Lighting Retrofit at HMP Parkhurst

The impact of the retrofit was significant. Across HB19 and HB20, the project delivered a combined reduction of nearly 20 kilowatts in connected load for every hour the lights are in use. Over the course of a year, this equates to more than 86,000 kilowatt-hours saved, comparable to the annual electricity consumption of around 25 to 28 typical UK homes.

Maintenance requirements have also reduced substantially. LED technology provides longer life and greater reliability than fluorescent systems, meaning fewer failures and fewer maintenance interventions. In a custodial environment, this reduces operational disruption and improves efficiency for facilities teams.

The project also delivered strong embodied carbon savings. By retaining existing luminaire housings, the need to manufacture, transport, and dispose of new fittings was avoided. Compared to full replacement, this type of retrofit can reduce embodied carbon by more than half while also minimising waste. As a result, the project supports both operational and lifecycle sustainability targets.

The lighting retrofit at HMP Parkhurst demonstrates how existing infrastructure can be upgraded in a practical, cost-effective, and sustainable way. By focusing on reuse rather than replacement, the project achieved measurable energy savings, reduced maintenance demands, and lower environmental impact.

For custodial estates with structurally sound luminaires, retrofit solutions offer a clear path to modernisation. They reduce risk, minimise disruption, and deliver long-term performance improvements while supporting net zero objectives.