It is important, from several standpoints, to establish the existing pattern of electrical usage and to identify those areas where energy consumption could be reduced. A month-by-month record of electricity usage is available from electric bills, and this usage should be carefully recorded in a format (possibly graphic) that will facilitate future reference, evaluation, and analysis.
The following list of items (where appropriate) should be recorded in the electric usage history:
1) Billing month
2) Reading data
3) Days in billing cycle
4) Kilowatthours (or kilovoltamperehours, if billed on this basis)
5) Billing kW demand (or kVA demand, if billed on this basis)
6) Actual kW demand (or kVA demand, if billed on this basis)
7) Kilovats (actual and billed)
8) Kilovar hours (actual and billed)
9) Power factor (average or peak, as billed)
10) Load factor (average use compared to peak use)
11) Power bill (broken down into the above categories along with fuel cost)
12) Occupancy level
13) Heating or cooling degree days
14) A electricity usage history, including appropriate remarks (such as vacation periods)
A listing of building operations, equipment, and energy conservation opportunities (ECOs) will also provide both a usage history and a basis for evaluating future improvement. The listing of this information, along with electricity usage, is part of the energy audit.
In general, there are four categories of ECOs. These four categories are as follows:
1) Housekeeping Measures - Easily performed (and usually low-cost) actions (for example, turning lights off when not required; cleaning or changing air filters; cleaning heat exchangers; keeping doors shut; and turning off redundant motors, pumps, compressors, and fans)
2) Equipment Modification - This is usually more difficult and more expensive because it involves physical changes to the electric system (for example, the addition of solid-state, adjustable speed drives; reducing motor sizes on existing equipment; removing light fixtures; adding automatic controls to reduce lighting in unoccupied areas; and modifying heating and cooling systems).
3) Better Equipment Utilization - The use of natural lighting as much as possible, the redirection of warmer air to cooler parts of the building during the heating season, and staggering starting times for tenants to reduce energy demand or consumption, or both.
4) Changes to the Building Shell - Improving the insulation quality of the building to reduce energy losses to the outside environment (for example, adding insulation, reducing infiltration, controlling exhaust/intake, etc.) and reducing heat gains in the inside environment by using reflective materials, shading, and insulation.