The report contains basic onformation which is considered necessary for advisors in public service and in private companies. Since completenss cannot be achieved in this matter the recommendations or statements in the report are the responsibility of the author(s) of each of the 8 chapters.
The report was prsented at the 11th CIGR Congress in Dublin 1989. the report is published by
and can be ordered from:
The Centre for Climatization of Animal Houses (IWONL)
Faculty of Agriculturals Sciences
State University of Gent
B-9000 GENT (Belgium).
Content of the second Report, 1989/1992 - 2nd and revised edition
The aim of the work for the Second Report was to cover the more practical aspects of climatization systems in livestock buildings. The work was carried out between 1984 and 1992. Chairman of the group of 1 l countries was Dr K Sällwik, Sweden and scretary was Dr. ir. J P A Christiaens, Belgium.
The report contains basic information which is conidered necessary for advisors in public service an in private companies. Since completeness cannot be achieved in this matter the recommendations or statements in the report are the responsibility of the author(s) of each of the 8 chapters.
Modelling the heat balance of pigs at animal and housing levels
E N J van Ouwerkerek, The Netherlands
Based on a computerised model of the heat balance of pigs and ventilation, different thermal factors in the environment can be evaluated with regard to animal comfort and well-being. The critical temperatures are given particular examination.
Moisture production and correction factors for sinsible heat
S Pedersen, Denmark
In the First Report it was mentioned that the equation giving the proportion between sensible and latent heat as a function of temperature was not accurate for all species and temperatures. A table with provisional correction factors for the sensible heat loss was therefore introduced. The corrction factor varied between 1.0 to 0.8 depending on application to cattle or pigs, dry or wet feed and floor type. Basic research on animal heat balance shows it is necessary tot ake into account production level (e. g. feed energy intake) and the physical laws for heat transfer in- and outside the animal when estimating the proportion between latent and sensible heat dissipation. It is suggested that the original CIGR equation should be adjusted with a term containing the lower critical temperature for the actual animal and its production level.
Design of ventilation systems
K Sällvik, Sweden
H. Bartussek, Austria (Calculation of natural ventilation)
A brief review of main aspects for consideration when designing a ventilation system:
A comparison between under-, over- and neutral-pressure systems concluded that:
- during winter either equal- or under-pressure-system is the best system
- during summer equal or over pressure should be preferred getting higher air velocities inside
to relief animal from heat stress and/or to ensure air distribution when windows or doors are
Incoming air may be characterzied by physical properties such as air velocity and temperature profile in the jet. Equations can be used to describe these factors as well as the jet projection and the comfort paramters at animal level.
Air inlets and fans are discussed form the aspects of the relationship between floq and pressure drop and also by their influences on the thermal invionment. Air inlets in particular are examined and characterised according to their effect on recirculating inside air and air inlet velocity. Entrance velocities below 0.2 M/s (i.e. porous ceiling) having no influence on air movements in the barn. Special attention is given to how to design and locate outlets to avoid or diminish contamination of the interior air by manure gases. A calculation method for exhausting ducts for manure gas exhausting are presented.
For natural ventilation both theoretical and practical expressions are presented for stack effect (winter) and wind effect (summer). An example is given for an insulated barn for 200 fattening pigs resulting in inlet area = outlet area = 12.3 m2.
Minimum ventilation problems in confined animal rooms
H Lilleng, Norway
The consequences of too high a minimum ventilation rate are analysed as are the causes i.e. leakages through an non-airtight construction reinforced by wind and thermal buoyancy, and air infiltration. The importance of installing adequate sizes of fan and using an appropriate control method ist pointed out.
Energy recovery in animal houses
M Rist, Switzerland
Different types of air to air heat exchangers are analysed with respect to different types of efficiency e.g. enthalpy and temperature. The energy efficiency will remain constant at 34% while the temperature effectiveness will decrease by increased air flow, assuming constant delta T. Increasing the temperature difference will increase heating capacity: however, freezing will occur as soon as outside temperature ist below -10 C For a heat pump, the coefficient of performance, COP, is presented for a winter period.
Cooling in animal houses
U Chiappini, Italy & J P A Christiaens, Belgium
The thermal requirements for different animals are reviewed. Means of cooling in livestock buildings are presented e.g. evaporative cooling, cooling air in underground pipes and cooling by showers.
Ventilation and heating control in animal houses
Italy & J P A Christiaens, Belgium
The theoretical considerations regarding characteristics of the house and the control equipment (e.g. proportional, three point and controls for heating especially floor heating) as discussed.
Dust and gases
S Pedersen, Denmark
Practical methods for measuring dust and gases are reviewed. The filter method for dust and
the detection tube for gases are still used the most. Results from dust measurements in
- Pig houses, farrowing: 1.4 - 1.8 mg/m3
- Pig houses, finishing: 0.8 - 10 mg/m3
- Houses for laying hens, battery: 1.5 mg/m3
- Houses for laying hens, floor housing: 6 - 40 mg/m3
Practical methods for reduction of indoor dust are reviewed and some results give: Ionisation: depending of cocentration of ions and fraction of the dust, gives 10% and 30% reduction of total and respirable dust respectively.
Electrofilter: the air flow through the filter should be equal or greater than the air flow by ventilation to get a reasonable dust reduction.
Oil spraying: gives a reduction to 10 - 50%; the most effective method.
Information on the influence of dust and gases on the health of both animals and humans and the CIGR recommendations for maximum gas concentrations are given. Notably, the prevalence of asthma and bronchities is doubled for pig farmers as compared to dairy farmers.
Results from ammonia measurements in different countries:
- Pig houses, farrowing: 6-40 ppm
- Pig houses, finishing: 2 - 50 ppm
- Houses for laying hens: 1 - 50 ppm
- Houses for cattle: 0 - 25 ppm