Tuesday January 15, 2013

Before the holidays I wrote a column on how to save energy in the home by changing our behavior. This week we’ll take a look at some of the ways that we can save energy by changing our driving behavior. Below are some simple measures -- most cost nothing and some even save money -- to reduce your energy use for transportation.

Drive less

Leaving the car at home when you could walk or ride a bike is perhaps the most obvious way to save energy in our transportation. These options aren’t always possible, due to where we live, the weather, or the seasons, but when it is possible to walk or bike instead of driving huge savings are possible -- not to mention the health benefits. The same applies at work; if you’re going out to lunch or need to run an errand, consider providing a little extra time and walking.

Carpool

Carpooling with another commuter can halve the energy consumption if the two riders live close by or one rider can be picked up on the drive to work. With three or more riders the savings are even greater. In some places carpooling offers advantages like access to HOV (high-occupancy vehicle) lanes on highways and preferential parking.

Combine trips

When you have to drive, try to combine trips. Schedule your grocery shopping when you’re coming home from work, or run some errands when you have to drive the kids to soccer practice.

Take public transit

Most forms of public transit (buses, light rain, commuter trains) use significantly less fuel per passenger mile than single-occupancy cars or light trucks. If public transit is an option for you (unfortunately, it often isn’t), take advantage of it. Not only will you save energy and reduce the wear-and-tear on your car, but you’ll also create time to read the newspaper, enjoy a good book, or catch up on e-mail.

Slow down

In a car, wind resistance increases at a cubed function of speed. That means that if you double your highway speed, your power requirements will increase eight-fold (2 cubed equals 8). I’ve experienced this pretty directly. One of our cars -- a 2003 Honda Civic Hybrid -- has a digital mileage gauge. On a number of occasions I’ve noted my fuel economy driving to the airport (when I’m running late and speeding along at 75 mph) and returning when I can putter along at a leisurely 55 mph. I haven’t done actual calculations to test that cubed function equation, but I’ve seen a dramatic difference: getting a little over 30 mpg at 75 mph, as I recall, and about 50 mpg at 55 mph.

Consumer Reports has examined this issue more thoroughly. The magazine measured the fuel economy of a 2.5-liter, 4-cylinder Toyota Camry driven at 55 mph to be 40.3 mpg, while at 65 mph the fuel economy dropped to 34.9, and driven at 75 mph it dropped to 29.8 mpg -- 26 percent lower than at 55 mph.

Remove the roof rack

If you’re not using a roof rack regularly, remove it to cut down on wind resistance. Even a fairly modest roof rack can easily cut your fuel economy by a few miles per gallon.

Lighten the load

The more weight we haul around in our cars or trucks, the more energy we use. If you keep sandbags in the bed of your pick-up for winter traction, remove them in the summer. Empty your trunk of those unneeded items you’ve been carrying and never use.

Avoid jack-rabbit
starts and stops

With in-town driving, gradual acceleration uses significantly less fuel than pedal-to-the-metal starting and stopping. I try to accelerate as slowly as possible (without inconveniencing oncoming cars) and avoid braking whenever possible as I approach a turn or traffic light. Wayne Gerdes, who coined the term "hypermiling" (a sort-of game to dramatically exceed the rated fuel economy of a car), recommends driving as if you don’t have working brakes.

Try to avoid coming to a
complete stop -- within reason

Your car uses a lot more fuel when starting from a complete stop so, when you have a choice, avoid coming totally to rest. When approaching a traffic light that’s red, for example, slow down so that you’re still moving when it turns green. Don’t violate laws or put yourself (or others) at risk in doing so, however. This isn’t a suggestion to roll through stop signs, or slow down so much when approaching a light that the driver behind you will try to swerve past you.

Avoid idling

If the engine is running and you’re standing still, your fuel economy is zero -- and an idling engine usually spews out more pollution than an engine that’s running at higher speeds. Several towns in our area, including Putney, Dummerston, and Brattleboro, now have no-idling resolutions in an effort to discourage the practice. With some vehicles, such as police cruisers and diesel equipment, there may have compelling reasons to keep the engines running, but for cars and light trucks, tuning them off usually makes sense.

Turn off cruise control
on hilly terrain

Cruise control is designed to maintain constant speed, but in hilly terrain a lot of extra fuel is used in accelerating up hills. A more fuel-efficient approach is to hold the accelerator pedal in approximately the same position approaching and going over a hill; your speed will drop but fuel economy will be better. On the downhill, allow your speed to increase (within the speed limit), using gravity to boost your fuel economy.

Final thoughts

Most of these strategies are common sense. But that doesn’t mean they always occur to us. Even an energy-efficiency nut like me has to remind myself to follow these practices as I seek to conserve.

Alex Wilson is the founder of BuildingGreen, Inc. and the Resilient Design Institute (www.resilientdesign.org), both based in Brattleboro. Send comments or suggestions for future columns to alex@buildinggreen.com.