Division 4.2 Techniques for efficient use of energy

This takes into account animal welfare requirements (e.g. concentration of air pollutants, appropriate temperatures), and can be obtained through several measures:

• automation and minimisation of the air flow, while maintaining thermal comfort zone for the animals;

• fans with the lowest possible specific power consumption;

• flow resistance is kept as low as possible;

• frequency converters and electronically commutated motors;

• energy-saving fans controlled according to the CO₂ concentration in the housing;

• correct distribution of heating/cooling and ventilation equipment, temperature sensors and separate heated areas.

Insulation material can be naturally impermeable or provided with an impermeable coating. Permeable materials are provided with a vapour barrier installed, as humidity is a major cause of insulation material deterioration.

A variant of insulation material for poultry farms can be heat-reflecting membranes, consisting of laminated plastic foils to seal off housing from air leakage and humidity.

More energy-efficient lighting can be attained by:

1. i..

   Replacing conventional tungsten light bulbs or other low efficiency light bulbs with more energy-efficient lights such as fluorescent, sodium, and LED lights;

2. ii..

   Using devices to adjust the frequency of micro flashes, dimmers to adjust artificial lighting, sensors or room entry switches to control the lighting;

3. iii..

   Allowing more natural light to enter, e.g. by using vents or roof windows. Natural light has to be balanced with potential heat losses;

4. iv..

   Applying lighting schemes, using a variable lighting period.

Use of heat exchangers. One of the following systems may be used:

• air-air;

• air-water;

• air-ground.

In an air-air heat exchanger, the incoming air absorbs heat from the exhaust air from the plant. It can be composed of plates of anodised aluminium or PVC tubes.

In the air-water heat exchanger, water flows through aluminium fins located in the exhaust ducts and absorbs heat from the exhausted air.

In the air-ground heat exchanger, fresh air is circulated through buried pipes (e.g. at a depth of about 2 metres) taking advantage of the low seasonal temperature variation of soil.

Heat is absorbed from various media (water, slurry, ground, air, etc.) and transferred to another location, via a fluid circulated in a sealed circuit using the reverse refrigeration cycle principle. The heat can be used to produce sanitised water or to feed a heating system or a cooling system.

The technique can absorb heat from various circuits, such as slurry cooling systems, geothermal energy, scrubbing water, slurry biological treatment reactors, or biogas engine exhaust gases.

A closed water circuit is installed below the floor and another is built at a deeper level for storing the excess heat or to return it to the poultry house when needed. A heat pump connects the two water circuits.

At the beginning of the rearing period, the floor is heated with the stored heat in order to keep the litter dry by avoiding moisture condensation; during the second rearing cycle, birds produce an excess of heat that is preserved in the storing circuit while cooling down the floor which reduces the breakdown of uric acid by reducing microbial activity.