Lighting advice

Warning: LED room lights can flicker

It's often claimed that LEDs don't flicker, but they do when connected to AC without a proper rectifier (see IEEE PAR1789). If you see "phantom array" effects (objects appear "dotted" when you move your gaze) you know your lights are flickering. Add in nystagmus and blindsight and you won't want the experience.

LEDs need a smoothing circuit (such as a large capacitor) to be flicker-free on AC. This circuit might not last as long as the LEDs, hence limiting the lifetime of LED bulbs with built-in smoothing circuits; many LED room lights don't have them. A dedicated LED installation with a switched-mode power supply should work, but if you need something for an ordinary lamp socket then beware.

CFL degredation (dimming)

The modern versions of "energy saving" CFL bulbs (with high-frequency electronic ballasts) give reasonably good light, but (like any phosphor-based device) they gradually dim due to phosphor degradation.

Dim CFLs might not be a problem if good task lighting is also available (but this is not always the case).
If bright light is important and task lighting is not available, then you could:
1. Replace the bulb before the end of its life
  - This is environmentally bad as they contain mercury (which also makes them unhealthy in an accident)
  - You might be able to move the dim bulb to another location where brightness is less important, if you have such a location.
2. Run several dim bulbs instead of one bright one (if you have the fittings)
  - This uses more power, which might or might not outweigh the cost and environmental impact of early replacement; it depends how often it saves a replacement.
3. Choose a bulb that is too bright to start with
  - Again this uses more power, see above
  - If you need to go beyond "100W equivalent", it could mean expensive horticultural lights.

In areas with high humidity and/or short running times (e.g. small kitchens or bathrooms), CFL electronics can cut out early. If this happens often enough to make CFLs uneconomical and unenvironmental (because you "get through them" too quickly) then see below.

Incandescents for humid rooms

If you experience CFLs cutting out very quickly in humid rooms, and you cannot control the humidity, you might be stuck with bulbs that do not include PCBs, which means either flickering non-rectified LEDs or hot power-hungry incandescents (switch off whenever possible).

(These notes assume the room does not have fluorescent tube fittings. If it does then you might have a problem: some high-frequency flicker-free electrical ballasts can take only 85% RH and only for 30-60 days/year; others are more tolerant, but many fittings try to be robust by using a magnetic ballast, which flickers at twice the mains frequency and might also flicker at the mains frequency if the tube's electrodes are bad.)

Clear xenon halogen bulbs (EU energy category B) were not included by the UK's 2009-2012 "phase-out" legislation or the EU's 2016 halogen ban.
- A B22 halogen (e.g. 42W for "60W equivalent") might be the best option for small kitchens that can't take CFLs, but check if it really is equivalent to 60W (i.e. 700 to 900 lumens; calling a 600-lumen bulb "60W" is dubious, and 42W for that is category C).
- While halogens don't save nearly as much as CFLs, a halogen upgrade should still pay for itself in less than an older bulb's lifetime, so anyone who has stockpiled older bulbs should be better off not using them and buying halogens.
Refrigerator and oven bulbs were also kept on by this legislation
- A clear 15W "Pygmy" refrigerator bulb can dimly light a small bathroom (if it's B22), but don't try this in a work area. (It might also be useful in small areas where a ceiling-level cupboard door collides with a pendant light due to inappropriate cable length.)

ESL unsuitable for UK use?

ESL bulbs use an unfocused electron beam on phosphor. As of 2011 it's difficult to find 240V ones, and they might turn out to be too heavy for the UK---a B22-to-E27 adapter won't overcome the effective weight limit of a Bayonet socket. Also Vu1 haven't yet explained how they've avoided X-rays in their unshielded bulbs (does their phosphor allow the use of lower-energy electrons?)

Task lighting

A fluorescent task light can be positioned closer to the work than an incandescent.
Some people put CFLs into old reading lamps (Anglepoise etc), but if the shade is not large enough to cover the CFL then it may glare (especially when positioned closely).
A purpose-designed fluorescent fixture is better, but some of them have ballasts that become annoyingly noisy later (and are also inefficient).