2. Getting involved
3. Standards Committees
4. NABau

DIN Standards Committee Building and Civil Engineering

Overview

This document (EN 17888-2:2024) has been prepared by Technical Committee CEN/TC 89 "Thermal performance of buildings and building components", the secretariat of which is held by SIS (Sweden). One factor that can have a significant impact on the energy consumption and carbon dioxide emissions of buildings is the performance of the building fabric. Since the performance of the building fabric has traditionally never or only rarely been tested on site, it was assumed that it functioned as originally designed. In recent years, however, a wealth of empirical evidence has emerged showing that there can be a discrepancy between the theoretical performance of the building fabric and its actual performance on site. This discrepancy between designed and measured performance is commonly referred to as the "performance gap" of the building fabric. For this reason test methods have been developed in CEN/TC89, WG13 that measure and verify the performance of building fabric on site and can determine the extent of a possible "performance gap". The aim of the DIN EN 17887 and 17888 series of standards is to provide a test method (Part 1) and an analysis method (Part 2) for measuring the aggregate in-situ heat loss of a building or test sample. This test and analysis method can be used as a sampling verification method for large-scale production, as confirmation of prototypes, as confirmation of the performance of particularly important buildings, and possibly as a diagnostic tool for determining the actual performance of individual building components and as a basis for further investigations and measures. The test method is applicable to building structures especially built for the purpose of characterizing the heat loss of individual building elements such as roofs or walls. The document does not apply to newly constructed or existing houses and apartments. These do not fall within the scope of this standard 17888, but are covered by standard 17887. Part 2 (analysis method) of the EN 17887 and EN 17888 series of standards is almost identical and is based on the same research work, measured under British weather conditions. The investigations included few periods with more extreme thermal boundary conditions (such as nighttime cooling under clear skies, higher solar radiation, etcetera), and therefore the measurement uncertainties and error tolerances specified in Annex D are only of limited applicability to locations in Germany with more variable environmental conditions. For this reason, Annex D is for informational purposes only. It can be assumed that measurement uncertainties of +/- 20% or higher apply (and not the specified +/- 6,3%) for houses and building structures where not all building elements and materials have undergone special thermal measurements in the laboratory in advance. A more realistic estimate of in-situ measurement uncertainty is given in ISO 9869-3 "Thermal insulation of building elements, In-situ measurement of thermal resistance and thermal transmittance – Part 3: Probe insertion method":2023, A.5.3, 5.4, and B.4. Since the effort involved in carrying out such in-situ measurements on entire houses or special structures over many weeks is high, experience with these measurement methods in Germany is limited, but has been available in some institutions for many years and should be further tested.

Responsible national committee

NA 005-56-98 AA - Measurement of thermal properties (national mirror committee for CEN/TC 89/WG 8, WG 13 and WG 14, ISO/TC 163/SC 1/WG 15, WG 16, WG 20 und WG 21)  

Responsible european committee

CEN/TC 89 - Thermal performance of buildings and building components