ISO 11855-5:2021

Overview

ISO 11855-5:2021 - Building environment design - Embedded radiant heating and cooling systems - Part 5: Installation - specifies uniform installation requirements for embedded radiant heating and cooling systems. The document applies to water-based embedded surface systems integrated into floors, ceilings and walls (no open-air gap panel systems). It defines installation preconditions and layer composition so that hydronic underfloor heating, embedded ceiling and wall systems perform as intended in residential, commercial and industrial buildings.

Key topics and technical requirements

• Scope and applicability: Focus on water-based embedded radiant systems integrated into the building structure; not for panel systems with open gaps.
• General structural preconditions: Sequence of work - pipework follows electrical/sanitary installations; building openings and wall plaster should be closed before installation.
• Building layers and components: Requirements for supporting base, vapour barriers, peripheral edge strips and interaction with different floor coverings.
• Insulating layers and thermal resistance: Thermal resistance R of insulating layers is calculated per ISO 11855‑3; recommended limits for downward heat loss:
  • New construction: limit outward losses to <20% of thermal output
  • Refurbished systems: limit outward losses to <30% of thermal output
  • Prescriptive guidance for insulation resistance values (examples given in the standard): 0.75, 1.25, 1.5 and 2 (m·K)/W depending on adjacent space and external design temperature.
• Peripheral strip (edge joint): Edge strip placement and fixation to accommodate screed movement and thermal expansion.
• Leak testing and initial heat-up: Procedures for pressure/leak tests and controlled initial heating-up of the emission surface to ensure integrity and performance.
• Floor coverings and installation details: Consideration of flooring type (wood, resin, etc.), vapour barriers, and stratigraphy-specific calculations.
• Ceilings and walls: Structural preconditions and insulation requirements for embedded systems in ceilings and walls.
• Annex on corrosion prevention: Informative guidance addressing material compatibility and protection.

Practical applications and users

ISO 11855-5:2021 is used by:

• Architects and building designers specifying embedded radiant systems
• HVAC engineers and system designers performing thermal and structural calculations
• Installers and contractors executing hydronic underfloor, ceiling or wall systems
• Building owners, facility managers and specifiers ensuring compliance and long-term performance
  Use cases: new residential, commercial and industrial construction, and refurbishment projects where embedded water-based radiant heating and cooling are specified.

Related standards

• ISO 11855-1: Vocabulary, symbols and comfort criteria
• ISO 11855-3: Design and dimensioning (thermal resistance and calculation methods)
  ISO 11855-5:2021 should be applied together with other parts of the ISO 11855 series for complete design, installation and control guidance.