Overview
EN ISO 15927-6:2007 (Hygrothermal performance of buildings - Part 6) defines how to calculate and present accumulated temperature differences-commonly expressed as heating degree-hours or heating degree-days-used to assess energy used for space heating. Published by CEN/ISO, the standard specifies definitions, computation methods and presentation formats for degree-day data, and provides approximate techniques for estimating values when full meteorological records are not available.
Key Topics
- Definitions and units: clear terms for hourly, daily and accumulated temperature differences, base temperature, monthly means and standard deviations.
- Direct calculation methods: exact computation of accumulated temperature differences from hourly or daily mean air temperatures.
- Approximate estimation methods: procedures to estimate monthly or period totals to any base temperature when only daily statistics or long‑term climatological data exist.
- Reference altitude & lapse rate: guidance on referencing degree-day data to a standard altitude and accounting for temperature lapse with elevation.
- Accuracy and data presentation: recommended precision, formats and conventions for publishing degree-day data for energy analysis.
- Limitations: does not cover methods that use a separate threshold temperature (different from the chosen base temperature).
Applications
EN ISO 15927-6:2007 is practical for:
- HVAC and energy engineers using degree-days to estimate heating energy demand or to normalize energy consumption for climate variations.
- Energy managers monitoring heating plant performance and comparing actual consumption against climate-adjusted baselines.
- Building modelers performing steady‑state thermal analysis for small or simple buildings where degree-day indices are appropriate.
- Policy makers and analysts assessing regional heating requirements, planning insulation or energy‑efficiency measures across building stocks.
- Meteorological services and data providers compiling and publishing standardized degree-day data for localities and regions.
Note: degree-days can be applied in reverse for cooling (“cooling degree-days”), but ISO 15927-6 cautions that cooling demand depends heavily on solar gains and humidity, so results are less reliable.
Related Standards
Part 6 is one of the ISO 15927 series on climatic data for buildings:
- ISO 15927-1: Monthly means of single meteorological elements
- ISO 15927-2: Hourly data for design cooling load
- ISO 15927-3: Driving rain index from hourly wind and rain
- ISO 15927-4: Hourly data for assessing annual heating/cooling use
- ISO 15927-5: Data for design heat load for space heating
These related parts are useful when more detailed climatic inputs (e.g., hourly time series or design load data) are required.
Keywords: EN ISO 15927-6:2007, degree-days, heating degree-days, accumulated temperature differences, base temperature, hygrothermal performance, climatological data, building energy.