A Practical Guide to LED Filament Bulbs in Period Homes

Why LED filament bulbs work in older houses

If you live in a Victorian terrace, an Edwardian villa or a 1930s semi, you'll know the feeling: the original cornicing, the picture rails and the panelled doors all deserve better than a cold, plasticky light source. For years the choice was between incandescent bulbs that looked right and used a lot of electricity, or early LED replacements that saved energy but looked clinical.

LED filament bulbs changed that. Instead of a single bright diode hidden inside a plastic housing, these bulbs use a row of tiny diodes mounted on a glass stem and coated in phosphor, so the light appears to come from a glowing wire — much like the carbon and tungsten filaments that lit these rooms a century ago. They use roughly 80 to 90 per cent less energy than the incandescent bulbs they replace, last far longer, and the better ones are dimmable. The catch is that not all of them are equal, and a few checks before you buy will save a lot of disappointment.

Colour temperature: the single most important number

Colour temperature is measured in Kelvin, and it is the thing most people get wrong. Traditional incandescent bulbs ran at around 2700K, while the older carbon filament lamps were warmer still — roughly 2200K. If you want a sitting room to feel like a sitting room, stay between 2200K and 2700K.

2700K is the safe middle ground: warm, faintly golden, close to an old 60W bulb. 2200K is noticeably amber, almost candle-like. It looks lovely in a hallway or dining room with dark wood and brass fittings, but it can make a pale grey or blue scheme look muddy. Anything above 3000K is best avoided in a period interior — bulbs sold as "daylight" at 4000K or 5000K will flatten a room full of original features into something resembling a showroom.

Also look for the colour rendering index, or CRI. Aim for 90 or above. Cheap bulbs at CRI 80 tend to make fabrics, timber and deep paint colours read slightly grey and lifeless.

Dimming: where most people come unstuck

Old dimmer switches were designed for resistive loads — a 60W filament bulb drawing a heavy current. An LED filament bulb might draw 4W to 6W. The dimmer simply cannot see it properly.

• Trailing-edge dimmers are what you want. Older leading-edge dimmers often cause buzzing, flicker, or a cramped dimming range where the bulb jumps from off to full brightness.
• Minimum load matters. Many dimmers need 20W or more. Three 4W bulbs on one switch is only 12W, below the threshold, and the result is flicker.
• Buy dimmable bulbs explicitly. Non-dimmable filament bulbs will flicker, hum or fail early if dimmed.
• Check the dimming range. Good dimmable bulbs go down to 5 or 10 per cent. Poor ones stop at around 30 per cent, which is not much use in a dining room.

On two-way circuits — a hallway with switches at both ends, for instance — test a single bulb before committing to a full set.

Base types and fittings in older properties

British homes use a mix, and older houses are rarely consistent from room to room. Check before ordering.

• B22 bayonet cap — the standard push-and-twist fitting, common in older British pendants and ceiling roses.
• E27 Edison screw — the larger screw fitting, found on many imported and modern fixtures as well as older wall lights.
• E14 small screw — chandeliers, candelabra arms and small wall sconces.
• B15 small bayonet — often in older decorative fittings and picture lights.
• E12 and E10 — rarer, usually confined to very old or miniature fittings.

Physical size matters as much as the base. A 130mm decorative globe will not fit inside a shallow glass bowl shade, and an oversized tubular bulb looks magnificent in an open pendant but disappears inside a drum shade.

Getting the look right in a period interior

Clear glass with a visible filament suits open fittings: pendants without shades, wall brackets, cage lights and exposed ceiling roses. Frosted or opal versions are better behind a shade or in a lamp with a fabric drum, where the filament would only look like a scribble through the cloth.

Useful shapes to know: the classic candle, ideal for chandeliers; the golf ball, good for small pendants and bedside lamps; the globe, suited to bathroom mirrors and open ceiling fittings; and the oversized tubular or squirrel-cage, which sits beautifully in industrial and Edwardian settings.

One practical point: filament LEDs run far cooler than incandescent bulbs, but they still produce some heat at the base. Most are fine in enclosed shades, but check the manufacturer's guidance, as heat is the main thing that shortens their life.

A quick checklist before you buy

• Colour temperature between 2200K and 2700K for living spaces.
• CRI of 90 or higher.
• Dimmable if you have a dimmer, paired with a trailing-edge dimmer rated for low loads.
• Correct base: B22, E27, E14 or B15.
• Physical size fits your shade, pendant and ceiling height.
• Buy one first, fit it, and look at it in the evening before ordering a full set.

Get those details right and a period home will feel exactly as it should: warm, layered, and lit by something that looks as though it has always been there.