A Trombe wall is a passive solar collector integrated into a building's south facade. A dark, high-thermal-mass wall (concrete, stone, or brick 200-400 mm thick) sits behind glass with a 50-100 mm air gap. The sun heats the wall to 45-65 °C and heat transfers indoors with a 6-10 hour delay — just in time for evening cool-down. For lobbies this means 20-40% lower heating costs in transitional seasons and stable comfort without convective drafts.
How a Trombe Wall Works
Solar radiation passes through glazing (6-8 mm tempered glass, low-e inner coating) and heats the massive wall. Thermal inertia: 300 mm concrete stores up to 200 kWh/m³, releasing heat indoors 8-10 hours later.
Vented Trombe wall: top and bottom dampers let heated air from the gap enter the room directly (convection), speeding warm-up. In summer, dampers redirect hot air outside while the wall acts as a thermal shield. Construction cost from $150/m².
Reception-Zone Applications
Trombe wall behind the reception desk on the south facade: interior surface clad in natural stone (slate, basalt, dark sandstone) at 28-32 °C — pleasant radiant warmth for both receptionist and visitors.
Reception Space designs desks aligned with the Trombe wall: shelves and panels attach through thermal-isolating bushings to prevent furniture overheating. Desk materials — Fenix NTM HPL or quartzite with low thermal conductivity.
Energy Efficiency and Construction
Savings: a 10 m² Trombe wall in a temperate climate saves 3,000-5,000 kWh/year = $360-600 at $0.12/kWh. In southern regions efficiency is 30-50% higher. Payback — 5-8 years.
Construction: load-bearing wall of heavy concrete (2,400 kg/m³) or brick. Glazing — tempered glass with low-e coating in aluminium framing. Gap 50-100 mm with ⌀100 mm vent dampers top and bottom. Waterproofing — EPDM membrane.
Modern Modifications
PCM Trombe wall: phase-change materials (paraffin, salt hydrates) replace concrete. Thickness just 50-80 mm at comparable thermal capacity. 60% lighter. PCM panel cost from $80/m².
PV Trombe wall: glazing is replaced by semitransparent PV modules (TPV). Simultaneously generates heat and electricity. Thermal-loop efficiency 35-45%, electrical 8-12%. The ideal solution for autonomous lobbies.