With the air temperature at -18F this morning, even I will admit it is cold out there. This past week I have had several calls and conversations with pig owners and growers on what can be done to tighten up curtain sided finishers. Several specifically asked about what can be done to help with the propane bill during placement in wean-finish curtain sided facilities in weather such as we’re experiencing in Minnesota this week.
One caller this week said their propane costs were averaging higher than $8 per pig placed in single stocked, 1200-head curtain sided rooms. This compares to an average LP bill of $0.50 per cwt of gain for all of 2007 for wean-finish facilities in a data set that I have access to. This amounts to $1.25 per pig. Even accounting for minimal propane usage during a summer fill and an increase in propane price over 2007, $8 per pig is a number that must be addressed.
In the next few months, I will be speaking at several state pork producer trade shows on the topic of ‘Managing Your Energy Expense’. In preparing for these presentations, the number one cause of higher than normal propane expense on the sites that I visit is management of the ventilation system. This includes how many fans are running when in minimum ventilation and the controller settings associated with minimum ventilation and furnace operation.
In addition to making corrections to ventilation controller settings, many producers are also considering temporary methods to tighten up their facilities to minimize the effects of wind on heat loss. A common method that many are using is to install ‘bubble-wrap’ between the bird netting and the north curtain. While ‘bubble-wrap’ has minimal insulation value, it does reduce many of the air leaks common to curtains, including end pocket leaks, and any small pin-holes that occur as curtains age.
When using materials such as ‘bubble-wrap’ or even just 6-mil plastic, keep in mind that you can make a facility too tight. If the emergency system in case of a power failure for the facility is magnetic curtain drops, there must be enough opening after tightening the facility that these can function. It’s helpful to remember that with a facility full of market weight pigs, in the event of a power outage, you’ve got less than 30 minutes to have emergency ventilation operating or death losses occur due to the rapid heat buildup in the facility. With growing pigs and in nurseries, you’ve got less than 1 hour before heat buildup begins to cause death loss.
Why such a short response time? It’s because rapidly growing pigs produce a large amount of heat. Published studies suggest that 200 pound pigs produce over 800 Btu/hr. Of this, approximately 600-650 Btu are sensible heat (air temperature) and the remainder is latent heat (moisture added to the air). Thus, a 1200 head room full of market weight hogs generates approximately 800,000 Btu/hr of sensible heat. This is more heat that 3 250,000Btu furnaces operating continuously.
If you use ‘bubble-wrap’, I recommend that with small pigs in the facility, you can close up the north curtain fairly tight, as long as the south curtain can drop at least 1-2 ft for emergency heat relief. With big pigs in the facility, you need to have at least 2 ft of drop available along the south side, or one foot on both the north and south. Anything less than this and you are at risk of loosing pigs.