The control problem in relation to electricity conservation

Mikael Togeby, AKF, Denmark

Abstract

The socio-economic profitability of using such a tool as free electricity audits for large companies depends to a high extent on the size of realized savings. If the savings are only half the size expected, the costs involved will have to be borne by these smaller savings. A number of control measurements indicate a big difference between the theoretical savings (after correction for partly realization) and the savings that can be controlled by measurements. This would not necessarily be a problem if it were not for the fact that the difference is always negative: The realizd savings are always smaller than the theoretical savings. The reason why many theoretical savings are too optimistic is to be found in two factors:

Many different types of information form part of the electricity savings calculation, such as utilization time, load ratio, etc. Many of these figures have to be estimated.
Such estimates are some times based on measurements. However, these measurements are often of limited duration, which is why even measurements do not remove the element of estimation completely.
Experience tells that a consultant who has been given the assignment of finding electricity savings tends to take a one-sided view and to over-evaluate the options for savings. Consulting services concerning electricity savings are often not the result of the company's own initiative. If, for example, free electricity audit are offered, the company's motivation for interacting with the consultants is often limited. Electricity savings are not the company's main interest -- they have accepted the audit because there were no commitments involved. With no commitment the companies are not engaged in controlling the result of the audit.