FC&A Magazine - Future Constructor & Architect
Product Specific
The power of pre-fab

With the Government set to favour off-site manufacturing on all publicly-funded projects this year, Paul Arnold, Remeha’s Product Manager, looks at how councils are using off-site-fabricated, bespoke-designed heating equipment to improve efficiency and quality while achieving time and cost savings.


A greater push on improving the energy efficiency of the UK’s non-domestic existing buildings is required to achieve the nation’s 80% emissions reduction target by 2050. While the Government has called on public sector professionals to lead by example, implementing efficiency measures can be a major challenge after years of austerity and funding cuts.

Fortunately, small steps can lead to big changes. In buildings that rely on ageing or inefficient boilers, for example, there is still huge scope for energy and emissions savings from cost-effective boiler replacements. Replacing any dated boiler plant with high efficiency condensing boilers can transform a building’s energy performance – reducing gas consumption by as much as 48%, in our experience.

Good quality installation is key to achieving long-term efficient building performance. But as engineers know only too well, it’s often carried out in challenging circumstances. Tight project schedules, combined with shrinking plant room space, and access restrictions, can complicate what can and should be a straightforward upgrade. Which explains the growing use of off-site-fabricated heating equipment for a rapid, high-quality solution to improved heating efficiency and reliability.

30% cost and time savings

Off-site manufacture currently accounts for at least 3 to 4% of the UK construction sector, according to the Building Engineering Services Association (BESA). With reports of 30% cost and time savings, tighter quality control and reduced waste, it’s an approach that offers significant efficiency benefits for both the contractor and end-user. The good news is that, when it comes to heating, off-site-fabricated heating equipment can bring similar benefits to refurbishment as well as new-build projects.

Bespoke design

A case in point is the availability of bespoke-designed rig and cascade systems to achieve time- and space-saving solutions for multiple boiler installations. By involving manufacturers at the design stage of the process, the unique requirements – or challenges – of the project and site can be factored in from the outset. This, in turn, reduces on-site time and labour for improved on-site safety and minimal disruption. And as the bespoke units are produced under factory conditions, there is the added benefit of factory quality assurance and pre-release testing.

So how and where is this heating technique used? One example is the recent boiler replacement programme carried out by TSS Facilities for Medway Council at Gun Wharf, its main council offices in Kent.

Overcoming common installation challenges

Disruption is a common deterrent to carrying out efficiency improvements. For Medway Council, one of the main considerations was to minimise heating downtime to allow the offices to remain operational throughout the upgrade. The decision was also taken to apply a plate heat exchanger (PHE) to achieve hydraulic separation between the boiler circuit and the heating circuit, and so optimise boiler performance and longevity.

With a lack of available space within the Gun Wharf plant room, the challenge for contractor TSS Facilities was to achieve a space-saving solution that could be easily connected to the existing system to meet the tight timeframe.

To achieve the required improved heating output, reliability and efficiency within these constraints, the contractor recommended installing five Remeha Gas 220 Ace floorstanding boilers on a bespoke-designed, off-site-fabricated cascade system.

“We’ve fitted Remeha boilers for many years and are impressed with their products and service,” said Mark Basset, Mechanical Installations and Asset Manager at TSS Facilities.

Space and time savings

Remeha worked with TSS Facilities to design a bespoke pipework arrangement that would save on-site time and labour and achieve the most effective use of the space available as well as integrating a PHE into the design.

After preparing 3D drawings to enable early visualisation of the layout, Remeha produced the pipework assembly in sections off site. These drawings then formed part of a comprehensive documentation pack for the client.

The design called for the PHE and the pump to be positioned behind the boilers. The pipework was then configured so that the system connection faced upwards, as requested by TSS Facilities.

“Having the option to design the position of the PHE and pump ahead of installation meant that we could improve access for easier future maintenance and servicing,” continued TSS Facilities’ Mark Basset. “And, while the pipework was being configured off site, we were able to work on the system pipework, which sped up the installation process.”

Increased productivity

Once the equipment was delivered to site, TSS Facilities bolted together the boilers, pipework connection components and the PHE, on its wheeled frame, and connected them to the existing system. It was a seamless process, as Mark explained: “The project went well from start to finish. Having the Gas 220 Ace boilers delivered in an off-site-fabricated system made our lives so much easier. It allowed us to schedule the project and team more accurately, increasing our productivity. At the same time, it saved downtime and installation time. The customer benefits too, with reduced costs and disruption at the installation stage, and easier servicing in the future.”

This heating solution smoothed the heating upgrade process, as Consultant John Richardson, working on behalf of the Council, explained: “By using the Remeha Gas 220 boilers, the contractor was able to strip out the old plant and carry out pipework modifications while the boiler sets were being fabricated off site,” he said. “This installation technique enabled the council to control the shutdown period required to complete the contract. The fully modulating Remeha boiler plant, in conjunction with upgraded controls, have greatly enhanced the building’s efficiency and the council’s carbon footprint.”

Win-win solution

As this project illustrates, use of off-site-fabricated equipment can benefit the entire supply chain. For the council, the result is high-performance heating and minimal on-site disruption. The consultant has full assurance that the specification and customer requirements have been met. And the contractors can schedule the project more accurately for improved site productivity, reducing downtime, and installation time. All of which makes everyone a winner.

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