Sucking Blowing ventilation - very confused

[idun]

Recently there have been adverts which show outside air being sucked into loft spaces to ventilate UK homes, and I do not get why anyone would want more cold air coming into a home.

Surely to ventilate, air being taken out, via a VMC, keeps the house ventilated and warm and also one can have this air warm air cleaned and put back into the house anyway.

When only cold comes in, into the loft space winter, how does that do other than cool a home down??????????

Does anyone know, and if so, can explain very simply to this lady of little brain, thankyou

[Théière]

Without a link to the exact item difficult to say. The roof space need to be vented to prevent rot etc but only so far, not the whole loft space just the bit between the breather membrane and the tiles if its a warm roof or under the eaves as well if its a cold roof where the insulation is between the joists above the ceiling if you follow me????

[Chancer]

I amdoing something similar for my own particular reasons which may be the same reason they are proposing it, in any case their claims are probably no more than hypothetical and pure marketting.

 

When I built/converted my own flat I used plain bac_acier roofing sheets over the kitchen and bathroom and tole bac-acier isolé over the lounge and bedroom, during the autumn i found that the uninsulated roofing sheets were running with condensation, it was dripping everywhere just as my newly converted outbuilding is doing at the moment, I knew that it would soak the laine de verre underneath, corrode the ceiling metalwork and maybe soak the placo as the drips were all channeled to the lowest point.

 

Aside from doing a sprayed underseal treatment to empêcher  the condensation from running I used 2 spare entries to my VMC to ventilate the roofspace above the laine de verre, cold outside air enters from the bottom, circulates hopefully evaporating the condensation and is then exhausted together with the warmer air from inside my baraque which had its own massive damp problems, all have been eliminated by the VMC, I have had a roof sheet off before to change the capacitor on the VMC and the insulation was dry and all the metalwork uncorroded.