Door Heat Loss Calculator
Estimate sensible and latent heat infiltration through doorways into refrigerated spaces using the Gosney & Olama (1975) air exchange equation for fully established flow (ASHRAE Equation 15).
Door Dimensions
Width and height of the doorway opening.
Doorway area A = 32.0 ft²
Air Conditions
Temperature and relative humidity for both sides of the doorway.
Outdoor / Infiltration Air
Cold Space / Refrigerated Air
ASHRAE Table 9 values are based on 90% RH in the cold room.
Door Usage
Frequency, duration of openings, and any protective devices.
1.0 = no protection, 0.15 = strip curtains, 0.10 = air curtain
Door open time fraction Dt = 16.7% (10.0 min/hr)
Heat Loss Result
Fully Open Heat Load591,388 Btu/h49.28 tons
Adjusted Heat Load98,565 Btu/h8.21 tons of refrigeration
D_t16.7%
D_f1.00
Calculated Air Properties
Intermediate psychrometric values used in Equation 15.
| Property | Infiltration | Refrigerated |
|---|---|---|
| Enthalpy, h | 42.40 Btu/lb | 0.75 Btu/lb |
| Density, ρ | 0.0708 lb/ft³ | 0.0863 lb/ft³ |
| Humidity Ratio, W | 0.01776 lb/lb | 0.00071 lb/lb |
F_m0.9509
Area32.0 ft²
Equation Reference
Gosney & Olama (1975) — ASHRAE Eq. 15
q = 795.6 · A · (hi − hr) · ρr · (1 − ρi/ρr)0.5 · (g·H)0.5 · Fm
With Your Values
q = 795.6 × 32.0 × (42.40 − 0.75) × 0.0863 × (1 − 0.0708/0.0863)0.5 × (32.174 × 8.0)0.5 × 0.9509
Step-by-step
A=4.0 x 8.0=32.0 ft²
hi − hr=42.40 - 0.75=41.65 Btu/lb
1 − ρi/ρr=1 - 0.0708/0.0863=0.1796
(g·H)0.5=(32.174 x 8.0)^0.5=16.0434 ft/s
Fm=[2 / (1 + (0.0863/0.0708)^(1/3))]^1.5=0.9509
q=product of all terms=591,388 Btu/h
qadj=591,388 x 0.1667 x 1.00=98,565 Btu/h
Fm = [ 2 / (1 + (ρr/ρi)1/3) ]1.5
- q
- Sensible + latent load, Btu/h
- A
- Doorway area, ft²
- hi, hr
- Enthalpy of infiltration / refrigerated air, Btu/lb
- ρi, ρr
- Density of infiltration / refrigerated air, lb/ft³
- g
- 32.174 ft/s²
- H
- Doorway height, ft
- Fm
- Density factor