Basic Introduction toBroiler Housing Environmental Control

Brian D. FairchildExtension Poultry Scientist

Department of Poultry Science

IntroductionBroilers have been selected for increased meat yield,

better feed conversion and high growth rates for manydecades. Fifty years ago it took over 12 weeks to raise a4 pound broiler. Through advances in genetic selectionand nutrition, a 5 pound broiler can now be raised in 6to 7 weeks. Genetics and nutritional improvements inbroiler production have been extremely important tothe efficiency of poultry meat production; however, thefull genetic potential of broilers can not be reached un-less the proper environment is maintained in the broilerhouse. The fast growing, modern broiler lines are moredependent on proper environmental conditions thanbirds from lines raised just a few years ago.

ConstructionBroiler houses in the United States are constructed

with wood or steel trusses and supports. The houses areclear span structures from side wall to side wall. Thetrusses are engineered to support the weight of the roofwithout the need of support posts that make it harder tocatch birds and clean out the house. The floor is typi-cally compacted dirt that is covered with bedding

material (wood shavings, peanut hulls, rice hulls, sand,etc.). House dimensions are usually 40-50 ft wide, 400-600 ft long with 8 ft high sidewalls.

Dropped Ceilings:To improve ventilation and reduce heating costs,

most houses now have dropped ceilings. Droppedceilings protect the trusses and ceiling insulation byacting as a vapor barrier. Dropped ceilings reduce theceiling surface area and allows for the installation ofceiling insulation to reduce heat gain in during hotweather and heat loss during cold weather. Modernhouses are well insulated with blown in cellulose orfiber glass batt insulation to reduce heat gain in thesummer and heat loss in the winter. Insulation values ofat least R-21 and R-7 are recommended in the ceilingand walls, respectively.

Solid Side Walls:Most houses are constructed with solid side walls

rather than having open sides with curtains. This pro-vides better insulation, reduces air leaks, providesbetter light control and allows the house to be heatedmore efficiently. The use of solid side walls provides asmooth surface compared to open sides walls withposts. This improves air speed during tunnel ventilationthat will increase the cooling of birds next to the wall.Another trend in new construction is the building oflarger houses. Houses as large as 70 x 600 ft have beenconstructed. If these houses prove to be cost effective,it is likely that most new houses will be constructed tolarger dimensions in the future.

Broiler Performance

Broiler Houses Clear Span Broiler House

HeatingMaintaining proper temperature to promote efficient

growth is key to profitable broiler production. Thus,heating a broiler house is extremely important fromboth a performance and economic standpoint. Chicksare not able to completely maintain their body tempera-ture until approximately 14 days of age. During thistime, it is crucial that floor temperature be maintainedbetween 85-90 degrees F with minimum variation. Theprimary fuels used in heating U.S. broiler houses arepropane or natural gas. Broiler heating systems includeradiant brooders, pancake brooders, forced air furnacesand radiant tube heaters. Brooders and tube heatersproject heat onto the floor. The hot air furnaces heat theair, which then heats the floor.

Hot air is lighter than cold air. This can result instratification with the air being warmer at the ceilingthan at the floor. Circulation fans are often used tomove hot air from the ceiling down to the floor. Usingcirculation fans to mix the warm and cool air can resultin as much as 30 percent fuelsavings and may improvelitter conditions as the warmerair on the floor helps drylitter. Paddle fans can also beused to mix air, but be carefulto ensure that the chicks arenot exposed to drafts.

VentilationVentilation delivers fresh air and removes excess

heat, moisture and undesirable gases from the broilerhouse. A typical ventilation system in a broiler houseconsists of fans, air inlets, evaporative cooling systemand controller/thermostats. Houses are designed to dealwith both cold and hot weather extremes.

Cold Weather Ventilation:

During cold weather, negative pressure ventilationis used to provide fresh air, remove moisture and mini-mize heat loss. Fans exhaust air out of the house creat-ing a slight negative pressure inside the house. Fresh airis pulled into the house due to the negative pressure and

enters through planned air inlets that are installed eitherhigh on the house side wall or in the ceiling. Theseinlets are designed to direct air across the ceilingallowing it to mix with warmer air located there and toheat up before coming into contact with the birds.Newer houses use computercontrollers to determine whenthe fans operate and for howlong. The combination ofcontroller and air inlets allowscontrol of how much air entersthe house and where it willenter and allows good airquality to be maintained whileminimizing heating costs.

Hot Weather Ventilation:

During hot weather “tunnel ventilation” is used tokeep birds cool. Tunnel ventilation systems consist offans at one end of the broiler house and large air inletsat the opposite end. The fans pull air the length of thehouse at a velocity of 500 feet per minute. Tunnel ven-tilation removes heat from the building rapidly andcreates a wind chill that provides additional cooling forthe broilers.

When tunnel ventilation alone is not sufficient tocool the broiler house, the evaporative cooling systemis activated. Energy in the form of heat is used to evap-orate water lowering the air temperature. Originally,evaporative cooling was accomplished using foggingsystems located inside the house. The fogging nozzlesprovided a fine mist of water that evaporated, thuslowering the air temperature. Occasionally there weresituations when this system was not used correctly. Asa result the air sometimes became saturated and all ofthe water did not evaporate, which led to wet litterproblems. This problem was corrected by moving theevaporative cooling system outside of the house. Fog-ging systems were placed on the end of the housewhere the air enters. The fogging nozzles sprayed a finemist of water onto fluted/perforated pads. The air wasdrawn through the pads where water was evaporatedand the air temperature was reduced. This system also

Radiant Brooder Pancake Brooder Forced AirFurnace

18-inch Circulation Fan

Air enters throughinlets in the sidewall or ceiling.

Radiant Tube Heater

had drawbacks, sometimes causing large amounts ofwater being wasted as it dripped off the pads.

Recirculating evaporative cooling systems havebecome popular as a solution to this problem and is theprimary evaporative cooling system being installedcurrently. With this system, water runs through a per-forated pipe at the top of the cool cell pads. Water runsdown and through the pad soaking it. Any water that isnot evaporated is caught in a trough at the bottom ofthe pad that delivers the unused water back to areservoir to be pumped through the system again.Depending on environmental conditions (temperature,humidity), incoming air temperature can be lowered 10degrees F or more.

Controlling House EnvironmentAlmost all modern broiler houses rely upon elec-

tronic controllers. Through the use of controllers, it ispossible to keep house temperatures within five degreesof the desired temperature regardless of outside temper-ature. This makes it possible to keep the birds comfor-table so they are not diverting energy from growth tostay warm or cool. The controller monitors house

environmental conditions and adjusts the heating, ven-tilation and cooling equipment as necessary to keeptemperatures constant. Today, controllers can monitortemperature in six or more locations throughout thehouse. Humidity can also be monitored, althoughadjustments to heaters and fans are usually done on atemperature basis.

As the house temperature fluctuates, the controllerwill turn on the brooders or fans as needed. The con-troller operates equipment in the house including:brooders, fans, inlet machines, curtain machines,evaporative cooling systems and lights. Many control-lers also allow house conditions to be monitoredremotely.

Using a computer and modem, a grower can callinto the farm and check the temperature and humidity,as well as, which heaters and fans are operating in allhouses. If needed, changes in the environmental set-tings can be made remotely using the computer.

Alarms and GeneratorsThe importance of the maintaining a comfortable

and stress-free environment for the birds cannot beoverstated. Modern broiler housing can provide theenvironment needed to optimize broiler performance,but this is entirely dependent on electricity and theproper operation of house equipment. It is difficult for afarm manager to be present 24 hours a day, every daythat birds are in the house. Therefore, it is important tohave an alarm system installed to let the farm managerknow when something goes wrong in the house.

While the system will not correct the problem itself,its main purpose is the get someone into the house toevaluate and correct the problem. Alarms are used tonotify if there is loss of power or if the house internaltemperature gets too high or too low in relation to thedesired temperature. The alarm system will activate asiren, usually located at the facility, to alert anyone

Recirculating Evaporative Cooling System

House Environmental Controller Generator

close by and an automatic phone dialer and/or pager tonotify the farm manager while he or she is away fromthe farm. In the case of power loss, emergencygenerators are used to operate ventilation, feeding andwatering systems to prevent catastrophic losses. Theemergency generator should have the capability ofautomatic power switch-over and be capable ofdelivering service for extended periods of time tooperate the systems mentioned above.

SummaryResearch on improving broiler housing is ongoing.

Energy costs are becoming more signi�cant to the

grower’s bottom line and housing construction, equip-ment and operation will be paramount in helping tomake sure the houses are operated as e�ciently aspossible. As technology and equipment is redesignedand developed, researchers will continue to examinehow broiler housing can be heated, cooled, and built insuch a way that modern broilers continue to reach theirgenetic potential using the most economical ande�cient methods.