WBD General Features
General Features
Background
Today, most problems with building systems are detected as a result of occupant complaints or alarms provided by building automation systems (BASs). Operators often respond by checking space temperatures or adjusting setpoints (or thermostat settings). The root causes of operation problems are often not diagnosed, so problems recur and the operator responds again by making an adjustment. When the operator diagnoses problems more carefully by inspecting equipment, controls, or control algorithms, the process is time consuming and often based on rudimentary physical reasoning and rules of thumb built on personal experience. Frequently properly operating automatic control is overridden or turned off when it appears incorrect and possibly the cause of a problem. Moreover, some problems do not manifest themselves in conditions that directly affect occupants in obvious ways and, as a result, go undetected. These problems may, however, affect energy costs or indoor-air quality. Automated fault detection and diagnostic (FDD) tools, like the Whole-Building Diagnostician (WBD), can help building operators manage buildings more efficiently by detecting and diagnosing operational problems. Furthermore, as performance contracting for services becomes more prevalent, the need for tools to ensure performance will increase.
Overview
The WBD is a modular diagnostic software system that provides detection and diagnosis of common problems associated with the operation of HVAC systems and equipment. Development of the system was supported by the U.S.Department of Energy (DOE) Office of Energy Efficiency, and Renewable Energy Building Technologies Program. The development team was led by Pacific Northwest National Laboratory (PNNL) and includes the Honeywell Technology Center and the University of Colorado Joint Center for Energy Management. By working with industry, DOE will speed the transfer of building diagnostic technology into practice.
The first prototype of the WBD, completed in December 1996, includes two diagnostic modules: the Whole-Building Energy (WBE) module and the Outdoor Air Economizer (OAE) diagnostic module. This homepage shows features and highlights from the current prototype (second prototype). The WBE tracks overall building energy use and alerts the operator when unexpected changes in consumption occur. This helps operators in isolating and correcting the causes of undesirable changes in consumption.
The OAE diagnostic module monitors the performance of air-handling units and detects problems with outside-air control and economizer operation. It detects about 20 different basic operation problems and many variations of each. The system uses color coding to alert the building operator when problems occur and then provides assistance in identifying the causes of problems and advice for correcting them.
The figure shows the flow of information between the two modules, the user interface, and the database within the WBD. The top portion of the figure shows potential paths for obtaining data for the WBD -- directly from a data logger, a text file, or building management system (BMS).
The WBD has proven successful in field tests in actual buildings by successfully finding problems without many false alarms.
Key features of the WBD include:- Provides automated detection and diagnosis of energy performance problems in commercial buildings
- Includes two diagnostic modules: the Whole-Building Energy (WBE) module and the Outdoor Air Economizer (OAE) diagnostic module
- Uses mostly data commonly collected by BMSs
- Stores all data in a database for easy use of data from a number of sources—BMSs, analysis tools, other databases
- Presents results graphically
- Allows users to hierarchically explore causes of problems and provides advice on how to fix them
- The WBD is expandable by adding new modules