4. Space and zone cooling for housed livestock and poultry

Space and/or zone cooling methods have been traditionally limited to evaporative pad cooling systems, high pressure foggers, or direct low pressure water spray systems accompanied most often with elevated airspeed control. Compression-based cooling is not traditionally used, except in specialty cases not covered in this chapter. Heat stress control for housed livestock and poultry is becoming an ever growing concern, fueled mainly by our changing climate, global expansion of HLPP systems in hot and humid climates, and the increased productivity levels of modern food animals where increased internal heat generation must be released to the environment.

#### 4.1. Heat production of modern food animals

Modern genetics has increased the productivity levels of our food animals. This in turn has increased the internal heat produced that must be dissipated to the surrounding thermal environment. For example, one study found that comparing pre-1988 to post-1988 heat production data, the total heat produced by modern pigs increased by 12–35% for 90 kg pigs at 15C and 5 kg pigs at 35C, respectively [6]. Similar increases are known in other animal and poultry groups as a natural outcome of increased productivity. Dissipating this heat to prevent heat stress has become challenging.

#### 4.2. Methods to increase animal heat dissipation

The typical HLLP system for heat stress control is a tunnel ventilated (TV) arrangement of fresh air inlets and fans along the long axis of the building (Figure 6a) or arranged in crossflow perpendicular to the long axis (Figure 6b). TV systems were first developed in the southeastern quadrant of the USA where the percent calm periods in the summer months can be high. For example, in North Carolina, the hot weather months are associated with up to 18% calm periods, far in excess of desired for proper hot weather NV ventilation performance. The TV HLLP system guarantees a specific average airspeed in the barn when required. The typical design airspeed is 2 m s<sup>1</sup> , but some broiler systems are being designed as high as 3ms<sup>1</sup> [7].

wide, 140 m long, with 4.25 m high sidewalls. If this building was ventilated for a 2 m s<sup>1</sup> airspeed in true tunnel ventilation mode (Figure 6a), the maximum ventilation rate would be

Figure 6. (a) True tunnel ventilated fan/inlet and (b) cross-flow tunnel ventilated fan/inlet arrangements for airspeed

common dairy housing arrangement, the maximum ventilation rate would be 4.28 106 m3 <sup>h</sup><sup>1</sup>

a 375% increase from typical and a 186% increase from true tunnel. In some cases, dairy buildings would be fitted with drop panels over the cow resting area, to accelerate cross-flow ventilation over the cows, allowing the overall maximum cross-flow tunnel ventilation rate to

In many cases, the elevated airspeed with TV systems is supplemented with evaporative pad cooling at the fresh-air intake and/or low pressure water sprinkling, especially in pig and dairy systems. Strategies are being developed to actively select the most effective cooling strategy in a suite of options based on the climate's ability to dissipate the sensible and latent heat generated by the animals [8, 9]. For example, in some situations, evaporative pad cooling might raise the humidity ratio to a point detrimental for latent heat release from the animals, instead, warranting the use of low pressure water sprinkling. Heat production and heat/mass transfer models continue to be developed to assist heat stress mitigation decisions [8, 9].

; a 200% increase from typical. If designed in cross-flow tunnel, a more

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;

2.30 106 <sup>m</sup><sup>3</sup> hr.<sup>1</sup>

control.

be reduced (see Figure 7b).

Designing the hot weather ventilation rate for airspeed control will in most cases significantly increase the overall building ventilation rate. For example, take the cases depicted in Figure 6. If the barn in question houses 1000–600 kg lactating dairy cows, the ventilation rate typically used, designed to keep internal temperature rise less than about 2C, is roughly 1.90 m3 hr.<sup>1</sup> kg<sup>1</sup> . This equates to a maximum building ventilation rate of about 1.14 <sup>10</sup><sup>6</sup> <sup>m</sup><sup>3</sup> hr.<sup>1</sup> . A typical dairy barn housing 1000 lactating cows would be about 75 m HVAC Techniques for Modern Livestock and Poultry Production Systems http://dx.doi.org/10.5772/intechopen.78785 7

normal operating conditions, ventilating for moisture control will also control targeted gases

Space and/or zone cooling methods have been traditionally limited to evaporative pad cooling systems, high pressure foggers, or direct low pressure water spray systems accompanied most often with elevated airspeed control. Compression-based cooling is not traditionally used, except in specialty cases not covered in this chapter. Heat stress control for housed livestock and poultry is becoming an ever growing concern, fueled mainly by our changing climate, global expansion of HLPP systems in hot and humid climates, and the increased productivity levels of modern food animals where increased internal heat generation must be released to

Modern genetics has increased the productivity levels of our food animals. This in turn has increased the internal heat produced that must be dissipated to the surrounding thermal environment. For example, one study found that comparing pre-1988 to post-1988 heat production data, the total heat produced by modern pigs increased by 12–35% for 90 kg pigs at 15C and 5 kg pigs at 35C, respectively [6]. Similar increases are known in other animal and poultry groups as a natural outcome of increased productivity. Dissipating this heat to prevent

The typical HLLP system for heat stress control is a tunnel ventilated (TV) arrangement of fresh air inlets and fans along the long axis of the building (Figure 6a) or arranged in crossflow perpendicular to the long axis (Figure 6b). TV systems were first developed in the southeastern quadrant of the USA where the percent calm periods in the summer months can be high. For example, in North Carolina, the hot weather months are associated with up to 18% calm periods, far in excess of desired for proper hot weather NV ventilation performance. The TV HLLP system guarantees a specific average airspeed in the barn when required. The

Designing the hot weather ventilation rate for airspeed control will in most cases significantly increase the overall building ventilation rate. For example, take the cases depicted in Figure 6. If the barn in question houses 1000–600 kg lactating dairy cows, the ventilation rate typically used, designed to keep internal temperature rise less than about 2C, is roughly

, but some broiler systems are being designed as high as

. This equates to a maximum building ventilation rate of about

. A typical dairy barn housing 1000 lactating cows would be about 75 m

below occupational standards such as those provided by ACGIH or OSHA [4, 5].

4. Space and zone cooling for housed livestock and poultry

the environment.

6 HVAC System

4.1. Heat production of modern food animals

4.2. Methods to increase animal heat dissipation

heat stress has become challenging.

typical design airspeed is 2 m s<sup>1</sup>

3ms<sup>1</sup> [7].

1.90 m3 hr.<sup>1</sup> kg<sup>1</sup>

1.14 <sup>10</sup><sup>6</sup> <sup>m</sup><sup>3</sup> hr.<sup>1</sup>

Figure 6. (a) True tunnel ventilated fan/inlet and (b) cross-flow tunnel ventilated fan/inlet arrangements for airspeed control.

wide, 140 m long, with 4.25 m high sidewalls. If this building was ventilated for a 2 m s<sup>1</sup> airspeed in true tunnel ventilation mode (Figure 6a), the maximum ventilation rate would be 2.30 106 <sup>m</sup><sup>3</sup> hr.<sup>1</sup> ; a 200% increase from typical. If designed in cross-flow tunnel, a more common dairy housing arrangement, the maximum ventilation rate would be 4.28 106 m3 <sup>h</sup><sup>1</sup> ; a 375% increase from typical and a 186% increase from true tunnel. In some cases, dairy buildings would be fitted with drop panels over the cow resting area, to accelerate cross-flow ventilation over the cows, allowing the overall maximum cross-flow tunnel ventilation rate to be reduced (see Figure 7b).

In many cases, the elevated airspeed with TV systems is supplemented with evaporative pad cooling at the fresh-air intake and/or low pressure water sprinkling, especially in pig and dairy systems. Strategies are being developed to actively select the most effective cooling strategy in a suite of options based on the climate's ability to dissipate the sensible and latent heat generated by the animals [8, 9]. For example, in some situations, evaporative pad cooling might raise the humidity ratio to a point detrimental for latent heat release from the animals, instead, warranting the use of low pressure water sprinkling. Heat production and heat/mass transfer models continue to be developed to assist heat stress mitigation decisions [8, 9].

Figure 7. (a) Dairy housing sidewall inlet with or without evaporative cooling pads and in some cases (b) drop curtains/ walls to force cross-flow ventilation over rows of cows, enhancing airspeed maintenance.

### 5. HVAC design for virus control

Disease transmission from herd-to-herd via aerosol transport is a concern, driving significant HLLP system changes to accommodate new and innovative ventilation designs. Many HLLP systems are being designed today to capture viruses before entry into a building. This movement has been especially prevalent in pig housing systems where the porcine reproductive and respiratory syndrome virus (PRRSv) has caused significant economic hardship. Building ventilation systems have been retrofitted to incorporate high efficiency filters at fresh-air intakes as a physical capture of the virus.

Two basic ventilation retrofit strategies have been implemented, one that maintains traditional negative pressure MV and a second option that utilizes a positive pressure MV system in a 'push-only' or 'push-pull' fan configuration. In a negative pressure filtration arrangement, primary (MERV 8) and secondary (MERV 16) filters are attached in the attic space to the existing fresh-air ceiling intakes as depicted in Figure 8a for an inlet depicted in Figure 4. This method suffers tremendously from the high infiltration rates common in many HLLP systems [10]. In negative pressure filtration systems, significant sealing of the building is required to limit unfiltered air from entering the animal zone through air leakage points, and this can be an annual challenge after each seasonal freeze/thaw cycle.

6. HLLP design for livestock and poultry welfare

using blowers and (c) filtration banks in a positive pressure filtration system.

Producers of food animals place animal welfare at the forefront of their operation. Several building design changes have evolved as a result of public pressure stemming from concerns related to animal welfare. The most prominent changes have been made in pig gestation and egg-laying facilities. Traditional gestation housing uses individual stalls (Figure 9a) from which precise nutritional needs can be maintained and monitored. Due to public pressure, the traditional stall gestation has given way, in some cases, to group housing gestation facili-

Figure 8. Virus filtration with (a) filters attached directly to ceiling fresh-air intakes in a negative pressure system, or (b)

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ties, with, in many cases, electronic feed dispensing and pig monitoring (Figure 9b).

In a positive pressure filtered barn, industrial blowers (Figure 8b), or equivalent are used to push air through primary and secondary filter banks (Figure 8c), maintaining the building operating pressure slightly above ambient, bypassing the infiltration issues common with negative pressure systems. The major drawback with positive pressure filtered systems is the tendency for moisture laden air to exfiltrate, potentially condensing in the building cavity. In positive pressure systems, care must be taken as well to control exfiltration for this reason.

HVAC Techniques for Modern Livestock and Poultry Production Systems http://dx.doi.org/10.5772/intechopen.78785 9

5. HVAC design for virus control

an annual challenge after each seasonal freeze/thaw cycle.

a physical capture of the virus.

8 HVAC System

Disease transmission from herd-to-herd via aerosol transport is a concern, driving significant HLLP system changes to accommodate new and innovative ventilation designs. Many HLLP systems are being designed today to capture viruses before entry into a building. This movement has been especially prevalent in pig housing systems where the porcine reproductive and respiratory syndrome virus (PRRSv) has caused significant economic hardship. Building ventilation systems have been retrofitted to incorporate high efficiency filters at fresh-air intakes as

Figure 7. (a) Dairy housing sidewall inlet with or without evaporative cooling pads and in some cases (b) drop curtains/

walls to force cross-flow ventilation over rows of cows, enhancing airspeed maintenance.

Two basic ventilation retrofit strategies have been implemented, one that maintains traditional negative pressure MV and a second option that utilizes a positive pressure MV system in a 'push-only' or 'push-pull' fan configuration. In a negative pressure filtration arrangement, primary (MERV 8) and secondary (MERV 16) filters are attached in the attic space to the existing fresh-air ceiling intakes as depicted in Figure 8a for an inlet depicted in Figure 4. This method suffers tremendously from the high infiltration rates common in many HLLP systems [10]. In negative pressure filtration systems, significant sealing of the building is required to limit unfiltered air from entering the animal zone through air leakage points, and this can be

In a positive pressure filtered barn, industrial blowers (Figure 8b), or equivalent are used to push air through primary and secondary filter banks (Figure 8c), maintaining the building operating pressure slightly above ambient, bypassing the infiltration issues common with negative pressure systems. The major drawback with positive pressure filtered systems is the tendency for moisture laden air to exfiltrate, potentially condensing in the building cavity. In positive pressure systems, care must be taken as well to control exfiltration for this reason.

Figure 8. Virus filtration with (a) filters attached directly to ceiling fresh-air intakes in a negative pressure system, or (b) using blowers and (c) filtration banks in a positive pressure filtration system.
