Overview
EN ISO 15927-4:2005 (ISO 15927-4:2005) specifies a method to construct a representative reference year of hourly climatic data for use in assessing the long‑term average energy use for heating and cooling buildings. It is part of the ISO 15927 series on hygrothermal performance of buildings and focuses on producing hourly meteorological input that preserves monthly means, frequency distributions and inter‑variable correlations while noting that the method is not suitable for extreme or semi‑extreme year simulations (e.g., moisture damage or cold‑year peak loads). Meteorological instrumentation and observation methods are outside its scope (WMO Guide No. 8 is the normative reference).
Key Topics and Requirements
- Purpose: Produce an annual sequence of hourly values (a reference year) representative of long‑term climate for energy simulation.
- Minimum data requirements: Hourly dry‑bulb temperature, direct normal and diffuse solar irradiance on a horizontal plane, humidity (relative/absolute or dew point) and wind speed at 10 m.
- Data base: Use at least 10 years (preferably more) of quality‑controlled hourly data measured per WMO guidance.
- Construction principle: Select the most representative month for each calendar month from the multi‑year record, then join months with smoothing so hourly values and cross‑correlations are retained.
- Selection method: Uses statistical ranking (including the Finkelstein–Schafer statistic) on daily means of temperature, solar radiation and humidity as primary parameters; wind speed is a secondary factor.
- Quality control: Missing or irregular values must be interpolated or corrected before use; three‑hourly synoptic data can be linearly interpolated to hourly values if needed.
- Limitations: Not intended to create extreme/semi‑extreme years or substitute for long continuous multi‑year hourly records where available.
Applications and Users
- Building energy modelers and simulation software developers who need a standardized, reproducible hourly climatic input for annual heating and cooling energy assessments.
- HVAC designers, energy consultants and researchers performing life‑cycle energy studies or comparative analyses across locations.
- Climate data providers and national standards bodies producing typical meteorological years for building performance simulations.
- Useful for generating distributed reference year datasets for use where long continuous hourly records are expensive or unavailable.
Related Standards
- ISO 15927‑1: Monthly means of single meteorological elements
- ISO 15927‑5: Data for design heat load for space heating (selection of extremes)
- ISO 15927‑6: Accumulated temperature differences (degree days)
- WMO Guide No. 8: Guide to meteorological instruments and methods of observation
Keywords: ISO 15927-4, EN ISO 15927-4:2005, reference year, hourly climatic data, building energy simulation, hygrothermal performance, heating and cooling, meteorological data.