Materials End-Use Efficiency to Reduce Industrial Energy Demand
Most proposed reductions in industrial energy use are reductions in the energy used to produce a constant amount of product, or substitutions of a less energy-intensive material. What are generally absent are "demand-side" or "end-use" approaches that change the way materials are used to reduce the amount that needs to be produced in the first place. As with building energy efficiency, the services delivered are maintained or improved.
The potential for this type of reduction in materials demand has not been explored comprehensively, so is not known. However, reducing materials demand across the board by 20%, would reduce industrial energy use by about 20% as well, with tremendous economic and environmental benefits. Many of these benefits are of such a nature that changes in production efficiency do not deliver. In general, end-use efficiency does not conflict with production efficiency; rather it complements it (except for reducing the rate of production facility turnover).
Since end-use efficiency is traditionally not considered an option for materials, little work has been done in the area. However, recent EETD work on paper use illustrates the topic well. Most office workers know from personal experience that the amount of office paper used is considerably larger than necessary to accomplish the tasks at hand, so the notion that paper use can be reduced is readily acceptable.
Our work has focused on "copy paper"—the type of paper used in copiers, printers, and fax machines. Most of our effort has documented baseline patterns of paper use, such as measuring the amounts used in different types of devices, activities, and organizations; the costs associated with paper use (particularly imaging); and particular use patterns, such as duplexing rates. We have assessed methods for reducing paper use and their potential, and benefits, and measured the effect of several interventions. Finally, we produced information that others can use to understand and improve their use of copy paper.
A key finding of our work is that while the cost of purchasing copy paper is typically only about $50 per office worker per year, the costs of use are generally about ten times this, or $500. This amount is large enough to make efficiency improvements compelling. We measured duplexing rates on many copiers over extended periods of time. We found that the rates vary widely and that even simple, inexpensive interventions can save considerable paper. In assessing technologies and policies, we have identified several good ways to transform future office equipment to reduce paper use without involving consumers directly. Finally, we provided background research for several "paper efficiency" requirements that were incorporated into the "Copier of the Future," a project of the International Energy Agency.
A Savings Example
An obvious way to use less paper is to use both sides of each sheet. This use is measured by the "duplexing rate," the fraction of images that are on sheets of paper imaged on both sides. For example, three images—two on one sheet and one on another—result in a duplexing rate of 67%. Duplexing rates are usually measured over a period of time for one or more pieces of imaging equipment.
Most copies made today are single-sided. Some documents need to be single-sided or are only one page; others need to be duplexed. However, for many copies, either is acceptable, so shifting some from single-sided to duplexed is a paper-saving opportunity.
For historical reasons, the majority of copiers have one-to-one copying as the default, but most copiers can be set to default to making double-sided copies.
We measured the duplexing rate on two copiers for several months, and after one month changed the default copy mode to double-sided. For both copiers, the average duplexing rate rose markedly with default duplex. On copier 1, the duplexing rate rose from 38% to 55%; on copier 2, it was already high at 59%, but maintained a 74% average rate. The reduction in paper use in both cases was just over 10%. The "national average" figure of 18% for this size of copier is questionable, but is the best data available.
The figure shows the data in more detail. The x-axis is the number of images made and corresponds to time. Each "stairstep" represents about 2 weeks. The duplexing rate below 20% is almost certainly a data-collection error, as the data point before it is also suspiciously high. The errors cancel each other out when calculating the duplexing rate for the entire period.
Similar results are likely for printers. A 10% reduction in copy paper use nationally would reduce annual paper use by about half a million tons, with a value to the economy in excess of half a billion dollars and energy savings equivalent to 1.6 TWh.
For more information, contact:
- Bruce Nordman
- (510) 486-7089; fax (510) 486-4673
For further information on reducing copy paper use, see the "Cutting Paper" web site.
This research is sponsored by the the Department of Energy's Waste Minimization Program and the Environmental Protection Agency's ENERGY STAR® Program.