Energy Management (EM)
What is energy management and what is it good for
Investors and property owners are well acquainted with the words „facility management“. Usually, they understand it as a comprehensive building maintenance including activities like cleaning and maintenance, security, gardening services, and the like. Concerning energy, their distribution and invoicing, a facility management provider usually covers meter readouts, cost allocation, and servicing of heating and cooling plants. The property owner has no idea if the consumed energy is appropriate to the size, age, and usage of the building; he seldom tries to move to another utility provider, and only exceptionally he considers replacement of building technologies before their lifetime is over, because this brings along unwanted costs.
However, there is another way how to operate buildings from the point of view of energy costs. It is called energy management. Under energy management we understand an expert service which offers a – and this is important – set of measures which relate to each other and complement each other. These measures are able to decrease energy costs while keeping or even improving the environmental comfort. It is mostly about heating, cooling and lighting energy, as they represent the most important part of the total building energy consumption.
For consumption evaluation and benchmarking, derived parameters are used. These are for example energy consumption per floor unit or day-degrees, energy consumption of a person per night in hotels, etc. Furthermore, other variables and constants must be available, such as number of accomodated guests, or occupancy of the offices. These values are processed, and from the results we are able to judge if the building operation is economical compared to other operated buildings or acknowledged standards.
Energy management in reality proceeds in several steps. In the beginning, the energy management provider carries out a local inspection and specifies which values are to be measured. At small properties, like retail shops or bank branches, usually the main consumption data of electricity, gas, heat and water, together with some environmental parameters, like reference room temperature, outside temperature, operation of main AHU unit, and supply and return water temperature, are enough. Either the measured values are read from the existing building control system, or the supplier must install his own sensors and a datalogger connected to the Internet. After the local inspection is finished, the supplier produces an indicative quote, so that the customer can see what and when he would receive for his money.
The energy management itself starts with an energy audit, which is a detailed report on the energy flows in the building. The auditor uses building plans, real consumption data from several years back, measured data from indicative measurings, and, last but not least, his own on-site experience. He or she must examine the usage of the building, patterns of the users, and their influence on energy consumption. At the end of the report there are several variants of recommended measures for energy savings, each of them containing expected return time and, of course, expected investment costs. All variants are proven by calculations. It is remarkable that significant savings may be achieved by changing of local operating regulations, which specify the proper way of building usage and operation. This kind of savings means little or no investment costs and thus it brings along short return time. Examples of these are resetting of setpoints and time schedulers, tuning of hunting control loops, control strategy based on weather forecast, etc.
The next step is the implementation of the agreed measures at the sites, installation of sensors and dataloggers, and introduction of the control mechanism: energy management software.
A general rule says that any technological changes, reconstructions etc. are implemented only if they show the return time approved by the customer. It showed up that operation cost savings in size of 20 to 30 % must be achieved by implementing of more small-scale, low-cost measures, which bring improvements in percents. It is necessary to work with the building in the timespan of several years, to understand its behavior, and follow step by step. A good example of this is stepwise reconstruction of the building control system: the system is replaced in stages to protect investments, disassembled components are used as spare parts for the existing panels, and the refurbished panels are integrated into a remote access SCADA. At some installation, it is also possible to replace the process station only, and get the application software under control while preserving all peripherials and power part of the panel.
The advantage of a professional energy management is that the auditor is independent from suppliers of technologies for eventual reconstruction, which guarantees objectivity. The report does not aim to make the customer invest into a particular product of a particular manufacturer. It was proven that recommendations concerning operating regulations, which are made by an external consultant, are acknowledged to be better than if derived from internal sources.
To be able to achieve and prove the operational savings, an easy-to-understand tool is essential. Such a tool has been developed and is offered by Domat Control System. For more information about the aplication ContPort visit:
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