Sample Exercise: Calculate Heat flow for an Assembly

  • Area
  • Temperature difference
  • Thermal resistance
  • Conductive heat loss equation: Q=AxΔT/RSI (from CHBA 2.1.3)
    • Q is rate of heat flow in Watts (W)
    • A is Area of surface in m2
    • Δ T is Temperature Differential between inside and outside in °C
    • RSI is resistance to heat flow in m2 °C/W

Heat transfer by conduction Calculation

Example: A wall section is 5m2 and has an RSI of 3.3528 (R20) an indoor temperature of 20°C (68°F) and an outdoor temperature of -10°C ( 14°F)

Q=A x ΔT/RSI

Q= 5 x 30/3.35

Q=150/3.35

Q= 44.78 W