| Buildings
Designing the internal environment for livestock buildings
Dr Martin Heywood , RIDBA Technical Consultant .
I 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 . This article considers some of the issues that should be addressed by building designers and farmers in order to improve the well-being of their livestock . 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
• Factors affecting the local wind speed including building location , altitude , shelter and proximity of other buildings .
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 ( normally below eaves height ), the location and size of the outlet vents ( normally at the ridge ) 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 , and can in some circumstances lead to corrosion of steel fasteners and fixings , 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 .
Image Courtesy of Glendale Engineering ( Milfield ) Limited
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 .
34 | Farming Monthly | September 2017 www . farmingmonthly . co . uk