The Rooftop Unit Comparison Calculator (RTUCC) compares standard- and high-efficiency rooftop air conditioners and heat pumps on a life-cycle cost basis. This web application is an alternative to custom 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 efficiencies, as well as full-load efficiencies, using prototypical EnergyPlus models.

The RTUCC assists decision-making regarding the purchase or replacement of packaged rooftop air-conditioning and heat pump equipment by estimating a product´s lifetime energy cost savings at various efficiency levels. Other key features include the following:

• The calculator is fully web-based.
• Menu-driven format is easy to learn and use.
• Estimates life-cycle cost, simple payback, return on investment, and savings-to-investment ratio.
• Simulates operation under specific climate conditions and building prototype for selected U.S. climate locations.
• Reflects user-specified air-conditioning or heat pump requirements and building-use patterns.
• Results are easily downloaded for further analysis and presentation.

The results obtained with the RTUCC will be useful to facility managers, financial officers, energy management professionals, air conditioning contractors, and other decision makers interested in maximizing both the energy efficiency and cost-effectiveness of cooling system investments. The calculator provides energy and cost estimates suitable for comparison purposes. The RTUCC was not designed to replace custom building load simulation software for heating and cooling systems design. Due to the dynamic nature of building heating and cooling, actual energy use will vary depending on the application.

The RTUCC is a screening tool that estimates a product's lifetime energy cost savings at various efficiency levels. It provides energy and cost estimates suitable for comparison purposes only. The RTUCC is not designed to replace custom building load simulation software for heating and cooling systems design. Actual performance and costs will vary depending on specific operating conditions. Neither the U.S. Department of Energy nor Pacific Northwest National Laboratory is responsible for any adverse outcome associated with results generated by the RTUCC.