Energy Mapping

Before starting to try to reduce energy use at any site, you need to know where you are using energy. This is so that you do not spend time on the small things, but rather concentrate on where you will get the “biggest bang for your buck.” For example, people get fascinated by the lights, but lighting uses less than 5% of the energy at most plastics processing sites. If you want to reduce your energy bill by 30%, then this is not the place to start!

Energy mapping is a technique that we developed to quickly assess how much energy a site is using in each area (services, machines, and site). Energy mapping uses a simple spreadsheet approach; a sample energy map for an injection molding site is available at www.tangram.co.uk/energy. (This obviously can be modified for other processes/machines.)

Energy mapping focuses attention on the big energy users and makes the priorities for action clearer. A reasonable energy map will take about four hours to produce, but it gives clarity in decision-making. You may be surprised with the results—especially the costs of services

Actions:

Start building an energy map.
Count the motors (and their sizes), count the lights, estimate the actual duty load and operational hours
If machine monitoring data is available, then this should be used to improve the accuracy of the energy map.
Use the actual energy bills for a year as a final “reality check” for the total energy used.
Start to use the energy map to quantify the potential savings, and prioritize your actions.

Note: Dr. Robin Kent is the author of Energy Management in Plastics Processing, published by Plastics Information Direct, and managing director of Tangram Technology Ltd., consulting engineers specializing in energy management in plastics processing. rkent@tangram.co.uk.