An increase in farm and bird size over the last 20 years has led to a jump in water usage on broiler farms. It is now not uncommon to see six- to eight- house farms, and houses themselves have increased in size from 40’ X 400 to 50’ X 500’+. These houses hold larger birds which require more cooling, and more cooling requires more water.
In addition, broiler farms have switched from naturally-ventilated houses with circulation fans to tunnel-ventilated houses with evaporative cooling systems. Evaporative cooling, in its most basic form, is a process in which liquid evaporates, typically into surrounding air, cooling the object or a liquid in contact with it. In a fan and pad system, outside air is cooled as it is drawn through wetted pads. Heat in the air evaporates water from the pads which are constantly re-dampened to continue the cooling process. Cooled, moist air is then delivered to the house through a vent in the roof or wall.
When it comes to evaporative cooling systems, or any water systems for that matter, one of the primary concerns is peak water usage. The chief concern is whether or not the water systems have enough capacity to supply the needs of the birds and the evaporative cooling system, even on the hottest day of the year.
“Twenty years ago peak water usage for a house full of birds was around two gallons per minute. Two rows of fogging nozzles in a naturally ventilated house would use about another two gallons per minute. So we only needed a well and water supply system capable of delivering a total of four gallons per minute,” said Mike Czarick, Extension Engineer at The University of Georgia.
“When the industry moved towards evaporative cooling pads, they produced close to double the cooling which required about twice the water (8 gallons per minute). To keep the large birds cool during hot weather, the industry increased air speeds in their tunnel houses (from 400 – 500 feet per minute to around 600 feet per minute),” said Czarick.
Higher air speeds require more fans, more pads and more water. People in the industry are also building wider houses (more space, more birds, more cash flow) which leads to an increase in per-house fan requirements and therefore water requirements. Because of these factors, the bird peak water usage can be more than three gallons per minute and the peak evaporative cooling system water usage could be as high as 15 gallons per minute. What this all equates to is a broiler house water system that necessitates close to 20 gallons per minute.
So why turn to evaporative cooling when there are other options? In today’s industrial environment, few aren’t concerned about cost and energy usage. The first thing that comes to mind for most people when climate control is discussed is air conditioning. Evaporative cooling, however, is far less expensive than AC. The use of a conventional AC system could cost up to ten times as much to install and maintain. Power usage on the typical farm during hot weather would also increase significantly.
In fact, according to Czarick, evaporative cooling is by far the least expensive method of reducing air temperature.
Czarick also reminds us that water is cheap. The aforementioned issues deal with peak water usage. When the birds are younger or when the weather outside is cool, water usage is considerably lower. Compared to processing plants and many other agriculture industries, poultry houses use very little water.