A Life Cycle Assessment Comparison of External Cavity Walls Using Different Types of Concrete Block

Abstract

AbstractThe use of cement-based concrete in construction has become more widely criticised due to the high embodied carbon associated with its production. Despite this, concrete is still the most used construction material in the world. This research examined the environmental impact of concrete blocks used in external cavity walls using life cycle assessment as the method of examination. The aim was to determine if concrete production emissions could be offset through a saving in operational emissions due to concrete's thermal properties and longevity. The environmental impact was determined using embodied carbon figures for the different concrete block types and operational carbon emissions from a model building simulation using each different cavity wall design. The embodied carbon figures were taken from the BSRIA Inventory of Embodied Carbon (ICE) guide. The research focused on concrete made using CEM I type cement as it is the most commonly used cement type and has the highest embodied carbon. Three different types of concrete block were chosen so that comparisons could be made. The concrete blocks used were a dense block, a medium-dense block, and a lightweight block. A brick and medium-dense block cavity wall were also chosen as this construction method is common in the UK. These were each used individually in their own external cavity wall. Four office buildings were modelled in IES VE software to simulate operation with people, HVAC systems, lighting, domestic hot water, and computers. The models were simulated in two different locations in the UK to determine how location and climate can affect emissions. The operational carbon emissions were obtained from the IES VE simulations. The results from the research showed that the medium-dense concrete block cavity wall had significantly lower embodied carbon in the production stage than the other designs. The medium-dense block wall also performed the best overall in both locations when considering the total operational emissions and the embodied carbon.KeywordsLife cycleCavity wallConcrete blockSustainability