This accommodation is made up from 2 multi-storey office blocks providing office and meeting room facilities for the Department of Transport. As opening windows are not provided, fresh air and heating requirements are provided by several large air handling units, gas fired boilers, chilled plant (refrigeration units and pumps) and in room fan coil units.

There is a dedicated chilled water system serving the computer switch and server rooms which are located on each floor of the building.

Methodology
An examination, by GENEX, of the controls maintenance regime in place (early 2006) highlighted the need to adopt a more pro-active approach to energy management. Following an assessment and review of the available sub-contractors, a new controls maintenance company was appointed (June 2006) and discussions took place with them identifying likely areas of energy reduction. Further meetings took place to review the effectiveness of each energy reduction measure and to explore new ideas.

Figure 1 shows the electrical consumption for the mechanical plant over the period from January 2006.

The first step change occurred during the June - July 2006 period when simple changes to the operating software saw electrical consumption for the mechanical plant fall by some 10%.

The second step change occurred during the August - September 2007 period when the main supply and extract fans were converted to inverter control and savings in the region of 12 - 15% were observed.

Subsequent changes to the control systems operating strategy
• Allowed the room temperatures to drift upwards by 1 - 2°C from around 15:30 hours,
• Disabled the chillers but maintained the chilled water pumps thereby using the stored coolth in the mass of the
  chilled water,

Figure 2 shows gas consumption for the building over the period from January 2006; this shows a significant reduction in gas consumption during the heating season 2006 to 2007.
Note that the kitchen provides a base load of around 1600 ft3 (less than 10% of the total).

Energy Reductions

Electricity - 6000 kWhr/month = £4,320.00/year

Gas - 10,000 ft3 /month = £3,277.00/year

CO2 Savings

Electricity - 30,384 kgCO2/year

Gas - 26,390 kgCO2/year