EN 1264:2021, a new standard for surface embedded heating and cooling systems

The EN 1264 series gives guidelines for surface embedded heating and cooling systems installed in buildings, residential and non-residential (e.g. office, public, commercial and industrial buildings) and focuses on systems installed for the purpose of thermal comfort. The standard EN 1264 is born in 1997 (first standard came in 1992 as DIN 4795 for floor heating) as technical standard for designing and installing radiant floors for heating purposes. In 2009 a revision of the standard took place in order to extend the existing calculation method for determining heat flow output also to other radiant systems (walls and ceilings) and operating conditions (heating and cooling). In 2021 the standard has been revised again (EN 1264:2021) to meet technological innovations in surface embedded system that has been devolped in more than ten years from the last changes. Q-RAD Consortium, formed by italian quality radiant systems manufacturers, has joined the international work group and contributed to the revision as italian delegate. The subject of EN 1264:2021 standard is the hydronic radiant systems, embedded in the structures in floor, wall or ceiling.


EN 1264:2021 main changes

The standard is published in English, German, French and Italian. It does not apply to: electric radiant systems and radiant systems with open air gap such as radiant false ceilings. The standard consists of 5 parts: (1-Definitions and symbols; 2 – Floor heating: Methods for the determination of the thermal output using calculations and experimental tests; 3 – Dimensioning; 4 – Installation; 5 – Determination of the thermal output for wall and ceiling heating and for floor, wall and ceiling cooling.

The main changes that have been approved of EN 1264:2021 are:

  • New types (even without insulation): included in part 1 of the standard
  • New definitions (part 1)
  • Materials and conductivity (part 2)
  • Insulation with studs (part 3)
  • Maximum surface temperature of radiant ceiling systems (part 3)
  • Many changes in part 4 on installation


New types of radiant systems and definitions (EN 1264-1:2021)

The introduction of new types of embedded surfaces HVAC (low thickness, low inertia) and the detail of existing types (Type A, rusticated and with smooth insulation) are the biggest novelty of UNI EN 1264: 2021 first part. These changes have been introduced in order to adjust the standard to currently available products on the international market. The types of embedded surfaces systems are described in Tables A.1 and A.2. The new stratigraphies are described in the infographic below:


Main typologies of surface embedded HVAC systems


Chapter 3 of EN 1264-1 “Terms and Definitions” also presents many new features and changes compared to the 2011 standard edition. Among these is the definition of “open air gap” which should clear up which systems are excluded from EN 1264 but unfortunately the standard still leaves the issue open for radiant ceilings.


Thermal insulation and ceiling heating temperature (EN 1264-3:2021)

Important changes of part 3 of EN 1264 regard the calculation of the thermal resistance of the thermal insulation with studs and the increase in the surface temperature of ceilings heating systems.
For floor heating systems with thermal insulation panels with studs (Type A and Type C systems), EN 1264: 2021 says that only the flat part of the panel (without studs) shall be considered in calculation of thickness while in the previous version of the standard an average had to be made between the flat part of the panel and the studs.
Regarding radiant heating ceiling, surface temperature limit value has been raised to 33 ° C (to comply with the requirements of the UNI EN ISO 11855 standard). During the EN 1264 revision, Q-RAD Consortium review of literature have pointed out that surface temperature can higher than 29° C (previous surface temperature limit) as shown by these studies:

Safizadeh and Wagner. 2018. Evaluation of Radiant Ceiling Heating Systems for Renovated Buildings based on Thermal Comfort Criteria

Griffith et al. 1974. Subjective Response to Overhead Thermal Radiation


EN 1264-3:2021 specifies the use in practical engineering of the results coming from EN 1264-2 and EN 1264-5. For heating systems, physiological limitations are taken into account when specifying the surface temperatures . In the case of floor heating systems the limitations are realized by a design based on the characteristic curves and limit curves determined in accordance with EN 1264-2. For cooling systems, only a limitation with respect to the dew point is taken into account. In predominating practice, this means that physiological limitations are included as well.


More details on the Q-RAD technical dossier, click here