Underground spaces build up carbon dioxide, moisture and sometimes radon, so they need at least two ventilation points, one high for exhaust and one low for intake. Daylight comes from a glazed south wall, light wells and clerestory windows, which keep the interior from feeling buried.
Ventilation and daylight are the two things a buried room must be given by design, because the earth supplies neither.
Air And Light Both Have To Be Brought In
A room with earth on all sides has no windows to open. Without a designed air path it develops carbon dioxide buildup, condensation and, in some geological areas, radon accumulation. Light has the same problem: a room with no daylight feels like a cellar, which is the mark of an unsuccessful design.
- Air: Ventilation Shafts and Chimneys.
- Light from above: Light Wells and Clerestories.
- Light and heat from the front: South-Facing Glazing.
What You Need
- A high opening and a low opening, connected to the outside by shafts.
- A glazed front or an opening toward the sun.
- Rain hoods and mesh for shaft tops.
Method: Plan Air And Light Together
Step 1: Place the low intake and the high exhaust at opposite ends of the room so air sweeps through it.
Step 2: Orient the glazing to the sun; in the northern hemisphere that is south.
Step 3: Add a light well or clerestory for rooms that are deep.
Step 4: Protect all openings from rain, animals and ingress of surface water.
Step 5: Check the result at the wettest and the hottest time of year.
Common Mistakes
- One opening only. No circulation.
- Shafts too low. Rain and animals enter; the parent article asks for at least 60 cm above ground.
- Light wells without drainage. They collect rain.
Safety
Bad air kills quietly
Carbon dioxide is heavier than air and pools at floor level. Dizziness, headache or drowsiness in a buried room mean get out and into fresh air. Never use a flame to test the air. See Carbon Monoxide Risks for stove hazards.
What’s Next
- Learn next: Ventilation Shafts and Chimneys
- Combine with: Passive Solar Building Design