**1.2. Unit processes**

The role and importance of energy audits varies from country to country. In a comparing study of factors influencing energy efficiency in the German and Colombian manufacturing indus‐ tries [7], firms and associations were asked about their view on energy audits. Among the German respondents 57 percent states that volontary audits is an important factor influencing the energy efficency in their country, while 61 percent of the Colmbian respondents states that volontary audits is an important or very important factor. When they were asked about their own measures and actions, 71 percent of the German respondents and 54 percent of the Co‐ lombian respondents stated that they would consider energy audits to increase energy effi‐

This audit method was developed in Sweden, in the Swedish manufacturing industry context. Evaluations of conducted energy audits in small and medium-sized manufacturing companies shows that the calculated technical potential for increasing energy efficiency performance varies from 16-40% of the total energy use. For electricity the calculated potential is up to 60% [8]. If the suggested measures are implemented and if the potential is reached or not depends on the barriers and driving forces for energy efficiency. The energy price can play an important role. For Swedish industry, energy prices have risen significantly in recent years. Between 2000 and 2006 electricity prices in Swedish industry almost doubled and oil prices rose by about 70 percent [9,10]. This trend has not declined. In January, 2010, prices on the Nordic electricity spot market arose to some 130 Euro per MWh. The electricity price increases were partly due to the deregulation of the European electricity markets as the deregulation has caused the national markets to converge and Sweden has for a long time enjoyed one of the lowest elec‐ tricity prices in Europe [11]. While the oil price increases may not create competitive disad‐ vantages for Swedish industry, the electricity price increases most likely will, as this is particularly related to the Swedish industry and the fact that the previously low electricity prices have resulted in a higher use of electricity in many Swedish industrial sectors compared

The methodology described is primarily for a technical energy audit with the aim to make the energy use more efficient and sustainable. In the audit, organizational issues and the sur‐ rounding society are regarded mainly as means to reach the goal, and are important driving

Energy audit models can be described in terms of the scope, thoroughness and aim of the audit [12]. The method presented in this chapter normally is used with a broad scope, covering the entire studied site. The thoroughness can vary from rough comb to fine comb and often the thoroughness varies between different unit processes in the same audit. As a top-down ap‐ proach is used, the auditor always starts with a broad scope and a rough comb. As the audit progresses and the key areas are pointed out, the data collection and analysis become more detailed. Lytras [12] also describes the aim of an energy audit as either to point out general energy saving areas or to propose specific energy saving measures. With the method described in this chapter, pointing out the general energy saving areas is one way to identify specific

ciency performance.

116 Sustainable Energy - Recent Studies

to their European competitors.

forces to implement changes.

measures and prioritize them.

**1.1. Classification of energy audits**

A unit process is defined by the energy service to be performed and industrial processes may thus be divided into two categories of unit processes:



**Table 1.** The unit processes used at Linköping University, divided into production and support processes.

Unit processes are a way to divide the energy use of an industry or other businesses into smaller parts. The unit process perspective also enables one to question the methods used for different processes. Air flows in ventilation systems are sometimes high because the ventilation system may be dimensioned both for ventilation and cooling. If you see that the device is taking care of two different processes you also see that there is a point in adjusting the flow depending on the cooling demand.

**•** Identify possible solutions.

**•** Calculate the economic impact.

**•** Calculate the impact of the solutions and analyze them.

The energy audit is basically a project with the aim to suggest energy efficiency and conversion measures. The basic method is the project method, but the actual workflow does not follow the straight project line from survey to measures. In practice you will start analyzing problems and identifying solutions as soon as you start collecting information for the survey. The anal‐ ysis and ideas for measures will also affect the need for data collection. Ideally, the method may be described as an iterative process, as shown in Figure 1, where the iterations stop when

Industrial Energy Auditing for Increased Sustainability − Methodology and Measurements

http://dx.doi.org/10.5772/51717

119

The iterative method is combined with a top-down approach. In this case, it means that the studied object (organisation, business or site) is initially considered as a unit, with its streams of energy and materials (Figure 2). The total use of different kinds of purchased energy is quantified. The material use and the products may be described but not necessarily quantified.

The next step is to describe the unit processes and analyse them in terms of energy use (Figure 3). The first overview of the energy use makes it possible to relatively quickly identify key

areas where additional resources are needed for measurements and analysis [17].

**2.1. Top-down approach and iterative method**

you have enough data to suggest relevant measures.

**Figure 1.** Schematic workflow for an industrial energy audit.

**Figure 2.** The top level of the top-down perspective for an energy audit.

The concept is based on the objective of the industrial process, the mixing of materials, cooling or drying a product, the production of compressed air or to carry goods, etc. Unit processes are considered to be the smallest components within an industrial energy system. Unit proc‐ esses are general for all industries, thus providing opportunities for comparisons of a given unit process, such as forming, between different industries. Using the unit processes to rep‐ resent the "building blocks" of energy use also enables modelling, e.g. simulation or optimi‐ zation modelling of industrial energy use. For example, see [16].
