ISO 16544:2012

Overview

ISO 16544:2012 specifies equipment and procedures to condition thermal insulating products for building applications to an equilibrium moisture content under defined temperature and humidity. The default conditioning atmosphere is (23 ± 2) °C and (50 ± 5) % relative humidity (RH). The standard covers un-faced products and products with moulded skins (faced or surface-treated products are normally excluded). It also provides provisions for conditioning and testing in tropical countries using different temperature/RH conditions.

Key topics & technical requirements

• Purpose: Bring test specimens to equilibrium moisture content before physical or thermal testing.
• Conditioning atmospheres: Primary atmosphere 23/50; alternative tropical atmosphere (27 ± 5 °C / 65 ± 5 % RH) where relevant.
• Apparatus:
  • Temperature-and-humidity controlled chamber capable of maintaining 23/50.
  • Temperature-controlled ventilated oven (taking air from 23/50) able to hold elevated temperatures such as 40 ± 5 °C, 70 ± 5 °C or 105 ± 5 °C as specified in product standards.
• Specimen preparation:
  • Retain full-size product skin/facing/coating where present.
  • Square specimens of (200 ± 1) mm sides; thickness equals original product thickness.
  • Number of specimens as per product standard, otherwise at least three.
• Conditioning procedure:
  • Two-step approach: Step 1 bring moisture into the hygroscopic range, Step 2 condition to equilibrium in 23/50.
  • Alternative single-step (Step 2) if specimen already within hygroscopic range.
  • Special notes on hysteresis: sorption by absorption vs desorption can lead to different equilibria; perfect equilibrium may take long and is accepted within defined accuracy.
• Measurements and calculations:
  • Linear dimensions per ISO 29768; volume used for moisture calculations.
  • Annexes provide methods to determine limiting moisture-change values and calculate conditioning time (including use of Fourier-number based calculations).

Applications & users

ISO 16544 is used to ensure consistent pre-test moisture conditions for:

• Manufacturers of insulation materials (EPS, XPS, PUR, MW, ICB, etc.)
• Independent testing and certification laboratories
• Product specifiers and building-material researchers
• Quality control and compliance testing for performance properties (thermal resistance, dimensional stability, mechanical tests)

Proper moisture conditioning reduces variability in downstream tests (thermal performance, mechanical properties, water absorption) and ensures comparability of results.

Related standards

• ISO 12571 - Hygrothermal performance of building materials (sorption properties)
• ISO 29768 - Determination of linear dimensions of test specimens
• ISO 16536 - (referenced for increasing moisture content procedures)
• This standard is part of a family of ISO/EN test methods for thermal insulating products (see ISO 16544 introduction for related test methods).

Keywords: ISO 16544, thermal insulating products, conditioning to moisture equilibrium, 23 ± 2 °C, 50 ± 5 % RH, hygroscopic range, conditioning procedure, test specimens, ventilated oven, tropical conditioning.