Replacing a bulb immediately — instead of waiting for an incandescent bulb to burn out — yields the biggest financial and environmental benefit, according to Keoleian.

Replacing all bulbs in a household would be the equivalent of removing roughly 5.3 million to 6.4 million cars from the road, according to an estimate from Katharine Hayhoe, chief scientist at the Nature Conservancy.

“The basic problem we have is often our default [choice] is not the best, and not necessarily the cheapest,” Hayhoe said. “It’s just the default.”

(As a practical note: Choose LEDs between 2700 and 3000 kelvins to match the soft, yellow-white light of old bulbs; 4000K to 6500K bulbs will have a cooler or bluish light, according to the Consumer Federation.)

Energy consumed by electronic devices in standby mode accounts for 5% to 10% of household energy use — adding up to an extra $100 a year, on average, according to the Center for Sustainable Systems.

The Center recommends unplugging devices when not in use or plugging them into a power strip and turning off the power strip.

Households can save up to 10% a year by turning the thermostat 7°F to 10°F from its normal setting for eight hours a day, according to the Energy Department.

Savings can total roughly $90 a year, according to Mel Hall-Crawford, director of energy programs at the Consumer Federation of America.

That’s the equivalent of the emissions from driving the average passenger car 80 miles, according to the Environmental Protection Agency.

Households can also consider using a drying rack instead of a drying machine, experts said. Drying is responsible for 71% of the electricity required to wash and dry a load of clothes, according to an estimate from the Sustainability Consortium.

Individuals can also ensure a dishwasher is full before running it, and even setting a timer in the shower to avoid overuse of hot water, experts said.

Replacing single-use plastic with reusable alternatives has become easier than ever for households, said Eberhardt of the Environmental Defense Fund.

Consumers can replace Ziploc bags with silicon bags; Saran wrap with beeswax wrap; plastic water bottles with reusable bottles or a water filter; and plastic straws for portable, reusable ones, experts said.

(The same applies for single-use, non-plastic items like paper towels — which come wrapped in plastic and could be replaced with dish towels or sponges.)

“You’re really cutting your weekly grocery costs and it’s better for the planet,” Eberhardt said.

More than 95% of plastic packaging is made from fossil fuels, Hocevar said.

And most isn’t recyclable — a commonly misunderstood fact about the plastic Americans toss in blue bins, he said. Even plastic that can be recycled is often only recycled once.

It’s then burned or put in a landfill, both of which contribute to the release of planet-warming gases, he said.

Buying non-perishable items in bulk is also generally cheaper and cuts down on plastic packaging, Hocevar added.

Those emissions may come from sources like food production, transportation and packaging. Cows, for example, generate a lot of methane, a greenhouse gas that’s much more potent than carbon.

Families can consider “meatless Mondays,” for example, to reduce their consumption of red meat, Eberhardt said.

About 1 in 4 Americans reported eating less meat (beef, pork or chicken) over the past year, according to a Gallup poll from early 2020. The environment was their No. 2 reason for doing so, behind health.

Trade groups representing farmers and beef producers — the American Association of Meat Processors, American Farm Bureau Federation, National Cattlemen’s Beef Association and North American Meat Institute — didn’t return CNBC’s requests for comment on this article.

Jerry Bohn, a Kansas cattleman and president of the National Cattlemen’s Beef Association, recently pushed back on the notion of decreased consumption of red meat for Americans.

“U.S. farmers and ranchers are the best in the world when it comes to producing safe, wholesome and sustainable high-quality beef for American families, and doing it with the smallest possible footprint and we’re committed to continuing on that path of improvement,” he said in April.

Families should also try reducing the amount of food they throw away, Eberhardt said.

About 30% to 40% of food produced in the U.S. isn’t consumed, with that waste largely on the consumer end — which then produces greenhouse gas as it decays, Eberhardt said. Her family creates a basic meal plan at beginning of every week to avoid buying excess food.