Good ventilation is essential for the health and well-being of both a building and its occupants. Efficient space heating requires a building to be airtight. Controlled ventilation is essential. Could a responsive Decentralised Mechanical Ventilation with Heat Recovery (d-MVHR) be a quicker|cheaper|better whole-house solution?
An interesting thing that I was made aware of recently, is that the natural gas piped into our homes produces a surprising amount of water vapour when it combusts.
With modern boilers, this is not a problem since they are well sealed and vented via flues to the outside. However, where there are gas fires, gas hobs or gas ovens, these might contribute to the total amount of moisture in the house, thus raising the humidity & potential for condensation.