Indoor Air Temperature and Ventilation in Uninsulated Loose Housing Cowsheds with Different Types of Non-transparent Roofing in Hot Summer
¹ Tartu College, Tallinn University of Technology,
78 Puiestee Srt., EE51008 Tartu, Estonia, e-mail: aime.ruus@ttu.ee
² Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life
Sciences, 62 Kreutzwaldi Str., EE51014 Tartu, Estonia; e-mail: vaino.poikalainen@emu.ee
³ Plant Production Research, MTT Agrifood Research Finland
MTT, Vakolantie 55, FIN03400, Vihti, Finland; e-mail: kwame@mappi.helsinki.fi
⁴ Department of Agrotechnology, University of Helsinki,
Koetilantie 3, FIN00014 Helsinki, Finland; e-mail: Jukka.Ahokas@helsinki.fi
Abstract:
As the indoor temperature of uninsulated cowsheds is in correlation with outdoor temperature, it may happen that indoor temperatures in cowsheds soar in hot summer. Roof temperature and spatial distribution of indoor air temperature at 1m (cow level) was studied in 8 uninsulated cowsheds with three different types of roof – non-asbestos cement sheets (4 cowsheds), metal (2 cowsheds) and insulated with 25 mm mineral wool plate (2 cowsheds) at outdoor air temperatures 26.8…32.0°C in at least 25 points of the cowshed. All openings were open in the cowsheds.
Roof (indoor surface) temperature values of 47.1°C were recorded as highest at non-asbestos cement roof in outdoor air temperature of 30°C. The average indoor surface temperature of the insulated roof (28°C) was about as high as outdoor air temperature (29°C).
Average indoor temperature in cowsheds varied 27.6-29.7°C. Smallest indoor-outdoor air temperature difference (t) was 0.8°C and occurred at lowest outdoor temperature (26.8°C). The biggest t of -2.3°C occurred at highest outdoor temperature (32°C). If the roof was insulated, t varied -0.5-1.1°C. In four cowsheds with non-asbestos cement sheet roof, t of 0.8…-1.9°C was recorded. In cowsheds with metal sheet roof, t of – 1.2… -2.3°C was recorded.
Standard deviation of indoor temperatures at the measurement points s (describes the ventilation efficiency) was s=0.59…0.84 in the cowsheds with insulated roof and s=0.46…0.66 in the uninsulated ones. The ventilation in cowsheds was good and air moving schemes uniform.
As a result of the investigation, the following conclusion can be made: indoor air temperature and ventilation efficiency in hot summer days are not influenced by roof material (non-transparent) or the presence of insulation.
Key words:
air temperature, summer, uninsulated cowshed, ventilation