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Advanced RTU Technical Reports & Presentations

Technical Reports

The Advanced Rooftop Unit (RTU) Campaign compiled the reports below to help you better understand, evaluate, and overcome common technical barriers and challenges to implementing high-efficiency RTUs, advanced RTU controls, and automated fault detection and diagnostics (AFDD).



High-Efficiency RTU Replacement: Hawaii and Guam Energy Improvement Technology Demonstration Project
This report describes a demonstration by the Naval Facilities Engineering Command (NAVFAC) and DOE examining new or underutilized energy technologies specific to energy savings from high-efficiency HVAC systems.

Field Evaluation of the Performance of the RTU Challenge Unit: Daikin Rebel
This report documents the testing of a Daikin Rebel rooftop unit – the first RTU to meet DOE's RTU Challenge specification – and a standard unit in the field and compares the seasonal efficiency of the two units.

Commercial Roof-top Units in Minnesota: Characteristics and Energy Performance
This study from the Minnesota Department of Commerce characterizes the market of available RTUs to inform the improvement or development of utility conservation improvement programs, which aim to reduce the energy consumption of new and existing RTUs.

Part-Load Performance Characterization and Savings Potential of the RTU Challenge Unit: Carrier WeatherExpert
DOE recognized Carrier’s 10-ton WeatherExpert model as meeting its RTU Challenge specification. This report documents the development of part-load performance curves to estimate the potential savings from the use of WeatherExpert units compared to other standard options.

High-Efficiency Heating Rooftop Units
This report from Advanced RTU Campaign Supporter Nicor Gas summarizes an evaluation of a high-efficiency condensing RTU and its potential as an energy efficiency measure for the utility's commercial customers.


RTU Embedded Diagnostics: AFDD Development, Field Testing, and Validation
DOE and the Bonneville Power Administration evaluated retrofit advanced RTU controllers and found that annual RTU energy consumption was reduced by an average of 57%.

Smart Monitoring and Diagnostic System for RTUs
The Smart Monitoring and Diagnostic System (SMDS) is a low-cost technology that helps building owners and managers keep rooftop air conditioner and heat pump units operating at peak efficiency. This case study highlights the results of SMDS field demonstrations.

Laboratory Assessment of Retrofittable Variable Speed Controller for Compressor and Supply Fan of Unitary Air Conditioners
Southern California Edison, an Advanced RTU Campaign Supporter, compared the performance of a 5-ton packaged RTU with and without the variable frequency drive (VFD) technology under controlled laboratory conditions. This report describes the results.

Advanced Rooftop Control Retrofit Field Test Results
This multi-year research study was initiated to find ways to improve packaged heating and cooling equipment operating efficiency in the field. The objective was to determine the magnitude of energy savings achievable by retrofitting existing packaged RTUs with advanced control strategies.

Advanced Rooftop HVAC Unit Controls Pilot
Minnesota’s Center for Energy and Environment field-tested products that claimed to deliver energy savings to existing rooftop air handling systems. Three optimizers demonstrated product maturity and market readiness for pilot testing; this report summarizes the results.

Energy Implications of Retrofitting Retail Sector RTUs with Stepped-Speed and Variable-Speed Functionality
This study uses whole-building energy simulation to estimate the energy impact of stepped- and variable-speed RTU fan motor retrofits in the retail environment. The results allow retailers to estimate the building-level energy savings associated with this retrofit measure.

Energy Savings and Economics of Advanced Control Strategies for RTUs with Gas Heat
Pacific Northwest National Laboratory evaluated a number of control strategies that can be implemented in a controller, which can be retrofit into an existing unit to improve the operational efficiency of packaged HVAC equipment.

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