Hygrothermal fRsi & 2D Junction Simulator
Solid Masonry (450mm) Corner Thermal Bridge & Intermittent Heating Dynamics
Wall U-Value
0.70 W/m²K
Uninsulated: ~1.8–2.2 | Historic Target: ~0.70 | EnerPHit: ~0.15
Indoor Setpoint Temp (Ti)
20.0 °C
Outdoor Design Temp (Te)
-1.0 °C
Standard Irish/UK winter design condition: -1.0 °C to 0.0 °C
Indoor Relative Humidity
55 %
Heating Regime
Continuous 24h Heating (Constant Ti)
Intermittent 16h / day (8h setback to 15°C)
Intermittent 8h / day (Morning/Evening burst, setback to 14°C)
Severe Intermittent 4h / day (Unoccupied setback)
Thermal Physics Rules of Thumb:
fRsi ≥ 0.75:
Compliant under Irish TGD-L / UK BR497 for dwellings (Mold threshold at 80% RH).
fRsi ≥ 0.70:
Continental European baseline (DIN 4108-2).
2D Corner Effect:
Geometric thermal bridge causes the internal corner surface temperature to drop ~15–20% below the 1D field wall.
1D Wall Surface (Tsi)
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fRsi:
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2D Corner Surface (Tsi)
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fRsi (2D):
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Critical Mold Dew Pt (80% RH)
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Absolute Dew Pt:
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Corner Assessment
Calculating...
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Exterior (Te)
Thermal Gradient (°C)
Interior (Ti)