Building cooler homes for a hotter future in Indonesia

In Piayu Village in Batam’s Sei Beduk subdistrict, many families live in homes with metal roofs and cement-sheet materials that absorb and retain heat. Rapid urban development has reduced green space that once helped moderate local temperatures, while air conditioning remains beyond the reach of many households.

Evidence generation

Arwin Soelaksono, Program Director of Habitat for Humanity Indonesia, says the project is designed to generate evidence that can improve housing solutions for low-income communities. “We are testing which cooling measures work best, what they cost and whether families are willing to adopt them. The findings will help us design more effective and affordable homes for communities facing rising temperatures.”

According to Jim Kendall, a consultant supporting the project, Batam’s relatively stable climate makes it an ideal research setting because interventions can be tested under comparable conditions throughout the year. Kendall led design of the project with Karnen Dasen, Program Development Manager, and worked with Rudi Nadapdap, Senior Manager of Field Operations, both from Habitat Indonesia, to provide technical support in the project’s implementation.

Many studies focus on individual cooling measures in isolation, while Batam’s project compares multiple interventions side by side, helping identify which approaches deliver the greatest benefit for families.

While many studies measure air temperature and humidity, this research is using Wet Bulb Globe Temperature (WBGT) Meters to measure heat stress, a more accurate measure of what the human body actually feels by including radiant heat that significantly influences how hot a home feels to its occupants, particularly in low-cost housing.

Results to date

By mid-September 2026, all 10 new climate-responsive homes had been completed, and 30 existing homes had been retrofitted using five passive cooling approaches, including roof ventilators, solar-reflective paint, reflective roof insulation and ceiling, rooftop gardens and external roof shading systems. The remaining retrofits of the 10 control group homes will be completed shortly.

Several phases of thermal performance testing were conducted. These included baseline testing to see the performance before any improvements, and testing of singular and combined retrofits to explore the increased benefit of combining separate interventions. For example, some households that installed roof ventilators also applied solar-reflective paint or other variations. Performance testing was completed on October 1, and the data is currently being analyzed to identify the findings of this research.

“We’re looking at three key factors: cost-effectiveness, thermal performance and cultural acceptability,” says Kendall. “Understanding that balance is essential if these solutions are to be scaled.

The lessons emerging from Batam will help inform future climate-responsive housing designs across Indonesia and other Habitat entities operating in similar climates. Habitat Indonesia plans to combine findings from Batam with earlier passive cooling research on Java Island to identify the most effective approaches for different communities.

Adapting to changing climate

For Soelaksono, the importance of the work extends beyond comfort. Extreme heat can worsen health risks, reduce productivity and diminish quality of life, particularly for families already facing economic hardship.

“Passive cooling offers an affordable way for communities to adapt to a changing climate. We hope this research can help make housing improvements more sustainable and accessible for those who need them most,” he says.

Since 1997, Habitat for Humanity Indonesia has been working with families to build or improve a place they call home. Through multisector partnerships, Habitat builds resilient homes with communities, strengthens policies and inspires action for housing. Learn more at habitatindonesia.org