Mental Health in the Heat – Ahmedabad, India

Ambient air temperatures in India have broken record highs. Solutions are needed to build heat resilience in communities and adapt to increasing heat from climate change. Sunlight-reflecting cool roof coatings may passively reduce indoor temperatures and energy use to protect home occupants from extreme heat. Occupants living in poor housing conditions are susceptible to increased heat exposure.

Heat exposure can instigate and worsen mental health. The worst adverse health effects are experienced in communities that are least able to adapt to heat exposure. By reducing indoor temperatures, cool roof use can promote mental wellbeing in household occupants.

The long-term research goal of the investigators is to identify viable passive housing adaptation technologies with proven health benefits to reduce the burden of heat stress in communities affected by heat. To meet this goal, the investigators will conduct a cluster-randomized controlled trial to establish the effects of cool roof use on mental health in Ahmedabad, India.

Increasing heat exposure from climate change is causing and exacerbating heat-related illnesses in millions worldwide – particularly in low resource settings. June 2024 was the 13th consecutive hottest month on record globally – shattering previous records. Heat exposure can instigate and worsen mental health conditions, including depression, anxiety and aggression. Adaptation is essential for protecting people from increasing heat exposure. The built environment, especially homes, are ideal for deploying interventions to reduce heat exposure and accelerate adaptation efforts. However, there currently is a lack of evidence on a global scale – generated through empirical studies – guiding the uptake of interventions to reduce heat stress in low resource settings.

Sunlight-reflecting cool roof coatings passively reduce indoor temperatures and lower energy use, offering protection to home occupants from extreme heat. The investigators therefore aim to conduct a cluster-randomized controlled trial investigating the effects of cool-roof use on mental health outcomes in Ahmedabad.

The trial will quantify whether cool roofs are an effective passive home cooling intervention with beneficial health effects for vulnerable populations in Ahmedabad. Findings will inform regional policy responses on scaling cool roof implementation to protect people from increasing heat exposure driven by climate change.

Arms and Interventions

What is the study measuring?

Primary Outcome Measures 

Secondary Outcome Measures 

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Collaborators 

• Heidelberg University
• Rutgers University
• Boston University
• Indian Institute of Public Health, India
• Sika
• University of Auckland, New Zealand

Investigators 

• Principal Investigator: Collin Tukuitonga, University of Auckland, New Zealand

What’s our take on it!

Cool roofs could be one of the most powerful tools we have across society:
lower heat, lower energy use, lower CO₂, lower peak demand, lower grid stress, cooler cities, better human and animal health, less water use, better sleep, better productivity, fewer heat-related deaths. The value chain is huge.

But here’s the blunt truth:

Most cool roofs today are just white paint dressed up as climate tech.

They reflect well on day one, degrade fast, chalk, collect dirt, lose reflectance, and fail under real solar loading. The “SRI” score disappears and the benefit goes with it. You’re lucky to get 18 months of genuine performance, and 5–10 years before the coating needs replacement — which means waste, money, maintenance, landfill and zero real climate impact.

Why? Because nearly all of them are:

• straight acrylic bases
• titanium dioxide pigment for colour
• no infrared blocking
• no thermal mass control
• no ceramic structure
• no defence against UV breakdown

They rely entirely on visible-light reflectance, while 53% of the solar spectrum — the infrared heat — punches straight through. White paint can’t stop it.

Why is this a problem?

Because it means we’re solving the wrong problem — and getting the wrong results.

Here’s the reality, straight:

1. You can’t cool a roof if you only manage the visible spectrum.

Reflecting light is not the same as blocking heat.
Most “cool roofs” only work on the 44% of solar energy in the visible band.
They do nothing to control the 53% that’s infrared, which is where the actual heat sits.
So the roof still loads up with heat. The building still gains heat. HVAC still works overtime.

2. Fast reflectance decay kills real-world performance.

Once the white coating loses its reflectance — dirt, chalking, UV oxidation — performance collapses.
Lab results might say “0.80 SRI”, but 12–18 months later that drops to 0.55…0.40…0.30.
Heat comes straight back in.
And the customer never knows why.

3. Acrylic systems are simply not engineered for harsh solar environments.

Acrylics soften, oxidise, chalk and embrittle under UV + heat.
That means:

• cracking
• flaking
• water retention
• faster dirt pickup
• short duration (5-10 years)
• thermal stress cycling
  And eventually, total failure.

4. No IR blocking = no protection of the substrate.

If the coating lets infrared heat through, the roof deck still bakes.
That means:

• higher internal temps
• thermal expansion and contraction
• membrane fatigue
• premature roof ageing
• higher cooling energy demand
  It’s a band-aid trying to cover a bullet hole.

5. No thermal diffusivity control = heat moves into the building anyway.

Even if a roof looks “white”, heat still moves through the material quickly.
High diffusivity = fast heat penetration.
So the interior heats up hours earlier and stays hot hours longer. Better than black!

6. Short lifespan = more carbon, more waste, more cost.

If a cool roof needs to be recoated every 5–10 years, the climate benefit evaporates:

• more manufacturing
• more raw materials
• more transport, labour, scaffolding
• more landfill
• more emissions

The net CO₂ “savings” disappear once you add real lifecycle cost.

7. Policy gets distorted — and the wrong solutions get scaled.

Governments adopt “cool roofs” thinking they’re climate solutions.
But if the coating degrades, loses reflectance, and delivers almost no IR control…
the city doesn’t actually cool.
The grid doesn’t get relief.
People aren’t measurably safer in heatwaves.

It becomes climate theatre instead of climate action.

8. The community pays for a solution that doesn’t solve heat.

People expect lower indoor temperatures.
Instead, they get:

• hotter rooms than promised
• rising electricity bills
• heat stress
• poor sleep
• reduced productivity
• ongoing repainting cycles

It erodes trust — and it delays real adoption of proven heat-blocking technologies.

Now imagine the opposite.

A coating that blocks infrared, slows thermal diffusivity, resists UV, resists breakdown, and maintains performance for decades. A coating that doesn’t just shine white for a lab test — it actually prevents heat from entering the substrate, regardless of colour, dirt, or weathering.

That’s a different category.
That’s not “cool roof”.
That’s heat-block technology.

IR blocking means:

• the building envelope takes less heat load
• air conditioners run less
• peak grid demand drops
• indoor temperatures fall naturally
• asphalt softens less
• urban heat island shrinks
• animals suffer less heat stress
• school performance improves
• mental health improves
• worker safety improves
• CO₂ drops for every kWh avoided
• far less maintenance, waste and repainting
• critical infrastructure lasts longer

All from controlling the radiation load at the surface — not trying to counteract it with bigger HVAC systems, higher energy bills or “whiter whites”.

The industry’s problem is simple:

They’re stuck in a reflectance mindset because it’s easy to market, easy to test, and easy to sell. But reflectance alone is primitive. It ignores physics. It ignores infrared. It ignores thermal diffusivity. It ignores durability. It ignores real world conditions.

If we want cool roofs to actually solve societal problems at scale, they need to stop being just another acrylic white paint — and evolve into materials that block heat, not simply reflect light. Similarly this trial will be based on an acrylic coating…this will be a problem in 5-10 years. While the trial

About the Trial

• The trial is on ClinicalTrials.gov as NCT07251218 and on other registries/aggregators. It’s listed as a cluster randomised controlled trial in Ahmedabad, India, focused on mental health outcomes related to cool-roof use. Link
• A related global trial, NCT06579950, is running in multiple countries (Burkina Faso, Mexico, India, Niue) looking at cool roofs and health (including mental health), indoor environment and economic outcomes. Link
• Several closely related Ahmedabad cool-roof studies (with full PDFs) already exist, but they are not this RCT: a 2020 cool-roof indoor temperature study in Ahmedabad slums, a 2024 informal-housing heat adaptation study, and a 2024 “Hot Take: Cool Roofs” report on women workers. Link

Given that, here are 5 key points about this mental-health trial, based on the official registration and linked programme documents:

1. Design and aim
   It is a cluster randomised controlled trial (cRCT) testing whether applying sunlight-reflective “cool roof” coatings to homes in low-income communities in Ahmedabad improves mental health outcomes (depression, anxiety, eco-anxiety, PTSD, anger) by reducing indoor heat exposure. Link
2. Population and scale
   The trial expects to enrol about 800 adult household occupants in informal / low-resource housing, randomising clusters of households to either receive a cool-roof coating or continue with usual roofs (control). The focus is explicitly on people living in hot, poorly insulated dwellings who are particularly vulnerable to extreme heat. Link
3. Intervention
   The intervention is a sunlight-reflective cool roof coating applied to existing roofs, designed to lower indoor temperatures and reduce energy use (fans, AC where present) by reflecting more solar radiation. It is a passive adaptation: once installed it does not require behaviour change or power to keep working. Link
4. Outcomes and follow-up
   Primary outcomes are mental-health measures (e.g. standardised scales for depression, anxiety, aggression / anger, eco-anxiety, PTSD) assessed at baseline and repeatedly over roughly 12 months, capturing hot and cooler seasons. Secondary outcomes include indoor temperature and humidity, perceived thermal comfort, sleep, and possibly economic indicators (healthcare visits, productivity), aligning with the broader global cool-roof trial framework. Link
5. Status and policy intent
   The Ahmedabad mental-health trial is active and not yet complete. Registry entries show primary and overall completion currently expected around January 2026, so no results or protocol PDF have been posted yet. The authors explicitly state that findings are intended to inform city and regional policy on scaling cool roofs as a low-cost climate-adaptation and mental-health protection measure for vulnerable communities. Link

Other publications for Heat Management in Ahmedabad:

• A 2020 indoor-temperature study in Ahmedabad slums showing that simple cool-roof interventions (Thermocol insulation, solar-reflective white paint, ModRoof) significantly reduced indoor temperatures compared with tin, asbestos and concrete roofs. Link
• A 2024 exploratory paper on cool roofs and health impacts in informal housing in Ahmedabad, which links cool roofs to reduced heat stress and discusses health pathways. Link
• A 2024 “Hot Take: Cool Roofs” report about women workers in an Ahmedabad slum, documenting lived experience of heat, productivity loss and the potential role of cool roofs in adaptation. Link

https://www.htsyndication.com/us-fed-news/article/clinical-trial%3A-assessing-the-effects-of-cool-roofs-on-mental-health-in-ahmedabad%2C-india/555776247

What’s missing in the Trial

The trial description reveals some weaknesses, gaps and possible blind spots – areas where it may not deliver the impact people hope, or where it could be improved. Here are what I see as the key concerns and possible focus areas for improvement. I call out which ones matter most if you’re evaluating this from a “real-heat-block vs marketing cool-roof” perspective.

⚠️ What the study may not deliver — or where it’s limited

1. Only visible-light reflectance and emittance — not true heat blocking or diffusivity

The intervention in the trial is a “sunlight-reflective cool roof coating.” That means the coating aims to increase solar reflectance (visible wavelengths) and thermal emittance (radiating some absorbed energy) — but it does not block infrared radiation or manage thermal diffusivity / conductivity. Link
For your kind of technology (ceramic, infrared-blocking coatings), that’s a critical gap. If the coating only reflects visible light, much of the thermal load (infrared heat) will still penetrate. So even if the trial finds modest mental-health benefits, that doesn’t validate the kind of deep “heat-block” performance you believe is essential.

2. Short-term or moderate reduction of indoor temperature — may not hit meaningful thresholds

A related informal-housing study in Ahmedabad found cool-roof interventions lowered indoor temperature by only about 1 °C to 1.5 °C on peak summer days. Link
Given that thermal discomfort, heat stress, sleep loss and health effects often require larger temperature reductions (especially in humid, poorly insulated housing), such small drops might not translate into strong or lasting mental-health benefits.

3. Confounding variables — housing type, ventilation, environment, occupant behaviour

Even with roof coatings, many factors influence indoor heat exposure: ventilation, ceiling height, building materials, occupancy, shade/trees, humidity, occupant behaviour (use of fans/AC), maintenance, surrounding environment, social conditions, etc. The informal-housing study acknowledges that indoor comfort improvements came from a mix of factors, not just the roof coating. Link
That means isolating the effect of the “cool roof” — especially on mental health — will be hard. The trial’s design tries to control by randomising households, but real-world variability may still swamp the effect.

4. Mental-health measures rely on self-report — subjective, influenced by many non-thermal factors

They use self-reported questionnaires (PHQ-9, GAD-7, SWEMWBS, etc.) over 12 months. Link Mental health is influenced by far more than indoor temperature — socio-economic status, stress, noise, community support, work, health, social events. If these aren’t tightly controlled or stratified, the temperature effect may be lost.

5. Durability and long-term performance omitted

The trial assumes a “coating once, measure for 12 months” model. It doesn’t assess long-term degradation (weathering, dirt, chalking, infrared absorption over years, maintenance cycles). That matters a lot in real life. If the coating’s reflectance drops — the cooling benefit vanishes. Their protocol doesn’t appear to include follow-up beyond 12 months. Link

6. Blanket assumption the coating behaves same across climates & building types

They’re testing in Ahmedabad — a hot, likely dry/rainy, humid-wet climate (depending on season), with particular building typologies (slums, informal housing). Results may not transfer to other climates (humid tropics, arid zones, temperate zones) or housing types (metal, concrete, insulated, uninsulated, multi-storey). The study doesn’t model that diversity in its design.

7. Overpromised “mental health → climate policy” pathway

Even if they detect a statistical effect on depression/anxiety, scaling that to “heat adaptation policy” requires more evidence: long-term health outcomes; repeatability; cost-benefit; durability; maintenance regimes; social, behavioural, economic context; building stock diversity. This trial is only a first step.

✅ What they should focus on — to make the data useful for serious “heat-block / passive cooling” advocacy

If I were designing the “next generation” of a study (from your perspective), here’s what I’d demand:

• Use infrared-blocking, low-diffusivity, ceramic-based coatings (not just reflective acrylic paint). That matches physics, not marketing.
• Measure roof surface temperature, heat flux through roof deck, indoor air temperature, humidity, thermal comfort, and energy use — not just self-reported health. Include objective data (sensors, thermography) over months/years.
• Monitor durability and degradation: reflectance/diffusivity/emissivity loss over time, dirt accumulation, weathering, maintenance needs.
• Collect long-term health and comfort data, over several years — not just 12 months. Heat stress effects often accumulate.
• Include diverse building typologies, climates, occupancy behaviours — to test how coating performs in real-world variation.
• Evaluate cost, lifecycle carbon, maintenance, waste — to compare benefits vs hidden costs realistically.
• Correlate thermal performance with energy consumption, peak load demand, occupant behaviour, and urban micro-climate — to scale results to city- or region-level impacts.

My Take — This Trial Is a Useful First Step, But It Can’t Validate Real “Heat-Block” Solutions

This study could show whether reflective cool roofs yield measurable mental-health or comfort improvements — and that would support the case for passive cooling in informal housing.

But from a serious performance and climate-resilience viewpoint (infrared blocking, lifecycle performance, energy and carbon savings, durability) — this trial misses the point.

If the industry wants real solutions, not marketing illusions, the focus must shift. Reflective white paints may help a little. But they won’t deliver long-term structural change needed across entire communities and neighbourhoods.