ISO 18523-2:2018 PDF

Overview - ISO 18523-2:2018 (Energy performance of buildings, Residential)

ISO 18523-2:2018 defines standardized formats and schedules for presenting the usage conditions of buildings, zones and spaces used as input data for building energy calculation and modelling. Focused on residential buildings, the standard covers occupancy schedules, operation of technical systems, ventilation rates, domestic hot water (DHW) use, appliance use, fixed lighting and internal heat gains. It prescribes typical and average conditions (not extreme sizing assumptions) and provides categories and levels of time/space averaging to match different calculation granularity.

Keywords: ISO 18523-2:2018, energy performance of buildings, residential buildings, schedule and condition, energy calculation, occupancy schedules, ventilation rates, domestic hot water, internal heat gains, building energy modelling.

Key topics and technical requirements

• Schedule formats: Definitions and formats for daily, weekly, monthly, seasonal and annual schedules; how to allocate daily schedules across a standard year.
• Occupancy and internal gains: Standardized ways to represent occupancy levels, usage patterns, and resulting internal heat gains from people, lighting and appliances.
• Technical system operation: Schedules and operational conditions for heating, cooling, ventilation and other building systems (including local exhaust and demand-controlled ventilation).
• Ventilation and DHW: Specification of ventilation rates and domestic hot water usage profiles as inputs to energy calculations.
• Lighting: Applicable to fixed installed lighting fixtures - schedules and conditions to derive lighting energy and heat gains.
• Categories and granularity: Classification of residential building types, zones and spaces; multiple levels of time and space averaging to suit simple or detailed energy models.
• Informative data and examples: Annexes provide sample daily time-use, annual schedule formats, examples for heating/cooling schedules, ventilation, DHW, appliances and category lists.

Note: For residential buildings containing non-residential spaces, ISO 18523-1 (Part 1) applies for those zones.

Practical applications - who uses it

• Energy modelers and simulation engineers: Use consistent input datasets for HVAC sizing alternatives, compliance checks and retrofit analysis.
• Building designers and HVAC consultants: Adopt standardized occupancy and system operation assumptions for design-stage energy performance assessments.
• Policy makers and compliance bodies: Define regulatory default schedules and harmonized methodologies for residential energy labeling and building codes.
• Software developers: Implement interoperable schedule formats in building energy modelling tools and simulation engines.
• Researchers: Compare case studies using standardized inputs to ensure reproducible results.

Related standards

• ISO 18523-1 - Part 1: Non-residential buildings (applies where residential units contain non-residential zones).

Using ISO 18523-2:2018 ensures consistent, reproducible residential building energy calculations by standardizing how schedules and usage conditions are defined and shared.