Site heat meters and work-rest schedules for construction contractors
TL;DR Heatmeter puts a heat meter on each construction site and turns its readings into a work-rest schedule that supervisors actually follow, with water and shade checks logged. Contractors and developers pay per site per summer. What it sells is fewer heat collapses and steadier output, and a city-wide alert isn't part of it.
India loses more working hours to heat than any other country. The ILO put the loss at 4.3% of hours in 1995 and projects 5.8% by 2030, the equivalent of 34 million full-time jobs[1]. Construction is where that loss is growing fastest.
The site numbers back it up. In a Chennai-area study of 442 workers, 82% worked above the international heat threshold in the hot season and 47 of the 52 construction workers reported heat-related health problems[2]. A 2026 survey of 1,560 outdoor workers across Tamil Nadu found 88% over the threshold in summer[3]. And yet most sites still run on a fixed shift, with whatever water and shade the supervisor happens to arrange.
What it does, in regulatory terms - workplace heat measurement and work scheduling only. Heatmeter does not monitor workers' bodies, diagnose heat illness or give medical advice. It supports the employer's general safety duty under the OSH Code 2020[4].
Each site gets a fixed wet-bulb globe temperature (WBGT) meter that reads heat, humidity, sun and wind together. Every hour the supervisor's phone shows the plan for that hour - how many minutes of heavy work, how many of rest, and which tasks should move to early morning. The supervisor ticks off water, shade and buddy checks, and new arrivals from cooler states get a lighter first week. The contractor sees every site on one screen, along with a summer record they can show a developer or an inspector.
The original version of this idea pitched hyperlocal heat prediction and alerts for whole cities. IMD forecasts and state heat action plans already warn the public for free, and NDMA has issued advisories on a heat index for preparedness[5]. The gap is at the worksite, where a forecast has to turn into a decision about who works when.
The worker benefits but the contractor or developer pays. The first buyers are mid-size contractors with 5–30 live sites and developers who must show lenders and listed parents a safety record. A handheld WBGT meter costs about ₹53,000 (US$549)[6], so most contractors don't own one. The test price is a per-site summer fee (our assumption), set against a single lost day of crew output.
The OSH Code came into force on 21 November 2025 and folded the Factories Act and the construction workers' law into one code[7]. It requires employers to provide a safe workplace and lets inspectors stop work where workers are in danger[4]. The 2024 heat wave, which killed at least 219 people by early June by media counts[8], made heat a board-level topic for builders.
Nobody publishes a figure for what Indian employers spend on heat safety. The firmest numbers are on exposure, where 85% of the construction workers in the Chennai study said heat cut their output[2] and the 2026 survey saw perceived productivity loss nearly double from winter to summer[3]. For context there's the ILO's 34 million job-equivalents lost by 2030[1]. That's the size of the problem, not your market.
One US safety-tech firm sells wearables plus a site unit that estimates WBGT and sets work-rest cycles automatically[9]. Another sells heat-stress prevention as an occupational health service[10]. Both are built for US budgets and for body sensors though. In India heat warnings come from IMD and city heat action plans, and we found no service that turns site readings into a daily schedule for contractors.
| Difficulty | Moderate (42/100) |
| Starting capital | ₹60 L–1.2 Cr |
| Time to launch | 6–9 months |
The meter is the easy bit. The hard part is getting a site supervisor to stop work at 1 p.m. when the contractor wants a slab poured, which means schedules simple enough to follow and a reason for the contractor to back them. Sales are seasonal too. If you miss February then you wait a year.
No sector licence to sell a heat meter and a schedule, but your buyers' labour law shapes the product.
Building this outside India? The categories above usually have a local equivalent, so check with your own regulator.
Don't trust AI to judge whether a worker is unwell. Heatmeter measures the site, not the person, and anyone showing signs of heat illness goes to a medic.
Want to work out the AI layer for Heatmeter? Talk to Yash →
Here's what can go south -
I think this is worth trying if you've run construction sites or EHS teams and can talk to site engineers in their own language. If you want to sell a sensor and walk away then it isn't for you. Prove two things first - that three contractors will pay for a full summer, and that supervisors follow the schedule on at least four days in five.
Plan for roughly ₹60 L–1.2 Cr, covering WBGT meters, the supervisor app and a summer of field staff.
No special licence while you measure site conditions only. The safety duty under the OSH Code stays with the contractor, and you'll need DPDP compliance for worker data.
Yes, anywhere outdoor crews work through hot summers. Check local workplace heat rules first, since some countries already set mandatory limits.
The free Heatmeter validation kit has the line-by-line capital breakdown, the effort scoring, the labour-code checklist, a 14-day validation sprint with pass/fail targets, a 90-day launch plan, 10 interview questions for contractors and supervisors, and 5 assumptions to test. Download the kit →
Thinking about building Heatmeter or something close to it? The make-or-break work is getting contractors to treat a rest break as part of the job and not as lost output, and I help founders work through exactly that kind of problem. 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.