Overview
ISO 11855-2:2021/Amd 1:2023 is an important international standard focusing on building environment design specifically related to embedded radiant heating and cooling systems. This document serves as an amendment to the 2021 second edition and provides updated guidance for the determination of design heating and cooling capacity for these embedded systems in buildings.
Targeted primarily at architects, engineers, and HVAC professionals, this standard helps to optimize the design of radiant systems by clarifying calculation methods and system classifications. By doing so, it improves energy efficiency, comfort, and performance in modern building environments.
Key Topics
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System Classification and Types
The amendment defines five distinct types of radiant systems based on pipe positioning and construction:
- Type I: Pipes embedded directly in a thermal diffusion layer (e.g., screed)
- Type II: Pipes embedded within thermal insulation with an added conduction layer
- Type III: Capillary tubes placed directly inside a thermal diffusion layer
- Type IV: Pipes with a thermal reflection layer and an air gap beneath floor coverings
- Type V: Pipes embedded directly in structural construction (Thermally Activated Building Systems, TABS)
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Calculation Methods for Heating and Cooling Capacity
The document provides simplified methods tailored to each system type, including updated criteria for selecting appropriate methods. It corrects and refines formulas for calculating:
- Heat output
- Thermal resistances and conductivities
- Heat flux limits relative to surface and room temperatures
These calculations enable precise estimation of the system’s capacity to maintain desired indoor thermal conditions.
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Thermal Parameters and Material Characteristics
The amendment refines parameters such as:
- Thicknesses of insulation and screed layers
- Thermal conductivities of different materials and layers
- Pipe dimensions and placements
- Heat conduction factors specific to construction and pipe arrangement
This is crucial for accurate modeling of radiant heat transfer within embedded systems.
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Diagrams and Figures
Detailed floor, wall, and ceiling system schematics accompany the text, illustrating system types and pipe placements. Updated figures (Figures 2-6 and others) support visual understanding of the system configurations.
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Limit Curves and Heat Flux Values
The standard introduces methods to determine maximum permissible heat fluxes for safe and effective operation, accounting for factors like surface temperature limits and room temperature differentials.
Applications
ISO 11855-2:2021/Amd 1:2023 is essential for:
- HVAC System Design – Enables engineers to accurately size embedded radiant heating and cooling systems ensuring thermal comfort and energy-efficient operation.
- Building Energy Modeling – Assists in integrating radiant systems into building energy simulations with reliable thermal capacity values.
- Sustainable Building Projects – Supports green buildings by promoting efficient radiant system design aligned with thermal performance standards.
- Retrofit and Renovation Projects – Helps assess existing embedded systems for upgrade or compliance with updated performance criteria.
- Technical Standardization – Harmonizes calculation methodologies across international projects, facilitating global trade and cooperation in building services.
Related Standards
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ISO 11855 Series
This amendment is part of the broader ISO 11855 series addressing various aspects of embedded radiant heating and cooling systems. Other parts cover terminology, installation practices, testing, and operation.
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ISO 16813 – Building environment design - Indoor environment principles
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ISO 7730 – Ergonomics of the thermal environment - Analytical determination of thermal comfort
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CEN/TC 228 – European Committee for Standardization standards related to heating and water-based cooling systems in buildings
Integration with these and other building performance standards ensures a comprehensive approach to thermal system design and occupant comfort.
By adhering to ISO 11855-2:2021/Amd 1:2023, professionals can achieve optimal design, safety, and efficiency in embedded radiant heating and cooling systems, reinforcing sustainable and comfortable building environments worldwide.
Open preview (PDF)Building environment design — Embedded radiant heating and cooling systems — Part 2: Determination of the design heating and cooling capacity — Amendment 1
