Plug loads in commercial buildings are a growing area of energy use. They can be as much as 50% of total energy use in buildings that have addressed other efficiency areas such as the building envelope, glazing, HVAC and lighting. Managing the area of occupant energy use is a high priority to achieve energy reduction targets and climate change policies. This presentation by Cathy Higgins, Research Director at New Buildings Institute, was given at the E Source Energy Managers Round Table, Boulder CO. in April 2013.

1. Office Plug Loads:
Energy Use and Savings
Opportunities
Cathy Higgins, NBI Research Director
April 25, 2013

3. Answer 3 Questions:
1. How much energy
is used by office
equipment?
2. How can energy
use be lowered?
3. How much savings
is possible?
…based on field research

4. How much energy is used
• Typical Office Spec:
4-6 watt per square foot (W/sf)
Actual 1990 ~ <1.5 W/sf.
Actual now <1 W/sf
• Computers:
–
–
–
–
Originally - 300+ watts
Early 1990s - 120 watts
EPA in mid 90s - 75 watts/12 in sleep mode
Laptops – 15 watts

5. Energy Use Trends
5
Source: Graph created by Ecova with data from EIA 2008 Annual Energy Outlook

6. Source: D. Kaneda, IDeAs and Intregal Engineering

7. Types of Plug Loads
Study Set = Office Equipment

8. Measured Energy Use
Small High Performance Office
Oakland, CA
Plug Loads
10%
30%
Natural Gas
26%
HVAC and Net
Electric
34%
Lights
Non-server plug loads
~ 6% of total bldg energy

9. Energy Use by Device Category
Desktop
Computers,
Imaging
Equipment and
Monitors
were 95% of the
total energy use of
the studied loads
Percent of the Studied Plug Load Energy Use – Office

10. Off Hour Ratios – too high!
Not
Success
Findings

11. How to lower energy use and
savings amounts

12. 1. Software
optimize energy
saving modes
using power
management
controlled at
equipment or at
the information
technology (IT)
department level

13. 2. Hardware
use advanced power
strips and timers to
reduce or eliminate
loads off hours;
procure energy
efficient office
equipment with best
in class when
upgrading or
replacing

14. 65% of Desktop Computers Were Often Left Operating
in Idle Mode or on Overnight and Weekends


Idle Mode: ~58W
Baseline: 9.6 kWh/week
14

15. Replaced a Desktop Computer by a Mini-Desktop
Computer and Enabled Power Management


Idle Mode: ~58W
Baseline: 9.6 kWh/week


Idle Mode: ~20W
Improved Case: 0.43 kWh/week
Energy Reduction
= 95%!

16. Printer, Calculator, Speakers Drew Continuous
Power Overnight and on Weekends

Baseline: 5.8 kWh/week

17. Timer Plug Strip to Turn Off the Printer, Calculator and
Computer Speakers from 9 p.m. to 6 a.m. on Week Days
and all Day on Weekends
 Baseline: 5.8 kWh/week

Improved Case: 3.26 kWh/week
Energy Reduction
= 44%!

18. Most Computer Monitors Drew High Active Power Compared
to High-Efficiency Models Available Today


Active Mode: ~40 W
Baseline: 0.37 kWh/week
18

19. Replaced a Computer Monitor with a Comparable, HighEfficiency Model



Active Mode: ~15 W
Baseline: 0.37 kWh/week
Improved case: 0.24 kWh/week
Energy
Reduction
= 35%!
19

20. Baseline Monitor & Top Ten
- 43%

21. 3. People
Engage occupants and
operators: provide simple,
easy-to-understand
information and reminders
(prompts) to encourage
users to change personal
practices (behaviors) so
equipment is not left
operating unnecessarily.
Utilize green leases,
campaigns and competitions

22. Energy Report to one user
400
Annual Energy Consumption (kWh)
350
300
-57%
250
- 57%
200
150
100
50
0
BASELINE CASE
IMPROVED CASE - ENERGY REPORT
Small Office

23. Behavioral Approach
Calendar Reminders
% Savings
over Base
(avg)
2-31% (6%)
Poster with Remote Control
Didn’t use
Feedback Monitors
51%
Energy Report
57%
Tenant Guidelines, Campaigns

24. Savings Outcomes
Small High Performance
Office Oakland, CA

25. Summary for Low-No Cost Savings
• Software: Equipment Power
Mgmt Software - Turn equipment
off when not in use (at device
or thru IT)
• Hardware: Plug Strips and
Timers to control equipment at
the device
• People/Behavior: Prompts,
Feedback, Campaigns, Green
Policies, Competitions.

26. Best in Class Equipment
• High Savings (20-90% better)
• Only Cost Effective at
procurement
• Replace desktops with laptops
• Monitors
• Imaging Equipment
• Peripherals

27. Consider reductions in the number of
plug in items.
Ensure all items are
powered down when not in use

29. Case Study – Real Savings
Buffalo, NY City Hall - 1,000 Employees
Estimated Savings of $71,400 at 12 cents/kWh
# of
Units
Equipment
Low-cost/No-cost Energy
Efficiency Measures
% Saved
With
Extreme
Office
Makeover
Total
Electric
Bill
Savings @
$0.12
PC/Monitors
1000
Shut off & Power Mgmt
69%
$55,857
Printers
330
Shut off & Power Mgmt
31%
$4,138
Copiers/Doc. Centers
75
Shut off & Power Mgmt
67%
$6,815
Faxes/Scanners/MFDs
25
Shut off & Power Mgmt
37%
$289
Task Lights
38
Replace w/CFLs
72%
$117
Water Coolers
43
Turn off Hot Water Taps
48%
$1,522
Refrigerators
22
Replace Old Ineffic. Units
54%
$1,718
Coffee Machines (Lg)
17
Turn off at night/timers
25%
$597
Vending Machines
2
Replace w/ENERGY STAR
62%
$354
62%
$71,407
Total Equipment Users
1000
Source: Sabo, NYSERDA Power Mgmt. Program

30. Whole Building
View
• Office equipment:
• 6% of the total building
energy use at the study sites
• 6-12% at avg. bldgs
• Savings represented 1-3% at
the study sites.
• Could be double in average
buildings thus 2-6% of total

31. Market
Connections
Outcomes

32. Zero Energy Buildings

33. Source: Pleiss, Hootman, NREL

35. Plug Load Points
• Plug loads in offices are now many times larger than
efficient lighting loads
• Even in the “best” offices, plug load use in
Unoccupied hours is at least 50% of the Occupied
hours
• NBI measured peak load density of all loads, which
best reflects installed capacity, maxed out at 2.0
W/SF
• You can’t get to savings targets without addressing
plug loads

38. Office Plug Loads:
Best Practice Guideline

40. to
Office
Equipm
ent
Savings

41. Summary in Sets of 3
• Energy Use of office equipment plug loads:
– Desktop Computers
– Imaging Equipment and Peripherals
– Computer Monitors
• Approaches to save energy:
– Software
– Hardware
– People: Information and Prompts
•
Priority no–low cost strategies and technologies*:
– Aggressive Power Management Settings
– Plug Strips and Timers
– Occupant Reminders and Prompts
*Note: Replacing equipment with low-energy models is a high saving strategy and
is low or no cost at the time of planned replacement.

42. Questions?