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The Smart Thermostat: Using Occupancy Sensors to Save Energy in Homes Jiakang Lu, Tamim Sookoor, Vijay Srinivasan, Ge Gao, Brian Holben, John Stankovic, Eric Field, Kamin Whitehouse SenSys 2010 Zurich, Switzerland

The Smart Thermostat: Using Occupancy Sensors to Save Energy in Homes

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The Smart Thermostat: Using Occupancy Sensors to Save Energy in Homes. Jiakang Lu, Tamim Sookoor, Vijay Srinivasan, Ge Gao, Brian Holben, John Stankovic, Eric Field, Kamin Whitehouse SenSys 2010 Zurich, Switzerland. Motivation. 43%. State of the Art. Too much cost!. $5,000 - $25,000. - PowerPoint PPT Presentation

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Page 1: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

The Smart Thermostat: Using Occupancy Sensors to Save Energy in Homes

Jiakang Lu, Tamim Sookoor, Vijay Srinivasan, Ge Gao, Brian Holben,John Stankovic, Eric Field, Kamin Whitehouse

SenSys 2010Zurich, Switzerland

Page 2: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Motivation

2

43%

Page 3: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

State of the Art

3

$5,000 - $25,000Too much cost!

Page 4: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

00:00 24:0008:00 18:00

Home

State of the Art

4

55

60

65

70

75

Te

mp

era

ture

(oF

)

Too much hassle! Too much hassle!

Home Home

Setpoint Setpoint

Setback

Home

User discomfort

Energy waste

Page 5: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

5

“How much energy can be savedwith occupancy sensors?”

Page 6: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Using Occupancy Sensors

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HomeHome HomeHome

Page 7: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

“Reactive” Thermostat

The Wrong Way

7

00:00 24:0008:00 18:00

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mp

era

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Home Home

Shallow Setback

Increase energy usage!

Slow Reaction Inefficient Reaction

Page 8: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

00:00 24:0008:00 18:00

Our Approach Smart Thermostat

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Home Home

Fast reaction Deep setback Preheating

Automatically save energy!

Page 9: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Rest of the talk System Design

Fast Reaction Preheating Deep Setback

Evaluation

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Page 10: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

1. Fast Reaction “Reactive" Thermostat

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00:00 24:0008:00 18:00

55

60

65

70

75

Te

mp

era

ture

(oF

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Home Home

Inactivity detector

Active/Inactive

User discomfort

Energy waste

Page 11: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

1. Fast Reaction Smart Thermostat

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Pattern detector

Active/Away/Asleep

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Home Home

Detect within minutesWithout increasing false positives

Page 12: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

2. Preheating“Why preheat?” Preheat – slow but efficient

Heat pump

React – fast but inefficient Electric coils Gas furnace

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00:00 24:0008:00 18:00

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Home Home

Energy wasteEnergy waste

How to decide when to preheat?

Page 13: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

16:00 18:00 20:00

PreheatReact

Arrival Time Distribution

2. Preheating

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Exp

ecte

d E

nerg

y U

sage

(k

Wh)

3

2

1

016:00 18:00 20:00

Time

Optimal Preheat

Time

Page 14: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

16:00 18:00 20:00

3. Deep Setback

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Arrival Time Distribution

00:00 24:0008:00 18:00

HomeHome55

60

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75

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mp

era

ture

(oF

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Earliest expectedarrival time

Optimal preheat time

Deep setback

Shallow setback

??

Page 15: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Rest of the talk System Design

Fast Reaction Preheating Deep Setback

Evaluation

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Page 16: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Home #Residents # MotionSensors

#DoorSensors

A 1 7 3

B 1 3 2

C 1 4 1

D 1 4 1

E 2 5 1

F 3 5 2

G 3 4 1

H 2 5 2

EnergyPlus Simulator

Evaluation Occupancy Data

16

Energy Measurements

Page 17: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Energy Savings

17

OptimalReactiveSmart

Smart: 28.8%

Reactive: 6.8%

A B C D E F G H

En

erg

y S

avin

gs

(%)

-10

0

10

20

30

40

50

60

Home Deployments

Optimal: 35.9%

Page 18: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

User Comfort

18

ReactiveSmart

Smart: 48 min

Reactive: 60 min

80

A B C D E F G H0

Ave

rag

e D

aily

Mis

s T

ime

(min

)

40

20

60

100

120

Home Deployments

Page 19: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Person Types

Generalization

House Types

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Zone 1 Minneapolis, MN

Zone 2 Pittsburg, PA

Zone 3 Washington, D.C.

Zone 4 San Francisco, CA

Zone 5 Houston, TX

Climate Zones

Page 20: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Impact Nationwide Savings

save over 100 billion kWh per year prevent 1.12 billion tons of air pollutants

“Bang for the buck” $5 billion for weatherization Our technique is ~$25 in sensors per home

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Page 21: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Conclusions Three simple techniques, but able to achieve

large savings: 28% on average low cost: $25 in sensors per home low hassle: automatic temperature control

Promising sensing-based solution

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Page 22: The Smart Thermostat: Using Occupancy Sensors  to Save Energy in Homes

Q & A

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Thank you!