There is no need to disable dynamically emitted light by switching materials or using renderables using the Drag[en]gine. The Physically Based Rendering uses high defninition range rendering. If your emitted light has an intensity of 1 or less while the object stands in the sun with over 10 intensity all around the emitted light is not going to contribute much to the illumination of the scene which is consistent with the real world. If your materials shines at night just add an emissivity texture and forget about the rest. It will just work.

This texture property is also used for holographic materials, ghosts or other objects where typically transparency effects are used in other game engines. Transparency effects are though physically wrong for these materials. Furthermore transparency is slower than emission. In the Drag[en]gine you have to use a physically correct way to define these materials. You have to set the solidity texture property to 0. This turns the material fully invisible not rendering it at all while still emitting light.