Not sure of your actual query but you should be aware that AFAIA Spanish authorities look at holiday homes and deem them to have earned an income for you even though they are not rented out and tax you accordingly @ 25 %.
If you do decide to let the property then you have to declare the profit to the irish revenue and pay tax on the profit from rental income. You can offset any tax paid in spain against the tax due in ireland.
See [broken link removed] in general and example rent account and how foreign rents are taxed in particular