High Quality Content by WIKIPEDIA articles! Dynamic insulation is a form of insulation where cool outside air flowing through the thermal insulation in the envelope of a building will pick up heat from the insulation fibres. Buildings can be designed to exploit this to reduce the transmission heat loss (U-value) and to provide pre-warmed, draft free air to interior spaces. This is known as dynamic insulation since the U-value is no longer constant for a given wall or roof construction but varies with the speed of the air flowing through the insulation. Dynamic insulation is different from breathing walls. The positive aspects of dynamic insulation need to be weighed against the more conventional approach to building design which is to create an airtight envelope and provide appropriate ventilation using either natural ventilation or mechanical ventilation with heat recovery. The air-tight approach to building envelope design, unlike dynamic insulation, results in a building envelope...