Illustration: Mr Cuddington
The effect doesn't stack with itself. You don't get half of half price if you play two copies of Renovation at once. This is because each one gives a discount based on the marked coin price, which is the number printed on the blue price tag on the card.
If you play two copies, you simply have two different ways to get half price.
The same goes for other effects that give half price. You can have multiple ways of accessing half price builds, through different abilities such as Building Contractor, but they can't be combined together.
The half-price discount only applies to cards that are priced in coins. Prices marked in Alien Influence or any other currency are not reduced.
You can use Renovation on any of your closed attractions, no matter how they came to be closed, whether it be through the event itself, another event played by a competitor, a City event card, etc. The pin symbol and the wording makes Renovation an enduring effect throughout the entire round. Whenever you build an upgrade, if the attraction is closed, you can build on it for half the marked coin price.