ISO 11855-7:2019

Overview

ISO 11855-7:2019 is part of the ISO 11855 series on building environment design for embedded radiant heating and cooling systems. This part defines the input parameters and calculation procedures needed to determine heat flow in water‑based and electrical surface heating/cooling systems relative to the medium differential temperature. The standard supports a uniform, model‑based assessment of thermal performance (surface temperature, temperature uniformity, nominal heat flow density, nominal medium differential temperature and characteristic curves) for systems embedded in floors, walls or ceilings without open air gaps.

Key Topics

• Scope and applicability: Applies to water‑based and electrical embedded surface systems in residential, commercial and industrial buildings; excludes panel systems with open air gaps.
• Calculation approach: Thermal performance is determined by calculation from design documents and a model, using temperature variation (Δθ)‑based methods aligned with ISO 52031 and ISO 52000 concepts.
• Input parameter determination: Procedures for deriving product‑specific inputs such as equivalent internal temperature, temperature variations due to emission and control systems, and corrections for stratification, control intermittence, hydraulic imbalance and radiation.
• Material and layer treatment: Specific heat capacity of the embedded system (Csys) is calculated by summing layers above the insulation; pipe material and the water in pipes are excluded from this specific heat calculation.
• Orientation corrections: The standard provides orientation‑dependent correction coefficients (A and B) - derived from numerical simulations - to adjust temperature variation estimates for ceiling, floor and wall installations.
• Symbol list and formulae: Defines symbols, subscripts and key formulae to produce consistent input parameters; Annex A contains a worked calculation example.

Applications

ISO 11855-7:2019 is intended for professionals involved in the design, energy assessment and commissioning of embedded radiant systems:

• HVAC and building services engineers calculating system heat output and energy performance
• Energy modelers and building performance analysts requiring consistent input parameters for simulation
• Product manufacturers developing embedded heating/cooling panels and supplying product data
• Architects and façade/structure designers integrating systems into floor, wall or ceiling constructions
• Regulatory bodies and certifiers assessing compliance with energy performance and comfort criteria

Use cases include system dimensioning, dynamic energy calculations, performance comparison across products, and preparing input data for building energy simulation / EPB (Energy Performance of Buildings).

Related Standards

• ISO 11855-1 (definitions, symbols, comfort criteria)
• ISO 52000 (EPB assessment framework)
• ISO 52031 (method for calculation of system energy requirements and efficiencies)
• Other parts of ISO 11855 series (design, dimensioning, installation, control)

Keywords: ISO 11855-7:2019, embedded radiant heating and cooling systems, input parameters, energy calculation, water‑based surface heating, electrical heated embedded systems, thermal performance, medium differential temperature.