I wish to rent a parking space. The agency indicates that in case of termination, I must give three months' notice. If I am transferred for work, can I claim a reduction of this period?

No. The rental of a parking space does not fall under the provisions of Article 15 of the July 6, 1989, law on residential leases. You must therefore respect the three-month period provided in your lease unless it includes a clause for reducing notice in the event of a job transfer.