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Resting Heart RateNCT07592117

Assessing the Effects of Cool Roofs on Indoor Environments and Health in Tavua, Fiji

A study testing Cool roof in people with Resting Heart Rate and Blood Glucose Control, run by Aditi Bunker at 1 site in Fiji.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts
Official record
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Trial summary

Ambient air temperatures in Fiji are increasing due to climate change. Solutions are needed to build heat resilience in communities and adapt. Sunlight-reflecting cool roof coatings may passively reduce indoor temperatures and energy use to protect home occupants from extreme heat. Read more about this study

Who is it for?
Ages 18 years and olderHealthy volunteers can take part
What is being tested?
Cool roof
Could I receive a placebo?
No, everyone receives an active treatment
How many people
800 participants
Where
1 siteFiji
Study dates
18 May 2026to 1 Sep 2027
Phase
Interventional
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • Permanent household resident.

Who cannot join

  • Roof damage, inaccessible or instability of roof adversely affecting cool roof coating application.
  • Participant unable to provide written/verbal informed consent.

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Fiji1 site
  • Fiji National University

    Suva

    Donald Wilson, +6798053931, donald.wilson@fnu.ac.fj

    Donald Wilson

About this study

Official title: A Cluster Randomised Controlled Trial (cRCT) Evaluating the Effects of Cool Roofs on Health, Environmental and Economic Outcomes in Tavua, Fiji

Ambient air temperatures in Fiji are increasing due to climate change. Solutions are needed to build heat resilience in communities and adapt. 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 in Fiji are susceptible to increased heat exposure.

Heat exposure can instigate and worsen numerous physical, mental and social health conditions. 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 physical, mental and social 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 in Fiji. To meet this goal, the investigators will conduct a cluster-randomized controlled trial to establish the effects of cool roof use on health, indoor environment and economic outcomes in Tavua, Fiji.

Read the detailed description

Increasing heat exposure from climate change is causing and exacerbating heat-related illnesses in millions worldwide - particularly in low-resource settings. Heat exposure can instigate and worsen health conditions, including cardiovascular, metabolic, endocrine and respiratory disease, heat-related illnesses, pregnancy complications, and mental health conditions. Adaptation is essential for protecting people from increasing heat exposure. The built environment, especially homes, is ideal for deploying interventions to reduce heat exposure and accelerate adaptation efforts. However, there is currently a lack of global, empirical evidence guiding the uptake of interventions to reduce heat stress in low-resource settings.

Cities and towns of LMIC are among the most vulnerable to the adverse impacts of climate change and are likely to experience increases in ambient air temperature over the coming decades. People in Fiji are exposed to year-round heat and low humidity. The combined burden of heat and NCDs places Fiji's population at greater risk of adverse health effects from heat extremes.

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 health, environmental and economic outcomes in Fiji.

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

Being tested
Cool roof
Keywords
Hot temperature, Humidity, Housing, Heart rate, Cardiovascular, Depression, Mental health, Blood glucose, Diabetes, Cool roof, Heat stress
Medical subject headings
Depression, Personal Satisfaction, Dehydration, Sleep Initiation and Maintenance Disorders, Aggression, Psychological Well-Being, Diabetes Mellitus, Heat Stress Disorders

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Cool roofOther

    Cool roofs are a heat-reflecting material that can be applied to existing household roofing in the form of a liquid-applied membrane. Cool roofs work by increasing solar reflectance (the ability to reflect the visible wavelengths of sunlight, reducing heat transfer to the surface) and thermal emittance (the ability to radiate absorbed solar energy) thereby reducing the amount of heat transferred into the home.

Study groups in NCT07592117
Study groupRoleWhat they receive
Cool roofExperimentalHouseholds will receive sunlight reflecting 'cool roof' coating on their roofs.
Receives: Other: Cool roof
No cool roofNo interventionNo cool roof application. Households will keep their original roofing for the duration of the trial.

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Resting heart rate

    Resting heart rate in beats per minute measured as the average of three readings in the left arm over one hour using portable automated sphygmomanometers.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  2. Blood glucose control

    Three month average of blood glucose in mmol/mol measured as glycosylated hemoglobin (HbA1c) using capillary blood and the HemoCue® HbA1c 501 System.

    Measured: Two measurements will be taken: one at baseline and one in the last month of three consecutive hottest months.

  3. Depression

    Self-reported presence and frequency of symptoms of depression assessed using aggregate score of the Patient Health Questionnaire 9 (PHQ-9). Minimum score of 0 and a maximum score of 27 with a higher score meaning a worse outcome.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

Secondary outcomes (22)
  1. Heat-related symptoms

    Self-reported heat-related symptoms in the past month, assessed using a recall questionnaire.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  2. Physician diagnosed heat-related illnesses

    Self-reported new diagnosis from a medical practitioner of a heat-related illness in the last month assessed using a recall questionnaire.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  3. Food insecurity

    Self-reported experience based measure of individual food security assessed using the Food Insecurity Experience Scale (FIES).

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  4. Diet quality

    Self-reported individual food group consumption in the previous 24 hours assessed using the Diet Quality Questionnaire (DQQ).

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  5. Hospitalization

    Self-reported overnight hospital stay in the past four weeks assessed using a recall questionnaire.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  6. Health-related quality of life

    Current self-reported health-related quality of life assessed using the EuroQol EQ-5D-5L quality assessment tool. The minimum and maximum scores for the EuroQol EQ-5D-5L quality assessment tool are -0.59 and 1, respectively. A score of 1 represents the best possible health state, while scores below 0 indicate health states that are considered worse than death.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  7. Indoor thermal comfort

    Self-reported household heat, humidity and comfort experience over the last four weeks assessed using a recall questionnaire.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  8. Coping ability

    Self-reported coping strategies for high indoor temperatures assessed using a recall questionnaire.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  9. Life satisfaction

    Current self-reported life satisfaction assessed using the World Values Survey. Values can range from 1 to 10 with a higher score representing greater life satisfaction.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  10. Healthcare provider utilization

    Self-reported healthcare provider utilization in the past four weeks assessed using a recall questionnaire.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  11. Systolic Blood Pressure

    Maximum blood pressure (mmHg) during systole measured as the average of three readings in the left arm over one hour using Blip portable automated sphygmomanometers.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.

  12. Diastolic Blood Pressure

    Minimum blood pressure (mmHg) during diastole measured as the average of three readings in the left arm over one hour using Blip portable automated sphygmomanometers.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.

  13. Intimate partner violence

    Recall questionnaire assessing the presence or abscence intimate partner violence in the past 4 weeks.

    Measured: Eight measurements: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  14. Inner Ear Canal Temperature

    Internal body temperature (℃) measured once using Braun digital ear thermometer.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.

  15. Dehydration

    Dehydration as indicated by urine specific gravity ≥1.020 measured as urine specific gravity using Siemens Multistix SG dipstick.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  16. Sleep quality

    Self-reported sleep distrubance assessed using the Athens Insomnia Scale (AIS). Values range from 0 to 24 with a higher score indicating a worse outcome.

    Measured: Eight measurements: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  17. Aggression

    Self-reported personal aggresion assessed using the Buss-Perry Aggression Questionnaire-Ultra Short Form (BPAQ-ML).

    Measured: Eight measurements: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.

  18. Productivity

    Self-reported job absenteeism and presenteeism assessed using the Health and Work Performance Questionnaire Short Form (HPQ-SF).

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.

  19. Indoor air temperature

    Indoor air temperature (℃) measured using Hobo MX1101 heat and humidity measurement device.

    Measured: Measurements at 15 minute intervals for 12 months.

  20. Indoor relative humidity

    Ratio of the amount of water vapor present in the air to the greatest amount possible at the same temperature (%) measured using Hobo MX1101 heat and humidity measurement device.

    Measured: Measurements at 15 minute intervals for 12 months.

  21. Indoor heat index

    Index that combines air temperature and relative humidity (℃) based on temperature and humidity measurements from the Hobo MX1101 heat and humidity measurement device calculated using the formulae endorsed by the US National Oceanic and Atmospheric Administration.

    Measured: Measurements at 15 minute intervals for 12 months.

  22. Household energy expenditure

    Self-reported household energy expenditure assessed using a recall questionnaire from the head of the household.

    Measured: Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted18 May 2026
  2. Study start18 May 2026 (estimated)
  3. Primary completion1 Sep 2027 (estimated)
  4. Study completion1 Sep 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Masking
Double blind
Who is masked
Investigator, Outcomes assessor
Enrolment
800 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07592117
Sponsor's protocol ID
3728168
Other IDs
226745/Z/22/Z
Status last verified
May 2026
First submitted
11 May 2026
Last updated
18 May 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: Data that can be shared unconditionally underpinning the published research articles will be made available to other researchers at the time of publication, and data will be linked via the article DOI. Data that cannot be unconditionally shared upon publication owing to confidentiality or data protection requirements will be identified as such and a contact email will be provided in relevant publications for data access enquiries by other researchers. Individual names of study participants and identifying factors will be removed prior to data sharing. It is expected that demographic data of people at the study sites (family size and composition, basic socioeconomic indicators) may contain personally identifiable information and location data. All such data will be removed prior to storage on online data repositories and therefore will be available to be publicly shared at the time of publication of manuscripts.

Questions about this trial

What is this clinical trial studying?

A study testing Cool roof in people with Resting Heart Rate and Blood Glucose Control, run by Aditi Bunker at 1 site in Fiji.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 1 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: opening soon, as of the sponsor's last update on 18 May 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Fiji. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Aditi Bunker (+49 6221 565344, aditi.bunker@uni-heidelberg.de), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Resting heart rate (time frame: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 May 2026.

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