WattDepot: A software ecosystem for energy data collection, storage, analysis, and visualization

WattDepot: A software ecosystem for energy data collection, storage, analysis, and visualization Robert S. Brewer, Philip M. Johnson Collaborative Software Development Laboratory Information and Computer Sciences Dept University of Hawaii at Manoa http://csdl.ics.hawaii.edu/

Motivation
Research on changing energy use behaviors
Need to collect & analyze energy data
Requirements
Collect data from many meters
Sub-minute data collection
Easy to simulate sensor data
Internet-accessible repository
Visualization variety & flexibility
Open source
Could not find an existing solution
Developed WattDepot

Architecture Devices Meters WattDepot Sensors WattDepot Server WattDepot Clients HTTP HTTP

Sensors
Software to collect data
Interface to specific meters
Store data in server via HTTP
Designed for flexibility
Encapsulates vendor-specific code
Any platform or language
Just needs to output XML over HTTP
Current implementations
TED 5000 home energy meter
Veris power meters
Modbus/TCP meters
Sensors Server Clients

Servers
Central data repository
RESTful HTTP API
Pluggable back-end database
Data represented as XML or JSON
Devices represented as Sources
Server-side capabilities
Aggregation of sources (virtual sources)
Data interpolation

Servers: Virtual Sources
Virtual sources combine sub-sources
Maps real-world entities to system
Hierarchy can be multi-level
But meter clocks may not be synchronized
Saunders Hall Floor 2 North Saunders Hall Floor 2 South Saunders Hall Floor 2 Saunders Hall

Servers: Timestamp Problem
Unsynchronized clocks cause problems
Naïve data comparison difficult

Servers: Data Interpolation
Data resampling at arbitrary times
Linearly interpolate between data points
Solves timestamp problem for virtual sources

Clients
Data extraction & visualization
Any platform or language
Using REST or Google Visualization APIs
Current implementations
Real-time monitors
Charts
Geographic visualizations
Android mobile application
All independent of data input source

Clients: Heatmap and Gauge

Clients: GeoMap

Related Systems
Pachube
Commercial hosted data storage
YouTube for sensor data
Limits on rate of data storage
Arbitrary data means no energy “smarts”
Google PowerMeter
Smart meter data storage & visualization
Data limited to 15 min intervals
Focus on single-family homes

Our Application
Dorm energy competition
30 floor-level meters
Real-time data
Extensive competition web app
Customized goal-based visualizations
Google Spreadsheet intermediary
High performance “cloud cache”
Build higher-level data abstractions
Easy to prototype visualizations
Simulated energy data critical
Allows progress while meters are installed

Dorm Energy Visualizations

Future Directions
Privacy
Sources currently public or private
Limited authentication support
All current applications use public data
Data aggregation
Needed when comparing private data
Sensors
Additional meter support

System Availability
Hosted on Google Code
http://code.google.com/p/wattdepot/
Open source under New BSD license
Discussion list
http://groups.google.com/group/wattdepot-users

Q&A
Ask away!
Contact: rbrewer@lava.net,
[email_address]

WattDepot: A software ecosystem for energy data collection, storage, analysis, and visualization

by Robert Brewer

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