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Annual electrical energy requirements of five cooling strategies for lactating dairy confined housing in the eastern United States

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  10th International Livestock Environment Symposium (ILES X)  .(doi:10.13031/iles.18-125)
Authors:   Ted L Funk, Curt A Gooch, Richard R Stowell, Jiangong Li
Keywords:   Cooling, dairy heat stress, temperature-humidity index.

Abstract. Management of today‘s high-producing dairy cow involves careful consideration of the sheltered environment in which she is housed. Dairies in the eastern US must be designed for a wide range of weather conditions; and warm weather, encountered to varying extent in all states, places cows under heat stress unless some method of artificial cooling is provided.

Five different confined-housing indoor environmental conditioning systems for lactating dairy cows are modeled to estimate annual operating times and per-cow electrical energy requirements for ventilation and cooling. The systems compared are: cooling fans, cooling fans plus sprinklers, whole-barn mechanical ventilation, whole-barn mechanical ventilation with wall-mounted evaporative cooling pads, and air conditioning. For locations in each of eight key dairy-producing states representing the eastern U.S., ten sets of stochastic weather data were generated and used as the bases for computing hourly ambient psychrometric conditions. Operational stages of the various dairy housing ventilation systems, and their estimated electrical power inputs, are linked to the hourly local climate conditions. A threshold heat stress condition (temperature-humidity index, THI=70) for lactating cows, with qualifying air speed and other housing variables, determines when the various cooling strategies are activated in the barns.

The study provides annual estimates of the hours of fan operation at discreet stages, and the per-cow electrical energy needed, for each of the systems. Hot-weather (stage 3) fans of mechanical ventilation systems were projected to operate an average of 750 to 3,800 hours a year depending on location. The electrical energy estimates show a corresponding range of 95-235 kWh per cow for operating fans in a mechanically ventilated barn, compared to 120-660 kWh per cow for running supplemental cooling fans in a naturally ventilated barn. The total electrical energy usage for air conditioning ranged from 979-3,386 kWh/cow. Results can be used to inform investment choices among the various confined-housing technologies.

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