Abstract. Air infiltration through unplanned inlets is an integral component of any ventilation process. Air infiltration affects the quality of the room environment and can also increase winter heating costs. Precise data on air infiltration is very important in the design of animal room ventilation systems. Nineteen mechanically ventilated (negative pressure type) swine finishing rooms in Iowa were tested for their air infiltration potential. Using the data of 17 rooms, air infiltration rate through the whole room (i.e., total air infiltration, It), curtains (Ic), fans (If), and net building shell (other components, Io) were quantified. Power law equations were developed for infiltration prediction of different room configurations grouped on the basis of their construction style, age, ceiling material, curtain perimeter, and fan backdraft shutter area. All power law models reported in this study were adjusted to predict standard (sea level) infiltration rates. At 20 Pa pressure difference across the room envelope, the predicted standard It infiltration rate for the 17 rooms was 5.96±1.49 air changes per hour (ach); whereas, the predicted standard Ic, If, and Io infiltration rates were 1.49 ±1.00 ach (about 25% of It), 1.52 ±1.38 ach (about 26% of It) and 2.90 ±1.42 ach (about 49% of It), respectively. The standard It infiltration rate trended lower for rooms (n=8) from single room layout barns (5.85 ±1.66 at 20 Pa), rooms (n=8) having a non-metal ceiling (5.85 ±2.15 at 20 Pa), and rooms (n=8) aged = 13 years (5.85 ±2.15 at 20 Pa). The infiltration resistances, calculated using standard sea level infiltration rates, indicated that the curtain, fan, and other infiltration areas of swine finishing rooms changes with barn layout, age, construction material, and pressure difference. Methodology to convert measured infiltration rates to standard sea level weather conditions and to any desired room location was included. Keywords: Infiltration, Swine finishing Barns, Swine finishing rooms, Infiltration prediction, Infiltration quantification, Ventilation.

Corn is the primary feed grain in the U.S., and it accounts for more than 90 percent of total feed grain production and use. Besides this, corn is the primary input for the U.S. ethanol industry. This results in tremendous infrastructure for handling and storage of corn and byproducts throughout the year. The flow properties of ground corn, which is a principal ingredient of animal feed, are very complex in nature. Many physical and chemical properties viz. angle of repose, bulk density, moisture of the product, protein content in the surface layer, etc. affects the flow properties of corn and its products. Flow through a hopper is a typical example of complex flow. Bridging or caking of feed material in feed hoppers are common problems, and many times blocks the flow completely leaving animals without feed. Daily changes in temperature and relative humidity affect the equilibrium moisture content of feed. Size of corn particles affect angle of repose, bulk density and cohesive forces between particles, and thus flow characteristics of the feed. In this study, flow characteristics of ground corn were examined as functions of particle size and moisture content. Feed utilization was historically maximum (i.e. minimum ratio of feed consumption to weight gain), when mean particle size diameter is about 822 microns for roller milled corn flour. In recent times, livestock producers have found that feed efficiency can increase as particle size decreases. Furthermore, excess moisture makes flour sticky and hampers free sliding of particles over each other during flow. Keeping this in view, different combinations of particle sizes and product moisture content were studied with the objectives of understanding and enhancing corn flour flowability.

Infiltration is an integral part of the ventilation system and process. Infiltration affects the quality of the barn environment and can also increase the winter heating cost. Precise data on infiltration is very important in the design of ventilation systems for animal barns. Many researchers have suggested that ASHRAE's 'crack' method is not suitable for predicting infiltration of animal barns. Among the available methods, pressurization methods are commonly used in infiltration quantification and the power law model gives the best prediction of the infiltration rate. For this research project, 18 swine finishing rooms and three swine gestation rooms were tested for their infiltration characteristics. At 20 Pa pressure difference across the room envelope, the average as-is leakage rate for the 18 swine finishing rooms was 6.43±1.68 ACH; whereas, the average leakage rates through curtains, fans and other components were 1.47±0.71 ACH (about 23% of as-is), 1.63±0.77 ACH (about 25% of as-is) and 3.33±1.23 ACH (about 52% of as-is), respectively. Of the three "filtered" sow barns that were monitored where air tightness is very important to prevent entry of viruses like PRRV, the more conventional designed facilities, where filters are only added to the ceiling attic inlets, were not very tight (roughly 2 ACH). A much tighter barn, with an infiltration value of 0.1 ACH, was obtained in a specially designed large sow building where the filters were built into the ends of the building and an extensive amount of foam sealant was used.

The greenhouse technology can be a key for sustainable crop production and to achieve food security in the regions facing the problems of food scarcity. It gives assured crop production and also increases the productivity. But, the high initial cost is one the biggest concern in the adoption of the technology by the farmers. Over the period, many scientists and engineers helped to reduce the cost of the technology. In most of the cases, it is done by using alternate construction materials or by using innovative environmental control technology. A comprehensive review of low-cost greenhouse technologies is taken in the article. Also, the economic analysis of some of the greenhouse production operations from different parts of the worlds are summarized along with their environmental impacts.

Abstract. Data collected on 17 swine finishing rooms from the Midwest region of the United States was used to study the relationship between infiltration rate and selected room characteristics. Effect of individual room characteristics on room infiltration rate were tested by simple linear regression (SLR) while multiple linear regression (MLR) was used to develop models for improved prediction. SLR results revealed that the total (It) and other (Io; non-curtain/fan locations) swine finishing room infiltration rates were inversely related to room width and directly related to room length and ceiling height. As expected, rooms with higher curtain end pocket overlap, curtain closure overlap distance, and in excellent condition had reduced curtain infiltration (Ic). To reduce fan infiltration (If), fan and pump-out cover perimeter and fan area should be minimized. Power law equations fitted for groups of rooms were found ineffective in accounting for the large variability in infiltration rates of swine finishing rooms as compared to MLR models. MLR models developed for It and Io prediction at 10, 20, and 30 Pa pressure differences were found to improve the prediction over power law models for groups of rooms. At 20 Pa, prediction differences compared with individual room measurements for It rate using the suggested MLR model, as compared to power law models for groups of rooms, were less by at least 61%; whereas, in the case of Io rate, prediction differences compared with individual room measurements were less by at least 49%. Recommendations made in this article, with respect to the relationship between a particular room characteristic and room infiltration rate, could be used as guiding principles along with other design criterion to reduce infiltration rates in remodeled and new swine finishing rooms. Keywords: Infiltration, Swine finishing rooms, Ventilation.