The effect of insulation thickness on lifetime CO2 emissions

M Totland,R A Bohne,T Kvande

doi:10.1088/1755-1315/323/1/012033

Abstract

This paper assesses the total carbon emissions of a single-family home designed and built for Norwegian conditions, according to current standards (TEK 17), using an LCA approach. Various combinations of insulation thicknesses are assessed to identify which combination is most efficient in lowering the lifetime emissions as well as in which part of the building envelope additional insulation is most efficient in reducing the lifetime greenhouse gas emissions of the building. Overall, increased insulation resulted in lower lifetime emissions; the increased embodied emissions generally being outweighed by the energy savings resulting from the increased insulation thickness. The location of the insulation is the factor that was found to have the largest impact on the lifetime emissions. When increasing the insulation thickness from 100-500 mm, changing only one component at a time, the operational emissions were most sensitive to the insulation thickness in the walls, with a 26 % decrease compared to 7% and 3% for the roof and floor respectively. The most efficient cases tended to have little insulation in the floor (100 - 150 mm) and relatively high insulation thickness in the wall (350 mm). The most variable component was the roof, varying from 150 to 400 mm.

Highlights

According to the IPCC 19% of the global CO2 emissions, and 32% of the final energy consumption in 2010 could be accounted to the building sector[1]
The location of the insulation is the factor that was found to have the largest impact on the lifetime emissions
When increasing the insulation thickness from 100-500 mm, changing only one component at a time, the operational emissions were most sensitive to the insulation thickness in the walls, with a 26 % decrease compared to 7% and 3% for the roof and floor respectively

Summary

Introduction

According to the IPCC 19% of the global CO2 emissions, and 32% of the final energy consumption in 2010 could be accounted to the building sector[1]. In recent years there has been an increasing focus on reducing the carbon footprint of buildings, which in colder climates like in Norway, focuses on reducing heat loss and lowering the operational energy consumption. Increasing the insulation thickness, ensuring airtightness and eliminating thermal bridges are steps taken to bring the use phase energy consumption down. These measures are reducing the lifetime energy use and emissions, but at what cost? The solutions to reduce the carbon footprint of buildings are increasingly ”engineered”, relying on more materials to further reduce the emissions. Increasing the insulation thickness will potentially reach a limit where adding more material can not further decrease the energy use without it affecting the user-friendliness or increasing lifetime emissions

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