**2.4. Energy survey and analysis − Introduction**

With the energy survey you will be able to create a power balance and an energy balance with the incoming energy allocated to different unit processes. To be able to suggest energy effi‐ ciency and conversion measures you also need to understand how the processes work, at least when it comes to energy use. The aim of the energy survey is not necessarily to create a very detailed map of the energy use, but to find the potential for energy efficiency measures and potential conversion to renewable energy sources.

By starting with an overview of the energy system and using a top-down approach it is possible to find the potential changes at the structural level, and avoid being limited to details. By combining the top-down approach with an iterative method for the data collection, it is pos‐ sible to go further into details without getting overwhelmed with detailed data that is not really needed.

**•** Step 5: Create an energy balance after adjustments (showing the impact of the suggested

Industrial Energy Auditing for Increased Sustainability − Methodology and Measurements

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The main purpose of the data collection is to give you basic data to identify relevant unit processes, to create a power balance and energy balance for these processes. Another purpose is to get enough data to be able to suggest adequate measures for energy efficiency and con‐ version. The origin and quality of information can vary greatly. Focusing solely on the energy

Before you have even visited the object of your survey, you can review the statistics concerning the use of electricity, district heating, fuel and water. You might also have supply of other media, such as steam or compressed air. Also try to get statistics on (or estimate) the production rate during the same period. Production data will enable you to estimate the specific energy use, for example in terms of kWh per produced unit, per hours worked or per tonne of raw material used. This can be useful both for allocating the energy and for calculating the result

You can also ask the staff what activities are going on at the studied site, to get a picture of the

The electricity sales company and the electric grid owner are sources for the electricity supply data you need. It is good to have as much detailed data as you can when it comes to electricity use. The grid owner can provide consumption data with hour by hour resolution to their customers (at least in Sweden). If the object of the survey is small or if it has small sub-meters, there might be a problem to get hour by hour data. Energy data for a whole year, regardless of the time resolution, is recommended for analyzing the dependence on outdoor temperature.

Detailed data on the total electricity use during the period for which you are mapping the unit processes is also important. Sometimes you can use the customer ID number and a PIN code to get the hour by hour use from the supplier via the Internet. In that case it is easy to also download data for the period when you make your own electrical measurements. Another

From the invoices you can get information on prices, power use, reactive power, etc. The in‐

To some extent it is possible to analyze the data before visiting the company. You can compare the energy use graphs for production hours during different seasons to find electrical heating and cooling loads. You can also compare idling energy losses in different seasons and analyze

voice from January typically contains a summary of the energy use for the last year.

data, the potential data sources can be categorized as shown in Figure 4.

unit processes and energy flow you should look for when you get there.

option is to log the total incoming electricity during the same period.

total energy use, power peaks, reactive power, etc.

measures).

of suggested measures.

*2.5.1. Electricity supply data*

**•** Step 6: Confirmation of audit results.

**2.5. Step 1: Gather statistics, drawing and plans**

There are different ways to get the data you need. Provided that the top-down perspective is used, you don't have to collect all possible data about every device. The data collection begins with the most accessible data at the most general level which is considered useful by the auditor (using a top-down approach). The analysis starts with analyzing that initial data. The analysis will probably raise questions, which are used to guide the coming data collection procedures.

**Figure 4.** Some possible energy data sources for energy surveys.

At some level you have to stop the data collection despite not having all the answers. The limit is often the time reserved for the project, but it can also be the possibility to measure, practical obstacles to changing a process or the lack of historical data. It is often necessary (and possible) to use data from a more aggregated level, together with some analysis, calculations and as‐ sumptions. The data collection procedure could be carried out in the following way:


To complete the audit you need to take two more steps:


By starting with an overview of the energy system and using a top-down approach it is possible to find the potential changes at the structural level, and avoid being limited to details. By combining the top-down approach with an iterative method for the data collection, it is pos‐ sible to go further into details without getting overwhelmed with detailed data that is not really

There are different ways to get the data you need. Provided that the top-down perspective is used, you don't have to collect all possible data about every device. The data collection begins with the most accessible data at the most general level which is considered useful by the auditor (using a top-down approach). The analysis starts with analyzing that initial data. The analysis will probably raise questions, which are used to guide the coming data collection procedures.

At some level you have to stop the data collection despite not having all the answers. The limit is often the time reserved for the project, but it can also be the possibility to measure, practical obstacles to changing a process or the lack of historical data. It is often necessary (and possible) to use data from a more aggregated level, together with some analysis, calculations and as‐

**•** Step 1: Gather statistics: electricity, district heating, fuel, water, production rate, etc. Gather

sumptions. The data collection procedure could be carried out in the following way:

**Figure 4.** Some possible energy data sources for energy surveys.

**•** Step 2: Visit the company during operating hours.

**•** Step 3: Visit the company during non-operating hours.

To complete the audit you need to take two more steps:

**•** Step 4: Create a power balance, energy balance and allocate energy use.

drawings and plans.

needed.

122 Sustainable Energy - Recent Studies

The main purpose of the data collection is to give you basic data to identify relevant unit processes, to create a power balance and energy balance for these processes. Another purpose is to get enough data to be able to suggest adequate measures for energy efficiency and con‐ version. The origin and quality of information can vary greatly. Focusing solely on the energy data, the potential data sources can be categorized as shown in Figure 4.
