Cool-roof retrofits with logged indoor temperatures, so funders see what changed
TL;DR Coolroof fits reflective coatings or under-roof insulation on tin and asbestos roofs in low-income homes, schools and small workshops. Temperature loggers go into each treated room and a matched untreated one. CSR teams and city heat programmes pay per roof and get a summer report that shows how much cooler the rooms actually got.
If you live under a tin or asbestos sheet then your room's temperature follows the sun. In an Ahmedabad slum study, a thermocol ceiling under asbestos kept rooms about 2.5°C cooler than bare asbestos, while white paint on tin gave about 1°C[1]. That study covered just 16 homes for one week in October, mind you.
The money for cool roofs exists but proof of results is thin. Heat action plans in eight Indian cities include white-paint cool roof programmes, yet only three use surveillance data to adjust what they do[2]. A 2026 review found no study that checked modelled temperature drops against observed readings, and noted that reflective coatings fade or gather dust[3].
So funders are paying for roofs without knowing which ones worked.
Coolroof does two things together. First, it retrofits roofs with the cheapest option that fits each building - reflective paint on sound tin, an insulated false ceiling under asbestos, or a better covering where the sheet has given up. Second, it puts a small temperature and humidity logger in every treated room and in similar untreated rooms nearby, and records right through one summer.
The funder gets a site-by-site report with degrees saved at 3 p.m., hours above 35°C before and after, and which coatings need a second coat after the dust season. Homeowners and school heads see the same numbers on a simple card.
I narrowed the seed, which pitched city-scale heat-island mitigation with thermal monitoring. Cooling a whole neighbourhood takes trees, materials and planning that no startup controls. A single roof is a job one crew can finish in a day and its result can be measured in the room right below it.
The family, student or worker under the roof benefits but rarely pays. CSR teams, foundations and city heat action plan cells pay per roof, and more and more of them want evidence of outcomes. Small factory and warehouse owners with sheet roofs are a second buyer who pays directly, since hot sheds slow workers down. Cool roofs cost from about ₹5 per sq ft for lime paint up to ₹100 for china mosaic tiles[4]. The measurement fee on top is an assumption to test.
Cities are writing cool roofs into their heat plans. Telangana put a draft cool roofs policy into its 2021 heatwave plan[4], and the 2025 review of eight city plans found white-paint programmes common but monitoring rare[2]. The 2026 scoping review called for real-world trials in low-income settings[3], which gives funders a reason to pay for measured results.
I found no public figure for what India spends on cool roofs. The narrowest number comes from one Ahmedabad housing non-profit, which says it has helped more than 27,000 households in 1,066 slum settlements put in cooling measures, including reflective paint and modular roofs[5].
Ahmedabad alone had about 82 km² of roof area in 2018[4], which is useful context but not a market.
That non-profit runs cool roof work in Ahmedabad with the city corporation and a US environmental group as partners[6]. Paint companies sell reflective coatings through dealers, and contractors apply them. What I didn't find is a firm that installs roofs and also hands the funder logged indoor temperatures for each site, though web search was down when I checked.
| Difficulty | Moderate (42/100) |
| Starting capital | ₹55 L–1 Cr |
| Time to launch | 3–6 months |
Painting roofs is simple. The harder parts are honest measurement, which needs matched control rooms and loggers that survive a summer, and selling to CSR teams who budget once a year and want a partner they trust. Fragile asbestos roofs also mean strict safety rules for your crews, no shortcuts.
Roof retrofits need no special licence, but a few rules still apply to your crews and loggers.
Building this outside India? The categories above usually have a local equivalent, so check with your own regulator.
Don't trust AI to make health claims about residents from room temperatures. Report degrees and hours, not medical outcomes.
Want to work out the AI layer for Coolroof? Talk to Yash →
Here's what can go south -
I think this is a good fit for a founder with construction or NGO field experience who is comfortable with spreadsheets and summer site visits. If you want a software company then this isn't for you.
Prove two things first - that across 50 roofs you can show a clear, logged indoor drop, and that one CSR funder pays more for the measured version than for paint alone.
Plan for roughly ₹55 L–1 Cr, mostly for crews, materials, temperature loggers and working capital between CSR payments.
No special licence. You need company registration and GST, WPC approval if loggers use Wi-Fi or Bluetooth, safe working practice on fragile roofs and household consent.
It can be if funders pay extra for measured results. Paint alone sells cheaply, so the logged temperature report is what earns the margin.
The free Coolroof validation kit has the line-by-line capital breakdown, the effort scoring, the building-code, radio and site-safety checklist, a 14-day validation sprint with pass/fail targets, a 90-day launch plan, 10 interview questions for CSR teams and factory owners, and 5 assumptions to test. Download the kit →
Thinking about building Coolroof or something close to it? The make-or-break work is measuring honestly and getting a CSR team to pay for proof and not just paint, and that's a conversation I enjoy having. If you need a hand, you know where to find me. Talk to Yash →
For illustration only. Names are fictional and ideas hypothetical; sourced facts are real but may be out of date. Nothing here is legal, financial or professional advice, and Yash Khatri is not personally liable for any use of it. Read the full disclaimer.