ISO 11855-6:2018

Overview

ISO 11855-6:2018 - "Building environment design - Design, dimensioning, installation and control of embedded radiant heating and cooling systems - Part 6: Control" provides guidelines and uniform requirements for the control of embedded radiant heating and cooling systems. It covers water-based (and, where appropriate, other fluid-based) systems integrated into floors, walls or ceilings without open air gaps. The standard is applicable to residential, commercial and industrial buildings and focuses on ensuring systems perform as designed, avoid condensation and protect building fabric (it does not cover panel systems with open air gaps, heated/chilled ceiling panels or beams, nor is it a test standard).

Key Topics and Requirements

• Control system design and documentation: Control strategies and specifications shall be included in design documents; systems must vary output and maintain room/surface temperatures as designed.
• Control levels:
  • Central control - building-wide supply temperature and distribution management (mixing valves, supply/return monitoring).
  • Zone control - groups of spaces with similar temperature requirements controlled together.
  • Local (room) control - individual room sensors and actuated manifold valves for occupant comfort and energy savings.
• Control performance classes: Manual, automatic, timing (scheduled setbacks), and advanced timing with optimized restart strategies.
• Sensors and inputs: Outside temperature sensors, room temperature/humidity sensors, floor/surface sensors, supply/return medium temperature sensors - used for feed-forward and feedback control and integration with a Building Management System (BMS).
• Condensation prevention: Controls must avoid surface condensation in cooling mode (e.g., limiting minimum supply water temperature based on measured dew point).
• Hydronic control details: Mixing valve control, flow control (new in 2018 edition), and recommendations to control mean water temperature (average of supply and return) for more direct relation to space flux.
• Dynamic factors: Influence of thermal mass, self-regulating effects of embedded systems and control of Thermo Active Building Systems (TABS) are addressed.
• Informative guidance: Annex A provides example control concepts for radiant floor heating–cooling systems.

Applications and Users

Who uses ISO 11855-6:2018:

• HVAC designers and engineers specifying hydronic radiant systems
• Building services consultants and BMS integrators implementing central/zone/room control
• Architects and project managers coordinating embedded system integration with building structure
• Facility managers operating and maintaining radiant heating and cooling systems Practical uses include designing control logic, selecting sensors and actuators (mixing valves, pumps), setting condensation protection, and optimizing energy use through zoning and timing strategies.

Related Standards

• ISO 11855-1 (definitions, symbols, comfort criteria) - normative reference
• Other parts of ISO 11855 series (Parts 2–5, 7) cover sizing, dimensioning, installation and TABS design
• ISO 52031 (energetic calculations) - related for energy performance input (under development at time of publication)

Keywords: ISO 11855-6, embedded radiant heating and cooling, hydronic control, radiant floor cooling, TABS, mixing valve, condensation control, zone control, room sensor, BMS.