The Climate Battery
The Problem
Greenhouses trap sunlight during the day. They get hot — sometimes too hot. But the moment the sun sets, all that heat escapes through the glass. By morning, the temperature inside can be barely above freezing. You either burn propane, run electric heaters, or accept dead seedlings after the first hard frost.
The Idea
A climate battery stores daytime heat underground and releases it at night. The concept is simple: blow warm greenhouse air through pipes buried in the soil. The soil absorbs the heat. When temperatures drop, the thermal mass radiates warmth back up. No fuel, no grid power, no moving parts beyond a single fan.
How It Works
During the day, a thermostat-controlled fan pulls warm air from the greenhouse peak down through a vertical riser into a network of buried corrugated pipes. As air travels through the pipes, it transfers heat to the surrounding soil. The cooled air returns through a second riser on the opposite end. At night, the process reverses — the warm soil heats the cool air passing through.
Our Design
We designed this for a 4 × 5 meter greenhouse. Eight 110mm corrugated drainage pipes run the full length in two layers — four at 80cm depth, four at 120cm. Each pipe sits in a gravel bed — 15cm of clean 20mm gravel surrounding the pipe on all sides. The gravel prevents soil from clogging the corrugations and ensures condensation drains freely instead of pooling. A 12V inline fan mounted in the south riser moves air at roughly 100–150 m³/h. The whole system runs off a 50W solar panel and a small battery. No grid connection.