DIYbanter - View Single Post - Trickle vents: fitting after-market ones

wrote:
Consider instead, some form of passive stack or mechanical whole-house
ventilation

How much is this going to cost me?

It might be easiest if I just slept with the window open.

It is indeed. However the BCO will tell you that leaving windows open is
a security risk, and insist on some form of thiefproof ventilation at
ground floor level, and probably above it too.,

Bruce