LED bulbs are the most efficient lighting technology ever widely available. They use 80-90 percent less energy than incandescents, 50-60 percent less than halogens, and last 15-25 times longer than either. The financial payback is measured in months. The environmental impact is unambiguously positive.
Yet many apartments still contain a mix of older bulbs, halogens that were the default in 2010, or even incandescents that survived because the fitting was awkward to change. This article is about why and how to finish the LED transition, for owners and tenants alike.
The math, briefly
A standard incandescent bulb uses 60 watts. An equivalent LED uses 6-8 watts for the same brightness. Across 1,000 hours of use per year (a typical living-room lamp pattern), that’s 60 kWh vs. 6-8 kWh. At UK electricity prices, the saving is roughly £15 per bulb per year.
A halogen uses 40 watts; LED equivalent uses 5-6 watts. Saving: roughly £8 per bulb per year.
For a typical flat with 15-25 bulbs, full LED conversion saves £150-400 per year. The upfront cost is £30-100 depending on bulb count and quality. Payback period: 3-9 months. Lifetime savings: many hundreds to a few thousand pounds.
The bulb-buying basics
Modern LED bulbs are sold by lumens (brightness), watts (energy use), and colour temperature (Kelvin). The general guide:
- Lumens to replace standard bulbs:
- 40W incandescent ≈ 450 lumens.
- 60W incandescent ≈ 800 lumens.
- 75W incandescent ≈ 1100 lumens.
- 100W incandescent ≈ 1600 lumens.
- Colour temperature:
- 2700K = warm white (matches old incandescent feel; good for living rooms, bedrooms).
- 3000K = soft white (slightly cooler; good for hallways, kitchens).
- 4000K = cool white (bright, slightly clinical; good for task lighting, bathrooms).
- 5000K+ = daylight white (very cool; good for offices and workshops).
For most rooms, 2700K-3000K is the right choice. Avoid the 5000K “daylight” bulbs in living spaces, they look harsh and clinical.
Where to use which bulb
Room-by-room guidance:
- Living room: 2700K, dimmable bulbs in main fittings, lower-wattage in lamps for evening ambient lighting.
- Bedroom: 2700K, lower-wattage bulbs (40-60W equivalent) for restful lighting. Avoid bright cool light before sleep.
- Kitchen: 3000K-4000K for tasks (chopping, cooking); 2700K for ambient.
- Bathroom: 3000K-4000K, IP44 rated for moisture areas (near shower).
- Hallway: 3000K, lower-wattage (40W equivalent is usually enough).
- Home office: 4000K for the desk; 2700K elsewhere for ambient.
Dimmable bulbs
If your fittings have dimmer switches, you need dimmable LED bulbs. Standard LED bulbs in dimmable circuits will flicker or fail.
Two notes about dimmable LEDs:
- They cost slightly more than non-dimmable equivalents (£3-5 extra).
- They sometimes have compatibility issues with older dimmer switches. If a bulb flickers or won’t dim properly, the dimmer may need replacing with a modern LED-compatible model (£15-30, requires basic electrical work).
For tenants: you can replace dimmer switches with LED-compatible versions but should keep the original to reinstall when you move out.
The bulbs to avoid
Not all LED bulbs are equal:
- The cheapest supermarket bulbs. Often poor light quality, shorter life, and noticeable flicker. The savings versus quality brands aren’t worth it.
- “Smart” bulbs you won’t use. Wi-Fi or Bluetooth bulbs are useful only if you’ll actually use the connectivity. For most lamps, regular dimmable bulbs are simpler and last longer.
- RGB colour-changing bulbs in living spaces. Most people use white most of the time; the extra cost rarely justifies the occasional party use.
- Bulbs without proper energy ratings. EU energy labels are mandatory for compliant products; their absence usually indicates a non-compliant product.
The bulbs worth paying for
Quality LED brands (Philips, Osram, Soraa, IKEA’s mid-range) cost £4-10 per bulb but offer:
- 15,000-25,000 hour lifespan (vs. 5,000-10,000 for cheap brands).
- Better colour rendering (CRI 80+, vs. CRI 70 for cheap bulbs, the difference is visible).
- No noticeable flicker.
- Better dimming compatibility.
- Manufacturer warranty (2-5 years typical).
The per-bulb premium is small and the per-year cost is lower because the bulbs last longer.
Specialised fittings
Some apartment lighting situations require specific solutions:
- GU10 spotlights: common in kitchens and bathrooms. LED GU10s are widely available and easy to install.
- Halogen capsules (G4, G9): often in pendant lights and decorative fittings. LED equivalents now exist but check carefully for size and brightness match.
- Linear fluorescent tubes (T5, T8): sometimes in kitchens or basements. LED tube replacements work in most existing fittings but may need a bypass to skip the ballast.
- Integrated LED fittings: some modern fittings have LED chips built in rather than replaceable bulbs. Avoid these if possible, when the LED fails (eventually), the whole fitting needs replacing.
Disposal
LEDs contain electronics and small amounts of materials that shouldn’t go to landfill. Most large hardware stores (B&Q, Wickes) and supermarkets have collection points for old bulbs. Use them.
Old halogens and incandescents can go in general waste (no special materials). CFLs (compact fluorescents) contain small amounts of mercury and require special collection, never put in general waste.
Related: Winter Heating Savings: A Realistic Tenant’s Playbook
The tenant advantage
One of the underrated benefits of LED conversion for tenants: the bulbs are yours. When you move out, take them with you. Replace with the original cheaper bulbs (if you kept them) or leave the LEDs as a small upgrade for the landlord.
A box of 20 LED bulbs is around £40-60 and follows you flat-to-flat for the next decade.
Related: Energy Monitor Plugs: Worth the Investment?
The honest summary
The LED switch is one of the few sustainability interventions where the financial, environmental, and practical cases all align unambiguously in the same direction. Lower energy bills, lower carbon emissions, longer bulb life, better light quality, fewer ladder trips to change bulbs.
For most flats, the entire conversion takes a weekend afternoon and £30-100 in bulbs. The payback is measured in months. The bulbs follow you across moves. There is essentially no downside to completing the transition, and substantial reasons not to delay.
Related: Which Energy-Efficient Appliances Are Actually Worth the Upgrade?
How to put this into practice this week
The most reliable way to translate a guide like this into something that actually changes your week is to pick the single highest-use change in it and ignore everything else for the first fortnight. The rule is the same one that makes physical training work: load is fine, variety is fine, but the consistent application of a small number of well-chosen movements is what produces results. Sustainability follows the same logic. The dozen interesting interventions you have just read about will all matter at some point. The two you build into your routine first will matter the most.
If you genuinely cannot pick, default to the intervention with the strongest financial signal. Where money and impact line up, the habit forms easily because the reinforcement happens monthly on a bill rather than abstractly in the climate news. Once that habit is invisible, the next one is easier to add. Six months of one small habit at a time produces a meaningfully different household, and you will barely notice the transition while you live through it.
The energy math in one table
| Section | What the article covers |
|---|---|
| The math, briefly | A standard incandescent bulb uses 60 watts. |
| The bulb-buying basics | Modern LED bulbs are sold by lumens (brightness), watts (energy use), and colour temperature (Kelvin). |
| Where to use which bulb | Room-by-room guidance: |
| Dimmable bulbs | If your fittings have dimmer switches, you need dimmable LED bulbs. |
| The bulbs to avoid | Not all LED bulbs are equal: |
Sources and further reading
Frequently asked questions
Quality LED bulbs (Philips, Osram, IKEA mid-range) typically reach their rated lifespan, 15,000-25,000 hours, or 10-15 years of typical use. Cheap bulbs often fail at 3-5 years.
Usually a compatibility issue with the dimmer switch. Replacing the dimmer with an LED-compatible model (£15-30) almost always solves it.
Modern 2700K bulbs from quality brands match the colour temperature of incandescents closely. Cheap bulbs often look colder than their stated temperature suggests.
Replace immediately. Halogens use 5-8x more electricity than LED equivalents; the energy savings dramatically outweigh the cost of replacing working bulbs.
