How Energy-Efficient Lighting Saves Money and the Environment

Lighting is about 10 percent of a typical American household's electricity, and it is the one part of that bill that can be cut by three quarters without anyone in the house changing how they live. The case is usually made with a percentage. It is more persuasive, and more useful, to make it with the actual numbers for an actual house, and then to be honest about what the environmental side of it is worth.

The household arithmetic

A lamp costs what it draws multiplied by how long it runs. Take a house with 30 fixtures, a mix of 60 watt incandescent lamps in decorative fixtures and 50 watt halogen downlights, on for an average of three hours a day. That is around 1,650 watts running about 1,100 hours a year, or 1,800 kilowatt hours. Replace every source with an LED of the same light output, 8 to 9 watts each, and the load drops to around 260 watts and 285 kilowatt hours.

At 16 cents per kilowatt hour, the US residential average, the saving is about $240 a year. It recurs for the life of the fixtures, which on a good LED is 50,000 hours, or roughly 45 years at three hours a day. Even allowing that nobody keeps a fixture for 45 years, it is the cheapest long-term saving available in a house, and it starts the day the lamps are changed.

The lamp changes are the second saving. Thirty incandescent lamps at 1,000 hours each and three hours a day means about 33 lamp changes a year across the house. The same fixtures on LED means none for decades. Multiply a $4 lamp and ten minutes on a ladder by 33 and it is a real number, and in a house with a tall stairwell it is a real inconvenience.

The environmental arithmetic

The 1,500 kilowatt hours saved in the example above did not come from nowhere. On the current US grid, generating a kilowatt hour emits roughly 0.4 kilograms of carbon dioxide on average, less in the Pacific Northwest and more in the coal states. So the household saving is about 600 kilograms of carbon dioxide a year, which is roughly what a car emits over 1,500 miles. It is not enormous on its own. Across the roughly 130 million households in the country it is the output of several power stations, which is why the federal efficiency standards that phased out incandescent lamps in 2023 were worth the argument.

There is a materials side as well. A compact fluorescent lamp contains a few milligrams of mercury and has to be recycled as hazardous waste, which most were not. An LED contains none. It is an electronic component with a small circuit board and a heat sink, and it goes to electronics recycling, but it can be handled without gloves and it does not release anything if it breaks. And a fixture that lasts 50,000 hours instead of 1,000 is 50 fewer lamps manufactured, shipped and discarded.

The saving that only counts if the light is good

None of this holds if the LED gets replaced in two years because the room looks wrong. Early LEDs did look wrong, blue and flat, and a lot of them were taken out again. The cure is to specify color quality alongside efficiency. 2700K or 3000K for a residential interior, so the light is the color of the incandescent it replaced. 90 CRI as the floor and 95 or better where there is timber, stone or fabric, so the room's colors survive the change. And a dimmer that matches the driver, so the lamp does not flicker at low levels and get pulled out in irritation.

A fixture that does all three costs more than a bargain lamp. The saving in the example above pays for the difference in the first year or two, and the fixture is still in the ceiling long after the cheap one would have been replaced twice.

Beyond the lamp: where the rest of the saving is

• Dimmers. An LED at 50 percent draws close to 50 percent of the power, unlike an incandescent, which stayed inefficient as it dimmed. Most evening use in a house is at half level or below, so a dimmed LED scheme saves well beyond the headline figure.
• Occupancy sensors in the rooms nobody remembers to switch off: the garage, the laundry, the pantry, the walk-in closet.
• Timers or an astronomical clock on exterior lighting, so it comes on at dusk and off at a set hour rather than at dawn.
• Daylight. The cheapest light is the light through the window. Furniture arranged so the desk faces the window, blinds that diffuse rather than block, and a light-colored wall opposite the glass all reduce how long the fixtures are on.
• Doing the high-use rooms first. Kitchen, living room and the corridor to the bedrooms run the most hours. Convert those and most of the saving is banked before the guest room is touched.

Labels and what they mean

ENERGY STAR is a certification for lamps and fixtures that meet efficiency, color and lifetime thresholds set by the EPA, and some utilities offer small rebates on labeled products. It is a reasonable floor for consumer lamps. For architectural fixtures the useful figures are on the spec sheet: lumens per watt for efficacy, the L70 lifetime in hours, and the CRI and R9. A fixture at 100 lumens per watt with a 50,000 hour L70 rating and 95 CRI is a better buy than a labeled lamp that scrapes the threshold on each.

Putting it together

The order that works on a house: replace the sources in the rooms that run the longest hours, choose the color temperature and CRI so nobody wants to change them back, put dimmers on the main layers, and add sensors where lights get left on. The electricity saving arrives on the next bill. The lamp changes stop. The carbon saving is modest per house and large in aggregate. And the house looks better than it did, which is the part that makes the change stick.

Our fixtures run at up to 97 CRI in 2700K through 4000K, carry a five year warranty, and come with drivers matched to TRIAC, 0-10V, DALI-2 or Casambi control. Send us the fixture list from the house as it is and we will show the comparison against our range, with the light levels calculated so the new scheme is as bright as it needs to be and no brighter.