CE139 - Energy Saving Trust

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Modern methods Insulating formwork Aircrete block and plank Figure 7 Insulating formwork with reinforcement ready for concrete pour Description Insulating formwork uses two layers of rigid foam as permanent shuttering for a reinforced concrete wall. The insulation can be in the form of two sheets of rigid foam tied together, or in the form of large hollow blocks. Attributes affecting thermal performance The fact that the finished structure has a continuous layer of foam (usually polystyrene) internally and externally means that thermal bridges are effectively eliminated from areas of plain walling. The structures are very airtight. Figure 8 Aircrete blocks and planks being used to form walls and intermediate floor of a dwelling Description Aircrete has been in use for many years in blockwork, but a recent innovation is the use of thin joint techniques, where a thin (4mm) layer of special adhesive replaces the normal relatively thick mortar joint. Large planks of reinforced aircrete can also be used to produce both ground and intermediate floors, and also to create a pitched roof structure. Attributes affecting thermal performance To achieve good levels of energy efficiency aircrete would usually be used in conjunction with supplementary insulation (either as part of cavity masonry or as external insulation to a solid aircrete wall). The thin joint system is beneficial because there is a much lower cross section of mortar acting as a thermal bridge. Building energy efficient buildings using modern methods of construction
Costs and conclusions The build costs of dwellings will be influenced by many factors including: • The number of dwellings. • The size and built form. • The level of energy efficiency attained. • The construction technology. The conclusion from the case studies presented is that high levels of energy efficiency are readily achievable with a range of modern methods. Although costs vary widely between the schemes, the range is in line with current costs for new-build housing indicating that using modern methods of construction can deliver higher energy efficiency standards, whilst still remaining cost competitive. • The standard of finishes. • Amenity levels provided. • Infrastructure costs. It is therefore very difficult to draw any firm conclusions by comparing the costs of different schemes. In the case studies below cost data are reported, although it has not been possible to check whether the costs quoted have been calculated on an equivalent basis. The scale of the projects varies widely, from a single dwelling to several hundred dwellings, with similar differences in terms of the associated infrastructure works. The relative costs for the different projects should not, therefore, be interpreted as being indicative of the relative costs of the different construction technologies. Building energy efficient buildings using modern methods of construction
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Page 3 and 4: Introduction Home energy use is res
Page 5 and 6: Modern methods Volumetric construct
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CE139 - Energy Saving Trust

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