How does electrical contracting ntracting

BY DAVID ADAMS

Off site construction, where sections of buildings are constructed and then taken to site, is starting to become a reality in the UK. But what does this mean for electrical contractors?

FOR AS LONG AS ELECTRICIANS

have been installing electrical infrastructure in new buildings, most construction projects have followed a familiar pattern, with contractors working through fi rst and second fi xes, commissioning and testing on-site. In recent years, however, an alternative method has become more widespread. During off site and/or modular construction projects, whole small buildings – or components of larger buildings – are constructed in a factory, then moved to the building site for assembly.

Each component’s mechanical and electrical work is commissioned and signed off in the factory. Services are then connected together when the building is assembled on-site. In some cases, electrical contractors will complete the work in the factory and/or on the building site, but many modular manufacturers now employ their own staff to do all the necessary work at both locations.

Modular building has become a more attractive option for many developers, particularly when a building features repetition – as in an apartment block. It can be quicker and more cost-eff ective than conventional construction, and mass production within a factory produces lower carbon emissions than traditional construction methods.

Modular building company Elements Europe, part of the international construction and manufacturing Pickstock Group, claims that using off site construction cuts vehicle movements on building sites by 70 per cent and increases overall productivity by 25 per cent compared to traditional construction. Use of modular methods may also help the construction industry mitigate the eff ects of ongoing skills shortages, which may be exacerbated further by Brexit.

Th e Royal Institute of Chartered Surveyors (RICS) is calling for the government to support the use of these

construction methods by local authorities, housing associations and developers, in an attempt to tackle the housing crisis.

STANDARD PRACTICE

Paul Collins, technical services manager at Certsure, believes the ability to ensure consistent quality inside a factory is one of the most important reasons behind the growing momentum for modular. “In a factory you’ve got a controlled, consistent environment for construction and quality assurance going through each stage,” he says. “When you’re on a building site you don’t necessarily get that.”

Modular construction can be used for diff erent types of buildings: industrial, retail, in schools, hospitals and elsewhere – but the biggest growth area remains residential blocks of fl ats, including student accommodation.

Sebastian Fielding, director at Vector Design Consultancy, in modular buildings. Crest Nicholson has said it plans to build 2,000 modular homes per year in the near future. Berkeley has created a new subsidiary, Berkeley Modular, which will build modular housing at a new, purpose-built factory

81m: THE HEIGHT OF APEX HOUSE, IN WEMBLEY; THE UK’S TALLEST MODULAR BUILDING

Left, far left: modular homes at NU living's Beechwood development in Basildon, Essex. Below: modular construction in progress

has worked with construction companies and contractors on such projects, and describes the typical modular building as a large student accommodation block mixing pre-built studio apartments with bed and desk areas, two-ring kitchen hob and en-suite bathroom, with multi-occupancy units where bedroom/en-suite pods are built around modules containing communal kitchen and living areas.

One building of this type is Apex House, in Wembley, London – currently the tallest modular building in Europe. Th e 29-storey, 81-metre high block contains 558 student rooms. It was designed by architectural fi rm HTA Design, and completed in 2017. Th e modules used, which weigh between 12 to 17 tonnes each, were built by modular specialist Vision Modular. During assembly, up to 11 modules could be attached to the building each day, allowing the block to be completed within 12 months.

HTA has also designed a residential development at 101 George Street in Croydon. Th is will have two towers of 38 and 44 storeys, containing 546 new homes for rent; they will be the tallest modular buildings in the world. Vision Modular will again supply the modules, and the development should be completed during 2020.

MODULAR ACTION

Manufacturers are creating production facilities capable of making multiple types of modular buildings. For example, modular specialist ModularWise builds whole extensions that can be used by local authorities to add downstairs bathroom facilities to social housing, along with complete modular houses and other bespoke buildings, including retail units.

Th e company’s main production facility at Knighton, Powys, produces housing units, while its second facility, at Shobdon in Herefordshire, produces non-residential buildings, usually on a bespoke basis. At the time of writing, the Knighton factory is completing 28 apartment modules for a scheme in Edinburgh, with another 16 to follow, then 75 houses. During the same time period, the Shobdon facility will have produced about 30 or 40 bespoke units.

“When I fi rst started working here in late 2017 we were doing a couple of houses per week, but now we’re getting massive orders,” says ModularWise designer and business development manager Mike Rutland. Projects in the pipeline include another 50 apartments for a scheme in Milton Keynes and 155 houses for a new development in Scotland.

Th e UK’s largest construction companies are also investing heavily

‘In a factory you’ve got a controlled, consistent environment for construction and quality assurance going through each stage’

in Northfl eet, Kent. It is expected to be operational during 2020, and will use a new technique based on standard components that can be applied in diff erent types of building.

Housing associations have also partnered with off site or modular home manufacturers; Places for People, for example, made a major investment in ModularWise in 2017. “Th ey see a huge demand for social housing and they see modular as one of the key ways to support that demand,” says Rutland.

In May 2019 Places for People announced a partnership with modular home manufacturer Ilke Homes, from which it will purchase 750 homes. Th ese investments are backed in part by government: in 2018, Places for People received a grant from Homes England to deliver more than 2,600 homes – one of eight housing associations to receive such grants.

Another housing association, Swan, has a modular factory in Basildon, Essex, where it plans to produce 400 homes per year. Its in-house developer, NU living, builds modular housing using cross-laminated timber. Th e timber absorbs some carbon, meaning homes built using this material are actually carbon-negative for the fi rst year after construction. At the time of writing, NU living has a development pipeline of more than 8,000 homes.

EARLY MOVERS

For the past two years, Essex-based electrical and mechanical services contractor Newtons Group has done the electrical and mechanical work on modular houses built by NU living, both in the Basildon factory and when the buildings are assembled on-site.

Newtons’ director Harry Leeson says it has been very useful for the company to have been involved from the early days of the factory’s operation, as both its staff and the designers creating the modules were able to identify and overcome operational problems as they arose. “It took a little while to get everything up and running –

OPPORTUNITY OR THREAT?

Vector’s Fielding expects to see increasing use of modular construction wherever it is a fi nancially attractive option for developers. “Th is could become very widespread, because of the speed of construction on-site,” he says. “When you consider how tight some of those sites can be, here’s a way to build that doesn’t require much space.”

However, Leeson doesn’t think contractors working on conventional construction projects should be concerned about the growing popularity of modular construction. “I don’t think there’s anything to worry about from a mechanical and electrical perspective,” he says. “Th ere’s always going to be a demand for skilled expertise.”

Nor does Rutland think modular buildings will totally replace traditional methods. “Housebuilders are still going to be doing traditional construction,” he says. “Th ey’re still going to need sparkies.”

But modular buildings may provide work for other contractors in any case, whether through opportunities to develop expertise in working with modular buildings or providing maintenance thereafter; when working on smaller modules added to existing conventional buildings; or providing additional services for the new buildings, such as solar PV or electric heating.

“You’ve got to embrace it,” says Fielding. “It’s the way it’s going to go, because of the speed of construction and the ability to have quality control in the factory. For low-cost, good-quality housing solutions it’s a good product, and there’s a big shortage throughout the country of that type of accommodation.”

Leeson also thinks contractors should see the rise of modular as an opportunity, rather than a threat. “We should all be trying to push to get into this area,” he says.

you’re taking a delivery model suitable for mass production and applying it to the construction industry,” he says. “But now I see this really taking off .”

Contracts manager Dean Macey leads a Newtons team that works at the factory, along with a smaller team that connects up the services on the building site. At present, the team usually works on houses consisting of a ground-fl oor module and two upper-fl oor modules, but they will shortly be working on a slightly larger house with a single module for each fl oor.

“It’s the same principle working on each building, but there are diff erent sizes and shapes of module you have to work on, so if you think you’ve found an answer to a problem with one module you may then fi nd you have to rethink it when you’re working on a diff erent layout,” says Macey. “It is a challenge, but it is interesting, trying to overcome those problems.”

ELECTRICAL TESTING OF MODULAR BUILDINGS

Electricians working on modular buildings should note the following points: • Only continuity, insulation resistance and polarity testing should be carried out on the electrical installation of the sitebuilt assembly on their completion at the factory. Results obtained from live testing will only give an accurate representation of ‘as installed’ conditions when the assembly is permanently connected to the supply from which it will be fed when in use • The electrical installation of the assembly should be subjected to full inspection and testing after its final connection to the electrical installation of the building • Prefabricated modules may be transported for long distances by road and/or rail to their place of installation and may be subjected to significant jolting and vibration during the journey. As a result, it is essential that the ‘dead’ tests carried out at the factory are repeated to reconfirm continuity, insulation resistance and polarity prior to progressing to the live testing. The results of this repeated ‘dead’ testing can be compared to the values recorded when testing was carried out at the factory prior to transportation, to verify that no damage or deterioration has occurred in transit. All relevant live testing should then be performed.

David Adams is a freelance business journalist