As previously mentioned, these self illuminated objects had their physical properties set to: not to receive or cast shadows;not visible to the camera and not visible to reflection/refraction.
For interior shots, depending on the camera angle or/and camera shader (i.e. Wraparound(lume)); it may prove to be troublesome; if this is the case, avoid using this technique. If your interior scene requires too many physical photometric lights, try to be "economic" with their settings. By that I meant disabling the "shadows" function of some of the less relevant lights in the scene.
The trick is to achieve the same result with decreased rendering times.
Shadows cast by physical lights often contribute a great deal for the final rendering times.
To compensate for the depth in the scene, use the ambient occlusion on diffuse toggle of all objects.
I hope you have found this post useful.
New Book: 3D Photorealistic Rendering: Interiors & Exteriors with V-Ray and 3ds Max
More tips and Tricks:
Tips & tricks for architectural Visualisation: Part 1
Essential tips & tricks for VRay & mental ray
Creating Customised IES lights
Creating a velvet/suede material