Detailed Energy Audit

The detailed audit, also known as a maxi audit, site-energy audit or done site energy audit, expands on the preliminary audit. It is carried out through collecting more detailed information about the operation and performing a more detailed evaluation of energy conservation measures. It follows effectively the similar steps as the standard audit; thus, it is broader in scope and commonly takes more time. Computer simulation tools are classically employed, and more detailed metering of consumption is undertaken. The economic analysis includes an integrated systems approach that accounts for interactions in implementing multiple retrofit measures, like as lighting or HVAC.

The reasons of a detailed audit are to identify exact recommendations and make suggestions for energy savings. This category of audit offers the most accurate estimate of energy savings and costs. It accounts for the energy use of all main equipment and operations, and involves detailed cost saving calculations and project cost. It could be used to formulate action plans for the implementation of these recommendations based on the investment needed, ratio, payback period, cost benefit etc.

Utility bills are collected for a period of 12-36 months to permit the auditor to evaluate the facility's energy demand to rate structures, and energy usage profiles. The additional metering of specific energy consuming systems is frequent performed to supplement utility data. In-depth interviews along with facility operating personnel are conducted to gives a better understanding of main energy consuming systems as well as to gain an insight within the variations in consumption and demand.

This kind of audit helps in identifying all energy conservation measures suitable for the facility. A detailed financial analysis is performed for every measure based on detailed implementation cost estimates; site-specific operating cost savings, and the customer's investment criteria. Enough detail is provided to justify project implementation.

So far, you have studied about the concept of energy audit, its goals and the kinds of energy audit. You might now such to know as to how energy audit is conducted in a power distribution utility. This is what we discuss in the further section. But before that, we would such as you to check your own understanding of the concepts you have studied so far.

The several steps in the methodology for conducting a detailed energy audit for an industry might be outlined as follows:

1.   Gathering and collating information in a specially designed, "Energy Systems Questionnaire" format, for the industry under study.

2.   Inter- and intra-industry comparison of the collected data.

3.   Assessment of present efficiency index for energy consumption in the industry/process.

4.   In-depth study of plant operations, equipment and systems for a common review of the energy systems to assess the operational efficiency and potential for economizing.

5.   Evaluation of the full recommendations for energy saving/conservation,

6.   Formulation of detailed action plans/strategies in consultation with plant management for implementation of the identified energy saving measures.

7.   Training operating personnel in the specifics of energy conservation to enable them to implement the recommendations and also to monitor the progress on a periodic basis.

Let us now study how this methodology could be applied to the power distribution systems. You have studied previously that in the procedure of supplying electricity to consumers, energy losses occur on account of technical and commercial reasons. The technical losses are because of energy dissipation in the conductors and the equipment used for transmission and distribution of power. Commercial losses are caused because of pilferage of energy, defective meters and meter reading errors and energy not accounted for (Table).

                               Table: Energy Losses in the Power Distribution System

In an energy audit of a power distribution system, the energy losses are to be computed for every element of the network on the primary of actual energy sent out and actual consumption as recorded through the meters installed on both sides of the element.

It might not be possible to conduct energy audit for the entire power system of a utility in one go. This could be because of organizational, financial and logistical constraints. Therefore it might have to be conducted in stages. A compact area of the power system would have to be identified and energy audit studies taken up. We now elaborate briefly the proccess to determine technical and commercial losses for an 11 kV feeder.