Commercial ovens have large, thick floors to them, so there is a large volume of material to gain and hold heat. As a result, commercial ovens are relatively unaffected by the baker opening and closing the oven door; there is just so much thermal mass that the loss of a bit of hot air doesn’t matter.
How can a home baker hope to compete with the commercial oven? There are several ways.
1. The home baker can buy a round pizza stone. These are usually not more than 12-14 inches / 30-35 cm in diameter and about half an inch / 13 mm thick. They hold the temperature and give the home baker a good, hot surface to place dough on. The down side is that they can crack and they will get crudded up with baked-on oil, tomato sauce, and the like. They also have a fairly small baking surface.
2. The home baker can also buy a ceramic insert for the oven. These look like small boxes made out of tiles. They fit inside the oven and replicate the results of a commercial oven. They work pretty well, but they are very expensive at around $150-200. They aren’t all that big, either.
Finally, the home baker can go to a hardware store and buy some cheap red quarry tiles. These are 1/4 inch / 6 mm thick and 6 x 6 inches / 15 x 15 cm. He should also have a few of these cut in half. These tiles cost about 45 cents each, and it will take about eight to cover the wire rack in the oven. If you need more thermal mass, just buy twice as many and double the layer. If — when — they get badly stained and crudded up, just trash them and get some more. If the discoloration doesn’t bother you, you can use them forever.
Here are two pictures of tiles, one showing how they cover my oven rack and the other showing two nice clean tiles on either side of a well-used half tile.