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CPD: Innovative envelope solutions

This CPD’s objective is to outline the development of insulated panel technology and improve understanding of innovation in modular building envelopes, helping reduce project complexity and risk

This CPD is sponsored by Benchmark, a unit within Kingspan Insulated Panels, part of the Kingspan Group, the world’s largest manufacturer of insulated panels. Benchmark, Kingspan’s most recent initiative, started by using insulated panels as carriers for various facade types and now includes a modular unitised solution and a comprehensive facade range.

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Part 1: Building envelopes

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The main purposes of building envelopes are (1) to provide support by resisting mechanical load transfer; (2) to control energy flow and (3) to provide pleasing external and internal finishes. ‘To meet new legislation, the technical performance criteria of building envelope design have become so much more performance-driven that engineers and building technologists are now firmly in the driving seat,’ says Graham Fairley, director of facades at AECOM. ‘However, there is no point in creating an envelope system for a building which ticks all the performance boxes but looks like a car crash.’

Approved Document l2A 2010 sets the maximum allowable u-values for walls at 0.25 to 0.35W/m2K and the notional building u-value for cost-effective compliance in England and Wales is 0.26W/m2K. In recent years, a number of new approaches, loosely termed ‘modern methods of construction’, have emerged and the need to construct buildings faster, more safely and with higher performance criteria has generated new building envelope strategies, reflecting demand for prefabricated components, assembled on site using ‘dry’ construction techniques. Standardised components improve complexity management, enable consistent industry-standard tolerances to be achieved, improve on-site predictability, optimise work sequences, reduce improvisation due to weather and facilitate Building Regulations compliance.

Part 2: PIR insulated panels

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Kingspan’s insulated panels are manufactured with a PIR (polyisocyanurate) core, offering the following benefits: light weight for ease of installation; good thermal properties;fire safety with LPCB and FM approval; Building Regulations compliance; lifetime insulation continuity; good airtightness (5m3/hr/m2); availability in various widths and lengths; BS EN ISO 9001:2008 Quality Approval and compliance with ISO 14001, the Environmental Management Standard. The disadvantages are that they have low density and acoustic efficiency.

BRE Environmental Profiles quantify embodied environmental performance and all associated embodied impacts, providing data which avoids the confusion of claims and counterclaims about building performance and is reliable and comparable, enabling suppliers to present credible environmental information about their products.

They provide common guidelines for Life Cycle Assessment for a UK database of environmental information. This methodology complies with ISO 14041, an internationally recognised approach to environmental impact analysis of products and processes, and was devised by the BRE in partnership with the UK government and trade associations.

Kingspan has BRE-certified environmental profiles on a range of panel systems. These include Green Guide to Specification ‘A+’ rated systems.

Part 3: End of life management

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End of life management of PIR insulated panels is very topical in today’s marketplace. PIR panels produced since 2004 have been manufactured without any ozone-depleting substances and there is a commercial service for dealing with panels produced before 2004 responsibly.

ECOsafe PIR panels are manufactured without HFCs and have a commercial value that is an incentive to their disposal at the end of their life, subject to transportation costs. Shredder plants, such as the facility in Liverpool pictured below, offer a proven solution for dealing with insulated panels with non-ozone depleting blowing agents.

Part 4: System development (1)

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Metal-faced insulated panels were originally used to clad industrial buildings, using horizontal rails and cladding drop-rods. Metal-faced insulated panels have since expanded their remit, first by increasing spans and then by spanning from frame to frame, removing the need for intermediate steelwork.

They are now used on commercial buildings, supported by horizontal rails fixed to columns or equally on structural framing systems. Innovation in manufacture has developed a strong bond between insulants and steel outer sheets, enabling panels to be used regularly as carriers for facades. Ryder Architecture specified 1,320m2 of Benchmark Ceramic Facade for Units 3 and 4 of the Great Park commercial development in Newcastle, comprising ash finish ceramic tile with slate cladding around the entrance.

Part 5: System development (2)

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More recently, Benchmark has developed new profiles to introduce shadowing and texture in building facades. Insulated panels are now available with new architectural features, which create an illusion of varying panel width, and with larger horizontal joint reveals and a wider range of vertical joint details, providing a pleasing level of architectural detail without adding complexity in the construction. Benchmark’s ‘Evolution’ brochure illustrates the new architectural features that are available.

Along with these developments in the possibilities of architectural expression, insulated panels can nowadays play a more significant role in the performance of the building envelope, as explained in the following sections.

Part 6: Innovative systems

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Kingspan has developed insulated panel technology through new envelope systems involving flush or pronounced prefabricated wall units bolted to primary steel or concrete structural frames. This eliminates all additional secondary support structure and isolates the envelope from the frame to eliminate edge deflection where it meets the facade. This system supports a range of ventilated facade types, which are easily combined. These panels perform as complete wall infill units and span from floor to floor.

Significant savings on secondary steelwork and installation are achievable.

Part 7: Unitised wall systems

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Benchmark’s unitised wall composite panel systems are manufactured to BS 9001:2008 and have certified Centre for Window and Cladding Technology building envelope compliance. Independent testing by CERAM demonstrates 60-year durability and the system’s fire performance has been tested to BS EN 1364-1. U-values of 0.095W/m2K and air permeability below 3m3/hr/m2 at 50Pa have been achieved.

Its inside-out fire resistance is 84 minutes for insulation and 90 minutes for integrity and the corresponding outside-in ratings are 94 and 116 minutes. Systems have a predicted single figure weighted sound reduction of Rw =25-50dB, depending on their thickness. They directly support internal liners and are designed to accommodate brittle plasterboard finishes.

Part 8: System features

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The thicker panels dictated by new regulations optimise spanning capability and the system is typically thinner than SFS equivalents. Insulation forms part of the unitised system, rather than sitting on top of it and can achieve required U-values with half the depth of built-up mineral fibre.

Maximum unit size is 7.2m x 3.6m, and height and width are interchangeable. Interface complexities are minimised by sitting the system proud of the frame. Modular units are fully reusable and potentially 100 per
cent recyclable. Mechanical handling reduces installation costs and cuts on-site damage, complying with health and safety guidelines by minimising manual handling.

The whole system is guaranteed by Kingspan. Refer to Benchmark’s Quick Guide for their full range of compatible facades or visit www.kingspanbenchmark.com

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