Dulaan Buudal: Finite Element Design of a Ger-Derived Passive Solar Bus Shelter for Ulaanbaatar

Ulaanbaatar is the coldest national capital, yet only 67 of its 1,287 bus stops have a heated cabin and in January 2026 about a third of the cabins in three districts were locked. This report proposes Dulaan Buudal (“warm stop”): an unpowered, unlockable timber shelter derived from the Mongolian ger and warmed by a glazed south face. Three models for the same 6 m by 3 m bay are analysed by the finite element method: (A) a half-ger lattice shell in Siberian larch, (B) a bent-rib half-ger in Mongolian white birch and (C) a larch gridshell “solar scoop”. Each is loaded with the prescribed 0.25 kPa roof live load and a wind pressure of 1.5 kPa, repeated at 2.0 kPa, in 19 combinations to AS/NZS 1170.0, and checked for stress, strength and deflection to AS 1720.1. Each model was run in Strand7 and reproduced by an independent solver to six significant figures, and checked by hand. All three pass: peak utilisation is 0.82 to 0.89 at 2.0 kPa and peak serviceability displacement 6.0 to 8.8 mm. A five-criterion weighted comparison selects Model A in eight of nine weighting scenarios: 533 kg of timber, 140 kg CO2e in the frame, and full headroom over 14.1 m2 . Wind governs every member, and the foundation is the critical element, needing about 131 kN of ballast. A first-order heat balance shows Model A is 12 to 14 K warmer than outdoors on dark winter mornings and 15 to 22 K warmer in the evening, provided the doorway is closed by a flap.