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This diagram explains the function of an Earth Air Tunnel (EAT), a passive heating and cooling system that uses underground pipes to regulate indoor temperatures year-round.
How it works:
Underground pipe system: Air passes through pipes buried at least 2 meters deep. At this depth, the ground temperature remains relatively stable compared to the surface.
Air inlet & outlet: Outside air enters through an inlet (chimney) and flows underground before entering the building through an outlet.
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In Summer:
Outside air: ~35 °C
Underground soil: ~25 °C
As hot air passes through the buried pipe, it cools down to 25 °C before entering the building.
➡️ The house stays cooler without mechanical air conditioning.
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In Winter:
Outside air: ~6 °C
Underground soil: ~16 °C
Cold air warms up to 16 °C in the buried pipe before entering the building.
➡️ The house stays warmer without extra heating.
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Benefits:
Energy-efficient: Uses natural ground temperature to reduce heating and cooling loads.
Low-cost operation: Only requires a fan for air circulation (if natural draft is insufficient).
Eco-friendly: Reduces dependence on electricity or fuel.
It’s a sustainable design principle often used in green buildings and passive architecture to maintain comfortable indoor climates naturally.
