Tunnel vent for poultry

To reduce energy consumption we must understand the basic physics. wind speed is related to the cross sectional area of the house. Thus to reduce energy consumption per square meter of house we must:- 1) reduce the cross sectional area of the house- by lower ceilings. 2) make the house longer....up to 160m or even more. Remember that a 160M house will use the same energy to reach a given wind speed as a 80M house or even a 40M house.

House and Ventilation should be properly designed keeping in view the requirements in relation to prevailing weather conditions of the house locality. Followings points play significant role in energy economy. 1: - House should be insulated and air tight, so that there is no leakage of air and least heat transfer either way. 2: - Fans should be selected carefully with above 20CFM per Watt. Large capicity cone fans will better suit. 3 Evoparative cooling pads should be carefully selected for better cooling capacity. Select thickness height and flute angle which best fullfills tunnel requirements. As some cooling pads Like with flute angle 45/45 will resist more to air passing than others like 60/30 and 45/15 flute angle. 4: - Cleaning and good maintenance of Fans (Fan belts etc), cooling pad will give energy effeciency for long time. As dirty Fan clogged with feathers, dust etc will loos it efficiency upto 40%, which can be restored by cleaning only periodically. Similarly Pads clean maintenance will more energy effecient than clogged ones. 5 Fans should not be installed agains wind direction ( by installinf Fans againstthe direction of air, will create more resistance to air expelled from the house and vice versa. 5: - House should be air tight, so that warm air entering through leakage points will raise the temperature of house, which will put on more fans to combat heat/ high temperature. 6: - Controllers with more option of stages should be installed, so that fans are put on one by one, so that better energy can be saved. this type will save energy by keeping on lesser number of fans in comparison to lesser number of stages as this type of controller will pun on/ Off fans in groups instead of single. 7: - Walls should be insulated with 14-16 R value and roof with R value 20- 22. Syed Maqsood Haider Jaffery

I am 100 % agree with Dr. Maqsood Jaffery remedies . these are the main things which maintain the inside temperature at optimum level, reduce the extra usage of energy. Dr. Naseem Anwar

I totally agree with Dr. Maqsood Jaffery's key notes on tunnel ventilation. Those tips are very much useful to overcome the energy loss in tunnel ventilation sheds.. I am thankful for such creditable and efficient tips . Regards, Dr. Jaydip

I agree with Dr Maqsood in addition the points mentioned to optimize energy utilisation we need to understand local climate and very important is understanding psychomertic chart and explain the operator in simple understandable language. by using good controller, outside climate, birds requirement we can optimise energy requirement for tunnel ventilated houses. Need to control pad inlet opening in line with ventilation requirement.

Dr. Maqsood has given too much detail about energy conservation for tunnel ventilation. I think while insulating the house if reflecting material is used it will work well as compared to insulation, as the house during whole day absorb heat and at night it dessipate heat. In other words after the house become hot it takes time to cool. I realy appreciate Dr. Maqsood providing valuable tips. Habib-ur-Rehman OLYMPIA

in addition, we should give more attention to relaive humidity , high humidity in hot climet can cause hotter effective temperature, and it also can cause colder effective temperature if it happen in cold climate. so we should combine controller of three kind variable, its are temperature, humidity and wind speed. so we can reduce humidity araound the hen house. avoid tree around the house, avoid paddle around the hen house. the conclution is less humidity = less power needed of fan = easier to close to effective temperature that birds needed.

Members participated positively ,in rainy season the practical is very much difficult as compare to theoretical.in short with hot & humid season tunnel ventilation is a hard job.as well as all other aspects, like selection of proper fans, wind direction, R values are very much important.i like appriciate Dr.Jeffary's contribution too. Thanks

always consult with the experts,try to talk with other poultry growers..sharing of ideas is much better!.. use buffles if your ceiling is to high,use NOBAC,a chemical that reduces ammonia and heat!use alloy fan blade,heavy alloy blade is good for against the wind direction..dindo from philippines

I agree with most of the comments posted until now. Nevertheless, I would like to point out that increasing the length of the house may reduce the energy consumption in some extend, provided that the static pressure doesn’t reach levels that the fans can’t sustain at low energy costs. These relatively high static pressure levels may be reached with quite short houses if the houses are equipped with deflectors or have low beams like in Pakistan (8-9 feet). The second issue coming with longer houses is the difference of temperature between the 2 ends. Birds are producing heat which warm up the air. For example, broilers are producing 4 to 6 watts / kg LW / hour sensible heat (2 kg broilers at 35 kg LW / m² produce 140 watts per m² per hour). The longer the house, the higher the difference in temperature. It is possible to reduce the effect of house length on difference of temperature between the 2 ends by the mean of inside fogging. In Brazil growers are using the cheap technique of low pressure inside fogging (15 bars) successfully. Fogging 1 g of water per m3 reduces the temperature by 2°C and increase humidity by 10% along the house. Reducing the cross section by the help of deflectors is an alternative. Deflectors are very useful to push the air speed on the birds. They are also helpful in case the ceiling has a slope by preventing differential air speed with low speed close to the side walls and high air speed in the middle. Several factors have to be taken into account to decide the size of deflectors: height of the ceiling, type of fans and length of the house. As a kind of rule of thumb, deflectors can be lower in short houses than in long houses, with fans resisting well to static pressure than not. They don’t prevent from having good renewing rates around 160 – 180 m3 / m² / hour to dilute the heat produced by birds. Obviously, house air tightness is crucial. Insulation (against conduction) is not so important for hot weather if we consider the experience of Brazil and Thailand, but preventing radiation is a key point. Often, air speed is over estimated. Reliable assessment of air speed requires many measures across the house at 3 different heights. The equipment should be calibrated at least once a year. I believe that performing tunnel ventilation requires basically good cone fans selected according to the static pressure they will work against. The static pressure is depending on the length, cross section, smoothness of the inside surfaces and presence or not of obstacles (like nests in PS) and pad cells.

Everything in ur article is knowledgeable.I like ur discussion.Keep it up

Mr. Claude has discussed the topic very technically, fruitful information are provided. I would like to get the technical opinion of Mr. Claude, Can we install humidifier at the fanside of a shed to reduce temperature difference, bcs airspeed at this end will make environment comfortable? These foggers can be put on humidity sensors to controll humidity at desired level. What is your kind opinion? Thank you

In many countries which have buildings of 150 mts or longer, they have had good results by using a high pressure fogging system 500 psi ( 35 Bar) or greater. It is also important that you not install fogger lines too close to the exhaust fans or the mist will just exhaust out the end of the building. The goal of using the combination of evaporative cooling and fogging is to keep the differential from the pad end of the house and exhaust end to a minimum. ( These can be controlled by temperature and humidity depending on the type control you are using)

It depends on the housing conditions: if EC with litter belt then it is ok but i have seen sheds like layer open type with drooping pits which are covered all side in summer and cooling devise is operated then in that case it will lead other complications with ref to health and quality performance of the breeder. Tunnel ventilation is a costly issue where the volume of production demand of products and market price are correlated and promoter can add the cost for quality production in adverse environmental conditions. So deep litter system may work well also but commercial cage houses without manure belt my have to be studied more before implementation of close shed breeder operation or so. Rathm, India Poultry Consultant

what a very nice information about tunnel vent house. a leak -free and insulated house will also reduce cost of heating energy during brooding.

hi, everyone my question was: can we install humidifier in middle of the shed on walls to combat high temperature in the fan side area?

Dr. Muhammad- yes you can install preferably a system that operates at 500 psi ( 35 bar or greater). The reason for this is that the higher pressure system should not cause wet litter. This can be a problem with a lower pressure system. The experience in hot climates seems to indicate you can keep a more uniform temperature in the whole house and maintain dry litter condition when using this combination. As with all ventilation and cooling systems good management is critical. So if humidity is too high you may not want to introduce more humidity into the air. Also keep in mind if you have high air speeds 600 ft per minute or greater ( 3mts/second) the closer the misting nozzles are to the exhaust fans you will be exhausting mist out with the air, thus getting less actually cooling.

I agree with Jose Sala even if I would be less straight about the water pressure to use in order to prevent difference of temperature between air entrance and fans. I have seen excellent conditions and performances in the center of Brazil, which is dry and hot in Summer, with low pressure fogging (15 bars = 225 PSI). Houses were 125 x 13 m without pad cooling but with ceramic or net sprayed by water. About 18 lines of nozzles each with 10 nozzles delivering 5 liters / hour were installed along the house. The system was generally split in 2 or 3 circuits in order to adjust the quantity water according to birds age and climate conditions. The system was run on humidity sensor set at 75-80% maxi placed at 15 meters from the fans. Practically, at the end of the flock (about 3 kg broilers), the system was running 50% of the time during the hottest hours of the day. Birds feathering was slightly wet at the time the pump was turned off, then it was drying until the pump started again. Temperature was 27 °C at air entrance, 27 °C and 46% humidity close to the fans with 75% humidity. Air speed was 2 m / sec. This is one example but I have seen many cases where inside fogging was helpful in hot and dry climate. I agree that it is useless to have nozzles in the last 20 meters of the house. I am still wondering if in dry climate conditions, wetting the feathering is not helping to keep birds cool. I am aware that there is some danger is the feed becomes wet but low pressure fogging is much cheaper than high pressure. Anyway high pressure is also making the job of reducing the difference in temperature along the house. In fact, it allows to reducing a little bit the air flow in areas where the conditions are not hot and humid at the same time. It is advised to run houses at 3 meters / sec during hot waves but this is partly due to the fact that higher air speed means higher flow, so dilution of heat and less difference in temperature along the house. In areas where weather is hot and humid, I think that the 3 m / sec are required for both breeders and heavy broilers. Some fogging high pressure fogging along the house (1 to 1.5 g of water evaporated / m3 air) will reduce the 2-3 °C difference in temperature to 0°C. 3°C less close to the fans will improve the chilling effect of the 3 m / sec and allow good performances in long houses.

our building is 40 by 400 ft. i notice that the middle of the building has higher temperature compare to both end of the building. we are not using panel walling, we have no ceiling but no air leaks. please help me what to do.

Mr Esperidion, You have to measure the temperature of the roof inside the house with a contact thermometer, not a laser gun which will under estimate the actual temperature if the roof is metallic. When there is no ceiling, radiation from the sun on metallic roofs can lead to temperatures of 60 °C on the inside surface of the roof. Then the air speed will tend to catch the calories from the roof (0.3 Kcal per m3 will increase the air temperature by 1 °C). The air will become warmer as it moves towards the fans. I have seen differences in temperature of 6 °C between the 2 ends even with a quite good flow. Furthermore infrared radiation are also directly warming the birds, especially if the roof is not high. Why only in the middle of the house? Measure the temperature of the inside of the roof and the wall sides with a contact thermometer in various locations at different moments of the day. Maybe, it will give you the answer.