What is the potential for economizer use with UFAD systems?
During cooling periods, when outside air temperatures are several degrees lower than that of the HVAC systems return air, a buildings mechanical ventilation system can run on 100% outside air. This reduces the energy required in the process of cooling the supply, and re-circulated, air to the required temperature under normal operating conditions. This method of cooling, often described as free cooling, is only feasible in temperate climates where outside air temperatures are in the range of 21-24C (70-75F) by day and will periodically be less than the supply air temperatures (nighttime economizer cycles are frequently employed, for example). Enthalpy-based control is always recommended to ensure proper humidity control of the supply air entering the underfloor plenum. In comparison to ceiling-based systems, UFAD supply air is distributed at a higher temperature, typically 18C (65F) for UFAD, 13C (55F) for ceiling HVAC. In most temperate climates the increased number of hours during wh
