Shape the space between buildings as carefully as the rooms: make outdoor spaces partly enclosed and convex, like outdoor rooms, rather than leftover gaps around freestanding objects.
Rules · Materials · Site · Walls
Store the sun in heavy materials
Place heavy materials (concrete, stone, brick, earth) where the winter sun falls on them inside the insulated envelope, so that they absorb heat by day and give it back at night.
Thermal mass evens out temperature swings: a concrete floor or masonry wall warms slowly and cools slowly, damping the peak of the afternoon and releasing heat into the night. It is useful only if it is exposed to the sun or the room air and wrapped in insulation on the outside, and it must be shaded in summer, or it will store unwanted heat. In hot, dry climates the same principle, with thick walls and night ventilation, keeps buildings cool; the Eastgate Centre in Harare (1996) uses its concrete mass and chimneys to ventilate itself on the model of a termite mound.
Related rules
On an equator-facing window, make the overhang deep enough to shade the whole window from the high noon sun of summer, and no deeper, so that the low winter sun passes beneath it into the room.
noon sun altitude = 90° − latitude ± 23.44° · overhang D = window height ⁄ tan(summer altitude)
Make the envelope so well insulated and airtight, and recover so much heat from the exhaust air, that the building needs almost no active heating.
heating ≤ 15 kWh/m²·a · airtightness n₅₀ ≤ 0.6 h⁻¹ · heat recovery ≥ 75%
Lay out the rows east–west so that the long, glazed face of every house turns to the south (in the northern hemisphere), taking the low winter sun and shading easily from the high summer sun.
Put an open public green within about three minutes’ walk of every house, large enough to be used and not just looked at.
≤ 750 ft (≈ 230 m) from every house
Face the homes south behind glazed sunspaces; put workspaces on the north side, in the shadow of the row in front, where even light suits them; cover the roofs with sedum and gardens; and ventilate through wind-driven cowls with heat recovery.
Cite this page Chris Paton, “Store the sun in heavy materials”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/thermal-mass. Text, drawings and models licensed under CC BY-NC 4.0.