If your client's fireplace does not work or they just don't use it, you can recommend design and style tips that can transform the often-ignored fixture. Laura Gaskill at Houzz looks at some popular design tips.
One suggestion can be for your clients to use the fireplace for shelving as pictured:
"If your fireplace never worked (and never will), there’s no reason to pretend otherwise. Put the interior space to work by installing shelves to store books or display a collection. For even more punch, brush on a few coats of saturated color, like the bright blue shown here."