**2.6. Step 2: Visiting the company to collect data**

*2.5.2. District heating supply data*

124 Sustainable Energy - Recent Studies

*2.5.3. Fuel supply data*

*2.5.4. Other energy supplies*

by hour resolution data for the time of the audit.

welding gas for oxy-fuel welding are two examples.

**•** Water supply data, to be able to calculate the hot water use.

Some other data that might be useful include:

**•** Drawings of the building, floor plans.

and air flows.

**•** Drawing of the electricity supply systems.

**•** Energy efficiency measures that are already taken.

*2.5.5. Miscellaneous background data*

might be able to estimate the fuel use by calculating the heat losses.

Sometimes it is possible to get historical data on the energy used for district heating with hour by hour resolution, but often you have to be satisfied with the amount of heat used per month. Sometimes you can use the customer number and a PIN code to get data from the supplier via the Internet. If you ask for the service in advance, the supplier might be able to give you hour

Fuels such as oil, wood pellets or wood chips are mostly bought in batches. To be able to calculate how much fuel was used in the past, you need to know how much fuel there was to start with, the purchased amount and how much is left. If the needed data is not available you

There are also other possible energy supplies, such as steam, compressed air, liquid nitrogen for cooling, welding gas, etc. As long as someone is charging for the supply you might be able to get some historical data, but it is not always the case. It is a good idea to look for informal energy flows: Two neighbouring companies can share the same district heating supply, air handling unit or air compressor, there might be solar heating for hot tap water or the company uses residues, such as wood chips, from the neighbour for heating. Energy supply not con‐ sidered as energy can sometimes turn out to be important. Liquid nitrogen for cooling and

**•** Drawing of other energy supply systems, for example hot water pipes, compressed air pipes

**•** Information on the ventilation: Drawings of ventilation ducts, number of air handling units

Drawings can guide you to where in the system or in the building measurements can be made and what information to ask for. The drawings can also give you information that you can use directly. Air flows can be noted on ventilation drawings. Rated power for electric equipment, like motors and heaters, can be noted on detailed electrical drawings at the distribution board

**•** Information on time schedules for production processes, ventilation or lighting.

By visiting the company during production hours, you can find out how the processes work, examine the design and function of systems and equipment, validate the descrip‐ tions, drawings and layouts you already have (for example of building and air handling units) and fill in the gaps where you have no data at all. When you visit the company you have the opportunity to:


By speaking to key persons you can find out which unit processes are used at the company, uptime and downtime for different devices, operating hours for the factory and more. The key persons can be found among energy managers, production managers, caretakers, machine operators or others, depending on the organization. A caretaker or in-house electrician is a good guide when you want to find the devices you want to examine and the switchgear where to measure electricity. The production manager can inform you about the different production processes and their operating times.

Data on electricity use is mostly in focus. Data on airflows, water flows, pressure, temperature and size is often useful. Often you find set values and statistical data from sources like plans, technical documentation or monitoring systems. The main purpose of the survey is to get an overview - it is not necessary to measure all parameters during the survey to create the power and energy balance. Still, sometimes measuring is the easiest solution and more accurate and precise measurements might be necessary to be able to predict the results of proposed effi‐ ciency or conversion measures.

*2.6.2. Air flow measurements*

used by the fan motor.

*2.6.3. Temperature measurements*

connected to the studied equipment.

tilation ducts, the size of the duct must be known.

*2.6.5. Make an inventory of installed load and operating time*

probably have to use templates and estimates for these.

*2.6.4. Size measurements*

plications.

Air flow measurements can be used to calculate the ventilation heat losses, and also to roughly estimate the electric power used for the fan motors. On the other hand, the electric power used for the fan motor can also give you an idea about the air flow, and the electricity is often easier to measure. Sometimes the optimal way to find out the operating time for a machine or the working hours in a building is to log the ventilation air flow or temperature or the electricity

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Temperature data are particularly useful for calculating the energy use of the unit processes Space Heating and Cooling and Ventilation. Temperature measurements can be used to cal‐ culate the efficiency of heat exchangers for AHUs. To calculate the heat losses, the exhaust air temperature is crucial, but seldom registered by the monitoring system and even more seldom logged. To use standard values for efficiency of the heat exchanger is a useful shortcut.

Temperature logging can be used to identify operating time for equipment. A temperature probe can be attached directly to the surface of a machine or in an air flow or other medium

To analyze the heat losses from a building the size of the building and the properties of the building materials must be known. Measuring the size of windows and doorways, thickness of walls and height of ceilings is often part of the survey. For air flow measurements in ven‐

A fast and effective means is to count motors, light sources, computers and other devices and note their rated power. You find the rated power for motors and other devices on name plates or in technical documentation. Also note the rated cos φ for the motors, for future loggings of electricity - if you don't get the opportunity to measure the true power factor or cos φ, at least you have an idea of the figure. Even though the scientific literature provides examples of this approach, see e.g. [18], it is strongly recommended that the power factor is obtained by meas‐ urements. This is due to the wide variation of power factor which occurs from different ap‐

To get the energy use for computers, copiers, servers and printers, you can get a good enough estimate by counting the number of devices and calculating the power and energy used. You

To get the power and energy for light sources, a good method is to count the number of dif‐ ferent light sources and note the different rated power, printed on the light source, on the package or in technical documentation. This method works as long as the lighting is controlled by an on/off switch only. When you have discharge lamps, such as light strips, you have to

As the audit is a temporary project, the audit itself is not an incentive to install permanent meters. If sensors, for example, for power, current, air flow, pressure or temperature are al‐ ready installed and relevant data already logged or is possible to log, of course they should be used for the audit.

Sometimes you can also log the output signal directly from the control system with a voltage or current logger, depending on the type of signal, mostly 0-10 V or 4-20 mA. The logged information can be used directly as indicator of the uptime of equipment, e.g., an air handling unit. For further calculations you also need to know what real condition the signal represents and adapt your logged values to that.
