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Domestic Hot Water (DHW) Calculation — Module Overview & API Docs

Calculation of DHW needs according to ISO 12831-3:2018.

The goal is to evaluate and demonstrate the validity of the DHW calculation proposed by the EN ISO 12831-3:2018.
This work does not replace the standard; it is meant to be used along with the EPB standards.

Introduction

This module provides reference implementations to estimate daily, monthly, and yearly DHW volume and energy needs for buildings, following the logic and parameters in ISO 12831-3 and related EPB standards.
It includes:

  • A robust calendar generator based on [workalendar], to classify days as Working, Non-Working, or Holiday.
  • Core routines to compute DHW volume and thermal energy at delivery temperature, handling multiple building usage types (residential, accommodation, healthcare, catering, hotels, sport facilities, …).
  • Utility functions (e.g., month day counts) and correlations to determine equivalent persons and daily volume references for dwellings.

The API is meant to be clear, testable, and easily integrable into larger pipelines (e.g., hourly profiles, M&V checks, dashboards).
The module relies on a set of tabular inputs (EPB tables B_3, B_4, B_5) and physical constants provided by pybuildingenergy.

Data & External Dependencies

  • table_B_3, table_B_4, table_B_5_modified
    DataFrames providing reference values from EPB tables:
  • B_3: usage types and energy/area or per-unit intensities
  • B_4: activity types and daily volume per functional unit
  • B_5 (modified): residential typologies and liters/person/day
  • WATER_DENSITY, WATER_SPECIFIC_HEAT_CAPACITY
    Physical constants imported from pybuildingenergy.global_inputs.
  • Workalendar (external): provides country calendars and is_working_day / holidays(year).

⚠️ Ensure these tables/inputs are loaded in your environment before calling the main routines.