EMCS Data Exchange Challenges: The Real Story! Srinivas Katipamula, Ph.D. 2008 ASHRAE Summer Meeting Monday June 23 rd, Salt Lake City, UT
Outline Why do we need data from building systems? Challenges in getting data Examples of getting data Examples on how to use data Summary
Why do we need data? Buildings are not properly commissioned, operated nor maintained even though capabilities of energy management and control systems (EMCS) continue to increase Improper operations lead to inefficiencies and reduced lifetime of the equipment Effective monitoring can lead to: enhanced equipment performance better comfort improved equipment availability, and fewer complaints from building occupants
Infrastructure Requirements Source of data - sensors - part of EMCS Transport mechanism - ties sources of data to the nodes where they are processed and/or displayed Software applications that use the data to enhance building operation
What Can We do with Data? Identification of O&M opportunities, including scheduling problems, in the facilities by tracking performance Tracking energy use and end-uses building or group of buildings can lead to better monitoring and verification of guaranteed savings contracts better reporting, and benchmarking of building performance Ability to forecast energy budgets and purchasing plans Automated, remote fault detection and diagnostics Optimization across multiple buildings and building systems Ability to control load and equipment in response to varying utility rates (e.g., real-time pricing, time-of-use rates)
Where Are We Today? Most existing installations are based on proprietary control networks Some proprietary sub-networks connected by gateways Limited access to data on network Remote monitoring at workstations on the controls network, field panel displays or by dial up Some access for third party programs or custom connections
Where Are We Heading? Many new installation are using BACnet Having BACnet does not always mean data access is seamless Some vendors including BACnet now offer web services (http or https calls)
Data Access - Today Limited access to data on network Some access for third party programs via DDE, OLE, or custom connections Access to data critical More important converting information to knowledge Data Sources DDC Control System Trend Logs Direct Exchange In House or Third Party Application Alternate Sources Data Loggers Text Files
Challenges with Trend Logs No two vendors provide data in the same format Most provide comma-separated value format Some provide multiple columns of data in each file Some provide single columns of data in each file Treatment of missing and null values not standard Makes it difficult to automatically process data Filtering of data is essential before it can be used in a tool often manually
Direct Exchange of Data Many vendors and third parties provide data servers to access data directly from the EMCS DDE (Dynamic Data Exchange) OPC (Object linking and embedding for Process Controls) Requires a client-side application to access the data More reliable than trend logs
Example of a Custom Direct Data Exchange Client (BASLink) Collect periodic data for diagnosticians Support multiple EMCS types Local, network or remote data acquisition Define and control channel maps Define and control conditional integration Robust error recovery
BASLink System Architecture Network BASLink Server BASLink Server BASLink Client BAS Host A BAS Host B Dx Host C BASLink Client Telephone Line Dx Host D
BAS Server Example Internet TCP/IP BASLinkd BASDDE Module Vendor DDE Server Vendor Application Layer Protocol Vendor Network
BAS Server Trend Log Internet TCP/IP BASLinkd BASLOG Module Proprietary BAS Trend Log Files Proprietary Protocol Proprietary Network
BAS Server BACNet Internet TCP/IP BASLinkd BASBACnet Module BACNet Protocol BACNet Network
A Diagnostic Application with BASLink Client Network #1 Diagnostician #2 Diagnostician Dx Database BASLink Client BASLink UI Dx UI
Example of a Diagnostic System Data Sources Trend Logs EMCS Direct Exchange Alternate Sources Data Loggers Text Files Dx Outdoor-Air Economizer Diagnostician Data Filtering Dx Database Whole-Building Energy Tracking User Interface
Example of Integration of Customer Control Networks Building A kwh data HVAC data gateway Dial-Up Internet utility bills, building/production values, weather bureau, rates library,... ERP systems, accounting, alarm dispatch, other service providers Building B control system Corporate LAN/WAN Facility Management & Control System meter system data gateway user-specific information delivery via Web browsers generator
Monitoring Components from Multiple Vendors
Summary Enhanced building operations requires that we have easy and reliable access to data Although capabilities of EMCS have increased significantly over the past two decades, access to data is still not easily or reliably available Third-party tools are filling the gap, but in the long run need a better solution Web services might provide a way to overcome traditional problems