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Power and People

The environmental impact of computer operations - Part II

From "VS Workshop",  Access to Wang, May 1991
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Continuing our look into the environmental impact of computer use, here are some goals and possible strategies for reducing power usage and improving the physical comfort of computer users.

As before, the general goal will be followed by possible strategies for achieving that goal.

Goal #1: Reduce Power Usage

Strategy #1: Use smaller systems. The physical size of computer systems have been dropping with each new generation of CPUs. As these system get smaller their power needs have also been reduced. It is now possible to create an effective system that uses a fraction of the power required even a few years ago.

Smaller computer systems also require less cooling capacity, so they save power there as well. Many new systems are designed to work in the "office environment" - that is, without special cooling and power accommodations.

The chart in Figure 1 shows how the new systems compare through a comparison of three 10-user systems with approximately one gigabyte of disk storage and appropriate means for data backup. System A uses early disk systems and relies on large removable disks for backup. System B uses smaller fixed drives and a 9-track reel tape backup system. Finally, System C uses new-generation tape backup, SCSI drives, and asynchronous workstations.

Figure 2 shows the impact of these figures graphically. The startup power requirements assume that only one device is powered on at a time. Note particularly the startup power requirements of System A: this large short-term consumption has to be absorbed by the power regulation system each time the system is started.

Strategy #2: Use smaller disk drives. Newer disk drives resemble PC disks in their size but offer better storage and access times than older drives. When coupled with new-technology CPUs, these drives offer better performance and demand far less power. Since disk drives are typically the largest source of computer room heat, smaller drives can reduce the need for air conditioning -perhaps even eliminate that need.

Strategy #3: Shut down the computer when not in use. Most business computer operations remain powered on at all times. Some may be used intermittently during evenings and weekends; some require nightly use for backup or batch processing. At this time there are few means of shutting down a system without requiring the physical presence of an operator to bring the system back up.

The new smaller VS models - particularly the 5000 series - allow asynchronous terminals to act as the system console in addition to the more familiar serial models. It is comparatively easy to perform remote system operation on these systems, since nearly any 2110 or VT-100 terminal or emulation can be used to control the system. Larger VS systems may be controlled using the Wang Remote System Operation product, a product that allows communication with the PC system console for system control. Third-party vendors offer "smart" PCs that control batch updates, perform system backups, and (perhaps) shut down the system when it is not in use. To my knowledge, none of these options allow remote shutdown of physical devices - only the logical control of them.

PC laptop makers recognized the value of disk drives that power themselves off after a period of inactivity. Perhaps someday similar products will be produced for larger systems. In the meanwhile, a potentially valuable product awaits development.

Strategy #4: Shut down workstations when not in use. Workstation power consumption used to be less of the total than previously. The popularity of PCs as workstations has changed that; the newer workstations, such as the 4330, consume less power than a PC. It is also arguable whether PCs should be shut down every day, since hard disk drives and other components wear faster when powered on and off.

A compromise between service level and power usage is needed here. Your organization should determine acceptable service requirements establish a policy for shutting down workstations that balances power savings with reliable service from personal computers. Such a policy might be to power off monitors every weeknight and entire PC systems every weekend. (Beware Monday mornings if you accept this as your policy!)

This is another case where product development has not caught up with user need. Vendors?

Goal #2: Reduce the physical discomfort of end users

Strategy #1: Provide a comfortable work area. As those responsible for installing terminals, we can exert influence on the manner in which these devices are used. The comfort and safety of the end user should be considered before the workstation is dropped on their desk. Considerations in this category include:

Most of these specifications are mandated by law in European countries; the U.S. lags behind in placing importance on user comfort and safety. The large number of cases of Carpal Tunnel Syndrome in recent news stories and persistent stories of radiation emissions from VDTs should help change those attitudes.

It will take a combined effort on the part of users, employers, labor unions, furniture manufacturers, and the government to improve the working conditions of workstation users.

Strategy #2: Encourage good workstation habits. CRT displays have been known to cause eyestrain when used over a long period of time. The combination of poor image resolution, the pulsing light of the screen, and the compelling nature of computer work have caused discomfort in many users. Mixed with the usual hazards of the business environment - fluorescent lighting, stress, sedentary activities - they can have a negative impact on the overall health of the individual.

Most experts advise eye rests at intervals of a half hour of continuous activity. Changes in activity are also recommended. The technique of "palming" - covering the eyes with the palms for thirty seconds or more - can also help avoid the symptoms of eyestrain.

Experts on the employment environment suggest that computer users purchase a cheap digital watch that beeps on the hour and keep it near the workstation to remind themselves to take this rest. Some PC programs are also available to help encourage regular rests or changes in activities.

Other environmental considerations

Conclusion

By providing fast means of interchanging information without paper or land-based transportation, data processing is often an environmentally effective means of reducing resource usage. Attention to some by-products of data processing operations can further its benefit as an environmentally appropriate technology.


Figure 1: Comparison of Heat Output and Power Usage of Three 10-user Systems

Description Quan. Running Power Starting Power Heat Output
System A
    VS 85
    288 MB removable disk
    2256C DP/WP terminals

1
4
10

1,540
1,700
195

1,730
8,350
195

4,470
4,830
565
System B
    VS 65
    9-track tape drive
    314 MB fixed disk
    4230 DP/WP terminals

1
1
4
10

650
720
410
100

750
720
410
100

1,885
2,090
1,190
290
System C
    VS 5300
    Streaming tape drive
    320 MB fixed disk
    2110A terminals

1
1
4
10

300
230
100
51

300
230
100
51
1,706
670
500
148

Figure 2: Graph - Power Usage and Heat Output

[Graph comparing heat output for three VS system types]

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Copyright 1991 Dennis S. Barnes
Reprints of this article are permitted without notification if the source of the information is clearly identified