World Green Building Week – Retrofitting a factory
World Green Building Week is upon us again. With this year’s event focusing on changing perspectives on energy efficient buildings, it seems like a good opportunity to discuss the hidden potential of existing non-domestic buildings.
Whilst 90% of UK businesses rate energy efficiency as a high or quite high priority, the task of revitalising older offices and industrial buildings can feel like an insurmountable challenge. Yet, with a clear framework and plenty of drive and determination, even the draughtiest buildings can be transformed. We should know, having achieved it at both our sites in Herefordshire and North Yorkshire.
It’s fair to say neither site boasted particularly stellar energy performance. The Herefordshire complex between Shobdon and Pembridge includes two converted aircraft hangars and had most recently been used as a cement factory, whilst the Yorkshire facility in the village of Sherburn-in-Elmet had achieved a dire Energy Performance Certificate (EPC) of F.
To turn this around, we introduced formalised energy assessment frameworks at both sites. The assessments helped to identify clear areas for improvement allowing us to prioritise developments.
As might be expected from older industrial estates, the existing facilities at both sites were poorly insulated and required significant levels of space heating. To address this, we overclad the warehouses with more thermally efficient materials. At Sherburn, we installed over 30,000 m2 of insulated roof panels in a multi-stage programme. This allowed the factory to remain open throughout.
Natural light levels were another area of concern, particularly inside the warehouse areas. Rooflights provided an effective solution and polycarbonate rooflights make up almost 7% of the new roof at the Sherburn site. This provides an effective balance of natural light and thermal performance.
Besides these passive measures, several energy saving and generating technologies have also been introduced. The first major change was the introduction of a combined heat and power plant (CHP plant) at Pembridge. The gas-fired plant generates base electricity for the site and uses waste heat to warm the buildings.
To tackle the site’s hot water demand, we also added two anaerobic digester plants. The plants use maize silage and fodder beet along with chicken manure from local farms. The first plant, commissioned in 2014, can produce 500 kW of electricity along with 370 kW of heat. This reduced natural gas consumption at the site by 56% in 2015 compared with 2013. What’s more, nutrients from the poultry manure pass through the digester and are available in the digestate. This natural by-product can then be used as a sterile and odour free fertiliser.
Earlier this year, a new 1.65 MW biomass boiler was also fitted at the Pembridge site. The external unit provides heating for the production line and storage space areas.
Raising the roof
The large roof spans of warehouses are, of course, ideal for photovoltaic panel installations. In 2011, we fitted a 5,583 m2 array on the roof of the Pembridge site. With a design capacity of 800 kW, the array can meet approximately 10% of the site’s electricity demand. In 2014, we went one step further, installing a mammoth 15,000 m2 PV at Sherburn. The array covers an area equivalent to two and a half football pitches and generates around 2.14 GWh of electricity per year — enough to power roughly 500 homes.
We also introduced a number of smaller, but equally important, measures within both sites, including fitting smart LED lighting. To help organise these, an ISO 50001 certified energy management scheme has been introduced at Pembridge and Sherburn.
Worth the effort
The process of retrofitting both sites has taken a considerable amount of cost, management and work. However, the results at both sites show it has already been well worthwhile. The Sherburn plant now holds an EPC rating of A, whilst the measures introduced at Pembridge mean our main Kooltherm line should be running entirely on renewable energy by the end of next year.
To find out more about these measures, along with lots more fascinating information about the wider sustainability work we carry out, take a look at our latest Sustainability and Responsibility Report.
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