Thermal Performance of Insulated Constructions—Experimental Studies

Lars Gullbrekken,Jørn Gaarder,Steinar Grynning

doi:10.3390/buildings9020049

Abstract

Buildings that are designed to meet high-energy performance requirements, e.g., passive houses, require well-insulated building envelopes, with increased insulation thicknesses for roof, wall and floor structures. We investigate whether there are differences in the efficiency of thermal insulation materials at different moisture levels in the insulation and if there is a larger or smaller risk of natural convection in wood-fibre based insulation than in mineral wool. The work has mainly been performed by use of laboratory measurements included permeability properties and full-scale measurements of thermal transmittance of mineral wool and wood-fibre insulated constructions. In addition, calculations have been used to calculate resulting effects on the thermal performance of constructions. Results showed that the thermal conductivity was unaffected by moisture in the hygroscopic range. The air permeability was found to be approximately 50% higher for the wood-fibre insulation compared to mineral wool insulation. Measurements showed that the largest U-values and Nusselt numbers were found for the wall configuration. Calculation of the U-value of walls showed that in order to achieve the same U-value for the wood-fibre insulated wall as the mineral wool, it is necessary to add 20 mm insulation to the 250 mm wall and approximately 30 mm for the 400 mm wall.

Highlights

This article describes an investigation of the thermal transmittance of highly insulated walls, roof and floor constructions performed by measuring the properties of wood-fibre and mineral-based insulation materials
For the mineral wool insulation, the permeability was approximately twice as large parallel to the main fibre direction compared to the value compared to the value perpendicular to the main fibre direction
In the measurements we found that the thermal conductivity value of wood-fibre insulation increased by about 2%, see Figure 4 and Table 3

Summary

Introduction

This article describes an investigation of the thermal transmittance of highly insulated walls, roof and floor constructions performed by measuring the properties of wood-fibre and mineral-based insulation materials. One of the many sub goals of the ZEN center is to contribute to new and improved low CO2 materials and construction systems for buildings. Challenges in Buildings with Thick Insulation Layers. In combination with an increasing rate of innovation in the construction industry, this has led to the fact that the amount of thermal insulation used in Norwegian buildings is increasing. Earlier research has suggested that the total life-cycle carbon footprint of a building is largely linked to the production of the buildings [2]. The type of materials we used is crucial in achieving a future goal of carbon-neutral buildings. Among the most important building materials for withstanding the harsh Nordic climate are insulation materials

Methods

Results

Conclusion