Intervention(s)
This study investigates the potential for market-based scaling of cool roof technology in low-income urban neighborhoods in Ahmedabad. We combine an incentive-compatible WTP elicitation with three randomized treatment arms to assess whether providing additional interventions about cool roofs can increase households’ WTP.
Cool roofs are roofs that are coated with a white, sunlight-reflective paint that has been shown to reduce indoor building temperatures by up to 4-5°C (Kolokotroni et al., 2018). Unlike active cooling solutions such as air conditioning, cool roofs require no sustained energy input and only minimal maintenance, making them particularly suitable for low-income households facing unreliable electricity supply and financial constraints. Beyond direct thermal comfort and health benefits, cool roofs can reduce building energy consumption and contribute to mitigating the urban heat island effect (Broadbent et al., 2022; Santamouris, 2014). Despite their potential for reducing indoor ambient temperature, residential adoption in Indian cities relies primarily on NGO-led programs providing the coating free of charge (Akbari et al., 2011; Bunker et al., 2024; Natural Resources Defense Council, 2019, 2022; Mahila Housing Trust, 2024). This study examines whether and under what conditions households are willing to invest in the technology.
To measure household WTP, we employ the Becker-DeGroot-Marschak (BDM) mechanism, an incentive-compatible elicitation method in which respondents state their maximum willingness to pay for the cool roof coating offered at a subsidized price. A binding price is then drawn randomly from a pre-specified distribution: if the stated WTP equals or exceeds the drawn price, the household receives the product at that price; otherwise, no transaction takes place. The BDM mechanism incentivizes truthful revelation of preferences, as strategic misreporting cannot improve the respondent’s outcome. Within our study, the technology is offered at a subsidized market price, reflecting the study’s goal of informing realistic subsidy policies rather than measuring demand at full cost.
To test whether scalable, low-cost interventions can increase household WTP, participants are randomly assigned to one of four conditions: a control group and three treatment arms.
Participants in all four groups will first be invited to participate in a standardized community-based information session, in which the cool roof technology will be introduced. These sessions will focus on the basic functioning of cool roofs. Conducting such an information session before the actual WTP experiment is essential in a context where many participants might have never heard before of the product and would hence not be able to make an informed bid within the context of a WTP experiment.
In addition to the community-based information session, individuals are assigned to one of three treatment arms, thus receiving one of the following interventions:
Treatment 1 – Household education-entertainment video: Households in this arm are shown a short animated video of approximately 1.5 minutes. The video will be shown to the participants on tablets during the information session. The video explains the functioning of cool roofs and communicates the associated health and co-benefits. The video is also designed to be easily replicable and scalable. Informational interventions of this type have been shown to change behavior in similar contexts and might also be able to shift technology adoption (Grady, 2021).
Treatment 2 – Community Demonstration: In selected wards, a demonstration cool roof is installed on a building accessible to the local community. Residents are able to visit the site, observe the coating directly, touch the surface, and enter the building to experience the temperature difference firsthand. This experiential exposure addresses a key barrier to adoption identified in the literature, namely limited familiarity with and trust in new building technologies. The demonstration roof thus provides tangible, locally anchored evidence of the technology’s performance.
Treatment 3 – Combined Intervention: A third group of households receives both the household education-entertainment video and community demonstration. This arm allows us to test whether the two interventions are complementary and whether their combined effect on WTP exceeds that of either component alone.
Surrounding the quantitative experiment, an extensive qualitative research program explores both demand- and supply-side factors shaping cool roof adoption. This includes stakeholder interviews with government officials, community leaders, and cool roof producers/vendors, and focus group discussion to investigate household perceptions, decision-making processes, and barriers to adoption. The qualitative findings informed the design of the interventions and will be used to interpret the quantitative results, enabling a comprehensive assessment of the conditions under which market-based scaling of cool roof technology is feasible in Ahmedabad and comparable urban settings.