Short answer. No, not without his consent. Article 667 forbids any part-owner to open through the party wall a window or aperture of any kind without the consent of the others. It covers vents, holes for pipes and openings for light as much as windows, and half the wall being yours does not help.
What the law says
No part-owner may, without the consent of the others, open through the party wall any window or aperture of any kind.
Civil Code, Article 667 — No Openings Without Consent. Read the full provision →
Why owning part of the wall changes nothing
A party wall is held in common, and the usual instinct — that you may do as you like with your own side — is exactly what the article rules out. Piercing the wall is not use of your half; it goes through to the other, and it affects a thing the two of you own together. That is why the prohibition is addressed to a part-owner specifically. The remedy for the neighbour is correspondingly simple: he can require the opening to be closed, and the wall restored, without having to prove that it harmed him.
"Of any kind" is meant literally
The article does not distinguish between an opening for a view and one for light or air, or between a large window and a small one. A vent, an exhaust duct, a hole cut for a pipe or a cable, an air-conditioning sleeve, a glass block panel — all of them are apertures through the party wall. Nor does it matter that the opening is high, frosted, grilled or positioned so that nobody could see through it. The question is whether the wall has been pierced, not whether the neighbour's privacy has actually suffered.
First establish that it really is a party wall
A great many of these disputes are actually about which wall it is. If the wall stands wholly on your own land and is yours alone, this article does not apply, and what governs instead are the rules on distances for windows and views near a boundary. If it is genuinely common, the prohibition bites. The distinction is decided by where the wall sits relative to the boundary, who built and paid for it, and how it has been treated — and it is settled by a survey and the building records, not by the assumption that a wall between two houses must be shared.
Get the consent in writing, before the work
Consent is the whole of the exception, so it is worth having in a form that survives a change of neighbour or a change of mind — a written agreement identifying the wall, the opening, its dimensions and position. Verbal permission and years of tolerated existence are weak ground, particularly where the property next door is later sold. If an opening is already there and you are the one objecting, photograph it, date it, and put your objection in writing, since silence is what the other side will rely on.