Thermal Mass
This pattern is shaped by
Problem
Lightweight buildings — timber frame with drywall — respond instantly to temperature changes: hot when the sun shines, cold when it sets, overheated in afternoon and freezing by morning. The occupants are at the mercy of every weather fluctuation, and the mechanical systems run constantly to compensate.
Evidence and Discussion
Heavy materials — concrete, stone, brick, rammed earth, water — absorb heat slowly and release it slowly. A room with a concrete floor and masonry walls stays cool in summer heat and warm through winter nights, smoothing out the spikes that lightweight construction amplifies. The thermal flywheel effect is well-documented: buildings with high thermal mass maintain more stable interior temperatures with less energy input.
Therefore
in every room that receives direct sunlight or experiences temperature swings, incorporate thermal mass — a concrete or stone floor, a masonry wall, a water feature, or an earthen plaster surface. Place the mass where sunlight strikes it directly (south-facing floors, interior walls opposite windows). The mass should be exposed, not covered with carpet or drywall — you should be able to feel its coolness in summer and its stored warmth in winter.