HOUSING
PIH-92
pork industry handbook
PURDUE UNIVERSITY • COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA
Energy Conservation in Ventilating and Heating Swine Buildings
Authors
Robert L. Fehr, University of Kentucky
Raymond L. Huhnke, Oklahoma State University
Reviewers
Maynard Hogberg, Michigan State University
Larry Jacobson, University of Minnesota
Duane Miksch, University of Kentucky
David Shelton, University of Nebraska
Energy Inputs
Energy is used in swine facilities for the operation of fans, lighting, feed handling, creep heaters, water heaters, and supplemental space heaters. This fact sheet will discuss ways to save energy used for operating a ventilation system including supplemental heating. Most mechanical ventilation systems use energy to reduce the management required to maintain a productive environment. Usually, reducing energy use increases the level of management required. Some methods of saving energy may increase other production costs, such as feed, enough to offset the value of any monetary savings for energy. There are ways to reduce energy use without adversely affecting feed utilization or animal performance.

Environmental Control
Ventilation Principles. The primary goal of a ventilation system is to modify die environment to improve production while maintaining acceptable air quality levels for workers. The way ventilation systems operate has a major impact on energy use, especially supplemental heating. Ventilation systems are designed to vary air flows from minimum ventilation rates in the winter to maximum ventilation rates in the summer

(Table 1).
Ventilation rates vary because there are different air exchange needs at different outside temperatures. The ventilation system must limit temperature rise during hot weather, control temperature during mild weather, control humidity during cold weather, and control odors and gases.

When the outside air temperature is greater than the desired inside air temperature, the ventilation system can only limit the temperature rise of the air as it passes through a building, unless a cooling device is used. The air temperature increases as it moves through the building because of the heat added by the animals, lights, creep heaters, motors, etc. As the outside air temperature falls below the inside air temperature, temperature control is achieved by altering the ventilation rate until the heat losses from the ventilation air and building shell equal the heat
Table 1. Total Per-head Ventilation Rates for Swine Buildings During Various Times of the Year.
	Cold Weather	Mild Weather	Hot Weather
		-cfm-	
Sow & litter	20	80	500
Pre-nursery pig (12-30 lb)	2	10	25
Nursery pig (30-75 lb)	3	15	35
Growing pig (75-150 lb)	7	24	75
Finishing hog (150-220 lb)	10	35	120
Gestation sow (325 lb)	12	40	300
Boar (400 lb)	14	50	300
added. As the ventilation rate decreases, the relative humidity in the building increases. The ventilation rate must then be adjusted to balance the moisture removed by the ventilation air with the moisture produced in the building. During low outside temperatures, when the ventilation rate needed to control humidity is greater than the rate to control temperature, a supplemental heat source must be added to maintain the building air temperature.

The level of odors in a swine facility is another factor affecting the minimum ventilation rate. Odors will increase in any facility as the ventilation rate decreases. The most important energy conservation techniques are those that reduce the ventilation rate as much as possible while maintaining the minimum allowable room temperature as well as good moisture and odor control.
Cooperative Extension work in Agriculture and Home Economics, state of Indiana, Purdue University, and U. S. Department of Agriculture cooperating; H. A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Cooperative Extension Service of Purdue University is an affirmative action/equal opportunity institution.