When you look for advice, you often find wildly impractical schemes about remaking your entire life to reduce your „carbon footprint.” Or you end up having to sort through heaps of perplexing statistics about power usage and efficiency. Meanwhile, it can be tough to track down what most people actually need: a clear statement of the carbon consequences of, say, switching your light bulbs. And you’ll rarely find out if you’ll save enough on your energy bills to recover the cost of buying new appliances or changing your habits.

From 1990 through 2004, energy demand among 26 industrialized nations that furnish data to the International Energy Agency grew 14%. About half the increased demand was met through increased energy supplies and half through energy efficiency. Efficiency gains fell by half versus the period from 1973 through 1990, and the European Union now is trying to pick the pace up again.
Here are some answers to commonly posed questions about what to do – and what not to do – to get greener.

What are the simplest – and cheapest – things I can do to cut emissions?
„You can go crazy and get lost in the details and completely miss the point that every little bit helps,” says Carl Zichella, regional director in Sacramento, Calif., for the Sierra Club. Here are just a handful of things that may be obvious – and yet so many people don’t do them. Heat or cool your home less. Drive or fly fewer miles. Run electrical equipment less and use less water since pumping water uses a lot of electricity.

Buy more locally grown foods and goods that are manufactured nearby; they’re typically made with cleaner US manufacturing processes, and companies use less fuel to transport them. Plus, buy the most energy-efficient devices you can afford. In the US, look for appliances with the Environmental Protection Agency’s Energy Star label. In Europe, look for refrigerators or freezers with A+ or A++ ratings. The A-G ratings system was launched in 1994 and EU participants had until 2004 to meet the labeling obligations.

Some people may be confused by the fact there are two rating systems in use in Europe, depending on the product. Household products mostly have the A-G ratings but the most energy-efficient pieces of office equipment carry the Energy Star designation. Energy Star labeling has helped North Americans save $14 billion (€9.7 billion) on energy bills and cut emissions equivalent to taking 25 million vehicles off the road. Energy Star labeling appears on nearly 50 products in the US and Canada, everything from DVD players to light bulbs to air conditioners.

I’d like to start small. How much energy can you really save with light bulbs?
A lot. A 25-watt compact fluorescent produces about as much light as a 100-watt conventional bulb but uses only one-quarter of the electricity. Because of that, the US EPA estimates that the average 25-watt compact fluorescent will save the equivalent of 100 pounds of carbon dioxide per year. That’s about as much as a car generates driving 93 miles (150 kilometers), assuming it gets a typical 23.9 miles per gallon. Some governments are moving aggressively against conventional incandescent lighting. In the UK, for example, energy-efficient bulbs are expected to save five million tons of carbon dioxide a year by 2012, equivalent to the output of a one-gigawatt coal-fired power station. Household penetration rates of CFLs are above 50% in the majority of EU nations.

It seems like my refrigerator is a big energy hog, but it’s such a costly item to replace. When does it make sense to buy a new one?
First, let’s clear up a misperception. Compared with temperature-control systems, refrigerators don’t use that much electricity. In the US, they account for only 5% to 6% of an average household’s electricity use, behind items such as lighting (10%) and water heating (13%) and home heating and air conditioning (49%). In the EU-15, the top four residential uses are space heating, at about 20%, refrigeration at about 15%, lighting and water heating.

With that in mind, here’s a rough guide to replacing your fridge: If your unit was manufactured before 1993, it’s probably time to make the move. Today’s Energy Star models are twice as efficient as the average older unit, according to the EPA, and will make up for their higher initial cost within five years. In places where energy costs are high, they may completely pay for themselves in energy savings within 10 years. In Europe, look for units carrying the A, A+ or A++ designations, signifying they are especially energy efficient.

The A-class appliances are a significant part of the market, amounting to 71% of sales in the Netherlands, which offers special incentives, but falling to about 36% in Spain. An A++ unit uses about 200 kilowatt hours of electricity a year, 45% less power than a Class-A unit and 60% less than a Class-B unit. The amount of benefit to the environment depends on a nation’s energy mix. Nations with a lot of coal-fired power plants have higher carbon-dioxide emissions per kilowatt-hour of power consumed than nations like France or Norway that rely more heavily on nuclear power or hydroelectricity.

How much energy can I save by turning down my thermostat on winter nights?
A rule of thumb is that a two-degree reduction in the temperature setting on your furnace cuts energy use by 1%, according to the EPA. Moreover, houses that are well sealed and insulated, including heat ducts, use less energy because the furnace doesn’t have to run as hard. E.ON AG, the big German utility, is encouraging customers at its two US utilities in Kentucky, a big coal-burning state, to turn the house thermostat down two degrees in winter and up two degrees in the summer, which it says will reduce a household’s CO2 emissions by 3,200 pounds annually and will save $98 annually.

I drive a gas hog but I can’t afford a hybrid. Any other options I should consider?
If you want to cut emissions from your car, the simplest way is to drive less and walk or use public transportation, when you can. If a new car is warranted, look for one with better fuel economy – even small steps are meaningful. The average car sold in Europe puts out 160 grams of carbon dioxide per kilometer, based on automaker data analyzed by the European Federation for Transport and Environment, a Brussels-based environmental group. European automakers have agreed to reduce emissions to 140 grams per kilometer by 2008, as a new-car fleetwide average.

However, a general trend toward heavier, more powerful vehicles in Europe, as in the US, has made it unlikely the goal will be met. Hybrid sales are expected to be 0.3% of total sales in Europe this year versus about 1.5% to 2% of sales in the US Diesel engines are more popular in Europe than in the US They typically emit 10% less carbon dioxide than gasoline engines, but put out other harmful substances like soot. Whereas the US is focused on electric vehicles, Europe has focused on making diesels cleaner and more fuel efficient. The US will get more highly efficient European diesels in the next two years or so. For interesting and useful information on fuel economy and appliance efficiency in Europe, go to a site operated by the nonprofit group, TopTen International Group.

Does recycling household waste cut emissions?
Recycling reduces landfill gas generated by decaying matter and cuts down the industrial energy needed to manufacture new products. Recycling aluminum cans, for example, cuts the energy needed to make new cans by 95%. In the US, a four-person household that recycles all its newsprint, aluminum, steel, plastic and glass could cut its greenhouse-gas emissions from solid waste by 41% to 2,384 pounds from 4,072 pounds, according to the EPA calculator.

For comparison, that saving is nearly 10% of an average household’s carbon-dioxide emissions in a year, excluding transportation. In Europe, an estimated 67% of waste winds up in landfills, something the European Union is tackling with programs to encourage waste prevention, recycling, reuse and controlled incineration – methods it prefers over putting materials in permanent dumps. The EU bans certain types of waste, such as tires, and has set targets for reducing quantities of biodegradable rubbish.

Is it better to drive 500 miles or fly 500 miles?
Often, it’s better to fly than drive. The average US commercial flight in 2005 emitted 0.59 pound of carbon dioxide per passenger flying one mile, according to federal statistics, whereas the average US passenger vehicle emitted 0.93 pound per mile. In other words, a person flying 500 miles is responsible for 295 pounds of carbon versus 465 pounds driving, assuming the standard benchmark of 23.9 miles per gallon. But there are a couple of factors to consider.

The airline emission statistic is an industrywide calculation based on all flights and miles traveled, while the car statistic doesn’t take into account the number of people in a vehicle. So a full car could produce less carbon per capita. For instance, with four people in the car, emissions per person drop to about a quarter of a pound per mile, according to the EPA. Moreover, flights don’t get people to their final destinations. So you have to figure airline passengers will likely do some driving to reach or leave the airport – taking away a bit more of air travel’s emissions advantage.

We’ve become such a throw-away society. How do you fight it?
The EPA says solid waste, per person in the US, has nearly doubled to 4.4 pounds a day from 2.7 pounds in the past 35 years. Although recycling is important, it isn’t as effective as reducing the use of materials from the get-go. One way to do this is to buy goods in concentrated, dry or bulk form to reduce transportation and packaging costs. Favor refillable or reusable items. Pick flexible packaging materials instead of rigid packaging, since flexible packaging typically takes less energy to make and transport. Pick goods with the highest ratio of product weight to packaging weight, when possible. Example: tuna in a foil pouch rather than in metal cans.

How many years does it take solar-power systems to pay for themselves?
In the US, a 4,000-watt solar-power system costs about $20,000 after a 30% federal tax credit and can meet about three-quarters of many family’s electricity needs. Here’s a general guideline: In states with hefty financial rebates, like California and New Jersey, the payback period is seven to 10 years. It may be twice as long in states without local incentives or in places where there’s less sunlight on photovoltaic panels.

Germany leads the world, followed by the US and Japan, for solar installations. In Germany, a 2004 rule guarantees payment of 45.7 European cents to 62.4 cents for each kilowatt hour of electricity put back on the grid. This means systems pay for themselves in a decade, in many cases. More than 750 megawatts of photovoltaic panels were installed in Germany in 2006. (Wall Street Journal)