Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system

Transcription

1 WAS031 Offsite Construction Case Study Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system Sure Start Children s Centres use off site construction and EcoCanopy technology to achieve minimal waste production of 3% of the total materials used during construction. 90% of waste produced is recycled. This is achieved through an integrated design and construction process which provides a high-quality, sustainable end-product to be used by the Centres. Project code: WAS031 ISBN: Research date: February 2008 Date: May 2008

2 WRAP works in partnership to encourage and enable businesses and consumers to be more efficient in their use of materials and recycle more things more often. This helps to minimise landfill, reduce carbon emissions and improve our environment. Written by: Halina Mason of Mace Group, with the support of Ben Wheeler (Mace Group) and Paul O Neill (Bryden Wood Associates) Front cover photography: Photo1 EcoCanopy used as a Children s Centre at Icknield Infants and Nursery School, Letchworth, Hertfordshire. Second page image: Image 1 illustration of an EcoCanopy building. WRAP, Mace Group and BWA believe the content of this report to be correct as at the date of writing. However, factors such as prices, levels of recycled content and regulatory requirements are subject to change and users of the report should check with their suppliers to confirm the current situation. In addition, care should be taken in using any of the cost information provided as it is based upon numerous project-specific assumptions (such as scale, location, tender context, etc.). The report does not claim to be exhaustive, nor does it claim to cover all relevant products and specifications available on the market. While steps have been taken to ensure accuracy, WRAP cannot accept responsibility or be held liable to any person for any loss or damage arising out of or in connection with this information being inaccurate, incomplete or misleading. It is the responsibility of the potential user of a material or product to consult with the supplier or manufacturer and ascertain whether a particular product will satisfy their specific requirements. The listing or featuring of a particular product or company does not constitute an endorsement by WRAP and WRAP cannot guarantee the performance of individual products or materials. For more detail, please refer to WRAP s Terms & Conditions on its web site:

3 Executive summary Sure Start Children s Centres are using a component based factory fabricated building system comprising a series of standard components such as roof, wall panels and windows, internal and external cladding to provide interior spaces for the Centres being build in Herfordshire. The factory environment ensures a high level of quality, efficiency and reliability. Currently, seven centres of varying sizes are being developed using the EcoCanopy system for the Sure Start Children s Centres in Hertfordshire. 82 Children s Centres will be operational throughout the county by Typically, the centres will provide community meeting and training space, day care facilities and office/ professional consultation space. Of particular benefit to the schools programme is that the design and tendering process is reduced and the construction disruption on site is minimised. This is one of the main reasons for the reduced construction programme for EcoCanopy buildings. Berry Grove, which is made up of 14 EcoCanopy modules, took 10 weeks from commissioning. This represents a time saving of a third compared to traditional build which could take between weeks. EcoCanopy also offers the environmental benefit of dramatically reducing embodied energy within both the build process and materials. In addition the manufacturing process reduces material wastage. EcoCanopy buildings can also integrate micro renewables, including PV panels, solar hot water panels, wind turbines, and CHP. There is no limitation on the size of EcoCanopy buildings. They can be as small as a single 4x4m canopy or as large as a school. EcoCanopy is more affordable than traditionally procured buildings, yet offers a higher quality construction, materials and finish. Currently, the buildings being constructed for the Sure Start Children s Centres use 97% of material in construction with only 3% waste. Of the 3% of waste produced, 90% of unused materials are recycled or reused in burners, for heating or in furniture or block board manufacture. These targets are continuously improving with which each new project setting waste minimisation targets. Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 3

4 Contents Executive Summary 1.0 Introduction to EcoCanopy technology 1.1 Background to the Product Component Based Factory Fabricated Building System 1.2 Example of Current Use Sure Start Children s Centres 2.0 Waste Comparisons with Traditional Build 2.1 The Factory Process 2.2 Material and Labour Miles 2.3 Site Installation 2.4 The Environmental Benefits of using the EcoCanopy Product 3.0 Key features of the EcoCanopy Product 3.1 Material Saving and Waste Minimisation 3.2 Sustainability 3.3 Building Size 3.4 Affordability 3.5 Reduced Construction Programme 4.0 The Manufacturing and Construction Process 4.1 Integrated Design and Standardised Materials 4.2 Roof cassette 4.3 External wall panels 4.4 Waffle floor slabs 5.0 Modular Construction Further Opportunities 6.0 Conclusion Figure 1: Flow Diagram of EcoCanopy components. Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 4

5 1.0 Introduction to the EcoCanopy technology 1.1 Background to the Product Component Based Factory Fabricated Building System Sure Start Children s Centres in Herfordshire used EcoCanopy product to deliver the educational spaces required to provide flexible interior spaces for a number of functions. EcoCanopy is a component based factory fabricated building system comprising a series of standard components such as roof, wall panels and windows, internal and external cladding. The factory environment ensures a high level of quality, efficiency and reliability. The result for the Sure Start project are robust, permanent buildings with a lifespan identical to conventionally built buildings. Timber forms all the main structural elements, including the distinctive roof module which incorporates a north-facing skylight. This module consists of a roof cassette that contains all services (power, airconditioning, light, cctv) and arrives on site completely prefabricated. The cassette structure is made of a combination of timber beams and steel connections that allow the structure to be split into several parts for transport and easy reassembly on site. A range of internal and external cladding options can also be fitted to suit client and design aspirations: internally, changeable wall panels can be made of spray painted MDF (standard), fabric (for pinboards), metal (to hold magnets) or frosted glass; and externally, a timber wall cladding is provided as standard, but this can also be replaced with opaque glass, terracotta, metal panels, rendered panels, brickslips. Windows can be inserted at any point into these walls, as they follow the internal and external cladding in size and shape. These windows can also be inserted at low level to allow a view for small children where used for educational spaces. The system also features full height double glazed windows, 1.2m wide, that can be inserted like standard wall panels. EcoCanopy building system can create environments suitable for many functions. These include: Inspirational teaching and learning spaces. Contemporary library and museum and cultural spaces. Efficient and effective health care facilities. Sustainable event pavilions. Low carbon public and private housing. Accessible leisure and community facilities. Secure local history and archive facilities. Flexible office space and ancillary facilities. Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 5

6 1.2 Example of Current Use Sure Start Children s Centres Photo 2. The Berrygrove Children s Centre during construction. The centre is composed of 14 Canopy modules The EcoCanopy building system is currently being used for the development of Sure Start Children s Centres in Hertfordshire. Sure Start is a national government initiative aimed at improving outcomes for children and their families 0-5 years, by joining up access to education, healthcare and jobcentre plus services. In Hertfordshire, 82 Children s Centres will be operational throughout the county by At the time of print, seven centres of varying sizes are being developed using the EcoCanopy system. Typically, the centres will provide community meeting and training space, day care facilities and office/ professional consultation space. 2.0 Waste Comparisons with Traditional Build Prefabrication of EcoCanopy components addresses the issue of waste consumption in a number of ways; the factory process, material and labour miles, supply chain relationship and the site installation. 2.1 Site Installation The energy expenditure in the distances the finished products travel to the site can be offset against the reduced number of deliveries required compared to a traditional site, and the reduced number of journeys made by the workforce to and from site. Due to the light weight nature of the EcoCanopy panels and their relatively shallow depth they can be densely stacked on lorries for transportation to site. The densities achieved mean that very few deliveries are needed to site for the relatively large volume of building generated. Similarly the amount of labour required to construct the Eco Canopy is minimal meaning reduced load on labour miles. All the panels involved in the construction of an EcoCanopy, including the concrete waffle floor panel, are designed to be lifted and installed using a Telehandler. This is the only large plant required for the construction of the whole building and represents a significant reduction in comparison to a traditional process. With no additional works being required to create the enclosed shell of the building, beyond the connection of the panels, there is no site wastage. 2.2 The Factory Process Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 6

7 Unlike a building site that is constantly changing, the EcoCanopy factory site is a controlled environment allowing constant monitoring and refinement partially enabled by the repetitious nature of the process. This allows factors outside of the direct build process to be measured and addressed. Any waste produced is one factor that can be directly addressed and refined over time. Stock can be ordered and managed in a highly efficient manner that avoids over ordering and subsequent wastage. The EcoCanopy factory environment also allows greater protection of materials from physical and weather damage another benefit not possible on a traditional building site. Across the building industry materials are supplied in known sizes which are traditionally amended on site to suit the given situation. Prefabrication of EcoCanopy components means that the situation is always constant. Coupled with the savings realised by manufacturing in large volumes and the repetitious nature of the processes material wastage can be reduced across the board. The repetitive nature of the EcoCanopy means that the refinements of components is an ongoing process. For example, refinements are being reacted to in future runs of panels, further reducing the carbon footprint of these panels. By applying this across the board the EcoCanopy as a product is able to continually improve its energy efficiency. 2.3 Material & Labour miles Of the energy consumed by the building industry material and labour miles are a large factor. A fixed factory location can attract other material/ component fabricators to an area in a similar way to that of the car industry to the Midlands; alternatively a factory can be located in an area sympathetic to the location of critical suppliers. These are simple good business strategies aside from any energy efficiencies that result. In the case of the EcoCanopy the factory is located in close proximity to the main component fabricators and to suit the major transportation links. Local products can become more competitive when produced in large volumes in response to repetitive orders. The long-term relationships that generate this type of situation can only be built with suppliers when working in a production line environment. For the EcoCanopy product this has proven to be beneficial when it comes to the procurement of bespoke metal components. There is a large amount of skilled labour involved in a construction process and as such their services are in great demand. This in turn means that there is a requirement for individuals to travel, potentially also with any tools and equipment that they might require. Similarly they are likely to transport their tools in bulk whether they are needed for that particular job or not. Prefabrication of EcoCanopy components means there is not a requirement for transporting large amounts of tools and equipment to and from site. Similarly as the construction of EcoCanopy components is process based, trained labour can replace certain skilled labour. The EcoCanopy is designed to suit the factory process and as such the tasks involved with constructing the panels on the production line are deliberately simple. This has meant that the tasks are easy to understand and can be readily explained and reproduced by relatively unskilled labour. 70% of the labour at the EcoCanopy factory are form within a 15 mile radius of the factory. 2.4 The environmental benefits of using the EcoCanopy Product. The environmental benefits of using the EcoCanopy product are evident from the detail provided in the preceding sections. The key environmental benefits include minimisation of the number of materials delivered to the factory due to bulk ordering and the reduction in construction waste as a result of the prefabrication process. In additional to this all timber components used are sourced from managed forests and are FSA certified. All EcoCanopy buildings are designed to have natural ventilation and double glazing. Clients also have the option to incorporate micro-renewables into the building system. This could include PV panels, solar hot water panels, and wind turbines. Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 7

8 3.0 Features of the EcoCanopy Product 3.1 Material saving and waste minimisation Waste reduction is a key benefit of using the EcoCanopy product. Data collected by BWA has shown that there are number of significant waste savings made overall. These include: a third reduction on construction program compared with traditional build: currently using 97% of material in construction with only 3% waste. Targets continuously improving: and of the 3% of waste produced, 90% of unused materials are recycled or reused in burners, for heating or in furniture or block board manufacture. Figure 2 below demonstrates the minimal percentage of waste produced the high percentage of that waste which is recycled: Figure 2 Percentage of waste produced and recycled The Eco Canopy is unique in that the designers of the canopy system conceived and developed the design, created the factory process along with installation manuals and are the architects for the installation of the canopy. Such an in-depth and fundamental understanding of the product and its capabilities means all detailing and processes are sympathetic to and are coordinated with the canopy. This has a dramatic effect on the minimising of waste through design by minimising bespoke components, designing to material module sizes and ensuring the vast percentage of works can be carried out in the factory process. The construction and design team are charged with waste reduction targets for every new order received. This means reviewing and recognizing areas where improvements can be made, reviewing material specifications and working closely with the supply chain and factory to continue to achieve improvements in waste reduction. Table 1:The material savings achieved by EcoCanopy The key reasons for reduced waste generation are: Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 8

9 materials are well protected in the factory environment from damage due to weather conditions; components remain identical across all projects resulting in low material wastage; Waste generated % Waste disposal % Type % Reuse Recycle Landfill Design Design process Paper 50% Design reviews Paper 80% Design manual Paper 30% Manufacture Waffle Slabs Concrete 1-2% - % 100% Rebar 0% - % - Timber 1% - 100% - Internal Walls Timber 2-3% 60% 40% Plasterboard 2% - 2% Insulation 0% - - External Walls Structural timber 1-2% 60% 4% Timber cladding 2% 70% 30% Internal boarding 5% 50% 50% Insulation 0% - - Roof Canopy Structural timber 5% 80% 20% - Timber roof board 1% - 100% - Plasterboard 5% - - 5% Insulation 0% Glass fibre 1% - - 1% Electrical Instillation Wiring 0.01% % Mechanical Instillation Plastics 0.1% - 100% - M&E Packaging 100% - 50% 50% Shipping & Packaging Plastic packaging 100% - 50% 50% Metal straps 100% - 100% - Site Works Concrete foundation 0% Excavated land Varies Service off cuts 2% 50% 50% - Decoration material 2% 70% - 30% standardised components mean that the manufacturing process can be continually improved; and prefabrication and delivery of assembled components removes waste materials from the construction phase of the project. Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 9

10 3.2 Other benefits in the use of the system Sustainability EcoCanopy dramatically reduces embodied energy within both the build process and materials. The manufacturing process reduces material wastage. All timber components used are sourced from managed forests and are FSA certified. The building can also integrate all micro renewables, including PV panels, solar hot water panels, wind turbines, CHP etc. Daylight is maximized by the use of carefully orientated rooflights which have health and well-being benefits for occupants as well as cutting energy consumption. Low emissivity, argon filled double glazing is used throughout. Solar control glazing can be installed for south facing glazing to avoid excessive cooling loads. Heating to the building can provided by a system of under floor heating fed by an electrically powered air to water heat-pump unit. Under floor heating has been used in the Berry grove and Icknield Children s Centres. Heating flow and return design temperatures serving the underfloor system will be designed to be as low as possible (typically at 45/35 Deg C) to maximise the efficiency of the heat pump system, these low temperatures are also ideally suited to the use of under floor heating. Zone temperature control in all buildings is provided via direct acting thermostats coupled to the under floor heating system manifolds. Building Size The off site system is flexible in its use and can be used on projects of various sizes and on both single of multiple storey buildings. Photo 3 - From left to right: EcoCanopy building finishes, sky light in roof, finished product. Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 10

11 The variety of designs and configurations of the components is represented in the diagrams shown below. York Road Children s Centre Beechfield Children s Centre De Havilland Children s Centre Berrygrove Children s Centre Arlesdene Children s Centre Egerton Rothsey School Figure 3. Plans showing the variety of building sizes and configurations of current projects Affordability The product offers an affordable system with flexibility of use on projects of various sizes. Reduced Construction Programme As with many off site methods this system offers a reduced construction programme. The design time is reduced due to the use of standard components in all designs. While, the design can be unique and tailored to client requirements it is essentially made up of familiar part. For example the floor, walls and roof are a standard design. The cladding and addition of extra components, such as micro renewables, and the choice of cladding Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 11

12 and finishes, make each project unique, however, the basic structures are made up of the same component parts. Clients can also see existing examples of current projects, which will look similar to their end product, making the finished product easier to visualise in their own environment. Based on the construction program of recent projects, for example Berry Grove, which is made up of 14 EcoCanopy modules, took 10 weeks from commissioning. This represents a time saving of a third compared to traditional build which could take between weeks. A further benefit of the prefabrication and assembly on site of components is the minimisation of disruption to the site. The most intrusive work is the service connections (sewer and electricity) which can be scheduled for low traffic periods such as school holidays. 4.0 Manufacturing and construction process The manufacture, delivery and installation of the individual components is described below through a series of illustration which demonstrate the controlled process and environment in which EcoCanopy is constructed. The factory has standalone stations which construct each element of the buildings. 1 Waffle slab (floor) cage preparation 5 Spray booth for walls 2 Waffle Slab pouring 6 Assembly of roof cassette 3 Timber preparation 7 Pouring roof cassette 4 Walls assembled 8 Transportation of components to site Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 12

13 9 Assembly and installation 10 Internal finished and cladding applied Across the building industry materials are supplied in known sizes which are traditionally amended on site to suit the given situation. With prefabrication the situation is always a known and a constant. Couple this with the volume and repetition that prefabrication can offer and prefabrication can exert an influence beyond that of traditional build in influencing the known / standard size of a supplied material, (this is above and beyond the ability to design to standard sizes which is discussed elsewhere). In so doing material wastage can be reduced. The above is not a single phase process. The repetitive nature of prefabrication means that refinement of the components is an ongoing process. For example, refinements can be reacted to in a future run of panels, further reducing the carbon footprint of that panel. By applying this across the board a prefabricated product is able to continually improve its energy efficiency. 4.1 Integrated design and standardised materials EcoCanopy, like most buildings, consists of three types of building product: 1) Planar materials (board materials) From the outset of the design process all boarding material have been designed to modulate to standard board sizes (for example 1.2mx2.4m). This affects all linings, plasterboard, wall panels, floor boards, cladding etc. and minimises off-cuts to virtually zero. Even the triangular roof boards can be laid out efficiently on 1.5mx3m boards. The amount of material required is calculated as an exact figure, based on the manufacturing process, so no over ordering occurs. 2) Linear materials (beams, columns, studwork etc.) Timber beams, battens etc are procured to the required dimensions, thus minimizing the need to cut or machine. The design considers standard section sizes like 50x200mm or 50x75mm and standard lengths. Main roofbeams, a prominent feature of EcoCanopy, have also been designed to a standard width. But in addition (due to the continuous demand for relatively large quantities) the timber is produced to the right dimensions by the supplier. 3) Volumetric materials (insulation) Any works involving insulation take place at the same point in the factory. Any shape and size of off-cuts produced are being assembled and reused on successive or different components (For example, the smallest off cuts are used in the parapet of the roof modules). All materials are well protected in the factory environment and damage due to bad weather conditions does not occur, therefore reducing material waste. When the manufacturer orders in bulk, in excess of one particular EcoCanopy building, because components remain identical over all projects there is no material wastage. The bulk ordering generally applies to all materials used which in turn minimises the number of materials delivered to the factory. 4.2 Roof cassette The roof primary structure is timber with standardized metal brackets that connect the roof structure as well as locating walls and being the lifting points. The multi functional design of these components not only simplifies the construction process but also mitigates the need for a series of alternative parts/ processes to do the same job. The overlay to this primary structure is a highly efficient inverted roof build-up with recycled gravel ballast installed on site. As with all the timbers used in the Eco Canopy the use of man made timbers has been avoided wherever possible. Not only does this minimises the energy and wastage used in producing the raw timber components for Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 13

14 the canopy but also in mitigating any harmful resins and such that are commonly present in man made timbers. Where manmade timbers are required they are sourced locally to avoid unnecessary material miles. Figure 4 Component parts of roof cassette 4.3 External wall panels The primary structure of the walls is a repetitive timber ladder module with a mineral wool infill. This is clad externally with a seeda timber and weather screen build-up. Internally the wall is fire protected and faced in a timber panel with optional finishes to suite the client s needs. Windows are designed to fit within the ladder module so the panel construction remains the same with no additional components etc. being required. The window itself is timber framed and uses argon filled double glazed units with the option of solar films. Figure 5 Component parts of wall panels 4.4 Waffle floor slabs The floor slab construction is made from a structurally optimized concrete grid, similar to a waffle slab, using locally sourced recycled aggregates and cement substitutes. This is precast in the factory where the transportation of the raw materials is more efficient than having the grid delivered due to the volume of air that would otherwise be transported and the additional weight of the water content. The concrete grid supports insulative infills under and through a timber deck ready to receive the clients preferred floor finish. For increased efficiency under floor heating and other plumbing needs can be installed in the floor slab, should this be applicable, to further reduce works on site. Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 14

15 Figure 6 Flow Diagram of Component parts of EcoCanopy Module including Floor, Wall and Roof cassettes. 6.0 Conclusion The use of an off site method on Sure Start Children s Centres offers waste minimisation opportunities in the build programme. Through a sophisticated and efficient manufacturing process which is constantly refined and improved EcoCanopy have achieved reduction in material wastage, labour content and skilled labour requirement, material and labour miles, transportation and delivery costs, site preliminaries, and programme in comparison to traditional build solutions. As well as cost savings and environmental benefits EcoCanopy offers clients aspirational design compared to other component based systems without compromising the high quality end product. Reducing construction waste at Sure Start Children s Centres using the EcoCanopy system 15

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