Hydor have developed a version of their renowned Agri-Jet specifically to address stringent noise emission legislation where installations are in proximity to residential buildings - the largest unit in the range emits just 47dBA at a distance of 3 metres.
Meeting the criteria of local planning authorities is becoming increasingly difficult as most standard fans produce similar levels of noise. During the day time hours of 7am -11pm, noise levels of 55dBA to 63dBA are generally permitted. At night between the hours of 11pm - 7am, when fewer fans are normally required thanks to lower external temperatures, this reduces to only 45dBA to 57dBA. When planning permission is being sought, even lower noise levels would be preferable and therefore more readily accepted by the relevant authorities.