Good quality loft mounted units normally incorporate a heat recovery function to introduce more heat into the home when the loft is warm during the winter months. Heat recovery functions are normally either "Fixed Temperature Heat Recovery" which adjusts the flow rate of the unit to suit the loft temperature; or "Intelligent Heat Recovery" which adjusts the flow rate to suit the loft temperature and the way the home is heated. The latter type is particularly good in terms of energy efficiency. These systems are highly effective but do require proper application and installation for optimum performance. Units incorporating low watt motor technology (Low Energy Positive Input Ventilation Units) can provide a significant net energy gain to the home. These units are therefore very energy efficient, even when compared to natural ventilation systems such as Passive Stack Ventilation. Air is drawn in though the loft and is pumped into the landing of your house where it dilutes moist air and therefore reduces humidity levels and alleviates condensation dampness and mould growth Vent-Axia is a leader in low carbon ventilation with its innovative Lo-Carbon PoziDry PIV system which has gained prestigious accreditation from the British Board of Agrément (BBA) A mark of quality, safety and reliability BBA certification ultimately provides reassurance that a product is fit for purpose. BBA certification is awarded only to products and systems that have passed a series of comprehensive assessments – including laboratory tests, on-site evaluations, quality management checks and inspections of production. BBA certificates provide information that designers and specifiers can use to give them unbiased data on product performance, and certified products are recognised as fit for purpose by building control, government