1821 - Damp air goes up the chimney

As it does so, cold outside air blows in, and cold air holds less damp.

A constant draught keeps a house's walls and windows dry,

but it also blows down the back of the occupants' necks.

The invention of cement, and increasing skill in bricklaying, means that Victorian houses are very airtight. They need special ventilation bricks.

But everyone blocks them up with bits of cardboard.

Boffins are rightly worried about the lack of fresh air.

Town gas and indoor bathrooms breed mildew.

Building regulations start to mandate ventilation.

The Oil Crisis begins. James Burke appears on BBC ‘Tomorrow’s World’.

The ‘car of the future’, he says, will have ‘sensors’ controlling its brakes, heating, and engine fuel injection system.

The Passivhaus principle 'Build Tight and Ventilate Right' means in practice that you need a whole house heat recovery ventilation system.

This brings unparelleled efficiency and comfort, but is not cheap.

And this 'cyberman' is impossible to retrofit into normal houses.

With WallConserve, bringing modern levels of comfort and efficiency to an old house with solid walls is no longer disruptive and risky.

Wallconserve uses no new ductwork. The wireless sensors spot trouble before it happens and control existing tech in a new way.