By challenging traditional views industry might consider a wider perspective when it comes to our sources of data also. Looking at mean monthly ambient temperatures, say, is a ready source of data (from the meteorologists), but doesn't necessarily reflect conditions as experienced by pigs in controlled environment housing.

One such non-traditional source of data is illustrated here - taken from electricity data gathered for the Farmex/BPEX energy monitoring project.

In this case, the energy used by fans (from a limited sample of environmentally regulated grower and finisher rooms) has been converted to ventilation rate per pig place (using standard fan characteristics).

Measuring ventilation rates by electricity use is a simple and relatively low cost way to do it. Whilst it only gives a very general broad-brush picture it is, perhaps, no more generalised in its way than relying on monthly average outside temperature.

It does, at least, reflect to some degree the aerial environment in fan ventilated buildings, which outside temperature as such does not. Clearly, a larger sample of farms and buildings would giver a wider perspective of the industry as a whole.

Interestingly, the range of ventilation is not as great as might be supposed. July 2006 was somewhat exceptional as the very high temperatures meant that most fans ran at full speed most of the time.

Otherwise, the mean monthly ventilation rates varied by a factor 2 or 3 to 1. As with Nadis health reporting, this is the first full year, and longer term recording may give a better year on year impression.