Introduction Life Cycle Principles Embodied carbon - Concrete Block ...

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This table lists aggregate blocks up to 8MPa as having embodied carbon of 0.061 kgs of CO 2 /kg of concrete. The great majority of concrete blocks are 7.3 MPa and below so this is a fair approximation for aggregate concrete blocks in general. The embodied carbon level for aggregate concrete blocks is surprising low, this is because :- • Strengths are usually comparatively low though fit for purpose as strength demanded is usually compressive • Low levels of cement are required due to the low water: cement ratio in manufacture, this is facilitated by employing high levels of vibration in the block making machine • On average aggregate concrete blocks contain aggregate of which 24% is recycled and cement of which 19% is defined as cement replacements Listed below are some materials for comparison purposes. It can be seen that aggregate concrete blocks compare very favourably with a variety of common construction materials. Cradle to gate embodied carbon Material Kgs CO 2 /kg of material 8 MPa aggregate concrete block 0.061 Autoclaved aerated concrete 0.28 – 0.375 blocks (aircrete) Sawn softwood 0.45 Plywood 0.81 Steel – UK typical 1.77 General plastic 2.53 Note that the above products have different densities and that values for timber products exclude the calorific value (CV) of the wood Source : University of Bath Inventory of Embodied Energy (2008) Vers 1.6a Construction: • Based on reliable techniques that have been established over many years, aggregate block construction has introduced buildable innovations to improve performance to meet developing requirements. • The range of dimensions, strengths and surface textures, widely available from stock or with short delivery times allows flexibility and optimisation to meet project requirements. • Aggregate concrete blocks use the minimum amount of packaging consistent with providing safe delivery and handling. • Construction techniques and block weights have been developed to ensure that site handling operations are safe and minimise the potential for injury to site personnel. • A block built building will last more than 150 years.
In-Use performance: • External and separating/party wall thermal insulation solutions are available that contribute significantly to meeting Building Regulations thermal requirements and the future development of zero carbon construction 4 . • External cavity walls can be built with aggregate concrete blocks to U-values of 0.18 using conventional designs and cavities of between 100mm and 150mm depending on the type of insulation specified. Lower U-values can be achieved by either raising the quality of insulation and/or its thickness. • Thermal mass effects provide more efficient long term energy/carbon performance than lighter weight construction 5 . • Aggregate blocks are durable, fire resistant, not attacked by vermin or insects, do not introduce harmful substances into the internal environment of buildings and require minimal maintenance over the full life of the building. Block construction is resistant to flooding, a potentially increasing risk in the UK due to climate change. • The BRE Green Guide to Construction provides environmental performance ratings for typical UK constructions on the basis of A+ to E ratings. Many aggregate block constructions are at the higher performing A and A+ ratings 6 . • The Code for Sustainable Homes 7 and the BRE Environmental Assessment Method (BREEAM) 8 are currently the most commonly used sustainability assessment methods in the UK. Aggregate block construction attracts high levels of credits for: – Thermal performance (within Energy and Carbon). – Acoustic performance (within Health and Wellbeing). – Environmental performance ( due to high Green Guide ratings). – Responsible sourcing of materials (through ISO 14001 and BES 6001 certification). End of Life: • Buildings constructed with aggregate concrete blocks can be easily modified to extend their life and to accommodate the developing needs of occupiers or for a change of use. • Blocks are fully recyclable e.g. as a source of aggregate for future construction. References/Links 1. BS EN 15804:2012 “Sustainability of construction works. Environmental product declarations. Core rules for the product category of construction products” 2. British Precast Sustainability Charter. Independently audited annual returns representative of 60% plus of UK manufactures aggregate concrete blocks http://www.britishprecast.org 3. BRE BES 6001 “Framework standard for the Responsible sourcing of construction products” http://www.greenbooklive.com/search/scheme.jsp?id=153 4. CBA data sheets ‘External insulation of solid walls’ and ‘External walls thermal performance’. www.cba-blocks.org.uk 5. “A whole life CO2 argument for concrete blocks” Tom de Saulles CBA Spring 2012 Newsletter www.cba-blocks.org.uk 6. BRE Green Guide to Construction http://www.bre.co.uk/greenguide/podpage.jsp?id=2126 7. Code for Sustainable Homes http://www.planningportal.gov.uk/buildingregulations/greenerbuildings/ sustainablehomes/ 8. BRE Environmental Assessment Method http://www.breeam.org/ 9. Bath University Inventory of Energy and Carbon http://www.bath.ac.uk/mech-eng/sert/embodied/
Page 1: February 2013 Data Sheet 16 Uniclas

Introduction Life Cycle Principles Embodied carbon - Concrete Block ...

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