SIST ISO 18523-1:2020 PDF

Overview

SIST ISO 18523-1:2020 (identical to ISO 18523-1:2016) defines standardized formats and input data for building energy calculation for non-residential buildings. The standard prescribes how to represent the schedule and condition of building, zone and space usage - including occupancy, operation of technical building systems (HVAC, lighting, hot water), ventilation rates, hot water use and internal heat gains from people, lighting and equipment. It provides categories and recommended values in annexes for users who lack detailed site data.

Key topics and technical requirements

• Formats for schedules: daily schedules, hourly conditions, weekly/monthly/seasonal and annual allocations for consistent energy modelling.
• Levels of detail: multiple levels of time and space averaging depending on the required minuteness of the energy calculation (from coarse annual patterns to hourly, zone-level schedules).
• Parameters covered: occupancy density, simultaneous usage ratios, operation hours of service systems, ventilation rates (including demand control ventilation), maintained illuminance and internal heat gains (people, lighting, appliances).
• Category definitions: standardized categories for buildings, zones and spaces to help select appropriate schedule sets.
• Annex guidance: sets of daily and annual schedules, categories of spaces/zones and example buildings to aid application when measured data are unavailable.
• Design vs calculation assumptions: emphasizes that schedules in this standard represent typical/average use for energy calculation, distinct from peak assumptions used for equipment sizing.

Practical applications

• Standardized input data for building energy simulation and modelling (energy performance assessments, retrofit analysis, compliance checks).
• Creating consistent occupancy and system-operation schedules for energy modelling tools and BIM workflows.
• Supporting benchmarking and comparative studies by using uniform schedule definitions across projects.
• Informing facility managers and consultants when measured operational data are absent, using annex-provided typical values.

Who should use this standard

• Building energy modelers and simulation engineers
• HVAC and building services designers
• Energy assessors, compliance officers and auditors
• Architects and building performance consultants
• Software developers for building energy modelling and BIM tools
• Facility managers preparing energy performance analyses

Related standards and references

• Consult other ISO and national standards on energy performance of buildings, thermal insulation and HVAC performance (work under ISO/TC 163) for complementary requirements.
• Use the annexes in ISO 18523-1 when detailed occupancy or operational data are not available to ensure reproducible, comparable energy calculations.

Keywords: energy performance, building energy calculation, ISO 18523-1, non-residential buildings, schedules, occupancy, ventilation rate, internal heat gains, HVAC, building energy modelling.