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ARRA Building retuning
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Research Highlights

October 2014

PNNL Releases Version 4.3 of the DOE Rooftop Unit Comparison Calculator

The PNNL developed Rooftop Unit Comparison Calculator (RTUCC) compares high-efficiency rooftop air conditioners to standard equipment in terms of life cycle cost. This web application provides an alternative to complicated building simulation models while offering more detail than simplified estimating tools that are commonly available. While simplified tools are typically based on full-load efficiencies and full-load equivalent operating hours, the RTUCC accounts for local climate and partial-load as well as full-load efficiencies.

The Comparison Calculator assists decision-making regarding the purchase or replacement of packaged rooftop air conditioning equipment by estimating a product's lifetime energy cost savings at various efficiency levels. The results obtained with the Comparison Calculator will be useful to facility managers, financial officers, energy management professionals, air conditioning contractors, and other decision makers interested in maximizing both energy-efficiency and cost-effectiveness of cooling system investments. Version 4.3 of the RTUCC provides additional functionality needed to support the assessment of three specific high-performance RTU systems. The lead engineer responsible for the development of the RTUCC is PNNL Senior Energy Engineer James Miller. The PNNL Project Manager for the RTUCC is Senior Program Manager Linda Sandahl.

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