The next stage is a detailed analysis, which involves capturing information from electrical sub-metering and any gas sub-meters, such as for catering kitchens. A reasonable starting point is to gather a list of all sub-meters and records of energy use. Twelve months is a common period of appraisal, but analysis can be adjusted for any period. The best approach is to start at a basic level and build up the picture with more detail as one becomes confident in the method and the accuracy of data.
All energy consumption is assigned against 20 end-use categories. Fifteen of these are pre-defined and five are user specified, including the six official DEC separable energy uses. There is a maximum of 30 items that can be assigned to each of the 20 categories, and each item is referenced to the appropriate sub-meter.
The latest version of TM22 allows for 50 sub-meters. Where a building has more than 50 sub-meters the user will have to aggregate loads of a similar nature. A certain degree of judgement is required, especially if the aggregated load turns out to be a significant fraction of the total.
TM22 allows the user to account for energy in three distinct periods; core hours based on occupied period, out of hours (normally weekday nights) and weekends. This can provide a valuable insight into the building's energy consumption during occupied and non-occupied hours, helping to identify base load consumption and wastage.
Fifteen operational profiles for equipment use can be defined, which allows the on and off times to be set for equipment, and provides total annual running hours. Some profiles are prefilled but able to be edited, while the remainder are totally user-defined.
Seasonal use is considered within each profile, with a proportion of the year assigned to each seasonal period, winter, summer and spring/autumn. For example, buildings in colder climates may spend a greater proportion of the year running in winter conditions, with significant heating and lighting demands and minimal cooling.
As with its previous versions, the TM22 model requires a value for intensity of equipment use. For example, equipment may only be used 80 per cent of that time. The load factor is another requirement, which is the difference between the rating of the equipment and the actual power use. For instance a pump can be rated at 1 kW, but where it is supplied by a variable speed drive it may consume 500 W, thus providing a load factor of 0.5.
Once this level of detail is complete, TM22 will sort the data and complete reconciliation of the energy use against each of the sub-meters, and total energy use recorded by the utility meters. If half-hourly or quarter-hourly data is imported, the model can compare the amount of energy it thinks is being consumed at different times of the day with actual energy consumption being recorded.