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Commercial Rooftop Unit Working Group (RTUG)

Current Work: In 2013, Bonneville Power Administration (BPA) contracted with SBW and NorthWrite to develop a Premium RTU Retrofit Protocol. This would be a separate non-overlapping protocol from the Fan and Cooling Savings Protocol previously adopted by the RTF. Premium RTU Retrofits consist of supply fan control using variable speed drive, multi-speed or cycling; demand-controlled ventilation; and differential, integrated economizer control.

Materials

Previous Work: Starting in 2004, the RTF began conducting a series of data collection and analysis efforts to develop energy savings estimation methods for commercial-sector rooftop unit (RTU) and commercial split HVAC system O&M.  The result was the RTF standard protocol for Packaged and Split System HVAC - Fan and Cooling Savings, approved on March 13, 2012.

Five phases of protocol development work included:

  1. A review of the existing research data nationwide on the energy savings that could be attributed to RTU from maintenance programs,

  2. Initial work on a simplified field energy savings measurement protocol that also included discovery of a dry bulb economizer sensor problem that led to the development of a new digital sensor that is now installed as a requirement in all PNW RTU maintenance programs,

  3. A larger scale RTU field test sponsored by the Bonneville Power Administration of a simplified measurement protocol including annual measurement of energy use and savings in a subset of units. Also completed was an RTU measurement database of more than 100 RTUs that is publicly accessible on this web page,

  4. Further review and refinement of the energy savings protocol and development of a normal annualized use and savings calculator using true power measurement and weather data as the two key input data requirements, and

  5. Completion of the protocol and Standard Protocol and Savings Calculator that was approved by the RTF on March 13, 2012.

Results

Background Materials