With COVID-19 impacting the market economy and bringing in frugality, builders may no longer splurge on fancy facades and mindless energy consumption.
This essay is not a text in parody, spoof or satire, but a serious way to relook at what COVID-19 is doing to our construction industry – an industry which causes one-third of greenhouse gases, encourages building more than we need and leaves behind large built areas unused or underused while millions go homeless in an unjust and unequal world.
Every material ultimately comes from natural resources which we are simply wasting with disregard to the needs of hungry millions and the bleak predictions of extinction. Unfortunately, nearly everyone in the construction industry – administration, architects, engineers, institutions, builders – are all following this mindless approach to wasteful construction, all against nature. Today it is a virus affecting health, tomorrow it can be a virus affecting construction.
The above references to buildings could be factual, but any connection to the killer virus? One interesting parallel could be that COVID-19 is a killer of humans while construction is a killer of nature – both are killers.
Anyway, keeping the pun apart, the spread of the virus should not have happened to our civilisation. Whatever be the cause, it is a curse to the ever enterprising free spirit of our society, always striving towards a growth economy. Irrespective of its varied impacts, the major implication of the loss of human lives is a civilisational tragedy, which should never repeat in future.
Having said that, let’s look at what the virus has caused to us and made us do. While the actual construction at sites might not have stopped yet, it has reduced the manufacture of products, and sales of goods.
Flights, star hotels, national seminars, fine-dine restaurants, holiday resorts, car drives across regions, air conditioned spaces and such others which are among the major consumers of earth energy are going lean. Images of the nearly empty shopping malls from abroad are simply unbelievable. At this rate, the need for more built floors will also reduce.
Social distancing has reduced public events, while closure of offices and institutions has minimised both local and global travel. Large number of people would see a dip in their monthly incomes, a worrisome fact. However, economists well know how reducing incomes also mean reduced expenses and reduced choices. Majority of the pricey, branded, personal goods are not need based, but are aimed at the rich to spend their surplus income. After the initial jolt, the market economy ensures that expenses will adjust to meet the income level, creating the necessary equilibrium, possibly encouraging a simpler lifestyle rooted in lower-cost products and services.
Less use of energy
If global transport gets affected, local manufacturing gets a boost, lowering the embodied energy – a major criteria in sustainable buildings. A few rich nations such as Japan may be living in crammed office and house spaces, but most rich owners in cities build too much with thousands of building materials, especially to showcase the wealth in the facades and the interiors. Hopefully, frugality may step in.
Those who are tracking the global warming are recording a small decrease in temperatures, while the carbon emission during the virus days has already been less. The internet is already reporting the reduced pollution, cleaner air and reduced solid waste generation across the cities with virus breakout. We can wait for validation, yet by intuition we now know that the climate change created by humans is being challenged by the virus!
COVID-19 appears to be achieving what the decade-long climate campaigns have not yet achieved, for the given short period. However deadly it is, we need to be grateful to the lessons it is teaching us. Our ever growing, GDP-based, market-led, manufactured luxury lifestyle with no concern for cost, climate and culture cannot continue for ever.
Of course, shortly we would learn to control the virus and we may return to our bad old ways. Or, we may remember the lessons it has taught us, and thankfully, may not return to the wasteful buying and throwing.
It is time we change our lifestyle forever, with eco-friendly architecture and lower carbon footprint living.
Buildings are built completely out of natural resources, yet they do not become a part of nature and blend with it
We have millions of buildings and we are building millions more. But let’s imagine the shocking possibility that at least 75% of buildings will get demolished during the next 200 years and wonder where all the debris would go. Sounds absurd when we think how every shelter every other animal makes, returns to nature.
Look at the total weight of a building – floors, walls, roofs, doors, windows, toilets, everything. We build them to carry the load of us and our belongings. The building weight would be far more than our total weight. How illogic when we see a bird’s nest weighing less than its occupants. Today buildings figure in books, seminars, schools and tax papers – more as an owned asset, social image, family aspiration, functional performance, capital investment, operational costs, iconic architecture, innovative ideas, human creativity and many others.
Reality is buildings are built completely out of natural resources, located on a natural site, yet they do not become a part of nature – buildings that may blend with nature and become incognito are not always heard of.
Architecture started with shelter making, followed by the need for shade, security, storage, space, safety, protection, familiarity, comfort and such others – on most occasions, each one of these criteria is overdone in our design and construction industry.
From being ecological animals, we have shifted to being economical animals. From economical, it became personal and now we all live our individual aspirations with no due recognition to the eco-impact we are causing.
Connection to nature
We have forgotten that we vibrate better with natural materials due to our connection to nature vide geo, bio, electric, magnetic energy waves surrounding all of us. Of course, we study bio-mimicry, bio-morphism and bio-philia to design bio-climatic architecture, with recent thoughts on building biology also. But how many of us do all this, out of world population?
Our architecture needs to evolve from nature, made of nature and made for nature. Only then, it will become part of nature or someday become nature itself. That’s the simplest mode to realise eco-logics.
Eco-logic is not a great new term. It is what has created our only home called the Earth and the early tribes still live with the logic of their contexts.
Developed human societies created a human knowledge system called rational logic and told us to follow it in every aspect of our lives. In recent centuries, we have evolved modern human logic, as an opposite to eco-logic.
Will the human logic someday overpower the eco-logic is unknown to us, but the way climate change is threatening to change the course of our future, it appears like eco-logic will prevail over human logic.
Maybe its time to change our courses before we too become victims of what we have unleashed on the Earth – the age of Extinction.
An indoor courtyard is just what the architect ordered for a happy home.
As the world is sizzling with global warming, one design element is staging a major comeback – indoor courtyards. Be it atriums in tall hotels, spectacular indoor space in a mall, roadside restaurants or a finely finished house – designers are relying upon one of the oldest architectural ideas.
It is aesthetically attractive, experientially refreshing, and above all ecologically relieving to observe this trend. For all the mindless enclosure of large indoor space with stuffed-in experience and darker interiors, courtyards let in rejuvenating sunlight and breathe in the fresh air. Hopefully, more the courts, lesser the air conditioning.
The means of achieving courtyards and their impacts can be myriad. There can be a large sky-lit courtyard with green plants, serving as an extension of the living area, doubling as a private family space while having temporary partitions. A well-lit courtyard can take a designer staircase along its wall surface, be it in RCC, steel or stone slabs, becoming a focus of the space. Most often, courtyards connect two otherwise distinct spaces like living and dining, or dining and kitchen, creating a perception of largeness.
Typically, the courtyard is a completely indoor matter, while we call the outdoor spaces like gardens. But if one can intelligently redefine the outside setbacks, and run the building glass wall around it, we may get a larger sense of space within the same site area, thanks to the indoor to outdoor connect we are achieving.
Plants, pavers, seats, sand and other features complete the designer court.
Doors do the trick
There also can be an external courtyard, more like an opened up back or side yard, which is walked up directly from inside the house. Staggering the house walls very easily creates such side spaces, which are an unsaid extension to the inside. They also could be called as outside gardens. But with sliding, folding or collapsible doors, the outside becomes inside once we open the door shutter.
Most courtyards are enjoyed as an extension of living or dining, so seen across horizontally. The unusual angle of looking down into the court has to be actually experienced, to feel the beauty. The view will capture the space and objects below from a different, hence curious angle.
Let us imagine an internal courtyard with antique columns, large planters, built-in seats, indoor small water fountains and decent interiors – it will be a happy home. Sunlight flowing in may cheerfully flood the living and dining spaces built around it.
If most of this text has focused on aesthetics, it is not to ignore the ecology.
Majority of people in the design and execution teams know of the environmental advantages of the courtyard, but do not promote them out of some apprehension.
The sheer beauty and attractions suggested off the court above may lead more people to adapt them for many multiple advantages – ecological, aesthetical and functional.
Your house can be eco-friendly, local, vernacular, rural and yet structurally strong, with NIRD support.
Today there are thousands of institutions, architects, engineers and builders across India trying to promote non-conventional, eco-friendly alternatives in architecture and construction. And they all know why these appropriate ideas stay in the back burner – the majority of potential owners who are inclined to the non-conventional are apprehensive, and the rest anyway are not convinced!
After all, customised houses cannot have prototypes, demonstrations, samples, test walls, material trials, model houses or any kind of construction rehearsals. Naturally, worries persist tempting people go with the mainstream cement and steel-based house. Habits die hard, even in this age of attraction of the innovation.
Given this apprehension most house owners have the Hyderabad-based National Institute of Rural Development embarked upon a novel idea – actually constructing rooms and houses using the alternative, eco-friendly, local, vernacular and rural typologies handpicked from different regions of India.
Innumerable design, material and construction options can be seen, walked into and experienced across 15 built structures, with a visually sweeping master plan.
The list of ideas demonstrated is long, but to state a few – mud walls in stabilised blocks, adobe, cob and rammed earth; stone in random rubble walls; arch foundations; fly ash columns and walls; vaults with conical tiles; jack arch roof; Ferro-cement channels; bricks; laterite; bamboo mats; wattle and daub; filler slabs; stone roofs; corbels; brick domes; CGI sheets, MCR tiles; perforated jaali walls; brick panels roofs; precast slabs; catenary curves; conical tiled roofs; round Bhunga huts; stone and timber lower Himalayan house; skylights; rat-trap bond; bamboo house; stabilised non-eroding mud plastering; walls with exposed materials; rainwater harvesting; lime mortars; boulder pack foundations; sanitation methods; solar energy; tile support in wood and steel; and pre-cast lintels.
What makes these structures convincing is partly due to the expert teams who made the centre possible – AP Habtech; CSV – Wardha; Habitat Group of Thiruvananthapuram and Hunnarshala from Bhuj with secondary literature inputs from varied sources. As such, the Rural Technology Park demonstrates the do-ability of cost- and resource-efficient architecture.
Considering that such a unique centre for demonstrating the feasibility of ecological alternatives was done way back in 2003-04, it’s sad to see most of the ideas still being relegated to the back burner.
Being termed as Rural Technology Park could be a reason, for all that we see here can be in our unsustainable urban centres of today. For those who cannot travel all the way to Hyderabad just to see the model constructions, an extremely well-illustrated compilation by the technically qualified project team is available at the centre.
Seeing is believing
Scepticism and apprehension cannot be ruled out by assurances, especially while investing lifelong savings in one house. We cannot experience the house before it’s built, but at least seeing can be believing.
That’s what RTP at NIRD provides and proves.
How to build stylish, yet eco-friendly homes in the wake of radical shift in construction systems.
If we invite friends home for dinner, the choice of vegetables is among the starting points to decide upon the menu. The same curry listed in the culinary books becomes a different tasting dish with a different vegetable. Not the best example to quote, but so too in buildings where the same building type, say a school, could become different with varied materials.
All construction materials are sourced from nature, such as stone, bamboo, mud, clay, thatch, lime and timber. Of course, water too comes from there, but is rarely acknowledged! It may surprise many to know that every industrially processed and manufactured material also comes from nature.
Lime as the raw material for cement; iron ore to make steel; bauxite as the ore for aluminium; sand as the basis of glass; clay for ceramics; finally crude oil and coal for plastics. So the equation is simple – as we increasingly use cement, steel, aluminium, glass, ceramics and plastics in construction, we are increasing the resource consumption, process wastes, transportation costs, demolition discards and as such, the embodied energy of the building, which directly contributes to greenhouse gas emissions, global warming and climate change.
There have been radical shifts in construction systems today, especially in the multi-storey sector, yet standard foundations, walls, lintels, beams and roofs dominate the majority of projects.
Here, materials contribute more than building technology in making the building eco-friendly. This is not to demean construction options – more than half-a-dozen foundation types exist; roofs could be done in a dozen ways; walls can be built in more than 15 ways, and floors have multiple choices – but only to mention the sad state of affairs where very few easy-to-do constructions practises are now popular. Most houses are being built with just one type of foundation, wall and one type of roof!
In the past, every region had limited access to materials, hence the local vernacular style evolved which today may be wrongly felt by many as simple and monotonous. But that alone need not drive us to design strange combinations of modern materials which by default have lesser choices. Computer software applications with virtual or augmented reality generated images and animated walk-through complete the act of selling design easy ideas.
So, we end up with varied elements, forms, colours and combinations of surfaces to create what is today felt as attractive and unique elevations. Majority of them rely upon RCC frame construction, cement block or cheaper brick masonry, walls plastered and finished with putty, primer and paint.
Public buildings get finished with façade treatments, cladding panels and glass. How many of these are truly attractive, have a sense of collective aesthetics and follow the time-tested theories of beauty are questionable. Hence, the cacophony of architecture in every street, neither aesthetical nor ecological.
Plastered cement block wall coming in varied colours consumes much more of resources, uses chemicals and has more embodied energy than natural mud, stone or exposed clay blocks. As such, minimising cement blocks and painting are among the first step towards eco-friendly architecture. Zero maintenance by avoiding the need to re-paint, hence reduction in life cycle costs comes as a bonus point!
Ecological natural materials provide unlimited options towards wall elevations unlike what many people think. The variety possible by different material mix, pattern making, proportions, stylistic approaches and daylight throw far exceeds what the standard plastered walls offer. It’s the market at large looking for less work and more profits which undermines the aesthetic quality and environmental values of building with ecological materials.
As climate change is threatening every aspect of our lives, let us walk ecological sensitivity in every aspect of our constructions.
The plan to build a seven-storey structure in Cubbon Park may take a further toll on Bengaluru’s already shrunk lung space.
This ‘Green Sense’ essay has to sadly lament about the increasing lack of ‘sense of green’ among the decision takers and urban authorities, who appear to be in a mad rush to build on every piece of land available to build upon.
Last fortnight media was abuzz with the controversial news about the High Court of Karnataka allowing replacing a colonial building with heritage qualities with a new swanky 7-storey structure, edging the Cubbon Park. The park itself, one among the only two lung spaces of Bengaluru, is not only a precinct of natural heritage but also of innumerable events in the memory and history of the city.
Both the natural and built heritage of Bengaluru are at peril with the proposed construction.
Of course, Bengaluru today is a world city, a great achievement, but on the graves of what was Bangalore. More often than not, the majority of builders, residents, leaders and the authorities seem to be in a rat race to erase the invisible, natural and built heritage of the once-fabled city, replacing it with the visible, image-making projects of infrastructure, etc.
A simple truth even a high school student can understand is that constructions increase urban heat and gardens reduce urban heat. Construction activities contribute to nearly one-third of all global greenhouse gases, so directly cause global warming and climate change.
Bengaluru has been warming up at an alarming rate with innumerable heat islands within; so the time now is not for continuing the mindless construction activity that has already taken a toll on the once garden city.
Developing a settlement as a sustainable city cannot be achieved by the subject experts; incidentally, they are the least capable of doing so. Urban issues need to be equally participated, managed and decided by the people, politicians, administrators and experts. Cases like building in Cubbon Park are glaring examples to prove the state of affairs today, where the four are never brought together through participatory administration, transparency, stakeholders’ meet, public survey or any of them.
These four are the four pillars of urban administration, but sadly the people in power do not think so and go ahead as if only their voice matters. Of course, practically speaking, in democracy people decide their leaders and the leaders decide for the people. But theoretically, people still have the power to decide on matters concerning them.
Hence, the Cubbon Park project enraged people who reacted and protested. If the very first act of governance is taken on consensus, there would not have been any need to react, protest or resist.
As an individual or institution, we all seek to own our own buildings once we have the site, money and maybe the need. We do not cherish being in a rented place for too long, so justify every building project. The local governance refers only to rules and regulations to allow or disallow a project, never looking beyond into its ecological impact, local nuisances, impact on flora/fauna, matters of water table, cultural value, people’s memory, increased load on urban services, ripple effects of the new building, holding capacity of the area or any such deep matter.
Naturally, Bengaluru gets hundreds of buildings all over its geographical spread, as if the city can absorb all. It all sounds fair, but sorry, no city can and should grow like this, however beneficial it could be for a few people in the process.
The carbon footprint of Bengaluru could be matching that of any other energy-guzzling global city today, making it a villain of the Earth.
If a sense of garden prevails among our authorities, now is the time to slow down, restrict or even judiciously stop construction activities. Only then can we hope future generations would be able to live in a liveable city.
Flat clay tiles make a hourdi roof easy to maintain, and the aesthetics are stunning.
What is the most critical part of a house – foundation, wall, roof, openings or staircase? The obvious answer is the roof, hence maybe the metaphorical meanings when we say ‘roof over the head’. It is of course, less visible than the walls, hence often gets lesser attention, especially where front elevation looks are more demanding.
While walls enclose the room providing protection, it is the roof that provides the true shelter. Unlike any other element of domestic architecture, here we face multiple issues to grapple with. Immediate thought could be about the structural issues, as to how to support the roof itself. Traditional architecture worked around local materials to solve this issue, while modernity has opened up innumerable options.
People across the societies have felt the need to innovate on roofs, either because there never has been a totally satisfactory design or roofs have had the scope to play with them. While the flat and sloping roofs have dominated at large, all other options have continuously knocked at the door.
Contemporary architecture using advanced software to generate a profile, computer-controlled manufacturing of components and on-site technology to assemble them all have created some amazing roof forms across the world, with architects like Frank Gehry and late Zaha Hadid leading the pack of innovators. But do they mean in our small town contexts we need to be deprived of them? No.
The Learning Centre located at Salem proves the point. With the passion of promoter Sanjay and involvement of builder Arun, their team has managed to build a magical school building. It’s it not the just the roof which is special here, but the totality of design and building.
As such and with the concept of minimising cement and concrete, the design revolved around mud and clay.
Roofing with clay Mangalore tiles has been around for over the centuries, but it needs to be only sloping due to the interlocking grooves. By replacing them with flat clay tiles, one could create a curved profile. However, placement or direction of the clay tiles is important to ensure smooth curvature and to ensure that rainwater does not clog anywhere.
Typical computer formulae will not help in resolving the S-curved roof which adorns the school building, but only an experienced structural engineer like Ravindranath could resolve it. The structure also has domes, vaults, varied kinds of filler roofs, stone slab roof and such others. As such, the behavioural patterns of roofs need to be studied and equilibrium planned for.
Of course, special attention is called for while assembling the roof for labour safety, joint filling and waterproofing the joints. The fabrication also has to be done to precision, lest the blocks may not be seated properly.
Curved clay flat hourdi roofs have advantages other than merely the novelty. They perform better for speedier construction, reduce steel with their lighter weight, ensure different aesthetics as against RCC ceilings and are easier for maintenance.
Be it the roof, wall or the whole building, architecture should not be driven by the idea of fancy, however attractive these new designs may appear to be. All the elements of design and components of construction should together aim to provide a holistic perception and experience.
Mangalore tiles could be used to build walls, roofs, pavers and more.
Majority of Indians were and still are used to having a space in the house where they could be eating at noon, children playing in the evening and cousins staying as guests sleeping there at night. The space we enter into on the first floor, often called a family hall, is even now considered for such varied roles.
Termed as ‘multi-functional spaces’ in architectural language, they have been among the basic principles of saving resources by minimising the need for multiple rooms for multiple requirements. While this has been commonly known and is continuing, what is forgotten is the idea of materials being multifunctional.
Buildings had to depend upon the few local resources for all construction needs, so people learnt how to use them with minor modifications. This also led to high theories like ‘single material approach’ much advocated by thinking architects such as Shankar Kanade and his brother Navanath. We may connect the visual powers of Taj Mahal, White House or Red Fort for their single material.
When Govindarajan, retired from IFFCO, desired to have a small farmhouse in his land, he could not but notice how people around the village built. He chanced to see a wall built with Mangalore tiles and wondered what’s the roof tile doing in the wall.
Discarded low-quality pieces and tiles from demolished houses not good for re-use get the common preferences here. Besides, one could see them on compound walls, edging a pathway in the garden, topping a parapet wall or even as pavers in broken condition. These tiles are very good at compression, hence we can load lots of weight on them!
Easy to build
A wall with Mangalore tiles is easy, cheap and fast to build with. With the rock hard tile transferring most of the load, the role of mortar joint is reduced to a levelling course. Cement mortar does not stick well to the surface, hence stabilised mud mortar is both appropriate and economical.
Routinely, these walls were inside and outside plastered. If built with stabilised mud and left exposed to sun and rain, they can perform very well on multiple fronts. They keep the house much cooler, thanks to an undulating and micro-shading surface which does not absorb much of solar heat. With a coat of lime, the walls come alive with a rare texture.
Local practices of today are being ignored in the face of regional or global ideas, but let us remember when these ideas were attempted in the past, they were not called as local practices.
They were the mainstream practices of the day, with no exposure to the global of the day. Apparently, these neglected and seemingly insignificant ideas were sustainable, while much of our celebrated newer and engineered construction ideas do not seem to provide a trouble-free stay for even two decades.
Without localisation and without realising the multifunctional potentials of each material and each technique, we cannot achieve a sustainable future.
We can actually live all our life in a forest, with food, fabric and shelter taken care of, avoiding the urban claptrap. Tamandua Rain Forest Research Station in Peru tells us how.
Let us imagine we were to be living deep inside a tropical primary rain forest. There is no real local vernacular style yet, so how do we proceed to design? We need to freshly create a local architecture from the materials offered by the context. That’s what we get to see at the Tamandua Rain Forest Research Station inside the Amazon forest, next to Las Pedras River in Peru.
It could be a large raised floor with wooden planks open all around to let light and air filter in from everywhere. The height of platform and railing would discourage crawling reptiles, rodents and such others from entering. Dealing with hot humid air is simplified by high roof with total void below roof, to allow hot air to move across the roof bottom, rather than let it move downwards from the roof. Room divisions are done with low partitions, just to provide visual privacy.
How to build
There is no electricity, telephone or internet connectivity. How do we build? We need to discover ways of constructing with human skills and basic tools that are traditionally available. The jungle is replete with construction timber for structural members, veins to get rope from them and tall grass ideal for weaving for roofing purposes.
Make the roof steep to ensure faster flow of rain water and greater structural stability.
Everything from the toilet gets soaked into the soil below. If we run out of cooking gas, firewood is around aplenty, which can also provide hot water for bathing, if needed. Food without the fancy looks and urban ingredients is essential and healthy.
Essential supplies to run the Tamandua Research Station need to come from a shanty settlement an hour away by boat. The typical daily wastes too have to be taken back, not to litter the pristine nature.
The station is not for recreation, but for research and exploring nature, as such it is austere and frugal. Yet, it connotes the possibility that we can actually live so all our life, with food, fabric and shelter taken care of. If so, why have we forgotten the pleasures of simple living and the simple pleasures of living, caught up on the trap of unsustainable lifestyle?
Until a few years ago, there was no supplied electricity, but now there are a few solar photovoltaic panels that give a little quantity of power before it gets totally dark, when one relies on candles. Until a few years ago, there was no Trans Amazonian Highway connectivity, so travel took day and night across boats, road and walking.
It appears, as we move into the present and the future, we miss out on experiencing the past. Soon, we forget it and so too about designing with nature.
The architecture at Tamandua station is the real sustainable architecture. It is born out of Mother Earth and when it reaches its end, it will return to Mother Earth. If we can keep the jungle, the jungle will keep us. Architecture without carbon footprint.
The mundane mud pot placed strategically by a skilled mason can cool your house.
If people advise us to build only the way our forefathers built, to completely return to the vernacular ways and shun modernity, better not trust them fully. Returning to the past is, of course, a way of building eco-sensitively, but many not be either the sole way or the best way.
This is not to disapprove the benefits that we can learn from the past, but to forewarn ourselves about the possible traps in simply glorifying the past. Roofing practices provide good demonstrations for this theory. It’s well known how advanced were our seniors in providing long-lasting water-proof roofs with passive cooling and minimal annual maintenance. Comparatively, today we often complain about cracking and leaking concrete roofs which turn our houses into ovens in summer.
A thick layer of mud was among the simplest of solutions; it’s effective but not practical today in urban contexts, however much we may like to return to those age-old practices.
However, we may try to have a thick layer, but reduce the mass and weight by having voids inside. Roof heat transfers through conduction in solid materials and convection in empty space. Convective transfer of heat is very slow and much lesser than through solid mass. So, any hollowness embedded within the roof thickness reduces heat transfer, keeping the indoors slightly cooler.
In many regions of northern India, it was a common practice to place small mud pots, either tea cups or 6 to 7 inch diameter clay trays, 3 to 4 inch deep on the terrace, with the bottom up. So, there is a cavity now above the roof top.
This layer of pots is filled to level using screed, either plain cement concrete 1:2:4 if water-proof terrace is needed or one may use stabilised soil-cement mix. Some lime may be added to provide water-proof qualities. The final top surface may be finished with white heat reflective cool roof coat, for additional thermal comfort inside.
In a recent project in Vikarabad near Hyderabad, this technique was revisited. Of course the availability of the clay pots led to using lesser number of pots than what’s ideal, but as an experiment to check its feasibility today, it was a success. In this case, this layer was laid over tandoor stone roofing, reviving another vernacular practice. It’s sad that though clay pots have multiple uses and benefits, their production has reduced due to the onslaught of produced products.
The void should be completely inside the slab to trap the heat there itself. Of course, once the air in the cavity gets heated up, some heat transfer would happen due to convection, but that would be much lesser than otherwise with no void at all.
The best is to have a ventilated cavity roof, which cannot be achieved by this simple using of clay pots. Only for very hot regions we may try such more advanced modes of passive cooling.
Pots inside thick mud phuska roof is not a new idea, but among those which are being forgotten. Before they are fully lost, we need to check the possibility of their modern applications.