Last Tuesday the power went out at 6 in the evening. I was home in Kishangarh. It was 41°C outside.
In ten minutes my living room felt like the inside of a bread oven. The AC had been running all afternoon. The walls — brick, semi-dry mortar, putty, paint — gave up the temperature they had been holding back almost immediately. By the time the generator kicked in, the room had warmed by six degrees.
This is not a story about heat. It's a story about what's between me and the heat — which here, is essentially nothing.
How a wall is built in India
Walk into any new construction site in Rajasthan, Gujarat, Haryana or Maharashtra and you will see the same wall. Burnt clay brick on both faces, sometimes a single 230 mm leaf. Cement-sand mortar applied semi-dry on the inner and outer surfaces, around 12-15 mm thick. Then a thin layer of wall putty — gypsum or calcium-carbonate based — to give the smooth finish that gets painted over, or that gets left as the final surface.
A few weeks ago I wrote about the wall on my morning drive — the one that has failed three times in the same spot, the one that shows the brick underneath because the render keeps coming off. That wall has a waterproofing problem. But before the waterproofing, before the render, before any of that — it has an insulation problem. They all do.
That's the whole assembly. There is no insulation board. No air cavity designed to break the conduction path. No render system engineered for thermal performance. The mortar is structural and protective. The putty is cosmetic. The brick does what bricks do, which is conduct heat efficiently in both directions.
The U-value of this wall is around 2.0–2.5 W/m²K depending on brick density. For comparison, the Bureau of Energy Efficiency's commercial building code, ECBC 2017, sets a maximum of 0.397 W/m²K for walls in Hot & Dry zones — five to six times lower than what is being built every day.
The regulation that exists, and the regulation that doesn't
India does have an envelope code for residential buildings. It's called Eco Niwas Samhita, launched in 2018 by the Ministry of Power. On paper, it sets minimum envelope performance and aims to deliver 125 billion units of electricity savings per year by 2030.
In practice, ENS only applies to plots ≥500 m². Single-family homes, low-rise blocks, the typical PMAY-scale housing where the bulk of construction happens — most of it falls outside scope. And even within scope, ENS is a state-by-state implementation. Some states have notified it. Many haven't.
The result: ECBC for commercial buildings has been mandatory in 13 states. The residential code has no equivalent enforcement. So when the central government commits to building 20 million homes by 2029 under PMAY, the envelope of those homes is governed by habit, not specification.
Europe didn't get here by accident
In the EU, the Energy Performance of Buildings Directive entered into force in 2002 and has been recast four times. The latest version, EU 2024/1275, requires all new buildings to be zero-emission by 2030 and renovation of the worst-performing 16% of non-residential stock by 2030, rising to 26% by 2033.
What that meant on the ground was that the construction chemistry industry had to deliver insulation systems that worked, were affordable, and could be installed by trained crews. The most widely deployed answer was ETICS — External Thermal Insulation Composite System. EPS or mineral wool panels bonded to the structural wall with adhesive mortar, mechanically fastened, then a glass fibre mesh embedded in a base coat, finished with a render or finishing coat.
ETICS is what is between me and the cold when I am back in Murcia. It works. It can drop a wall U-value below 0.25 W/m²K with 60-80 mm of EPS. It is regulated under EN 13499 (EPS-based systems) and EN 13500 (mineral wool). Every component — adhesive, panel, base coat, mesh, finishing render — has a class and a test method.
There are alternatives. Internal insulation when external is impossible. Cavity wall insulation in retrofits. Insulated render systems where ETICS is too thick. Each has its application. But ETICS dominates the European façade insulation market because it is the most cost-effective system that delivers the U-values the regulation demands.
Why I think India misreads insulation
The most common reaction when I describe ETICS to colleagues here is "yes, but India is hot, we don't need insulation."
Insulation is not about cold. Insulation is about delta T — the temperature difference between inside and outside. A wall that loses heat in winter is the same wall that gains heat in summer. In Rajasthan summer the delta T between an air-conditioned room and the outside can hit 22°C. That is bigger than the delta T of a Madrid winter.
The energy that an Indian household spends to maintain that 22°C gap, against a wall that conducts heat freely, is enormous. ENS estimates 20% cooling energy savings just from envelope improvement. In a country where peak electricity demand is increasingly driven by residential AC, that's not a comfort question. It's a grid question.
The other missing piece — labour
Even if regulation tightened tomorrow, ETICS in India would face a second wall. Skilled labour.
A correctly installed ETICS system requires the adhesive applied with the right notch, the panels staggered, the mesh embedded with enough base coat coverage, the corner profiles set true, and the finishing render applied within the open time window. Done wrong, the system delaminates within three to five years and the manufacturer's warranty disappears.
Europe trained that workforce over twenty-five years through manufacturer certification programmes, trade schools and contractor associations. India has neither the certification ecosystem nor the contractor density. The few ETICS projects I've seen in India have been imported turnkey — installation crews flown in from outside.
That gap is fixable. But it is not fixable in two years, and it is not fixable without the regulation pulling demand first.
What this means for what I do
We make tile adhesives, mortars and renders. The same polymer chemistry — RDP, HPMC, cellulose ethers — is the chemistry of ETICS adhesives and base coats. The Indian construction chemicals industry could supply ETICS-grade systems tomorrow. What's missing is the spec, the trained applicator, and the regulation that makes the spec mandatory.
Until that changes, my walls in Kishangarh will keep giving up the cold the moment the power goes out. Yours probably will too.
Next week — AAC vs brick. Who wins, and under which conditions.
— Guillermo