Environmental Impacts of Multi-Storey Buildings Using Different ...
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Environmental Impacts of Multi-Storey Buildings Using Different ...

Environmental Impacts of Multi-Storey Buildings Using Different ... Environmental Impacts of Multi-Storey Buildings Using Different ...

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10.07.2015 Views

- 124 -Table 10.1: Percentage of operational, initial embodied and maintenance related embodied energy to totalenergy over the full lifetime of the buildings 13 .Concrete Steel Timber TimberPlusOperational energy to total lifetime 89 87 91 94energy (%)Initial embodied energy to total 9 11 7 5lifetime energy (%)Maintenance related embodied 1 1 1 1energy to total lifetime energy (%)Table 10.2: Percentage of operational GWP, initial embodied GWP and maintenance related embodiedGWP to total GWP emissions over the full lifetime of the buildings 14 .Concrete Steel Timber TimberPlusOperational GWP to total lifetime 72 73 86 95GWP (%)Initial embodied GWP to total 23 23 16 11lifetime GWP (%)Maintenance related embodied 2 2 2 2GWP to total lifetime GWP (%)Even though the total operational energy consumption is similar in all buildings, the relativeamounts of energy used for heating and cooling can be different, depending on the differentthermal envelopes and the relative amount of thermal mass in each building.The trends for energy consumption also apply to GWP arising from the operation of thebuildings. Small variations are seen due to the primary energy mix and the manufacturing ofsome materials, such as concrete, which result in the chemical emission of CO 2 .• What is the influence of construction materials on the initial embodied energyand GWP of buildings?The importance of the assumptions made in an LCA study as to what happens to buildingmaterials on deconstruction of the buildings after 60 years has a significant impact on theGWP, as timber and timber products have the ability to sequester carbon for long periods.Assuming all deconstruction materials are landfilled, Tables 10.1 and 10.2 show that the Steelbuilding has the greatest embodied energy (11%) and GWP contributions (23%), mainlycaused by the large quantity of structural steel, which has a high embodied energy and GWP.The TimberPlus building has the relatively lowest overall embodied energy (5%) and GWP(11%) contributions because it contains less aluminium and steel compared to the other13 This table does not show percentages for transport or end-of-life energy – hence, figures do not necessarilytotal to 100%.14 Note that this table does not show percentage contributions from GWP due to transport, end-of-life or carbonstorage. The apparent anomaly of the emissions from operational, initial embodied and maintenance adding upto more than 100% is offset by carbon storage in the timber materials in the landfill.

- 125 -building types, instead substituting timber-based products, such as Western Red Cedarlouvres and pine cladding.The main impact contributors for all building in terms of building components were thosewhich contained relatively large quantities of aluminium (louvres and windows) and steel(structure).However, the above analysis refers to a scenario where all the demolition materials are placedin landfill at the end of the 60 year lifetime of the building (and some of the materials areconsidered to decompose to methane which is released back to the atmosphere).A very different result is seen where materials are either recycled or emissions of gases backto the atmosphere at the end-of-life are prevented or those gases are used to displace the useof other fossil fuels.• What is the influence of construction materials on the maintenance relatedembodied energy and GWP of buildings?Maintenance related embodied energy and GWP of the buildings over the 60 year lifetimecontributed relatively minor environmental impacts compared to the initial embodied energyand GWP (building maintenance contributes only around 1 – 2 % to the total impacts (Tables10.1 and 10.2) and between 12 % (Steel building) and 21 % (TimberPlus) of initial embodiedenergy). However, there were noticeable differences, in maintenance impacts, betweenbuilding types and building components.The Steel building had the greatest maintenance related impacts, whereas TimberPlus had thesmallest. Fewer materials were required to maintain the TimberPlus building. Western redcedar, which lasts 60+ years, was used for louvres, balustrades, and reveals. These structuresdo not require replacement, resulting in a reduced overall impact for the TimberPlus building.The building components that required the most maintenance, with the largest contribution tototal maintenance related impact, were the windows. This is indicative of the large quantity ofaluminium required in the maintenance of the frames. The exception is TimberPlus which hadthe lowest impact because the aluminium components of the windows were replaced withWestern Red Cedar.A well designed and constructed building, with low maintenance related embodied energywill decreases the overall life cycle impacts.

- 124 -Table 10.1: Percentage <strong>of</strong> operational, initial embodied and maintenance related embodied energy to totalenergy over the full lifetime <strong>of</strong> the buildings 13 .Concrete Steel Timber TimberPlusOperational energy to total lifetime 89 87 91 94energy (%)Initial embodied energy to total 9 11 7 5lifetime energy (%)Maintenance related embodied 1 1 1 1energy to total lifetime energy (%)Table 10.2: Percentage <strong>of</strong> operational GWP, initial embodied GWP and maintenance related embodiedGWP to total GWP emissions over the full lifetime <strong>of</strong> the buildings 14 .Concrete Steel Timber TimberPlusOperational GWP to total lifetime 72 73 86 95GWP (%)Initial embodied GWP to total 23 23 16 11lifetime GWP (%)Maintenance related embodied 2 2 2 2GWP to total lifetime GWP (%)Even though the total operational energy consumption is similar in all buildings, the relativeamounts <strong>of</strong> energy used for heating and cooling can be different, depending on the differentthermal envelopes and the relative amount <strong>of</strong> thermal mass in each building.The trends for energy consumption also apply to GWP arising from the operation <strong>of</strong> thebuildings. Small variations are seen due to the primary energy mix and the manufacturing <strong>of</strong>some materials, such as concrete, which result in the chemical emission <strong>of</strong> CO 2 .• What is the influence <strong>of</strong> construction materials on the initial embodied energyand GWP <strong>of</strong> buildings?The importance <strong>of</strong> the assumptions made in an LCA study as to what happens to buildingmaterials on deconstruction <strong>of</strong> the buildings after 60 years has a significant impact on theGWP, as timber and timber products have the ability to sequester carbon for long periods.Assuming all deconstruction materials are landfilled, Tables 10.1 and 10.2 show that the Steelbuilding has the greatest embodied energy (11%) and GWP contributions (23%), mainlycaused by the large quantity <strong>of</strong> structural steel, which has a high embodied energy and GWP.The TimberPlus building has the relatively lowest overall embodied energy (5%) and GWP(11%) contributions because it contains less aluminium and steel compared to the other13 This table does not show percentages for transport or end-<strong>of</strong>-life energy – hence, figures do not necessarilytotal to 100%.14 Note that this table does not show percentage contributions from GWP due to transport, end-<strong>of</strong>-life or carbonstorage. The apparent anomaly <strong>of</strong> the emissions from operational, initial embodied and maintenance adding upto more than 100% is <strong>of</strong>fset by carbon storage in the timber materials in the landfill.

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