Install a Canadian well (earth-air heat exchanger)

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A Canadian well (also called an earth-to-air heat exchanger, or 'puits provençal' in French) draws outdoor air through pipes buried 1.5–2.5m underground, where soil temperature stays stable year-round (around 12–15°C / 54–59°F), before delivering the pre-cooled air into the building.

Outdoor air is drawn through buried pipes (PVC or polyethylene, 150–200mm diameter) running 30–50 meters underground. The soil exchanges its temperature with the air as it passes through, before it's fed into the building's ventilation system (ideally a heat-recovery ventilation unit). In winter, the same system pre-warms incoming air.

• Passive cooling with almost no electricity use (just a fan)
• Works year-round: pre-warms air in winter, pre-cools it in summer
• Quiet, durable system with no refrigerant gases
• Greatly reduces or eliminates the need for mechanical air conditioning

1. Commission a soil and feasibility study (ground type, available space)
2. Size the pipe network to the air volume you need to treat (typically 30–50m of pipe)
3. Have pipes installed by a professional with proper slope for condensate drainage
4. Connect the system to your ventilation unit or air handling system
5. Schedule regular filter maintenance and humidity checks inside the pipes