Back to the point , when I sat my city and guilds 1973, when they meant something, we calculater heat losses in a house using 3 air changes per hour for "health and comfort conditions". In the house that I rent out that has black mould problems I doubt if it has 3 air changes a week unless she farts then that probably would be a wet one and she smells like it ! she is a fat slob who drinks gallons of full fat coke with vodka and southern comfort thrown in, eats pizza and fast food junk I can see this by looking in the re cycling bins , I told her about ventilation and even removed the closers on the trickle vents but she just taped over them, she is a total slob got a better car than me , a tv set which stretches across an entire wall and has the eating habits of a rat and struggles to pay the rent.
So don't blame the property