EJOT UK has played a key role in the construction of the building envelope for an extensive new LEGO factory in Vietnam by providing thermally superior fixing solutions for the installation of more than 100,000m2 of flat roofing.
The EJOT Group collaboration, led by EJOT Asia, provided a complete building envelope fastening solution for the major construction project. It involved EJOT UK manufacturing and supplying more than 750,000 EJOT HTK 2G 50 tube-washers for use in combination with EJOT TKR fasteners for the roofing with EJOT Austria also supplying 120,000 stainless steel fasteners for the façades.
EJOT UK’s tube-washer and fastener combination was selected primarily because it enabled important sustainability and cost-saving goals to be realised compared to other fixing approaches.
The new US $1bn (€890 million) factory at the Vietnam Singapore Industrial Park III in Binh Duong near Ho Chi Minh City occupies a 44 hectare site and will create up to 4,000 jobs over the next 15 years. The LEGO Group’s sixth manufacturing site, and its second in Asia, aims to be the company’s first carbon neutral factory, meeting a minimum standard of LEED Gold, covering all areas of sustainability including energy, water, and waste.
Main contractor Cottecons delivered the new factory, with roofing and cladding contractor HTF Holdings tasked with the installation of the building envelope using fasteners supplied by EJOT’s Vietnamese distribution partner, HHK Asia. The building envelope features solar panels on its roof with a nearby solar project also constructed. These combined resources mean the site features more than 12,500 solar panels with a total capacity of 7.4MW, providing more than enough renewable energy to match 100% of the factory’s annual energy requirements.
The factory has also been designed to accommodate electric vehicles and highly energy efficient production equipment is used throughout. In addition, 50,000 trees will be planted to compensate for vegetation removed during construction.
Optimising the flat roofing performance
The design and specification of the building envelope was key to achieving the energy efficiency and longevity goals for the factory, with the added dimension of being able to facilitate the installation of solar panels across the roof area. A flat roof design was adopted featuring a Mapei TPO (Thermoplastic Polyolefin) membrane and a 150mm layer of Rockwool insulation to meet the demanding environmental conditions.
The tropical climate of the Binh Duong region means that average high temperatures are in the range of 30°C to 32°C throughout the year, with slightly cooler nights, and the area experiences significant humidity with regular rainfall during the wet season. Hence why the fastener specification had to be sufficient to resist corrosion risks and minimise thermal transfer through the roof structure.
The initial fastening proposal for the flat roof membrane was to use metal stress plates into which fasteners, long enough to accommodate the full depth of insulation plus embedment into substrate, would be used. This would have presented a difficult installation challenge using niche fasteners not easy to source.
However, an alternative approach was suggested by EJOT Asia’s technical consultants and EJOT Group’s Business Development Director for the Asia Pacific region, Ben Gallant whereby EJOT HTK 2G telescopic tube-washers, featuring a 50mm diameter stress plate, would be used instead of the metal stress plates in combination with EJOT TKR fasteners. This would enable a secure attachment to be provided for the roof deck at the deepest point.
Why EJOT’s HTK tube-washer and fastener combination was specified
This design was adopted due to the multiple benefits it offers over the original recommendation, most notably in terms of meeting the building performance objectives and delivering notable cost savings in the construction phase.
As the EJOT HTK tube-washer is manufactured from engineering-grade PE (polyethylene), it offers a significant reduction in thermal conductivity compared to using metal stress plates. The key benefit of the HTK tube-washer allows for a significant reduction of heat transfer through the building envelope from outside to in and vice versa. This is illustrated by the HTK’s thermal transmission figure of 0.25 W/(m²K), compared to an all carbon steel approach (stress plate + long fastener) of 51.9 W/(m²K).
With a lower thermal transmission figure, the lower the demands on energy-consuming air-conditioning systems to maintain a comfortable internal temperature. This helped to ensure the insulating properties of the tube-washer could contribute to the thermal performance required for the building envelope in the carbon neutral project.
In addition, the HTK tube-washer enables the use of shorter fasteners, which translates into significant savings across the roof. Material use is reduced due to less steel being required, which is a benefit from a resource minimisation perspective as well as a cost saving.
Long term durability is also guaranteed with the nylon composition used for HTK tube-washers as well as the EJOT carbon steel fasteners specified. They offer a flat roof fixing solution which is reliably resistant to corrosion, even in Vietnam’s tropical climate, fully compatible with the building envelope’s design life.
Driving higher performance globally through EJOT’s collaborative approach
The LEGO factory project in Vietnam demonstrates how architects, developers and building envelope contractors working on projects across the world can benefit from the full range of innovative fastening solutions provided by the EJOT Group.
Each division of the group has developed its own specialisms over the decades, often to reflect preferred methods of construction in their locality. Some aims, however, are becoming common for building envelope designers globally, particularly greater durability and improved thermal performance.
This is one of the reasons why EJOT UK’s export market is growing rapidly, particularly in Asia and Australasia, as Ben Gallant, business development director – Asia Pacific at EJOT Group, explains: “The building envelope for the LEGO factory in Vietnam features products from several manufacturers who work extensively in the UK and Europe, including EJOT, of course, but also Saint-Gobain, Rockwool and Mapei. That reflects how the building performance goals that have become the norm here are now being sought elsewhere in the world, including in more demanding climatic conditions.”
He continues: “The good news is that we have the fastening solutions needed to meet this challenge thanks to the vast product portfolio that has been developed across the EJOT Group. This has resulted in products like our UK-made HTK 2G tube-washer now being identified as a preferred fixing solution in international projects, which we are ideally placed to serve through EJOT Group’s established global logistics network and experience.”
To find out more about the EJOT HTK 2G tube-washer and TKR fastener combination, click here.
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