Benefits of off site manufacture

Transcription

1 Case Study Benefits of off site manufacture British Land Ropemaker site, London Ropemaker is a British Land commercial building on a prominent London city site. The site has 586,000 square foot net lettable space, with 21 storeys and three basement levels. The high profile development has impressive green credentials, including a BREEAM excellent rating, and has exploited a number of opportunities for Off Site Manufacture. This study reviews two products manufactured off site including Podwall washrooms supplied by Swift Horsman and Technik flooring supplied by Grants Ltd. Both systems were monitored on site using CaliBRE and SMARTWaste tools to evaluate the efficiency of the construction process and measure the waste generated. Other environmental and cost factors were also assessed. Start on site - 11 September 2006 Completion (shell and core) - 8 May 2009 Project, Construction and Cost management - Mace Aims of the research To assess off site manufactured products in comparison to traditional methods of construction in relation to: waste (site and factory); resource required on site; site efficiency and productivity (value added time); environmental impact analysis and end of life assessment; cost Direct and Indirect; installation time and health and safety. Results of this research show: The Technik floor product reduces overall waste and costs compared with traditional flooring. The Podwall product brings impressive gains in site labour efficiency and waste reduction, leading to a cleaner and more organised site, with the cost of the product being similar to traditional construction. There were no reported Health and Safety incidents for operatives working on the off site manufactured products. The waste generated in a factory can be controlled and more easily managed both at point of manufacture and on site. Off cuts are reduced, packaging can be reused and recycled, and remedial work is minimised (reducing waste and non value added time during construction). Technik flooring has a lower overall environmental impact than screeded and tiled flooring (measured in Ecopoints). Overall, British Land have been impressed with the quality of the finished washroom units and flooring.

2 2 Case study Off-site manufacture: Ropemaker Podwall (supplied by Swift Horsman) Features of the Podwall system A flexible modular walling system incorporating finishes and services. All elements manufactured off site in a controlled environment. Innovative fit out solution providing high quality female, male, and disabled toilet units throughout the development. Benefits of the Podwall Reduced off cuts and site waste. Reduced defects. Efficient bulk delivery, reducing C0. 2 BREEAM compliant sanitary ware. Low flow pipes and low water use toilet. Design quality - a full size pod is produced to allow a walk-around prior to agreeing final design. In order to reduce storage costs and minimise the risk of damage, Swift Horsman only delivers what is required for the floor. The wall pieces and ceiling cassettes are packed in the order that they would be assembled for efficiency. The flooring in the Podwall washrooms is not manufactured off site but instead comprises 600 x 600 x 30mm calcium sulphate floor panels supported by adjustable pedestals, with black granite floor tiles then laid on an adhesive bed. The floor tiling is time consuming and there is an opportunity to improve the efficiency by also manufacturing this aspect off site. British Land have used Podwall on several of our London office developments for the quality and consistency it provides. Swift Horsman s FSC credentials meet our requirement to use only sustainable timber on our sites. This year, Swift Horseman won British Land s Supplier of the Year (Developments) Award. Sarah Cary, Sustainable Developments Executive. Podwall construction process Layout Wall pedestals Walls Floor pedestals Ground tiles Ceiling and air ducts Sanitary fittings Basin units being fitted, and an example of a Podwall final product PODWALL research results performance breakdown (man hours on site) Storage of materials in the Swift Horsman factory Most time was spent erecting the Podwalls, including the washroom units (wash basins and toilets), which are an integral part of the system. The traditionally laid flooring contributes significantly to the overall construction time. Services are integrated into the Podwall, hence the first and second fix plumbing and electric comprise a small part of the overall build. 89% of time constructing the Podwall was added value time, with only 11% being non added value. This positive use of resources is largely due to factory precision and reduces requirement for remedial action due to human error. There is approximately a 40% saving to programme by using the Podwall. Each floor at Ropemaker had an 11 week programme to install the Podwall (3 blocks per floor - one ladies, one gentlemen and one disabled toilet), which would be equivalent to 15½ weeks for traditional fit out. Man-hours Walls Tiling Washroom units Ceilings Toilet pod flooring 1st fix plumbing Decoration Drylining 1st fix electric 2nd fix plumbing 2nd fix electric Washroom Pods Resource Analysis Total man hours per 100m 2 build - 1,486 Total man hours required to construct one toilet block of 59m The toilet pod flooring refers to the floor pedestal and the floor base (calcium sulphate tile). The tiling then refers to the ceramic tile laid over the top.

3 Case study Off-site manufacture: Ropemaker 3 Podwall waste Quantity and type produced, on site Because the Podwall is manufactured off site the waste on site is reduced. The largest proportion of waste generated is in the packaging, which ensures the product is protected between factory and site. The waste produced by remedial work or off cuts is minimised as the product is created in a controlled factory environment. Podwall toilets (walls, toilets/urinals, basins, vanity tops, ceilings) are transported to site on crates which are subsequently returned to the factory and reused. The polythene covering the crates and the plastic polystyrene protectors on the walls, doors and mirrors are only removed on completion. If well managed, the packaging waste produced can be recycled (as was the case on Ropemaker). m 3 waste per 100m 2 floor area built Packaging 7.96 Insulation 0.56 Metals 0.28 Plaster 0.56 Plastics 0.17 Timber 0.67 Total Across the Ropemaker site a total of approximately 213m 3 of waste was produced for all Podwall washrooms. It was not possible to measure waste on a comparable site using traditional methods, but it is anticipated that, given the low levels of waste observed during the monitoring of the Podwall, traditional waste would considerably exceed the Podwall waste volumes. Podwall basin units on crate, as delivered to site. Polythene protective covering removed, protective wood covering the basins and plastic panel coverings still in place. Waste management route The percentage of materials recycled from Ropemaker frequently exceeds 85%. From the off site products monitored, everything is recycled with the exception of insulation from the Podwall system, left over from sound proofing (0.5m³ per 100m² of build). Waste from the Podwall Site Factory Total m³ per100m m³ per 100m² 10.83m³ per 100m² Site waste comprises timber, plastic, plaster, insulation and packaging. Factory waste comprises plastic, metal, cardboard and commercial waste.

4 Podwall cause of waste The main cause of waste is packaging. This is because most of the material off cuts are generated in the factory rather than on site, reducing site waste. Packaging is required to protect the product during delivery, storage and construction. A small percentage of waste is linked to the methods of work used in installing podwall, such as off cuts. In a traditional build this waste would be more significant. An example of remedial work includes extra site work required following design changes. Cause of waste Methods of work 19% Packaging 80% Remedial work 1% Cost comparison Washrooms At Ropemaker the Podwall washroom package has a value of approximately 6m, with 54 toilet blocks being delivered across 1969m 2. Traditional build costs are based on Spon s Architects and Builders Price Book (2009) and are therefore indicative averages for building components. Where the specification would not change with a traditional build (e.g. in relation to sanitary ware, fixtures and fittings and associated works) the Swift Horsman cost figure has been used. The main differences in cost between the Podwall and the traditional system are in services installation and cubicles. This is because services are integrated off site into the walls and cubicles for the Podwall which explains the greater cost of these elements, whereas with traditional build the cost of installing services on site is higher. The traditional costs do not account for indirect costs such as the increased cost of waste and removal thereof and the increased programme time to install the traditional product. Cost Comparison Podwalls versus Traditional Overall comparison of the cost of delivering Podwall washrooms with traditional build. Costs include material and labour and preliminaries. / m ,000 1,500 2,000 2,500 3,000 3,500 Podwalls Traditional 3,056 per m 2 3,022 per m 2

5 Case study Off-site manufacture: Ropemaker 5 Cost breakdown comparison Washroom Podwalls cost breakdown ( /m 2 ) Cost breakdown for the Podwall system includes material, labour costs and preliminaries. Total: 3,056.74/m 2 Traditional Washroom cost breakdown ( /m 2 ) Cost breakdown for traditional washroom build includes material, labour costs and preliminaries. Total: 3,022.14/m Decorations Associated Items /m 2 Services installations 60.73/m 2 Associated Items /m 2 Floors (screed and tile) /m 2 Ceilings 27.77/m 2 Decorations /m 2 Walls (plasterboard, drylining) /m 2 Floors /m 2 Ceilings /m 2 Doors and Access panels /m 2 Sanitary ware /m 2 Doors /m 2 Cubicles /m 2 Cubicles /m 2 Fixtures and Fittings /m 2 Fixtures and fittings /m 2 Sanitary ware 1,300/m 2 Services installations /m 2 Walls The table below gives some more detail on the costed components, indicating where cost differences occur Build Elements Podwall Traditional Services installations Integrated into walls/cubicles/ceilings. Installed on site. Cubicles Services integrated into walling similar to below, including some glass finishes. Services not integrated. Laminate faced mdf with back panelling system and frame support. Walls Pre-manufactured galvanised steel support framework on adjustable floor support. Includes glass, lacquered and veneered panels. Drylining. Includes studwork, noggins, plasterboard, tape and jointing and skimming. Ceilings Proprietary MF suspended ceiling with apertures formed, and tape and jointed. Integrated electrics and lighting fixtures. Suspended ceiling, no integrating electrics or lighting. Decorations Mist coat and 2 coats of emulsion. Mist coat and 2 coats of emulsion. Floor Raised floor and tiling. Screed floor and tiling. Sanitary ware All sanitary fittings including basins, urinals, toilets, cleaners sink etc. Same sanitary ware as used in the Podwall. Fixtures and fittings Includes vanity units, make up shelves, mirrors, soap and towel dispensers etc. Fitted in the factory. Same spec as the Podwall, fitted on site.

6 6 Case study Off-site manufacture: Ropemaker Technik flooring (supplied by Grants of Shoreditch) Features of the Technik system A pre-fabricated panelised floor system that eliminates the need for wet screed. Pre-bonded tiled floor with tile modules placed on pedestals. Modules consist of calcium sulphate panels to which 15mm thick granite tiles have been bonded with adhesive. Panels are 750 x 350mm with a profiled edge to allow joining with adjacent panels. These are laid on pedestals. Technik floor panels can be produced to almost any bespoke module size. Benefits of Technik flooring Required thickness of the stone (and therefore the floor thickness) is reduced. Significant component parts are recycled (panel is 95% recycled paper). Shortened construction period (no drying time as with traditional screed). Minimal off cuts on site. No requirement for special machinery. Technik process Setting out Laying first pedestals and tiles centrally Run lines to correctly place rest of tiles Cut out around entrance/exit/lift door areas Apply wet grout Apply dry grout Attach fire barrier across entrance void Protect / cover; later polish Technik Research Results Performance Breakdown (Man hours on site) Screeded floor - 250hrs per 100m 2 Technik floor - 168hrs per 100m 2 The Technik flooring system was compared to a traditional screeded floor, which includes laying insulation, applying wet screed (sand and cement mix), waiting for screed to dry, and tiling. Tiling is the most labour intensive element of traditional flooring, and drying time for screed increases programme and risk of damage when wet. CaliBRE results show that 32% of time spent laying a traditional floor was non value added time compared with 17% for Technik floor. Technik s 83% added value time demonstrates the efficiency of off site flooring as well as the reduction in remedial work. Resource per 100m 2 floor area Insulation Screed Tiling Pedestal Floor Technik floor Screeded floor The floor element of the Technik floor construction refers to laying the composite pre-bonded tiles on top of the pedestals. Man-hours per 100m 2 floor area

7 Case study Off-site manufacture: Ropemaker 7 Waste amount comparison Waste breakdown per 100m 2 of build Flooring waste produced on site Technik floor compared to screeded floor: Cause of waste, comparison between Technik and screeded floor. Volume of waste per 100m 2 floor area m 3 per 100m 2 m 3 per 100m 2 Technik 2.32m 3 Technik Off cuts 0.1m 3 Screeded 2.97m 3 5m 3 Screeded Packaging 2.2m 3 2.0m 3 In addition to the above, at the factory 0.49m 3 of waste is generated bringing the total waste to 2.81m 3 per 100m 2. For all the Technik flooring at Ropemaker this equates to 24.56m 3 of waste (872m 2 ). If screeded floor with tiling had been used on site instead this would have amounted to 41m 3 of waste. The screeded floor generates a significantly greater amount of waste compared to the Technik floor. Screeded floor generates a large amount of polystyrene off cuts when standard size sheets are cut on site. Technik flooring considerably reduces off cuts and therefore site waste. Progress has also been made in reducing packaging waste, e.g. by minimising the size of polystyrene protectors between tile sections during delivery. Cost comparison Floor Embodied energy / environmental profile The Ecopoints score for Technik and screed is displayed Price comparison Technik versus screed flooring per m 2 Ecopoints Scoring overall environmental impact Comparison of Ecopoints % Technik floor 84 Screeded floor Labour Material Technik flooring offers an Ecopoint saving of 19% against traditional flooring Technik Screeded Total cost per m 2 : Screed Technik The material cost of screeded floor includes screed, insulation and tiling. Material cost of the Technik floor includes pedestals, pre-bonded tiles/panels, grout. Overall Technik floor is a cheaper option. In the stages of laying the screed floor the tiling costs the most both in terms of materials and labour. This pushes the price of the traditional floor up. Additionally, the materials associated with the traditional screed design take up a greater area within a warehouse and as such the cost is considerably higher to that of Technik floor. A programme/time saving of 25.7% is made by using Technik flooring, which clearly has a cost saving implication as well. A standardised environmental profile methodology was used to assess the impact of materials used in the Technik product over their life cycle (extraction, processing, use, maintenance, disposal). BRE Ecopoints measure the overall environmental impact of a product, covering a range of 12 issues rather than only C0 2 emissions (e.g. mineral depletion, water extraction.) The lower the points the better. The CO 2 impact of the Technik flooring system is higher than the CO 2 impact of the screed. However, the overall environmental impact of the Technik floor (calculated in Ecopoints per tonne) is lower than the screed. The higher CO 2 impact of the Technik flooring system is mainly due to the impact of transport to site. The higher overall impact of the screed is due to the greater use of resources.

8 Monitoring Tools Mace and BRE conducted the research and monitoring on this site and put together this case study. Mace and BRE used the established systems of SMARTWaste and CaliBRE to carry out monitoring on site. SMARTWaste is a tool to enable the measurement and monitoring of site waste. Skip contents are assessed at least daily, with any waste generated since the last round being logged. Where appropriate photographs are taken. Information collected includes: skip location; product and product sub-group (e.g. product packaging; sub-group cardboard); cause of waste (identifies which operations are creating the waste, e.g. design, packaging, methods of work, and then the cause, e.g. untrained labour); work package (identifies the part of the build programme the waste has arisen from, e.g. superstructure, and the package, e.g. timber frames); product dimensions (height, width, depth without including void spaces); other relevant notes are recorded and all data is recorded on a hand held computer and then uploaded to a computer. CaliBRE is a measurement tool developed from extensive experience by BRE in the measurement and productivity assessment of various methods of construction. The main task of the CaliBRE toolkit is to use real time performance monitoring to measure on site efficiency and objectively assess actual construction productivity and performance. The process of monitoring using CaliBRE is similar to SMARTWaste in that the observer records the location they are observing, but instead of monitoring waste the observer is monitoring personnel on site, and waste in terms of non-value added time. Therefore the location, work package and activity being carried out are recorded, along with any cause of non-value added time. Additional information For more information on off site technologies and waste reduction: Envirowise provides free government-supported environmental consultation, advice, and documentation for UK businesses. Buildoffsite is an industry-wide campaigning organisation that promotes greater uptake of offsite techniques by UK construction for all markets. WRAP (Waste & Resources Action Programme) helping the construction industry cut costs and increase efficiency through the better use of materials. While steps have been taken to ensure its 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. This material is copyrighted. It may be reproduced free of charge subject to the material being accurate and not used in a misleading context. The source of the material must be identified and the copyright status acknowledged. This material must not be used to endorse or used to suggest WRAP s endorsement of a commercial product or service. For more detail, please refer to our Terms & Conditions on our website Waste & Resources Action Programme The Old Academy 21 Horse Fair Banbury, Oxon OX16 0AH Tel: Fax: info@wrap.org.uk Helpline: freephone