LED Bulb Payback: A Room-by-Room Savings Worksheet

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LED payback depends on five inputs: the old bulb’s wattage, the replacement bulb’s wattage, daily operating hours, the delivered electricity rate, and the total retrofit cost. A claim that a whole-house swap saved a precise amount in a precise number of months needs receipts and circuit or usage records; GreenChoice does not have those records for this article.

The worksheet below lets readers calculate the result for their own fixtures.

Step 1: inventory fixtures by room

Record each lamp type separately. Do not assume every “60-watt equivalent” bulb has the same light output.

Room or fixture	Count	Old watts	LED watts	Lumens	Hours/day	Dimmable?
Example A19 fixture	1	60	8	800	3	No
Example BR30 recessed can	1	65	9	750	4	Yes
Example MR16 track head	1	50	6	500	2	Yes

The example rows illustrate the calculation only; they are not GreenChoice household measurements.

Step 2: calculate annual savings

annual kWh saved per bulb
= (old watts - LED watts) × hours per day × 365 ÷ 1,000

annual dollar savings
= annual kWh saved × delivered electricity rate

simple payback in months
= total retrofit cost ÷ annual dollar savings × 12

For the example 60-watt-to-8-watt swap used three hours per day, annual energy reduction is about 57 kWh. At $0.18/kWh, that is about $10 per year before considering HVAC interaction. Substitute actual usage and the full utility rate shown on the bill.

Include new dimmers, adapters, or fixtures in retrofit cost. Excluding them makes the payback look shorter than it is.

Match lumens before comparing watts

Watts measure power; lumens measure light output. Start with the desired light level and then compare wattage among bulbs that deliver similar lumens.

Typical replacement targets printed on many packages include:

Traditional bulb class	Common LED light-output target
40W incandescent equivalent	about 450 lumens
60W incandescent equivalent	about 800 lumens
75W incandescent equivalent	about 1,100 lumens
100W incandescent equivalent	about 1,600 lumens

Packaging claims still need to be checked against the Lighting Facts label or manufacturer specification.

Check efficacy, CRI, and R9

Lumens per watt (lm/W) is useful for comparing bulbs with similar light quality. Divide rated lumens by rated watts. A higher result means more light output per watt.

Color Rendering Index (CRI) describes how accurately colors appear under the light compared with a reference source. High CRI can matter in kitchens, bathrooms, art areas, and living spaces. R9 is a separate saturated-red rendering value that some manufacturers publish; it can help when skin tones, food, or wood finishes matter.

No single efficacy cutoff works for every application. High-CRI, dim-to-warm, decorative, and color-tunable products may use more power than a basic fixed-white bulb while serving a different purpose.

Choose color temperature by function

2700K — warm appearance commonly used in bedrooms and living rooms.
3000K — warm-neutral appearance often used in kitchens and bathrooms.
3500K–4000K — neutral-to-cool appearance often used for task, utility, or garage lighting.

Keep color temperature consistent within a group of fixtures unless variation is intentional. For tunable products, the Department of Energy explains that output and controls can vary by tuning method; see DOE’s color-tunable LED guide.

Dimmer compatibility is a system question

An LED labeled “dimmable” may still flicker, buzz, drop out, or have a limited dimming range on an incompatible control. Before buying a roomful of bulbs:

identify the dimmer model;
check the dimmer manufacturer’s compatible-bulb list;
check the bulb maker’s tested controls;
test one bulb across the full dimming range; and
confirm the fixture’s minimum and maximum load.

For a control upgrade, compare a Lutron Caseta LED dimmer or starter kit with the existing wiring and load. Search Amazon · Starter kit

Bulb lines to compare

GE Reveal A19 — a high-color-quality consumer line; verify lumens, CRI, CCT, enclosure rating, and dimmer compatibility for the exact SKU. Search Amazon
Cree BR30 — compare beam angle, lumen output, wet/damp rating, enclosure rating, and trim compatibility for recessed fixtures. Search Amazon

These are comparison starting points, not products GreenChoice has documented as owning or testing.

Smart bulb or smart switch?

Question	Smart bulb	Smart switch
Color or tunable white needed?	Often supported	Usually requires compatible bulbs or a separate system
Must wall control keep working normally?	Bulb loses connectivity if power is cut	Usually yes
Multiple bulbs on one circuit?	Each bulb adds cost and standby load	One control may operate the group
Rental or no wiring changes?	Often easier	May require installation and a neutral wire

Check standby power on the actual product rather than applying an unsupported value to the whole category.

Enclosed and recessed fixtures

LED electronics are sensitive to heat. Use bulbs explicitly rated for fully enclosed fixtures when the fixture is enclosed. For recessed cans, confirm the bulb or retrofit module is compatible with the housing, trim, insulation-contact rating, and local electrical requirements.

A dedicated recessed retrofit kit can be cleaner than mixing an old can, an adapter, and a bulb not designed for that thermal environment. Search Amazon

Verify savings after installation

The most defensible check is a fixture inventory plus actual operating hours. A circuit monitor such as the Emporia Vue 3 can provide additional data when the lighting circuit can be isolated, but a whole-circuit change should not be attributed entirely to bulbs if other loads share it. Search Amazon

Record the purchase date, SKU, receipt, rated life, and warranty. That creates the dated evidence needed to evaluate early failures and real payback later.