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Energy Efficiencies - Strategies for Minimizing Utility Costs in the Barn

by 5m Editor
7 May 2007, at 12:00am

By Harry Huffman, Huffman Engineering and Ron MacDonald, Agviro Inc. This article is from a collection of the scientific papers presented at the 2006 London Swine Conference.

Abstract

This paper discusses the importance of maintaining both the desired environmental temperature for the pigs being housed as well as exchanging sufficient air to maintain good air quality for maximum pig performance. Equipment sizing and efficiencies are discussed as well as proper control of these devices. Additionally, various lighting options are discussed since this is another significant energy user in many swine enterprises. The paper concludes with comments regarding heat recovery, possible alternative fuels and renewable energy sources.

Introduction

Energy prices have escalated rapidly in the last few years. Natural gas has risen from as low as $0.80/GJ to $8.00/GJ, a ten-fold increase. No other segment of farm costs has risen as quickly. Energy may still be a small percentage of overall annual expenses, but it is an essential input. Wasting energy not only wastes money, it causes pollution in the form of greenhouse gas emissions, and it has also been shown that the quality of indoor air and overall swine barn environment can be lowered. As a result, it makes good sense to manage our energy resources wisely.

This paper focuses on the main consumers of energy in barns (Heating, Ventilation, Lighting) and energy efficient technologies.

Cost of Energy/ Contracting

Energy costs have risen very rapidly in the last few years, Natural gas has gone from as low as $0.11/m³ to about $0.42/m³ (February 2006). Electricity prices have risen from $0.08/kWh to $0.11 and further increases are already scheduled.

Contracting natural gas can be arranged for one through five years. Typically the longer time periods have been the best bet for saving money. Short term has not been as valuable as simply staying with the market prices so far.

For small farms, staying with the price cap is recommended in the electricity world.

To evaluate various pricing and contracts, the best way is to check out www.energyshop.com, an independent company that will provide energy pricing from all companies selling gas and electricity. As well, the Ag Energy cooperative at www.agenergy.coop has new long and short term deals worth looking at.

Heat Balance and Air Quality

The two main goals in every livestock room environment are to maintain the room temperature within the comfort zone of the animals being housed and to also exchange sufficient air to maintain good air quality for both the animals and the stockmen. During the three cooler seasons of the year, the amount of air exchange provided can affect the room temperature. If the animals are not able to provide sufficient heat energy to offset the building shell losses plus the heat loss with the ventilation air, then the room temperature will be lowered. Of course, the remedy is to add sufficient supplementary heat to make up the difference or balance the heat flow. Heat gains must equal the heat losses to maintain a consistent room temperature.

Let’s look at a 500 pig capacity nursery room as an example of typical heat gains and losses. Typically these rooms start the pigs off at a relatively warm room temperature in the range of 29 or 30C depending on the weaning weight and then slowly allow the room temperature to drop over the next 6 to 8 weeks to approximately 21 or 22C. Even though this room will be reasonably well insulated, it will lose heat energy through all of the walls, ceiling, floor and foundation. These shell losses will reduce as the room temperature is lowered. The other main heat loss is that which exits through the ventilation fan. Interestingly, this heat loss continues to get larger as the pigs grow even though the room temperature is being lowered. This is due to the fact that more ventilation is required as the pigs grow to maintain good air quality. Since the small pigs do not provide a lot of heat energy to offset (or balance) these heat losses, supplemental heat must be added to maintain the desired room environment. But; how much heat? Table 1 summarizes the heat energy flows for this example nursery room.



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