Overview
EN ISO 15927-5:2004/A1:2011 is Amendment 1 to ISO 15927-5 (Part 5 of the ISO 15927 series) covering the hygrothermal performance of buildings and the calculation and presentation of climatic data used for the design heat load for space heating. This minor amendment (approved by CEN in November 2011 and published by ISO the same year) clarifies terminology and data‑processing rules used when preparing climatic inputs for heat‑load and HVAC sizing calculations.
Key topics and technical requirements
- Clarified normative reference: replaces the dated WMO guide citation with the undated reference “World Meteorological Organization: Guide to Meteorological Instruments and Methods of Observation, WMO - No. 8.”
- Revised definitions:
- Daily maximum temperature - defined as the maximum dry‑bulb air temperature during a day (00:00–23:00 or 01:00–24:00), taken as either the highest hourly mean or the recorded extreme on a maximum thermometer.
- Daily minimum temperature - defined similarly for the day’s minimum.
- Averaging rules for climatic parameters:
- Where hourly data are available, the relevant mean (θ) is to be calculated as the mean of 24·n hourly values over the specified period (explicitly specifying the acceptable day‑hour ranges).
- Where three‑hourly data are available, θ is calculated as the mean of 8·n three‑hourly values between the first and final days.
- These edits refine how meteorological inputs are determined from hourly or 3‑hourly datasets, ensuring consistency in design heat load calculations.
Applications
This amendment is directly applicable to:
- Heat‑load calculations and HVAC sizing for buildings
- Preparation of climatic input files for dynamic energy simulation and building energy models
- Development of design weather datasets used in calculating normative heating requirements
- Ensuring consistent processing of meteorological observations for compliance and reporting
Who should use this standard
- HVAC and building services engineers
- Building physicists and energy consultants
- Architects involved in thermal design
- National standards bodies and test laboratories preparing climatic datasets
- Software developers of building simulation and heat‑load calculation tools
Related standards
- ISO 15927 series (other parts addressing hygrothermal and climatic data methods)
- World Meteorological Organization: Guide to Meteorological Instruments and Methods of Observation (WMO No. 8) - referenced for measurement practice
This minor amendment improves clarity and data consistency for professionals using EN ISO 15927-5 in thermal performance, design heat load, and climatic data workflows.
