What If You Lived Underground?

Underground homes maintain a steady ~55°F year-round with no heating or cooling, which is exactly why 30,000+ people already live in the underground town of Coober Pedy, Australia. Living below the surface saves on energy, blocks weather, and requires only one infrastructure change to scale: artificial sunlight.

Real underground cities exist now. Here's what life would look like.

The temperature trick

Below about 30 feet, soil temperature stays nearly constant year-round. In most of North America that constant is 50-60°F. In hotter regions it can be 65°F. Either way, a deep underground home is cool in summer and warm in winter without HVAC.

This is why basements feel pleasant on August afternoons and weirdly warm in February.

Real underground cities

Three working examples:

• Coober Pedy, Australia: Opal mining town in the desert. Surface temperatures hit 122°F. Locals live in carved-out "dugout" homes — full living rooms, bedrooms, churches, hotels, all underground.
• Cappadocia, Turkey: The ancient city of Derinkuyu had 18 levels and housed 20,000 people for centuries. Carved into volcanic tuff.
• Montreal Underground City: 20 miles of pedestrian tunnels connecting offices, malls, and metro stations. Heavily used in winter.

The light problem

Humans evolved with sunlight. Without it, vitamin D production drops, circadian rhythms break, and Seasonal Affective Disorder hits hard within 2-3 weeks.

Solutions: full-spectrum LED lighting, light wells (vertical shafts that deliver direct sunlight), and fiber-optic sunlight piping (yes, this is real — Parans makes these systems).

Coober Pedy homes typically include skylights or shafts to surface for psychological reasons more than lighting reasons.

The air problem

Sealed underground space accumulates CO₂ fast. A typical 1,500 sq ft house with 4 people produces enough CO₂ in 8 hours to push indoor air past comfort thresholds.

Solution: forced ventilation with surface intake. Same systems used in submarines and modern skyscrapers. Underground living needs roughly 2× the ventilation infrastructure of above-ground homes.

The architecture

Underground rooms can be larger and stranger than above-ground rooms because gravity loads change. You don't need walls to support roofs — the surrounding rock does that. Domed living rooms 40 feet across are easier to build underground than above.

Wiring and plumbing get cheaper because you can route through any rock void. But initial excavation costs roughly 2-4× standard construction.

Daily life would shift

Without natural sun cues, you're more dependent on clocks and circadian-mimicking lights. Many underground residents report sleeping deeper and longer because there's zero light or noise leakage from outside.

Storms, hot summers, and cold winters become weather other people experience. Tornado season is just a notification.

Society would compress vertically

Cities could go 20-50 levels down with the same surface footprint. Helsinki already has a master plan for an "underground master plan" with 400+ identified facility sites including swimming pools, a data center, a church, and parking.

Real estate inverts. Surface land becomes parks, farms, and solar arrays — too valuable for housing. Underground levels become primary residential.

The downsides

• Mental health: Some people get acute claustrophobia. Studies in submarine crews show ~5% develop persistent issues.
• Vitamin D deficiency: Without supplementation, becomes endemic.
• Flooding: Underground living is fatally vulnerable to water table changes.
• Earthquakes: Counterintuitively, underground spaces are usually safer than surface buildings — but failure modes are catastrophic when they happen.

Why it might happen anyway

Climate change makes surface living harder in some regions. Cooling requirements alone could make underground homes economical in places like Phoenix, Dubai, and parts of Australia. Coober Pedy chose underground because the alternative was 122°F summers; many cities may face the same calculus by 2050.

Want more "alternative living" thought experiments? See what if you woke up on Mars or what if you could shrink to ant size.