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?

Exposed thermal mass (masonry, rammed earth, slab)

Passive

One of 2 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.

Absorbs daytime heat and releases it as temperatures drop, smoothing daily swings.

Cost

Medium

Upkeep

None

Skill to build

None

Lifespan

Matches structure lifespan (masonry/rammed-earth/slab mass doesn't wear out under normal thermal cycling)

Embodied carbon

Medium

Space / material use

High

Output timing

Continuous process

Skill to repair

None

Inputs

• Low-grade heat

Outputs

• Low-grade heat

Compare the 2 ways to meet this need

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

• Exposed thermal mass (masonry, rammed earth, slab) (This page)
  Can I use it? Works in a flat · No rebuilding needed
  What does it cost me? Upfront cost: Medium · Skill to build: None · Upkeep: None · Change to daily life: None · Works without the grid: Yes
  Choose it if you are building with heavy materials and want them to smooth out the day’s temperature swings.
• Water-based thermal mass (drum / water wall)
  Can I use it? Works in a flat · No rebuilding needed
  What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Light · Change to daily life: None · Works without the grid: Yes
  Choose it if you want to add heat storage to an existing sunny room, cheaply.

Sources

• Thermal storage wall design manual, 43 pages of build procedure

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.