Commercial unitary HVAC systems are used to cool approximately half of all commercial building space and are estimated to consume 0.74 quads of energy annually. Most military installations also use such unitary HVAC systems to cool many buildings and mobile applications. The objective of this project is to demonstrate the increased energy efficiency and reduced energy consumption of unitary direct expansion (DX) air conditioners equipped with ClimaStat technology. The project aims to (1) demonstrate the life-cycle cost benefits of ClimaStat technology in both installed and new unitary HVAC systems and (2) demonstrate and document energy savings of at least 15% along with significant indoor air quality improvements. Technology demonstrations will take place at Marine Corps Air Station Beaufort, South Carolina.

Technology Description

ClimaStat is a refrigeration-science technology that can be factory installed in new air conditioning equipment as well as field-retrofitted to existing equipment. The technology is based on a new paradigm for control of major elements of unitary HVAC equipment, including refrigerant management, compressor, cooling coil, and supply air fan. The technology involves modifications to the conventional DX system that result in more precise control of supply air over system evaporator coils, along with optimized refrigerant management, resulting in lower pressure differentials at compressors. ClimaStat advances unitary system technology by responding to varying latent (moisture) loads in addition to conventional sensible (temperature) load control. ClimaStat components are relatively simple readily available parts from the food and industrial refrigeration industry that are reliable, proven, easily maintainable, and low cost.

Implementation Issues

Implementation of ClimaStat technology can lead to increased energy efficiency, along with superior humidity control and fresh air ventilation, for DX air-conditioning units in both stationary and mobile applications. Substantial reduction of energy use by unitary HVAC systems in Department of Defense (DoD) buildings is the primary benefit. Additional benefits are longer HVAC compressor life due to reduced refrigerant pressure differential and reduced operating hours. Energy use reductions of up to 60% can be realized in systems utilizing reheat for humidity or temperature control. This demonstration of the ClimaStat technology, both as a retrofit to existing unitary systems and as an enhancement to new equipment, will provide a solid basis for technology deployment at all DoD facilities with unitary DX equipment and significant cooling loads.