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Heating - Solar air heater - Pig - building / Canada
Case study assignment
An agricultural enterprise requires you to conduct a feasibility study for a possible solar air heating system. This client owns and operates several swine operations and plans to build two new piggeries for the first growing phase known as pig weaning or nurseries.
Nurseries must be continuously vented with fresh air to maintain an indoor air quality respecting industrial agriculture standards. Poor ventilation practices result in high levels of relative humidity and ammonia which then introduce major animal health problems and significant production losses for the operator.
Solar air heating panels, with a non-glazed perforated absorbing surface, are suggested to reduce heating costs. This type of installation is gaining popularity among agricultural enterprises.
The operator is asking you to calculate the payback period of a solar air heating system when compared to a conventional ventilation system. The operator requires a maximum payback period of 8 years.
Site information
The nursery will be built in the region just east of Montreal, Quebec, Canada. Each one of the two buildings has a South face offering 952 ft². Each building requires a minimum ventilation rate of 6,300 cubic feet per minute (cfm). Exceeding this minimum flow rate improves the indoor air quality, as long as the fans can meet the requirements. Heating will be supplied by means of high efficiency propane gas burners with a seasonal heating efficiency of about 85%. Each building offers a floor area of 5,568 ft². The optimum indoor air temperature is 72 °F, but this temperature can vary from 67 to 77 °F. The walls and roof are insulated and have R values of 12 and 20 ft²-°F/(Btu/h), respectively (imperial units). The calculations must be based on the nine coldest months. As for the building orientation, the South wall carrying the solar collectors is off by 20° from noon azimuth. The solar collectors will be black in colour. Both buildings can be modeled as one combined building to help simplify the analysis.
Financial information
The maintenance and operational costs of solar collectors are nil. Propane costs about $0.45/L. For this project, a normal inflation rate (including fuel cost) is in the range of 2.5%. The enterprise expects to self-finance the project. Although subsidies are available to help pay part of the installation cost, you are asked not to consider these in your feasibility study.
Prepare a RETScreen study, documenting any assumptions that you are required to make, and report on the significant conclusions from this analysis.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
Results
In 2004, the MEMO farm asked SOLAG inc. to conduct a feasibility study pertaining to the installation of 1,900 square feet of the SolAgra solar collector on two of its buildings located in South Durham, Quebec, Canada.
For a swine operation, the nursery is likely one of the best applications for solar air heaters because the young pigs, weighing from 5 to 20 kg, are housed within the same building and require good air quality as well as a high temperature for their comfort and proper growth.
For the pig nursery, solar air heaters contribute clean heat which replaces that otherwise provided by the propane heaters. Besides this clean heat warming the incoming fresh air, solar air heaters also increase the rate of ventilation of the building, which has a direct positive impact on indoor air quality. Higher ventilation rates decrease the level of the relative humidity indoors. Subsequently, the piglet mortality rate is lower, the daily weight gain is higher, the incidence of diseases is reduced and the operation becomes more competitive economically.
System description
The solar collectors were black for maximum efficiency. The system has no heat storage capacity. In this pig nursery, more often than not ventilation air is drawn in through the solar collector, even at night, to benefit from the insulation effect and sometimes even during the summer when hogs are young.
Air preheated by the solar collectors is captured inside a duct within the attic space and is distributed through perforated ceilings in four chambers. The perforated ceilings allow even air distribution over the full ceiling surface.
The attic air duct has louvers which short circuit the solar collector air inlet when the outside air temperature exceeds that set for indoors.
Lessons learned
Solar air heaters offer significant opportunity for energy savings in virtually all farming operations in cool and cold climates, as well as crop drying around the world. Barns housing animals and mechanical and storage buildings are particularly suited for wall mounted solar air heaters because they generally have large windowless areas on all exposures.
Photo
Solar Collectors on an Agricultural Building, Quebec, Canada
References
Case study assignment
An agricultural enterprise requires you to conduct a feasibility study for a possible solar air heating system. This client owns and operates several swine operations and plans to build two new piggeries for the first growing phase known as pig weaning or nurseries.
Nurseries must be continuously vented with fresh air to maintain an indoor air quality respecting industrial agriculture standards. Poor ventilation practices result in high levels of relative humidity and ammonia which then introduce major animal health problems and significant production losses for the operator.
Solar air heating panels, with a non-glazed perforated absorbing surface, are suggested to reduce heating costs. This type of installation is gaining popularity among agricultural enterprises.
The operator is asking you to calculate the payback period of a solar air heating system when compared to a conventional ventilation system. The operator requires a maximum payback period of 8 years.
Site information
The nursery will be built in the region just east of Montreal, Quebec, Canada. Each one of the two buildings has a South face offering 952 ft². Each building requires a minimum ventilation rate of 6,300 cubic feet per minute (cfm). Exceeding this minimum flow rate improves the indoor air quality, as long as the fans can meet the requirements. Heating will be supplied by means of high efficiency propane gas burners with a seasonal heating efficiency of about 85%. Each building offers a floor area of 5,568 ft². The optimum indoor air temperature is 72 °F, but this temperature can vary from 67 to 77 °F. The walls and roof are insulated and have R values of 12 and 20 ft²-°F/(Btu/h), respectively (imperial units). The calculations must be based on the nine coldest months. As for the building orientation, the South wall carrying the solar collectors is off by 20° from noon azimuth. The solar collectors will be black in colour. Both buildings can be modeled as one combined building to help simplify the analysis.
Financial information
The maintenance and operational costs of solar collectors are nil. Propane costs about $0.45/L. For this project, a normal inflation rate (including fuel cost) is in the range of 2.5%. The enterprise expects to self-finance the project. Although subsidies are available to help pay part of the installation cost, you are asked not to consider these in your feasibility study.
Prepare a RETScreen study, documenting any assumptions that you are required to make, and report on the significant conclusions from this analysis.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
- Considering that the buildings were to be built in any case, some equipment is required, such as fans, controls, ducts and louvers, no matter which ventilation system is chosen.
- The nursery needs some heating during the summer, but only part of the time. Furthermore, the nursery is regularly emptied and cleaned between batches of piglets, and no heating is required during this time. This explains why space heating is required only during the 9 coldest months of the year.
- The costs associated with the two buildings are computed in the same simulation, because some of the costs are doubled such as the material costs, while other costs are not, such as that of the system design and the feasibility study.
Results
In 2004, the MEMO farm asked SOLAG inc. to conduct a feasibility study pertaining to the installation of 1,900 square feet of the SolAgra solar collector on two of its buildings located in South Durham, Quebec, Canada.
For a swine operation, the nursery is likely one of the best applications for solar air heaters because the young pigs, weighing from 5 to 20 kg, are housed within the same building and require good air quality as well as a high temperature for their comfort and proper growth.
For the pig nursery, solar air heaters contribute clean heat which replaces that otherwise provided by the propane heaters. Besides this clean heat warming the incoming fresh air, solar air heaters also increase the rate of ventilation of the building, which has a direct positive impact on indoor air quality. Higher ventilation rates decrease the level of the relative humidity indoors. Subsequently, the piglet mortality rate is lower, the daily weight gain is higher, the incidence of diseases is reduced and the operation becomes more competitive economically.
System description
The solar collectors were black for maximum efficiency. The system has no heat storage capacity. In this pig nursery, more often than not ventilation air is drawn in through the solar collector, even at night, to benefit from the insulation effect and sometimes even during the summer when hogs are young.
Air preheated by the solar collectors is captured inside a duct within the attic space and is distributed through perforated ceilings in four chambers. The perforated ceilings allow even air distribution over the full ceiling surface.
The attic air duct has louvers which short circuit the solar collector air inlet when the outside air temperature exceeds that set for indoors.
Lessons learned
- With solar air heaters, indoor air quality improves animal growth rate and feed efficiency, thus lowering production costs.
- Better air quality means healthier animals and lower veterinary costs.
- By reducing fossil fuel costs and therefore greenhouse gas production, solar air heaters can have a beneficial impact on the environment
Solar air heaters offer significant opportunity for energy savings in virtually all farming operations in cool and cold climates, as well as crop drying around the world. Barns housing animals and mechanical and storage buildings are particularly suited for wall mounted solar air heaters because they generally have large windowless areas on all exposures.
Photo
Solar Collectors on an Agricultural Building, Quebec, Canada
References
- Savaria, Réal, "Personal Communication," SOLAG Inc., 2007.
