Short answer is yes, they are.
An open fire is of course the traditional way to burn logs and can be attractive and cosy. It is however, a very inefficient method of heating as the uncontrolled air flow takes not only the hot air from the fire up the chimney, but also draws centrally heated air in from the rest of the house as well. This is replaced with cold, outdoor air drawn in to the house through drafts and vents.
Often an open fire will run at very low efficiencies (≈25%) resulting in large amounts of smoke and ash for very little useful heat output. It is also worth remembering that when an open fire is not in use then the chimney can allow large amounts of cold air into the room (products are available to close off a chimney when not in use). So an open fire may well be increasing other heating costs.
Open fires need a solid base to retain an ash bed in the smallest practical fire base. A coal grate is not suitable for wood, the best solution to this is to cover it with a metal base plate. All open fires need a fine mesh spark guard.
Did you know you can watch videos on YouTube of open fires? Here’s one for you to enjoy that lasts three hours – toasty!