Cooker hood extractor vent – how best to exit the house

[kitkat88]

We've got two options to terminate our cooker hood's extractor vent, the rest of the vent is horizontal after the cooker hood.

either…
(1) vent pipe goes upwards OR
(2) vent pipe goes downwards.

Given that it's hot steam and fumes, I would guess upwards, but I wanted to double check. Thanks in advance.

 

[DiyNutJob]

Going up would be more efficient. Heated air naturally goes up. It can be hotter than you expect.