The power of prefab

Published:  04 April, 2018

prefabricated, Chris Meir, prefabrication, prefabricated equipment, off-site, rig system, Remeha, Royal Academy of Arts, RA
Arup specified Remeha boilers on a bespoke rig system designed in four modules to facilitate positioning at the Royal Academy of Arts. (See box below)

Bespoke prefabricated heating equipment can deliver numerous benefits from increased efficiency and greater quality control to time, budget and labour savings. Chris Meir takes a look at the methods and benefits.

Prefabrication as a technique is a rapidly evolving technology. According to the Building Engineering Services Association (BESA), offsite construction currently accounts for at least 3% to 4% of the UK construction sector. It’s a method that brings numerous benefits with reports of 30% cost and time savings, tighter quality control and reduced waste.

When it comes to commercial heating plant, here, just as in construction, using off-site prefabricated equipment can achieve all these advantages and more throughout the lifecycle of the products.

A case in point is the bespoke, off-site fabricated rig system that can be designed to meet individual project requirements for increased time, labour and cost savings, enhanced quality assurance and improved energy efficiency.

Raising the efficiency of the UK’s existing buildings is a major challenge for the building services industry. But there is huge scope for efficiency savings in the nondomestic buildings that still rely on dated commercial boiler plant. After all, replacing ageing or failing boilers with high-efficiency condensing boilers and adding controls is widely acknowledged as an energy saving quick win.

Of course, the concept of using a rig system to speed up installation of multiple condensing boilers is not new. But the standard rig unit might not provide the perfect solution in every plantroom and could potentially require on-site modifications, especially if there are space limitations.

So how to avoid the ‘one-size-fits-all’ approach traditionally associated with prefabrication? By providing bespoke-designed rig systems that can be customised to meet the exact heating requirements of each individual project.

As with the standard rig, the arrangement of the boilers on the bespoke rig is designed to optimise heating performance. By sharing the load across multiple units, the condensing boilers can operate at part load where they are most efficient. The arrangement also makes full use of the boilers’ modulating feature, which enables them to match the building’s heat demand more accurately. All of which means reduced energy waste and lower bills.

At the same time, the in-built redundancy of the design makes the boilers easier to service, maintain and replace for improved whole life efficiencies. And the configuration reduces the use of each individual boiler, increasing their lifecycle for further longterm savings.

But this is just the starting point. It’s the ability to tailor the rig design to the project requirements that is central to its success.

The bespoke rig is based on individual boilers from 30kW to 300kW output, with no limit to the number that can be incorporated, although 16 is Remeha’s record to date. The designer can define the maximum and minimum output, the number of boilers and whether to use a back-to-back or an in-line layout. They can also address any physical site restrictions through a choice of header extensions and connections.

The art of prefab

As part of its extensive infrastructure masterplan, the Royal Academy of Arts (RA) consolidated the heating generation plant across its estate within one newly-designed central plant room. The overarching requirement was to develop a high-efficiency, futureproofed heating system across a unified RA site.

The RA’s new plant room is situated above the Sackler Wing of Galleries, on the roof of Burlington House. Working with Arup and CBRE, Remeha provided a bespoke, off-site fabricated rig solution that would meet the specific requirements of the project and site.

Fully documented and factory tested, the rig has provided a high-quality solution to achieving maximum turndown ratio and more sustainable operation. The single delivery of boiler plant and increased ease of installation offered by the rig greatly reduced site time at the RA, minimising disruption to the building users.

Bespoke to specification

The rig can integrate controls such as weather compensation, sequencing or building management system direct operation to optimise boiler performance and maximise seasonal efficiency. System integration can also be achieved through the bespoke rig. For example, if water quality is an issue, hydraulic separation can be achieved via the rig and a plate heat exchanger. Once the design is clearly defined, production is carried out in a factory environment with quality controlled end-of-line testing.

As the bespoke rig system can be designed to overcome space constraints, installation can be carried out in record time, making it the perfect solution on projects with tight or fixed schedules. The boilers are delivered into the plant room in the pre-assembled wheeled unit, ready for easy connection to the existing system.

Equally, where there is a requirement to complete multiple projects within a tight time frame, a bespoke-designed prefabricated rig provides a rapid, high-quality solution. This might be particularly relevant on school refurbishments projectswhere most work is scheduled to take place within the six-week summer holiday period.

A key advantage of using a prefabricated heating solution like the bespoke rig system is that it reduces the intensity of skills required on-site. This makes it easier for contractors to plan ahead and put these skills to use on other projects and so increasesite productivity. It also means that there are fewer hot works on site, creating a safer environment for the team with less possibility of injuries.

Detailed forward planning and collaboration at the outset means that the cost, size and specification are all fixed and in place before the bespoke rig is built – all of which helps keep the project on time and on budget.

Added to which, the project is less likely to be subject to delaysas the rig unit comes from one supplier. This in turn means only one delivery slot needs to be scheduled, lessening any impact on the local environment andreducing waste. At the same time, the reduced downtime means that the day-to-day operation of the building can continue as normal.

Benefits for all

Prefabricated bespoke rig systems bring benefit stakeholders at every stage of the project, from specification to installation to future maintenance. For the building owner, the bespoke design meets the need for reliable, highperformance heating. The off-site fabrication minimises on-site disruption and enables faster, easier installation. The improved asset management and BIM alignment associated with off-site prefabrication assist the facilities management cycle to keep heating efficiencies high.

But perhaps most importantly for the designer, contractor and manufacturer, by defining the design collectively before the build, they can be assured that the exact specification will be met.

Chris Meir is sales director at Remeha



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