The objective of this project is to understand the economic and environmental impacts of operating micro Combined Heat and Power (mCHP) equipment such as the Lochinvar XRGi 25. This project will include the installation and analysis of two newly installed XRGi 25s as well as monitoring and analysis of three mCHP systems in place at Maine National Guard bases.

mCHP technology has the potential to decrease a facilities' overall energy expenses while reducing greenhouse gas emissions. By analyzing multiple CHP systems operating with different controls strategies, energy prices, and fuels, this project seeks to identify conditions and thresholds at which mCHPs are cost effective and provide environmental benefit.

The XRGi is designed to integrate with existing thermal and electrical systems and can be flexibly configured to meet the needs of different sites. Because the equipment has a moderate electrical production capacity (24 kW) and flexibility of integration, there is potential for this technology to be broadly applied to various applications at Department of Defense sites. Although mCHP equipment has been adopted more broadly in Europe, it continues to be an underutilized technology in the United States. In order to support greater adoption, this project will demonstrate and quantify the economic and environmental benefits of incorporating mCHP equipment into existing building systems.

Technology Description

mCHP equipment simultaneously produces electricity and hot water. The XRGi 25 can provide superior economics in comparison with traditional water heating equipment and grid purchased electricity. In addition to economic benefits, operation of the XRGi will result in decreased environmental impact and improved facility energy resilience. This equipment works alongside existing mechanical equipment to add redundancy and does not require disabling or removing existing water heating capacity.

The economic performance of any mCHP installation is primarily determined by run-time and relative energy pricing. Facilities with high year-round demand for hot water are ideal applications. In a standard configuration, the equipment modulates in response to hot water demand. During utility outages, electrical generation is prioritized, and excess heat is rejected to an exterior radiator as needed.


Based on economic modeling of the XRGi 25, one 24 kW unit operating at a 90% duty cycle will produce 378,432 kWh annually. Savings in electricity and gas otherwise consumed by a boiler are offset by an increase in natural gas use and maintenance expenses. Net annual energy costs savings are estimated at $26,290 based on recent Illinois rates of $.11/kWh and $0.42/Therm. kW demand charge savings are not included. Based on an installed cost of approximately $165,000 per unit, reduced by tax incentives this investment will provide a simple payback period of approximately eight years.

  • Combined Heat and Power (CHP)