ISO 16358-2:2013

Overview

ISO 16358-2:2013 - "Air-cooled air conditioners and air-to-air heat pumps - Testing and calculating methods for seasonal performance factors - Part 2: Heating seasonal performance factor" specifies standardized methods to test and calculate the Heating Seasonal Performance Factor (HSPF) for air-cooled and air-to-air heat pumps covered by ISO 5151, ISO 13253 and ISO 15042. The standard defines test conditions, test procedures and calculation rules for seasonal heating performance used for marking, comparison and certification. It assumes any make‑up heating is provided by electric heaters running concurrently with the heat pump.

Key technical topics and requirements

• Scope and exclusions: Applies to air-cooled and air-to-air heat pumps covered by ISO 5151/13253/15042. Does NOT apply to water‑source or water‑cooled units, portable units with condenser exhaust ducts, individual assemblies (not complete systems), or absorption-cycle equipment.
• Definitions & metrics: Formal definitions for HSPF, Total HSPF (THSPF), Heating Seasonal Total Load (HSTL), Heating Seasonal Energy Consumption (HSEC), Part Load Factor (PLF) and degradation coefficient (CD).
• Test conditions and procedures: Mandatory seasonal test conditions, binning by outdoor temperature, and procedures to measure continuous and cyclic operation performance.
• Capacity classifications: Methods cover fixed‑capacity, two‑stage, multi‑stage and variable‑capacity units, with specific approaches for full, half, extended and minimum capacity operations.
• Calculations: Clear calculation methodology for HSPF and THSPF, including how to account for make‑up electric heating, temperature bin distributions, part‑load behavior and cyclic degradation. Normative annexes (e.g., Annex C) define testing for degradation coefficients; informative annexes provide figures and calculation examples.

Practical applications - who uses this standard

• Manufacturers and product designers: to report compliant HSPF values and design for seasonal efficiency targets.
• Independent test laboratories: to run repeatable, standardized seasonal performance tests for certification and comparison.
• Regulators and certifiers: to set energy labeling, minimum efficiency standards and compliance protocols.
• HVAC specifiers, consultants and building designers: to compare systems based on seasonal heating performance for climate‑specific selections.
• Energy program administrators: for incentive schemes that require standardized efficiency metrics.

Related standards

• ISO 5151 - Non‑ducted air conditioners and heat pumps: testing and rating
• ISO 13253 - Ducted air conditioners and air‑to‑air heat pumps: testing and rating
• ISO 15042 - Multiple split‑system air‑conditioners and air‑to‑air heat pumps: testing and rating
• ISO 16358-1 & -3 - Cooling seasonal performance factor and Annual performance factor (other parts of the series)

Keywords: ISO 16358-2:2013, HSPF, heating seasonal performance factor, air-cooled air conditioners, air-to-air heat pumps, seasonal performance testing, ISO 5151, PLF, THSPF.