Efficient = achieving maximum productivity with minimum wasted effort or expense. This is hard to calculate as so many variables.
With a home with electric heating in winter it makes no difference what bulb is used, as we want the heat produced by the bulb, only in the summer will there be a waste.
With heating that is cheaper than electric then using a bulb to heat the room will cost, however by how much, and will the extra cost of a LED bulb mean worth changing? So B&M BN22d bulb 1521 lumen 12.5 watt at £8.99 a pair is a good start point. It may be equivalent to 90W tungsten but you could not buy a 90W so must be considered as replacing a 60W bulb.
Assuming using gas for heating then a tungsten bulb will use £7.27 of electric over it's life more than a LED. This is less than cost of LED bulb, however only valid if replacing new tungsten which is unlikely, and does not include to cost involved of changing the bulb. The cost of the physical act of replacing means likely cheaper to replace all bulbs in a house together, failed or not, as cheaper than the charge for calling out some one to change them twice.
With the cost of changing in mind, we over light rooms, if we double the light required in each room, then 50% of the lights can fail before we replace them. This may work with industrial premises, however unlikely to work with domestic.
However it does raise a question, who should replace a bulb in domestic premises? The BA22d-3
will make it hard to replace with non energy saving a 15W LED version will cost around £15 compared with £5 for standard fitting, it is the same with the GU10L1 when compared with standard GU10 to get an LED lamp with the dimple needed so it will fit in a GU10L1 holder is near double that to a standard GU10.
They were made to comply with building regulations, Part L1 not sure if still valid in England.
I found if one starts to look at health and safety and building regulations you can go crazy, if for example the light at top of stairs fails in this house, there is normally enough light coming in through the window to allow safe egress, however when my father-in-law stayed over Christmas he could not find the light switch, and he walked past the toilet, and turned left at stairs instead, which he then fell down, hind sight is easy, we should have not turned off the light. This was compounded when my daughter decided to take him to hospital, then there was the A&E wait.
The whole lighting setup needs a look at - I have some ideas on that, and they don't include pendant lamp
