ISG has started work on two major projects valued at £135 million, as part of the Ministry of Justice’s (MoJ's) £4bn investment programme to create an additional 20,000 prison places across the UK.

The schemes at HMP Guys Marsh in Dorset and HMP Liverpool were procured through the Crown Commercial Service Framework.

Designed to be net zero carbon in operation and achieve a BREEAM Excellent environmental performance rating, the new house blocks feature air source heat pumps and LED lighting. Over 70% of the construction materials used are sustainably sourced, with the team utilising a Design for Manufacturing and Assembly (DfMA) construction approach to reduce the project programme and increase efficiencies.

The decarbonisation project philosophy extends to ISG's site accommodation, where 95% of the power required to operate temporary site cabins is derived from renewable energy sources. During the groundworks phase, vehicles will be powered by sustainably sourced Hydrotreated Vegetable Oil (HVO), which will deliver a 90% reduction in CO2 emissions, when compared with traditional diesel-powered plant.


Groundworks contractor Hannafin’s vehicles will be powered by sustainably sourced Hydrotreated Vegetable Oil (HVO), which will deliver a 90% reduction in CO2 emissions, when compared with traditional diesel-powered plant.

Working alongside ISG, Hannafin plans to use HVO throughout the duration of the project on its plant and equipment to maximise carbon reduction and support the project’s overall sustainability strategy.

Rhodri Davies, Senior Sustainability Manager at ISG, said: "HVO is a drop-in fuel replacement that has similar properties to diesel, so doesn’t require amending of existing infrastructure and is covered by warranties."

ISG is also building on its six-year partnership with HMP Liverpool, where the contractor has worked to modernise and upgrade accommodation at the prison, parts of which date back to the mid-nineteenth century. This latest £56 million scheme sees ISG deliver a full refurbishment in support of a proposed change in status at the prison from a Cat B to a Cat C facility.

The comprehensive programme includes site wide electrical infrastructure upgrades, supplemented by new highly efficient boilers, the restoration of all wings, and the addition of a new workshop. These upgrades will support the prison’s ambitious sustainability targets and reduce ongoing maintenance works in the long term.