Carnegie Mellon

Electricity Impacts of Data Networks

Carnegie Mellon University

Green Design Initiative

Francis McMichael - H. Scott Matthews

Chris Hendrickson - Hui Min Chong

Woon Sien Loh

Carnegie Mellon

Issues

• Vast majority of energy consumed by Information and Communications Technology (ICT) is electricity in buildings (residential + commercial)

• Places burdens on businesses, consumers, and energy policymakers to manage demand– Reports estimate ICT electricity use as 3-5% of US total

• ICT has implications on other digital and built infrastructures– Data networks, highways, airspace, logistics– ICT has not ‘replaced’ these, it is ‘overlayed’– And creates interdependencies between them

Carnegie Mellon

Office Building ICT Use

Total (B kWh)

ICT shareICT Total (B kWh)

Floorspace (Bill sq ft)

ICT Intensity (kWh/sq ft)

1992 206 3% 6 12 0.531995 300 5% 15 11 1.432000 360 9% 32 12 2.69

2020* 500 15% 70 17 4.18

Sources: EIA CBECS (1992, 1999), Annual Energy Outlook 2002 [Commercial electricity projected to increase 1.7% per year, commercial ICT 4% per year]

• Anecdote: roughly 200 sq. ft of total commercial space per person!• ICT electricity use in office buildings projected to increase a factor of 10

from 1992 levels, intensity a factor of 8 -> to 2% of all US electricity• To reduce burden, further ‘green building’ programs needed to offset

projected ICT electricity growth

Carnegie Mellon

Focus on Networking

• Wired networks operate up to 100 or 1000 Megabits per second (Mbps)

• Wireless slower, but increasing in speed (soon to go from 5 to 55 Mbps)

• CMU campus: ubiquitous wired, wireless networks– Every room on campus ‘wired’, every space ‘wireless’– 10,000 users; 350 wireless antennas @ 30 users each– Functional, but not equivalent, comparison– Show energy “to network 10,000 users wired/wireless”– Only ‘network’ - not ‘attached devices’ - in boundary

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Campus Network Model

120 Wiring Closets

Office/room equipment

350 WirelessAntennas

Main computer center

Carnegie Mellon

Two Data Sources

• Campus has building-level electricity meters installed– Several buildings have more than one meter when areas

have higher than average use– Used for “Main computer center electricity”– Not so useful for electricity of room/equipment

• Portable power meters to measure electricity use of pieces of equipment– Measure one of each, scale up via inventory

Carnegie Mellon

Metering SWAT Team

- Pass-through device with LCD ($300)

- Meter logs/outputs data, export into Excel

Carnegie Mellon

Summary of Estimates

AnnualElectricity(MkWh)

Power (kW)

Main Computing Center 4.2 480Office Network Equipment 0.01-0.11 15Wiring Closets – Wired Switches 0.2 30Wireless Transceivers & Switches 0.03 3Total 4.4 – 4.6 520

Carnegie Mellon

Analysis

• Network electricity 6% of total campus - 1.7 kWh/ft2

– In line with total office building ICT use in US

• Hard to compare to existing literature– A college campus not representative of overall demand, or even

commercial buildings– Our particular campus much more ‘Wired’ than other campuses

• Wireless endpoints use 10 times less electricity than wired– Caveats: speeds, installation and maintenance requirements different– Wireless speed bump coming (10x) but electricity use expected go

up only 50%– Relevance: more voice wireless than wired in the world

Carnegie Mellon

Future ICT Scenarios

• Demand for data bandwidth and technology– Generally doubles every year (Odlyzko)

• Wireless: catching up with installed wired speeds– Also: allows deployment in harsh geographies, less-developed

countries, new applications– Changing infrastructure needs of ‘cells’ (5 -> 0.01 km2)

• Optical: currently have optical ‘glut’– Both overbuilding, wavelength technologies

• Home networking (Voice-IP, DSL/cable, wireless)• Distributed computing (i.e. idle cycle sharing)

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Conclusions

• ICT/elec growing rapidly, becoming more pervasive– Growing at a rate much higher than average– High economic value makes it an unlikely target

• Assessing ICT impacts requires knowledge and management of infrastructures

• ‘Systems analysis’ paradigm extended to digital infrastructures– LCA and other tools helpful in doing this

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Support

• Principal Investigator:– Organization of Economic Cooperation & Development (OECD)

Environmental Policy Directorate (2000-02)– AT&T Corporation (1999-2002)– AT&T Foundation’s Industrial Ecology Faculty Fellowship Program

(1999-2001)– US/Japan Foundation, United Nations (2001-2003)

• Other– NSF, EPA, DOE (w/LBNL)– Green Design Consortium