How this calculator works
The A2L minimum room area calculator determines the smallest floor area (m²) of a machinery room or occupied space that satisfies the flammable-gas concentration limit for mildly flammable (A2L) refrigerants under IEC 60335-2-89:2019. The method: (1) identify the leakable charge from the entered system charge (kg) — IEC defines leakable charge as the full system charge for field-assembled systems; (2) divide by the LFLroom concentration limit for the selected refrigerant (in kg/m³, from IEC 60335-2-89 Annex T); (3) divide by the entered room height to get minimum floor area. ASHRAE 15 occupancy classes A (low-density public), B (high-density public), and C (machine room / restricted access) apply different LFL fractions — typically 25 %, 50 %, and not-limited respectively. Supported refrigerants: R-32, R-454A, R-454B, R-454C, R-455A with correct LFL and molecular weight values per ASHRAE 34-2022. This tool is a pre-design screening check; the final safety assessment must be made by a suitably qualified engineer per EN 378-1 or local DRAP/NEPRA requirements.
References: IEC 60335-2-89:2019 §7.4 and Annex T; ASHRAE Standard 34-2022; EN 378-1:2016+A1:2021; ASHRAE 15-2019.