Climate-Responsive Passive Solar
Climate-responsive passive solar in the Trans-Himalaya
Nepal's mountain communities live in some of the coldest inhabited environments on Earth, increasingly in concrete buildings designed to urban standards that fail in freezing winters. In the Dho Tarap valley (4,000 m) in Dolpo, the Dolpopa community is reclaiming vernacular, climate-responsive design — a process HICS has supported through more than seven years of embedded work. This programme adds what has been missing: empirical thermal data.
Twenty probes, cast into the building
As construction of the next building begins, HICS is installing a first set of 20 waterproof DS18B20 digital temperature probes embedded directly into the structure — in the foundation, through the walls, and across the Trombe wall — with more sensors added in later phases. Because the probes are cast in during construction, they measure what surface sensors cannot: how the building's thermal mass actually stores and releases heat. Connected for continuous thermal monitoring, they turn the building into a long-running experiment.
Foundation probes ▸
Track how the ground and footing buffer the interior against the deep cold of the Dolpo winter — the thermal mass beneath the floor.
Wall probes ▸
Placed through the wall section to measure the temperature gradient across it, revealing the wall's real-world thermal resistance (U-value) rather than a handbook figure.
Trombe wall probes ▸
A Trombe wall absorbs solar gain during the day and releases it at night. Probes across its thickness capture the charge–discharge cycle that is the heart of passive solar performance.
The probes use the 1-Wire DS18B20 in a waterproof stainless sheath — robust, cheap, individually addressable, and well suited to being embedded in masonry and concrete. The goal is a continuous dataset that lets us model and validate the building's thermal behaviour: comparing measured performance against simulation, and quantifying what passive solar design actually delivers at 4,000 m.
Heat flow through a Himalayan wall
Heat moves from warm to cold by conduction, described by Fourier's law:
For steady flow through a wall of thickness d and area A, the heat lost is set by the temperature difference and the wall's thermal resistance R = d/k:
Heating demand over a season is summarised by heating degree-days — the accumulated gap between a comfort base temperature and the daily mean, which the monitoring dataset lets us compute from real interior and exterior readings:
Crystal Mountain School, Dho Tarap valley, Dolpo (4,000 m).
DLP-001
Interior/exterior thermal record at Dho Tarap, 4,000 m.
Demonstration data · updates every 15 minutes
Thermal Sovereignty and Vernacular Resilience: Tracing Climate Adaptation and Technology Transfer in Dolpo, Nepal — a practitioner-led case study grounded in 7+ years of collaborative work with the Dolpopa community, triangulating longitudinal observation with in-situ thermal performance data. Pre-print forthcoming.
Construction is starting; the first 20 embedded probes are being installed now, with more to follow as the building rises. Live charts show demonstration data until the probe network reports continuously.