Lowtech Graph lists low-tech options for every need of a home. Here you can compare them, find tutorials to build them, and link them together into a circular system. Why low-tech?

Earth tube / ground-coupled air pre-conditioning

Passive

One of 3 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.

What your site needs

Ground area available for a buried intake duct run

A pipe buried in the ground that fresh air passes through before it enters the house. The ground a metre or two down stays at a steady temperature, so the air comes out warmer in winter and cooler in summer. It takes the edge off both heating and cooling.

Cost

Medium

Upkeep

Occasional

Skill to build

Intermediate

Lifespan

30-50 years for the buried duct itself if corrosion-resistant material used; the fan (if any) needs earlier replacement on its own cycle

Embodied carbon

Medium

Space / material use

Medium

Output timing

Continuous process

Skill to repair

Intermediate

Inputs

• Fresh air

Outputs

• Fresh air

Compare the 3 ways to meet this need

Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.

• Earth tube / ground-coupled air pre-conditioning (This page)
  Can I use it? Not in a flat · No rebuilding needed
  What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Light · Change to daily life: None · Works without the grid: Yes
  Choose it if you want fresh air warmed in winter and cooled in summer before it comes in.
• Earth-sheltered / semi-buried form (thermal stability)
  Can I use it? Not in a flat · New build only
  What does it cost me? Upfront cost: High · Skill to build: Intermediate · Upkeep: Light · Change to daily life: None · Works without the grid: Yes
  Choose it if you are building new and want indoor temperatures that stay even all year.
• Ground-coupled hydronic cooling loop (buried pipe + radiator)
  Can I use it? Not in a flat · No rebuilding needed
  What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Light · Change to daily life: None · Works without the grid: No
  Choose it if you want to cool an existing house on very little electricity.

Sources

• xpair.com (Tier B) / US DOE energy.gov (Tier A)

Limitations of this page

We don’t list sizing or quantities, as the yield of each technique depends on the quality of its build. The catalogue compares options but doesn’t dimension them. Regulatory notes are indicative, with a French example, and need to be confirmed locally.