Valiant House

Charlton Triangle Homes (CTH), part of the Peabody Group, prides itself on providing affordable, high quality homes to thousands of people. Maintaining the properties to the required standards is the responsibility of Peabody’s Electrical and Mechanical Services division. So when the Charlton Board reported some deterioration in the performance of the building services at Valiant House, a 17-storey residential block containing 93 flats in Charlton, South East London, the team was called in immediately to carry out a rigorous survey.

The findings were that, despite previous improvement work within the rooftop plant room, the ageing boilers at the heart of the central heating plant were beginning to show signs of inefficient and uneconomical operation.

A further issue was the gas main. It had reached the end of its 50-year-old life and, with thinning pipe walls, needed replacing to comply with new regulations and HSE requirements. SGN, which supplies the gas to Valiant House, was also preparing to replace its gas pipes through the building.

For CTH and Peabody, the challenge was to achieve a long-term heating solution that would reduce both utility bills and the carbon footprint of the building while ensuring uninterrupted continued use of the building. Working with an external consultant, they reviewed the findings and evaluated a number of proposals.

The options

Ground source heat pumps (GSHP) – this low carbon option, while in line with CTH and Peabody’s wider environmental commitments for a reduced carbon footprint, had to be ruled out as it wasn’t deemed technically viable at the time.

Replacing the gas main and pipe risers to the building – another option that had to be rejected as it would have required removing concrete through floors to access the existing pipework, creating extra work to protect the building structure. Running a gas main up the side of the building to the rooftop plantroom would have brought additional scaffolding costs due to the size and weight of the pipes.

Relocating the original rooftop plantroom – the Board’s preferred option involved installing new high efficiency condensing boilers in a newly created centralised ground floor plantroom at the rear of the building. The new boilers supply new Heat Interface Units (HIU), unvented indirect cylinders with electric back up, and individual heat meters in each property. This proposal included the replacement of cold-water tanks with new cost-effective sprinkler tanks and fire precaution upgrades.

The Charlton Board found this to be the most robust option. Relocating the plant room to the ground floor removed the need to run extensive pipework up the building, thereby minimising works on the floors and avoiding disruption to the residents.

Replacing the ageing, inefficient boilers with new, more energy-efficient condensing boilers – with a life expectancy of 20 years plus and capable of meeting the demand of the building – met the requirement for long-term improved reliability and efficiency and an immediate reduction in carbon emissions. CTH and Peabody were also keen to explore the possibility of upgrading to hydrogen boilers in the future to provide a non-disruptive route to low carbon heating.

Once this approach had been agreed, Milverdene was appointed the project contractor while Baxi Heating was asked to supply a heating and hot water solution.

Prefabricated, pre-assembled solutions

“Involving Baxi Heating from the outset paid dividends,” said Peabody’s Head of Electrical and Mechanical Services,

Ian Winterflood. “Consulting with them at the early stages meant that they were able to propose a tailor-made, prefabricated design that would achieve all of our project requirements and reduce the embodied carbon footprint of the refurbishment works.”

Baxi Heating and its subsidiary, Packaged Plant Solutions, recommended installing six Remeha Quinta Ace 115 boilers to meet the specification within the design parameters.The boilers were supplied with pipework, pumps and plate heat exchangers on an off-site prefabricated skid for fast and easy installation.

To enable rapid installation of the heating and hot water element in the individual properties, Packaged Plant Solutions provided the new Megaflo Eco 125 litre cylinders pre-assembled with the associated pipework. Supplying the Baxi HIU unit, together with controls and a heat meter, the prep-plumbed cylinders and first fix rails meant that Milverdene would be able to slide the equipment easily into the existing utility cupboard spaces.

“The major advantage for us was the time saved on site,” explained Ian. “The works began at the start of 2020, so with COVID-19 restrictions in place just a few months later, we were running a little behind.

“However, thanks to the prefabricated solution provided, Milverdene were able to complete the changeover in just one day and refurbish five properties a day, putting us firmly back on schedule. We also didn’t have to worry about multiple deliveries or materials being left on site as the solutions arrived pre-assembled and ready for installation just when needed.”

Once the electrics, radiator sizing and valves had been checked and a new sprinkler pipe and sprinkler heads fitted, the project was completed and delivered on time and budget.

“Charlton Board and the residents are delighted – the new plant room looks great and it all works brilliantly,” said Ian. “It’s a fantastic result and we are anticipating considerable energy and carbon savings from our new energy-efficient services.”

“Projecting forward, we will be investigating hydrogen boilers as a non-disruptive route to low carbon heating at Valiant House when the Remeha boilers reach the end of their life.”

Prefabrication benefits

• Time and labour savings, both on and off-site
• Cost savings – 13.4% on average, according to CIBSE
• Quality control – clean, controlled environment with end-of-line testing
• Reduced material waste – reduced environmental impact
• Improved asset management – ‘golden thread’ of building
• Easier to prioritise health and safety – reduced activity on-site and hot works
• Faster, simpler installation – reduced need for on-site specialist trades
• Reduced risk for all stakeholders

The project in numbers

• 93 – the total number of flats at Valiant House
• 6 – the number of Remeha Quinta Ace 115 boilers on the prefabricated skid
• 1 – the number of days required to change over the system
• 5 – the number of utility cupboards that were retrofitted in one day
• 3 – the number of hot works reduced on site through use of prefabrication

Quinta Ace boilers

• High efficiency boiler up to 99.6% Gross Calorific Value at 50/30 (30% load) – higher than average energy savings
• Low Class 6 NOx emissions levels from 29mg/kWh (0% O2 dry) – low pollutant emissions meet environmental regulations
• Quiet operation less than <52 dba – improved comfort

Megaflo 125 litre cylinders

• 600mm diameter pre-insulated double skin stainless steel vessels
• Supply up to 330 litres of 60C hot water per hour
• Integral pressure reducing valve can accept incoming cold water feed pressure up to 16 bar