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John Brown Engineering, Clydebank

Energy efficiency in the refurbishment of industrial buildings

Overview

John Brown Engineering Ltd, an international contracting and project management company, has a gas turbine manufacturing facility at Clydebank, on a site which was previously used for ship building. The facility consists of two large, long workshops with glass roofs, known as the ‘engine works’. Other buildings on the site consist of smaller manufacturing units and office accommodation.

A major refurbishment was carried out between 1989 and 1990 covering 24,600m2 of manufacturing space and 5,200m2 of office space.

Approach

Initial refurbishment work was carried out between 1977 and 1981. This included replacing the engine works roof with polystyrene insulated profiled cladding.

A major refurbishment was carried out between 1989 and 1990 covering 24,600m2 of manufacturing space and 5,200m2 of office space.

An energy efficiency survey carried out in 1987 suggested the following improvement measures:

  • Replacement of the existing steam warm air heating system with a gas-fired radiant system,
  • Installation of a BEMS (Building Energy Management System),
  • Replacement of inefficient boilers serving the office areas.

 

Following the survey, the company decided to take out a Contract Energy Management (CEM) agreement.  The seven year CEM contract covered the replacement of the space heating system, the installation of the BEMS, installation of fast-acting doors and the replacement of office boilers. The total investment in 1989 was £350,000. The CEM contract was based on predicted energy savings of just under 35%. This ensured John Brown Engineering benefited from energy savings without capital expenditure. 

Performance

The improvements made in 1977-1981 had the following benefits:

  • The U-value of the new insulated roofing was a 90% improvement on the old glass roofs.
  • Old mercury light fittings were replaced with sodium lamps, reducing electrical load from 304kW to 143kW, while improving lux levels by over 50%.

 

The control of space heating improved dramatically following the interventions in 1989/1990. Annual gas consumption reduced by 38% from 21.45 million kWh in 1988-1989 to 13.37 million kWh in 1990-1991. Zoning the site into 52 heating zones helped tailor heating to shift patterns.

In addition, maintenance and manpower related costs of approximately £48,000 per year (valued in 1992) were also been realised.

The fast acting door reduced heat loss from the workshops where forklifts frequently need to enter and exit. The door now takes only 3 seconds to open or close. Savings of 486,000kWh were predicted from this improvement.

Lessons

A period of ‘settling in’ was required following the installation of the new heating system, as staff had to be convinced that the new system provided a comparable heating level. Additionally, as the heating could only be controlled through the BEMS, not all staff were able to have direct control of the environment which caused some initial problems.

However, the workforce came to appreciate the benefits of the efficient and reliable heating system. The benefit of the fast-acting door is particularly felt by those working nearby.

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