist. As such, to let the required air and light, windows wereinstalled by the early human settlers. They were small, being built into the building volume, hencenaturally 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 suninto 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. Incase of flat roofs in hot arid regions, small stone slabs or sometimes an ornate window design as abox can be seen. The formal concrete slab projection as chajja appears to be a post-independencephenomena, further popularised by PWD norms. Irrespective of cardinal directions, sun movementpatterns, degree of shading required, type of building or any such criteria, we have been adding thisconcrete slab over the window everywhere. Most often, we do not know how effective this shadingdevice has been.

Incidentally, in dense urban housing areas, the chajja may also do more harm than benefit. Withneighbouring building standing tall, the whole wall of a building can be shaded, ruling out the needof chajja shades. With narrow setbacks between two houses where no direct sunlight reaches thewindows, 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 ofwater ingress.

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 4/10

Posted by rajeshkav

Leave a Comment

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 alsoto be attractive and culturally appropriate.

Posted in designs, fundamentals

Tags: chajja, light

The rough look is cool!

MAY 7

When you get rid of the straight lines, you have to use your imagination to deal with all thecurvatures.

Know the basics: Rough-textured walls receive less heat

(http://sathyaconsultants.files.wordpress.com/2012/10/may7.jpg)Have we ever tried to go close upto a tree trunk or a hill-side cliff? We notice the seemingly plain surface has a thousand minute folds.How is the surface of a seemingly smooth rock boulder? Close up, it is rugged and not in onesmooth plane. What about fruits, vegetables, timber logs or tender coconut shells? It is the samestory everywhere — all non-planar, rough textured, micro-folded and gently curving.

If nature never had a smooth, straight and fine finish, where did we humans get all these ideas forour constructions from? Why are we not trying to learn from and emulate nature?

Village scene

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 5/10

Leave a Comment

Incidentally, we have followed nature, but mostly during the bygone days. Let us look at anytypical Indian village home. This vernacular-style approach used to be rustic and not in perfectplane, being hand- or simple trowel-plastered.

Often there would be natural materials such as stone, timber or bricks left exposed, hence solarpassive, also creating a sense of local material and character.

Smooth-plastered walls receive more heat compared to rough-textured ones, since the latter castmicro shades within the wall, thanks to their roughness. If used in the natural state withoutplastering, brick and stone exhibit such a textured surface that they absorb much lesser heat.

Beauty of curved walls

Gentle curves are part of most objects found in nature, which could be blended with our regularwalls to get multiple benefits. We rarely make full use of all the four corners of the room, as suchconverting one corner into a curved edge does not reduce functionality. Critical areas where storage,furniture, shelves, platforms and such others happen could be left straight, while the movementareas and passages can flow along a curve.

There could be issues like fixing windows, casting curved lintel beams, workmanship, perfect plasterlevels and difficulty in using tools. However, if we are able to retain the sense of curve, the job is welldone.

In our context, building materials such as stone or brick are rectilinear, hence making the curveusing such geometrical blocks needs an expert mason.

Folded walls

Among the much less used variety is the folded wall typology. It was Laurie Baker who discoveredthat thinner walls with half-brick thickness save money, but need to be folded to gain strength.Incidentally, from an ecological perspective, these folded walls have add-on values!

They create so many external deep-set alcoves that most wall surface is under shade. Not all roomsof a house could be comfortable with folded walls.

In non-residential building types like those at Hosa Jeevan Daari at Melukote, such a wall planinternally creates storage niches, with an overall elevation that looks different and attractive.

Windows now set within the alcoves are well sheltered from rain, with no additional chajjaprotection needed. One approach can reap many benefits.

Posted in designs

Tags: chajja, designs, wall

How many RCC lofts do we need?

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 6/10

Posted by rajeshkavNOV 6

A ground or lower-level shelf can do the same function at a lower cost

Being practical: Go for smart storage spaces

(http://sathyaconsultants.files.wordpress.com/2012/10/nov6_1.jpg)There are few things we accept ina new house construction without blinking our eyes. The RCC lofts seen at 7′ level, also called thelintel level, is surely one among them.

It all started following the introduction of RCC during the last century. Lofts are projected from abeam in the wall, which also double up as the lintel beam above the window. Commonly, this lintelis run all along the wall, forming a continuous lintel. The idea became popular, for one could have aloft slab anywhere since the lintel beam is all around. So, the triad of RCC at 7′ level formed by flatchajja, lintel and loft came to stay, irrespective of how much of this RCC is critically necessary, apartfrom the time lost during the casting.

Earlier, all that we could provide was an occasional wood plank projected from the wall with twoangular wooden brackets supporting it. As such, the RCC lofts have become so popular that noroom goes without one or two of them.

Friend or burden?

(http://sathyaconsultants.files.wordpress.com/2012/10/nov6_2.jpg)Knowing our tendencies towardspiling up junk, it is no surprise that lofts have become our dear friends. Yet, occasionally, we betterquestion how many lofts we need. How often do we store heavy items which need a RCC slab? If we

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 7/10

Posted by rajeshkav

Leave a Comment

continue to collect over the decades, how many more lofts we may need? Even if we can cast themall today, how many of us can lift such weights up to the 7′ height?

Would a ground or lower-level shelf perform better than these high lofts? What about the dustcollected and cockroaches housed? Between eliminating junk and eliminating RCC lofts, whichoption should we choose?

RCC lofts are a rigid addition within the walls, which force kitchen cabinets or wardrobes to fit intotheir levels. With a variety of options available for such interiors, often the lofts become an obstacle.

Storing without costing

It is curious to realise that even without a RCC slab atop, the top level of any wardrobe can be usedfor storage, hence act as a loft!

The cost of slab can be saved, that could partly pay for the wardrobe cost! The kitchen lofts are lessaccessible while standing in front of the kitchen platform; as such, lower-level cabinets are morecomfortable any day.

Separate store rooms are possible if space and budget permit. If exclusive RCC slabs are desirable,the best location would be above toilets or passages, simply supported on side walls, with aminimum clear height of two ft.

Going green starts with minimising and eliminating unwanted consumption of constructionmaterials. All of RCC that goes waste at lintel level could be a testing place to check out thisprinciple.

Posted in designs

Tags: chajja, loft

Does your sunshade play its role?

OCT 30

‘Chajjas’ come in attractive types now but their placement is crucial for giving shade or lettingin light and air

Differing tastes: RCC slab projection on buildings started during the colonial times butmany buildings do without them

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 8/10

(http://sathyaconsultants.files.wordpress.com/2012/10/oct30_1.jpg)In the history of Indianarchitecture, chajjas have a curious place. You may not even recollect what part of building I amwriting about now or what is so curious about it.

Well, if we walk around historic towns like Srirangam or Sringeri or Thrissur, chajjas areconspicuous not by their design, but by their total absence. Up north, even in the desert dwellingsnear Jodhpur, traditionally there were no major chajjas.

Sunshades, more commonly called as chajjas, are the little horizontal projections along the externalwall, just above the windows to reduce sunshine and raindrops falling on the opening.

Local styles

The clay-tiled sloping roofs of south India normally extend deep beyond all walls, windows andverandahs providing climatic protection, as such never had a typical chajja.

In north India, often there would be a small beading-like projection, sometimes a moulding to dripthe water drop or a small stone slab above the opening. Only in important civic, religious or royalbuildings, one could see a deep sloping projection supported by ornate brackets placed at an anglebetween the wall and the projection.

(http://sathyaconsultants.files.wordpress.com/2012/10/oct30_2.jpg)As such, the RCC slab projectioncalled as chajja started during the colonial times, when buildings tended to be like a box, with flatroof, inviting vagaries of weather all around. In such cases, sunshades are necessary in our region forclimatic protection, though we tend to see many multi-storeyed buildings without chajjas.

The flat chajjas are cheaper, but jet out of the walls like the rim of a cricket hat, and make thebuilding look ordinary. They also tend to look discoloured after a few showers.

Builders have tried sloping ones, which demand deeper beams, tiles on top and painted finish at

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 9/10

Posted by rajeshkav

Leave a Comment

Builders have tried sloping ones, which demand deeper beams, tiles on top and painted finish atbottom — all leading to more RCC and cost. When chajjas happen between two houses within thenarrow space there created by the bye-law setbacks, instead of protecting, the chajja can cut off thepossible light and air into our own houses. There often are directions from where we get no majorsun or rain, making the chajjas there totally futile.

Interestingly, if heavy rain lashes and the window is left open, water anyway gets in despite thechajja!

Gaining popularity

All the analysis above is not to negate chajjas, but to ensure a better understanding of how andwhere to use them. In the recent years in Bangalore, Mangalore tile chajjas have gained popularity.They are supported by fabricated mild steel frame and can be fixed into the wall only where weneed, just before completing the building. Often, we have come across owners who wanted to checkout which windows need them for a year and then fix them accordingly. With sloping clay tile top,leakage is not an issue and the pricing is also reasonable. Such tiled chajjas compliment the greenaesthetics of the building.

Posted in designs

Tags: chajja, designs, sunshade

Always go for short and concealed lintels

OCT 16

Every era brings in a new wave of thinking and, with age, a new architecture is born. Conceptssuch as lintels and their design, for example.

(http://sathyaconsultants.wordpress.com/2010/10/16/always-go-for-short-and-concealed-lintels/oct16/)How often do we observe the house where our parents lived? What kind of lintel do wesee there? By any chance, do we live in a house built 30 or 40 years ago? When we return to such

9/23/13 chajja | Sathya Consultants

sathyaconsultants.wordpress.com/tag/chajja/ 10/10

Leave a Comment

old houses, we notice, there often was no monolith lintel beam concept.

The window frame would be placed in position, then the bricks would be carefully placed above theframe with equal projection on both sides, to start the remaining part of the wall. Here the brickstightly joined between the void, would act like horizontal means of load transfer, while a smallerpart of the weight would be taken care of by the window frame. This concept can be furtherdeveloped into what is called as flat arch lintels, which unfortunately is not very popular today.Instead of this bricks base layer, there could be a wood piece in some cases. During later years, thetrend of casting a RCC lintel after the frame placement also started.

However, there never were anything like lintel member running all along the house, yet thesebuildings have been with us for centuries. Having said this, let us also agree there are manyadvantages of continuous RCC lintels. The only plea here is to think if such lintels are judiciouslyrequired or not.

Required everywhere

Lintels are needed for sure above any and every opening, be it a door, window or wall niche. Whenwe provide them only above such openings, it is called as cut lintel system. They are short in lengthwith adequate bearing on the wall at their ends, and can be managed with minimum reinforcement.To save time, often they are cast on ground, to be lifted up once the walls are ready. Such pre-castRCC units also save on centering and concreting labour. Cut lintels may not offer any quakeresistance, and as such need to be evaluated against all other criteria.

Another popular approach is to merge the lintel with the wall material. Exposed brick walls maylook nice with the plastered RCC band, yet they can also be built without the lintel being visible. Theouter edge would have a brick, with the thin lintel behind. If it is a hollow clay block, the concretecan be filled within the hollow of the block, creating beam-like support. There have beenexperiments where hollow blocks have been cast into a monolith beam by inserting reinforcementbars into them. Such walls, with the chajja or the sunshade above the window, tend to look veryneat with the aesthetics of single material.

Posted in designs

Tags: chajja, designs

Blog at WordPress.com. The Mystique Theme.