It is concluded that the method of

It is concluded that the method of intermittent
measurements allows an important reduction of the
number of required measuring days to determine the
yearly NH3 emission from livestock buildings.
With this method, the required length of the measuring
period could be reduced considerably by using the
data of variables that are easily measured in mechanically
ventilated structures, namely ventilation rate and
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Emission, g h_1
Fig. 3. Measured (}) and predicted (}) ammonia emission over 1 month
INTERMITTENT MEASUREMENTS TO DETERMINE AMMONIA EMISSION 355
animal weight on this specific farm. The data from the
selected days were used to calculate a statistical model
relating the NH3 emission to these variables for this
specific manager and building. This model was used
in a next step to predict the total NH3 emission over a
whole year. This procedure of intermittent measurements
allowed the use of accurate, expensive and
labour-intensive equipment to be used on about 10
times more locations or installations compared to
the traditional measuring methods and limits the
required measuring days for expensive emission measurement
to 8.
An additional conclusion was that selection criteria
increased the accuracy of the predictions. The error in
this specific farm and for this manager was found to be
less than 3% when 8 days were selected throughout the
year on condition that 4 days were selected in the same
growth period and 4 other days were spread over at least
two other growth periods in that year. It is proposed
that all researchers who have yearly dynamic emissions