Is dynamic wall insulation the way to have ‘magic walls’ in your house?
Does dynamic insulation really work? There have been a few innovations emerging for better building performance over the last few years and months as building regulations tighten and we all seek cheaper and easier ways to meeting them. They include multi-foil insulations, super-coated glazing, and plug-in micro wind turbines.
Dynamic insulation is one that has been puzzling me for a while and here’s why.
This is a technology that draws fresh air into a building through the insulation “recovering heat that would otherwise escape from the building”. Not sure about this.
Two things worry me:
- The insulation across a wall thickness is supposed to work by keeping the external air separated from the cold outside. If you draw outside air through it, what you have done is brought the cold air into the wall structure – sort of halving the thickness of insulation?
- Secondly, moving air is far more effective at extracting heat from things. This is why we like a cooling breeze in summer or get freezing cold going for a walk in windy weather in the winter. So, my basic assessment says if you blow air through a building’s wall you will take more heat away than if you let it naturally convect away from the outside (for those physicists reading this, isn’t it something to do with Prandtl or Nusselt numbers?). What this would mean is that you cool the building down more if you use dynamic insulation than if you use conventional insulation and a separate ventilation system?
Am I missing something? Has anyone actually tested this concept side-by-side with an identical building using static insulation? I’d love to hear from you.
