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Balance of power in the piggery

by 5m Editor
3 August 2006, at 10:26am

UK - Does a 1kW kettle use less power than a 2kW kettle? Yes, but it takes twice as long to boil so the power consumption, and cost, is the same in each case.

Nick Bird, director of Berkshire-based farm energy and control specialists, Farmex, uses this example to advise pig producers to be wary of energy-saving claims for ventilation systems which simply rely on lower power rating and not greater efficiency.

"With fans working hard on many pig units at this time of year, many farmers think that lower power means smaller bills. Very often, however, lower power simply means systems work less well," he said.

To prove this point, Farmex as part of a two-year energy-monitoring project part-funded by BPEX, used its Dicam monitoring system to measure fan power consumption in two identical and equally-stocked second-stage rearing rooms in Shropshire. These housed pigs from 20 kg to 40 kg for a month in early summer.

Both automatically-regulated rooms had a set temperature of 20°C but Room A had a 530 watt fan motor while Room B had a 385 watt fan. Room A achieved an average temperature of 21.7°C using 65 per cent of maximum power, on average. Room B achieved a slightly poorer 22.4°C, but used 89 per cent of maximum power on average. Daily power consumption averaged 8.2 kWh in both cases, despite the fan in Room A having a more powerful motor.

"It's easy to assume that fans with a lower power rating will use less power overall, if only because they can't use any more power, but the lower-power fan has to run faster for more of the time to regulate the temperature which, in this case, it did slightly less well," commented Nick Bird.

ThePigSite News Desk

5m Editor