HydroSob HeatShield

Rajasthan's cities get rain and heatwaves, just never at the same time. HeatShield stores one to fight the other.

It's a biodegradable pad made from biochar and natural fibres. It soaks up rainwater when it falls and releases it slowly through evaporation when the heat arrives, cooling the ground with no power. It also improves the soil, supports greenery and locks away carbon. We designed it for schools, parks and public spaces.

We entered competitions under two team names, Greentech Pioneers and Carbon Mat, but the product was always HydroSob HeatShield.

My part was the numbers and the build: costing the pad, modelling how far it could realistically scale, and prototyping it.

WinnerGSL Eco Edd Green School Pledge (€100)

Highly commendedGSL Global Goals Competition, Sustainability

Round 2Conrad Challenge

Winner Award certificate: Aarav Sacheti, project Greentech Pioneers, winner of the GSL Eco Edd Green School Pledge Challenge 2025/26 — Winner, GSL Eco Edd Green School Pledge Challenge 2025/26 (as team Greentech Pioneers).

Commendation Award certificate: Carbon Mat, highly commended for sustainability, Global Social Leaders Global Goals Competition 2025/26 — Highly commended for sustainability, GSL Global Goals Competition 2025/26 (as team Carbon Mat).

How it works: soak up the rain, release it as cooling vapour in the heat.

Render of the HeatShield pad: hexagonal biochar tiles that lock together

See the HeatShield padInterlocking hexagonal tiles, biochar and natural fibre