Cost benefit study: Energy

Measuring to manage: Energy consumption of a multi-storey office building in London.
Built circa 1991 with an extensively glazed façade around a concrete frame, the office floors are fully air conditioned with heating provided by gas-fired boilers. The building also features a fully glazed full height atrium with escalators and passenger lifts and two light wells. Net lettable floor area of the building is 5,200m2.
 
Measuring and recording the facility energy consumption over a period of time allowed the landlord to compare the actual consumption against industry benchmarks.
 
ActionAnnual energy savings (kWh)Annual savings (£)Comments
No-cost interventions   
Optimise/commission AHU and chiller plant controls to reduce evening and weekend consumption330,000£29,000Saving based on 75% reduction to current out-of-hours base load. Ensure plant is linked to automatic BMS control and not manual override. Consider feasibility of linking tenant's supplementary a/c units to central BMS control.
Reduce hours of operation of a/c system96,000£8,000Suggested 7am to 6pm to gauge tenant reaction (2 hour savings). During summer fresh air fans could be started at 6.30am to flush out residual heat from the building.
Reduce hours of operation of heating system162,000£4,000Suggested 7am to 6pm to gauge tenant reaction (2 hour savings).
Increase cooling set point64,000£5,000Increase from 22oC to 23.5oC to gauge tenant reaction.
Reduce heating set point110,000£2,500Reduce from 22oC to 20.5oC to gauge tenant reaction.
Reduce operating times of escalators3,400£300Suggested 8am to 6pm to gauge tenant reaction (2 hours savings). Investigate further costs/savings from installing standby controls.