Calculates maximum allowable charge per AS/NZS ISO 5149.1 Annex A — Tables A.1 (Toxicity) and A.2 (Flammability). Exact conversion of True Partners Excel calculator.
Occupancy Category
Step 01 · Building type and classification
01Building / Occupancy Type INPUT
Category
b — Supervised / Workplace · Business officeVLOOKUP
Auto-populated from building type
Application
Occupancy Description
Emergency Exit Available
Only affects Toxicity B, Category c, <1PPL/10sqm, Class I
Location Classification
Step 02 · Refrigeration system location class
02Refrigeration System Classification INPUT
Class I = unit in space · Class II = remote plant room · Class III = fully outdoor
Step 05 · Floor area, ceiling height and net volume
05Floor Area (m²) INPUT
Ceiling Height (m)
Net Volume Ratio
0–1 · free space fraction (1.0 = empty room)
Space Volume = Floor Area × Height × Net Volume Ratio. Net Volume Ratio accounts for space occupied by stock and equipment — use 1.0 for empty rooms, 0.5 if 50% occupied by shelving etc.
AC Unit Location
Step 06 · System type and mount — h₀ auto-calculated
06System Type INPUT
Mount Type
h₀ — Release Height (m) CALC
2.2AUTO
Auto: Floor=0.6 · Window/Wall=1.8 · Ceiling=2.2
Actual Refrigerant Charge
Step 08 · Enter proposed charge for compliance check
08Proposed / Actual Charge (kg) INPUT
Awaiting Calculation
Enter system parameters and click Calculate to determine the maximum allowable refrigerant charge per AS/NZS 5149-1 Annex A.
Reference Guide
AS/NZS 5149-1 quick reference
Cat a — Public (hospitals, schools, malls, hotels)
Cat b — Supervised workplaces (offices, labs)
Cat c — Restricted access (plant rooms, cold stores)
Class I — Equipment in occupied space Class II — Remote compressor / plant room Class III — Fully outdoor Class IV — Ventilated enclosure
Note: For split systems / VRFs under AS/NZS 60335.2.40, refer to Annex GG of that standard — not AS/NZS 5149 Annex A.
Disclaimer: This calculator is a direct conversion of the True Partners Consulting Engineers AS/NZS 5149-1 Excel calculator. It provides guidance only in accordance with AS/NZS ISO 5149.1:2016 Annex A. For household split systems and VRFs refer to Annex GG of AS/NZS 60335.2.40. Results must be verified by a qualified refrigeration engineer. True Partners Consulting Engineers accepts no liability for engineering decisions made solely on the basis of this tool.
