| Buildings
Farm building design and the well-being of livestock
RIDBA Technical Consultant, Dr Martin Heywood, looks into some of the key areas that should be addressed by
building designers and farmers to improve the well-being of their livestock.
t is essential that animal
housing provides a
comfortable, clean and dry
environment, free from hazards
and health risks. The design of
the building and specification of
the materials used to construct it play a major
role in achieving these aims and, if done
properly, can lead to healthier, happier and
more productive animals.
Ventilation
The provision of adequate ventilation is
arguably the most important consideration
when designing a new building for animal
housing. A distinction needs to be made
between a well ventilated building and a
draughty one. Nobody, human or animal, wants
to live in a draughty building that lets in cold air
whenever the wind blows, causing discomfort
and potentially ill health. On the other hand, a
regular supply of fresh air is essential to
replenish oxygen, remove exhaled carbon
dioxide and control temperature and humidity.
Correct ventilation will reduce relative humidity
and the risk of respiratory infections, eliminate
stagnant air and avoid unwanted draughts.
Factors to consider when designing a
building for ventilation include: the dimensions
of the building and layout of any internal
partitions; the proposed occupancy of the
building; and factors affecting the local wind
speed, including building location, altitude,
shelter and proximity of other buildings.
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Even at fairly modest wind speeds, the
ventilation of a typical livestock building will be
governed by the “wind effect”, meaning that
sufficient fresh air will be supplied naturally by
the wind. A building containing livestock must,
however, be adequately ventilated even on the
calmest of days, relying on what is known as
the “stack effect” (warm air rising replaced by
cooler air). The adequacy of stack effect
ventilation for a given building will depend on
the location and size of the inlets, the location
and size of the outlet vents and the heat
generated by the livestock. A detailed design
procedure for calculating stack effect ventilation
is given in the RIDBA Farm Buildings
Handbook.
Condensation
Condensation occurs on a surface when the
temperature falls below the dew point for a
given relative humidity. Condensation does not
cause high humidity, but may be a symptom of
it if the temperature is low enough. Although
condensation can be a nuisance if it results in
dripping water, it is high humidity (i.e. moisture
in the air) that causes health problems in
livestock. The focus for the building designer
should, therefore, be on reducing humidity
through good ventilation rather than hiding the
problem through the use of absorbent
materials.
Other considerations
Buildings used for housing livestock should
have adequate levels of lighting, provided by
natural or artificial means, or a combination of
the two. Natural daylight is normally provided
by in-plane rooflights, often arranged in bands
along the roof. Since rooflights allow direct
sunlight to enter the building, there is a risk of
overheating in summer if the percentage area
of rooflights is too great. It may be possible to
use a smaller area, and therefore reduce the
overheating risk, by specifying cladding with a
highly reflective coating on the inside. Surface
finishes should be smooth and without sharp
projections to avoid injury to animals or people.
Walls should have a washable inner surface
that can easily be hosed down and floors must
be non-slip.
Conclusions
With careful consideration at the design
stage, it is possible to create a healthy and
pleasant environment, with adequate fresh air,
and lighting, humidity and temperature levels
that are comfortable for the animals. Good
ventilation and careful specification of materials
are the most important factors.
August 2018 | Farming Monthly | 31