Fireplace screens were born of necessity to keep sparks from flying out into the room. However, they can also serve a decorative purpose. They come in so many shapes, sizes, and designs, that you can make them a feature of the fireplace whether or not you need them or even use them functionally.
Wood burning fireplaces should cover the entire opening and may require a folding version to be effective. Aim to get a fireplace screen that is 3-4 inches taller and 10-12 inches wider than the fireplace opening. Gas fireplaces do not have to cover the entire fireplace so the size you choose should be compared against the size of your entire fireplace (surround and mantel) to ensure it is balanced.
Fireplace screens do block a small amount of heat. However, that may not be a concern if your fireplace is a big heat producer, as most wood-burning and gas fireplaces are. If they also protect your space from flying sparks, the tradeoff is worth it to increase the safety of your fireplace.
