EMIRIM is a project aiming to improve measurements of total hemispherical emissivity of reflective foils used in “reflective insulation” products. The project was initiated following a demand from the standardisation working group CEN/TC 89/WG 12 responsible for defining test methods and declaration rules for the thermal performance of reflective insulation products. It will help build confidence in total hemispherical emissivity data declared by manufacturers of insulation materials and facilitate the measurement of emissivity of reflective non-specular surfaces with controlled uncertainties.

A comparison of total hemispherical emissivity, organized by CEN/TC 89/WG 12, gave a high discrepancy of emissivity; for example results from 0.02 to 0.08 were obtained on the same reflective foil when comparing different measurement techniques. The comparison included “integrating sphere” instruments and commercially available portable instruments (reflectometers) like TIR 100-2 from INGLAS. The sources of discrepancies were not explained, likely explanations were the geometrical, thermal and optical configurations of instruments and the type of reference samples used for calibration (plane mirrors or diffusing reflectance calibrated samples).

In the project, a thorough experimental work will be performed to quantify the sensitivity of the main techniques used by end-users to the specificities of reflective foils: high reflectivity, reflection mostly specular but randomly oriented due to non-flatness. That work will allow the definition of appropriate reference samples and the production of the improved calibration and measurement procedures. Three national metrology institutes will improve their emissivity measurements facilities to calibrate the reference samples in total hemispherical emissivity with uncertainties below 0.02. The uncertainty sources of industrially used techniques will be assessed and the results validated by comparisons. The objective is an uncertainty below 0.03 for total hemispherical emissivity measurements performed by end-users on reflective foils.

Good practice guides for calibration and use of total hemispherical emissivity measurement techniques will be established. Proposals for improvement of standards EN 16012 and EN 15976 will be given to CEN/TC 89/WG 12 and to CEN/TC 254.

Start date : 1 June 2017 ;      End date : 31 May 2020.

This project is funded through the European Metrology Programme for Innovation and Research (EMPIR). The EMPIR initiative is co-funded by the European Union’s Horizon 2020 research and innovation programme and the EMPIR Participating States

Contact: Jacques Hameury