The Solar Gain Room
This pattern is shaped by
Problem
In northern climates with long, dark winters, a room that captures and holds solar heat transforms the experience of the season. Without it, winter is something to endure. With it, winter becomes a warm, bright, interior garden — the sunniest room in the house on the coldest day of the year.
Evidence and Discussion
A south-facing room with high-performance glazing, thermal mass flooring, and a closeable connection to the rest of the house can be 20°C warmer than outdoor temperatures on a sunny winter day, even without mechanical heating. The design principles are well-established: south-facing glazing (within 30° of true south), thermal mass floor (concrete, stone, or dark tile), operable vents to distribute warmth, and exterior shading or deciduous plantings to prevent summer overheating.
Therefore
in any dwelling north of 45° latitude, create a south-facing room with high-performance glazing, a dark thermal mass floor, and a closeable connection to the rest of the house. Size the glazing at roughly one square meter per five square meters of floor area served. Use this room as the warmest, brightest room in winter — a place for morning coffee, plants, and reading. In summer, shade it with deciduous trees or exterior shutters.