Tag Archives: energy-efficiency

Hang Dry Your Clothes

7 Replies

Clothes dryers are unnecessary luxuries that waste both energy and money. On one hand, they harm the environment since natural gas or coal must be burned to dry clothes (electricity comes from burning coal). On the other hand, clothes dryers are expensive. The cost of energy for a single load of laundry is around 40¢, which adds up to around $160 per year for a typical household (1). Yet besides the price of fuel, there’s also the cost of the clothes dryer itself, which is around several hundred dollars even before installation. The clothes dryer, then, is an expensive energy guzzler, a runner-up to the heater and air-conditioner.

Heat production inherently requires lots of energy, so even an energy-efficient clothes dryer wastes massive amounts of fuel. Producing any heat at all, however, is a silly idea; most of us enjoy an abundance of free heat each afternoon. Wherever there is sunlight, clothes can be hung-dry to harness no-cost natural sunshine. Hang-drying your laundry is minimalist, cheap, and low-tech — no drying machines or solar panels necessary.

Besides saving money on your energy bill, there are other reasons to avoid the clothes dryer. Clothes that are tumble dried get damaged quickly and need replacing more often. The tumble dry cycle, moreover, leads to static charge buildup (yes, you could add fabric softener, but why not just get rid of the source of the problem?). And most importantly, clothes dryers produce extra heat, making hot days more unbearable. When I used to live in sunny Southern California, daytime temperatures often exceeded 90°F (32°C) during the summer. When people used clothes dryers, it would feel 10°F (5°C) hotter inside the laundromat than outside. The sweltering heat would have been perfect for hang-drying laundry, but sometimes our culture forgets the painfully obvious.

Clothes can even be dried when it’s raining. If there’s no sunlight, simply hang your wet clothes indoors and allow the moisture to evaporate. Just make sure that the clothes get plenty of aeration. Sometimes, I use a fan to accelerate drying. I never let the occasional rainy day stop me from hang-drying my clothes during the rest of the year.

It’s simple to do laundry without a clothes dryer. Here are a few different methods:

  1. Use a simple clothesline. A sturdy clothesline can be made of metal wire, plastic, or natural fibers. Tie each end of the clothesline to a solid support (bars, poles, trees), then use clothespins or clothes hangers to attach your clothes to the line. In my house, we tie a piece of braided wire to the bars on our windows to support the clothesline. You probably don’t need to buy any equipment for this setup.
  2. Buy a retractable clotheslines. There are a few luxury models available that are much more elegant than my makeshift clothesline. Retractable clothesline fold away nicely for people living in tiny apartments.

    3. A 4-line retractable clothesline

  3. Buy a clothes rack. There are two types: the traditional, heavy-frame variety, and the newer, collapsible models. Both types will provide a vertical support for when you can’t find a pole to tie your clothesline to.

    A collapsible drying rack

    Before we gave away our possessions, we used to own a lightweight, folding clothes rack. It was perfect for our tiny apartment, since it was designed for high-density stacking, allowing us to dry plenty of clothes even on a tiny patio. Hsinya used them for delicate clothes that had to be laid flat to dry (some delicate fabrics stretch under their own weight when hung). It was flimsy, however, so it quickly broke under the weight of wet clothes.

    A sturdy collapsible clothes rack vs a flimsy broken one

    Traditional, heavy-frame clothes racks are much sturdier. You can get these used at a garage sale or flea market for very cheap. Because they can handle far more weight, these clothes racks are more practical for larger families. The only drawback is that they take up a lot of space.

    4. A rotary dryer

  4. Improvise. When you only have a few clothes that need to be washed, you can hang-dry them on chairs, nails in the wall, closet poles, or even staircase rails. Let your imagination run wild.

    5. Hang-drying your laundry is cheap, simple, minimalist, and low-impact. Why would anyone ever use a drier again?

    1. Mr. Electricity estimates a sample load of laundry to cost 49¢ using electric power and 31¢ using gas. If the average household does 7.5 loads of laundry each week, that comes out to 49¢ × 7.5loads/week × 52 weeks/yr = $191 for electric and 31¢ × 7.5loads/week × 52 weeks/yr = $120 for gas.
    2. Photo credits: Mike Lacon, CC BY-SA. greenlagirl, CC BY-NC-SA. ario_, CC BY-NC-SA. Noel Zia Lee, CC BY. Sarah Mae, CC BY-NC. Melissa Sanders, CC BY.

Save Money On Electricity

6 Replies

A typical American household might spend $100 this month on electricity. Over the course of the year, that bill will total $1200. Not only is our hard-earned money disappearing into thin air, but we are also destroying the environment in the process. That’s because to produce electricity, power plants must burn coal. Not only does this contribute to carbon emissions and smog, but forests are often destroyed in the coal mining process. The great tragedy, ultimately, is that saving electricity — and our money — is actually very simple. It only takes a few minutes to learn how to conserve electricity, but afterwards, you could save around a thousand dollars each year. That’s not a bad reward for helping to preserve the environment.

Many homeowners won’t bother with conservation simply because they don’t understand how electricity is being billed. Electricity isn’t tangible like gasoline is, so it’s difficult to figure out how electricity is measured, how much our devices use, and how all this is priced. As a result, it’s difficult to predict whether one electrical device is more wasteful than another. For example, most people know that a Hummer wastes more gasoline than a compact car, but few know whether a hair drier is more wasteful than a television. The mystery behind electricity pricing is what makes conservation difficult to practice, so before we start saving money, let’s first understand how electricity is billed.

Power, energy, and time are three related variables that follow this equation:

Energy = Power × Time

To better visualize these concepts, let’s use a rough analogy. Imagine we decide to build an old-fashioned water mill on a fast-flowing river to grind flour. The rate at which water flows influences how quickly the watermill works: the faster the river, the more flour we can grind. In a way, the rate of flow is similar to the power usage of a device: the more power your air conditioner uses, the more energy you will be charged for. Although we might measure water flow in units of feet per second, we measure electrical power in units of watts (W).

Power, however, is not what you are billed for (1). If a farmer rented a watermill to grind flour, he would probably be charged based on the amount of flour he grinds, not on the speed of the river. The amount of flour produced depends not only on the rate of water flow but also on the length of time spent milling. Likewise, our utility company doesn’t bill us for the power used but rather the total energy used. According to the equation above, the total energy is a product of power and time. Since the unit of power is in watts (W), and the unit of time is measured in hours (h), it would make sense to measure energy in units of watt•hours (W•h).

A single watt•hour, however, is a trivially small amount of energy. It’s the amount of energy that a one-watt device uses in one hour (1W × 1h = 1W•h), or what a two-watt device would use in half an hour (2W × 0.5h = 1W•h). For comparison, a single alkaline AAA battery contains around 1.15W•h (2). Measuring energy in watt•hours only makes sense for a tiny sliver of ultra-efficient devices, such LED flashlights. For the typical home appliance, however, it makes far more sense to price electrical energy in the much larger units of kilowatt•hours (1 kW•h = 1000W•h).

For our calculations, we’ll use the sample rate of $0.14/kW•h, which is the price of Tier 2 electricity from Southern California Edison as of June 2011 (3). (You’ll need to check your own electric bill to find out your exact rates.) Using this knowledge, let’s try to figure out how much it costs to operate some typical appliances:

  1. How much does electricity cost to run my laptop? I use my 2007, 13″ Macbook for about 4 hours/day, 5 days/week. During normal operation (light web surfing), it uses around 25W of power (4). 25Watts × 1kW/1000W × 4 h/day × $0.14/kW•h = $0.014/day. That is, I would pay around one and a half pennies each day to power my laptop. To figure out the cost per month, we multiply by the number of days per week, then by the number of weeks per month: $0.014/day × 5days/week × 4.5weeks/month = $0.315/month, or about 32¢ each month. To calculate the cost per year, we multiply by the number of months per year: $0.315 × 12 months = $3.78/yr, or almost four dollars each year.

    As you can see, laptops are actually cheap to power. In general, electronics designed to run on batteries are energy-efficient. (Just remember to turn them off or sleep them when not in use.) If you’re looking to save significant money, you’ll need to hunt around the house for big energy hogs. Let’s take a look at a more interesting example: central air conditioning.

  2. How much does electricity cost to run the AC during the summer? Let’s say we live in sunny Arizona, so that the AC is blasting 12 hours a day, everyday for 6 months of the year. We’ll estimate the power use of a 2.5-ton central AC at around 3500W during operation (5). One detail to remember for ACs is that they don’t usually run continuously. Air conditioners only operate when the room temperature exceeds what is set on the thermostat; all other times, the AC is in sleep mode. With this in mind, let’s estimate that the AC is powered on around 33% of the time. With the AC turned on 12 hours each day, we estimate that it is actually operating for about 4 hours each day. 3500W × 1kW/1000W × 4h/day × $0.14/kW•h = $1.96/day. The cost of operating monthly is $1.96/day × 30.5days/month = $59.78/month. The cost of operating it each year is $59.78/month × 6months/year = $358.68.

    With central AC, you would waste over $350 dollars each year. Part of the reason it’s so expensive is because central AC is cooling the entire house, when really all you need is to cool a single room. Air conditioning is also much more energy-intensive than using a fan.

  3. How much money would you save by using a fan in place of the AC? On the medium setting, a box fan might use around 60W power (6). 60W × 1kW/1000W × 12hours/day × $0.14/kW•h = $0.1008/day. The cost of operating monthly is $0.1008/day × 30.5days/month = $3.0744/month. The cost of operating it each year is $3.0744/month × 6months/year = $36.8928/year. Compared to the central AC ($358), that’s a savings of $321, or nearly 90%!

    As you can see, it pays to focus on the biggest energy-guzzlers first. Heating and cooling account for over 70% (7). The runners-up are probably lighting and refrigeration.

Monthly Cost = Power (in W) × 1kW / 1000W × h/day × Price (in $)/kW•h × days/month

Save 100% compare to the clothes dryer

Keep in mind five key tactics:

  1. Small is beautiful. All other things equal, a smaller device uses less power than a larger one. Central heating wastes much more energy than a portable space heater, and a widescreen-TV uses much more electricity than a smartphone. Save money by using the smallest appliance possible.

  2. Less is more. The less you use a device, the more money you save. Remember that saving electricity is not simply about lowering power consumption but also about lowering time used. Even Energy-Star appliances, if you leave them on all day, can waste money. So turn off devices when you’re not using them, paying special attention computers, monitors, televisions, lights, fans, air conditioners, and heaters.

  3. Not too hot, not too cold. The higher the setting on a device, the more power it uses. Turn the power on your device to the lowest setting to save plenty of cash. You can lower the power settings on most devices, such as hair driers, fans, desk lamps, and even kitchen ovens. This will make a huge difference in your heating and cooling bill. In the summer, keep your AC’s thermostat set above 80F, and in the winter, set your heater’s thermostat to lower than 60F. You could easily save hundreds each year (see above calculation).

  4. High-tech is nice. Check out compact fluorescent lightbulbs, energy-star appliances, better home insulation, front-loading washers, geothermal heating/cooling pumps, tankless water heaters, and top-opening refrigerators. Although these inventions all require an upfront cost, they will more than pay for themselves after a few years, if not a few months.

  5. But low-tech is even better. You’ll save the most money when you ditch electrical devices altogether. For example, I don’t use an air conditioner, fan, TV, smartphone, drying machine, or treadmill. Low-tech does more than save money on electricity; it saves on the upfront costs of buying equipment in the first place. If you’re serious about going green, low-tech is usually lightest on the environment.

Just like with gasoline, electricity prices will surely increase in the future. But if you lower electricity consumption today, you might be able to power your home using only renewable energy. This can help you lock in the cost of electricity, saving you plenty of money and lowering your carbon impact. Conservation, as always, is the key to financial and environmental sustainability.

  1. Usually you will be billed for energy alone, but a few utility companies have a demand charge based on your peak power usage. To illustrate, suppose you had three appliances: a washing machine, a microwave, and a vacuum cleaner. If you ran all three appliances at once, you would have a much higher peak use of power compared to if you ran one appliance after the other. The demand charge is based on the maximum power used at any instant for a given day (or month).
  2. Some batteries and the amount of energy they store.
  3. See Southern California Edison’s website.
  4. Two different estimates on Macbook power usage. I just approximated.
  5. Estimate provided by Mr. Electricity.
  6. Power data for different fans from SaveGreenly.com.
  7. According to the EIA, space heating accounts for 41% of energy consumption while water heating and air conditioning account for another 20% and 8%, respectively.
  8. Photo credits: Brian Talbot, CC BY-NC. alessandraelle, CC BY-SA.

The Jevons Paradox

4 Replies

Energy-efficiency has become the talk of the town. Scientists, marketers, journalists, and politicians alike are showering praises on the new technologies that promise to revolutionize our planet. From zero-emission electric cars, to smart electric grids, to green laptops, high-tech sustainable solutions seem to promise the world a brighter future (1). It’s a positive message at heart: to solve the world’s energy problems, all we need is better engineering. And with many prototypes near completion, who wouldn’t be excited?

The economists aren’t, for one. These contrarians are quick to point out that most attempts towards energy-efficient technology have proved utterly futile. History has repeatedly shown that energy-efficiency rarely leads to net energy reduction. In fact, quite frequently, efficiency improvements makes things worse by actually encouraging a net waste in energy. This counter-intuitive effect is known as the Jevons Paradox.

This energy-efficiency paradox was first described in the mid-1800s by a British economist named William Stanley Jevons. During this era, coal was the fuel that powered industrialization in Britain. Britain was blessed with this valuable resource: geologists estimated that it had around 90 billion tons of natural coal reserves (2). This ample supply of cheap energy provided the power for the nation’s vast array of steam engines. These engines, in turn, powered the manufacturing industries that made the British Empire wealthy.

Over time, Britain’s economy became increasingly dependent on coal. Since 1770, the amount of coal being consumed each year was growing exponentially. Assuming continued exponential growth, England would exhaust its vast coal reserves in the next 100 years — not good at all for the powerful British Empire. Engineers, therefore, were racing to produce machines with better energy-efficiency. If only efficiency increased, they believed, we could reduce the demand for coal. Jevons, however, knew better.

In 1865, Jevons published The Coal Question, which investigated the relationship between efficiency and total energy use. His results were absolutely startling: energy-efficiency was worse than useless — it was positively harmful. Historical records showed that the more efficient steam engines became, the more coal Britain ultimately consumed. Better technology within the 18th century had actually caused coal consumption to grow exponentially.

This paradox is best illustrated by example. Suppose the average car gets 25 miles to a gallon of gasoline, with each gallon costing $4. Using hybrid electric technology, engineers could create an improved car that gets 50 miles using a single gallon. As a result of this breakthrough, the improved car could produce the same amount of work using half the amount of gasoline.

The economics, however, look different from the consumer’s point of view. To the consumer, this improvement in efficiency has effectively halved the price of transportation. Whereas it used to cost $4 to travel 25 miles, now it only costs $2. Now that transportation is much cheaper, it’s possible to drive more than ever before. Our driver can now afford to do more than just commute to work; he can take cross-country road trips every month, if he so pleases.

Suppose our driver originally burned 10 gallons of gasoline each week. With new technology, he can save half the fuel, or 5 gallons of gasoline, each week. Unfortunately, our driver decides to take extra road trips, and drives an extra 150 miles each week. As a result, he ends up burning 8 gallons instead of 5. That’s 3 gallons more than what he could potentially have saved, had he kept his driving habits constant. We say that the rebound effect is 60%, since that is the percentage of potential savings that was forfeited (3).

At this point, it still looks like energy-efficiency could be of some use. After all, a 60% rebound effect still implies that 40% of the potential savings were retained. Isn’t it better to have our driver conserve 2 gallons of gas, rather than no gas at all? But here’s where it gets peculiarly disturbing: the rebound effect frequently exceeds 100%. Returning to our analogy, a rebound effect greater than 100% would means our driver is now burning more than 10 gallons of gas each week. If our sustainable car suffered from 120% rebound (3), that means 11 gallons of gas are burned instead of 10. This backfiring is the paradox that Jevons observed with steam engine technology.

What exactly happens to all of the potential savings?

For one, as machines become more efficient, engineers tend to add more features and provide better performance. Hybrid-electric cars might accelerate faster, become roomier and heavier, and include more electronics. Those extra creature comforts squander all the potential savings in fuel technology.

Drivers might also suffer from greenwashing. Let’s suppose our driver is environmentally-conscious. When he used to drive his old clunker, he’d feel guilty about wasting gasoline. But when he drives a zero-emission hydrogen car, he does so with clear conscience. After all, most people don’t stop to realize that hydrogen fuel requires energy to produce, which currently still uses coal to produce (4). Besides, he’s already spent thousands of dollars going green; what’s a little extra driving here and there?

But perhaps most importantly, average consumers simply don’t care about conservation. Many passengers take the bus each day, not because they care about the environment, but because gasoline is expensive. By increasing the fuel efficiency of cars, the effective price of driving decreases. This provides the average passenger with extra encouragement to drive instead of taking public transit.

Even non-driving activities contribute to the rebound effect. If our driver spends less money on gasoline because of fuel efficiency, he now has more disposable income. He might choose to use that extra cash for a cruise to the Bahamas or a plane ticket to Europe, activities which both waste tons of gasoline.

Altogether, these effects usually ensure that the rebound effect is greater than 100%.

The Jevons Paradox can be quite disheartening, especially after you realize how often it occurs.

  • Architects, for example, are now wasting more energy than ever before using energy-efficient LED lighting. They do this by plastering buildings with LED lights to create gigantic lighting displays (5). The buildings are lit all night, 7 days a week. Such lighting was previously too expensive using traditional lightbulbs, but energy-efficient LEDs now make it cost-effective.

  • As another example, refrigeration may result in increased energy usage. The benefit of refrigeration is that, by preventing food spoilage, consumers can save electricity the electricity used in food production. However, refrigeration inadvertently encourages us to buy too much food. Today, the average American throws away 40% of the food he purchases — you could hardly call that saving electricity (6).

  • Energy-efficient heating and cooling may have resulted in increased electricity demand. The problem is that energy-efficient air conditioners and heaters encourage people to leave these systems on longer. Lower costs might even encourage the average home-buyer to buy a bigger house. Any potential savings are thus wasted cooling and heating extra space (7).

The Jevons Paradox makes it clear that technology by itself can’t solve our present energy crisis. If new innovations aren’t accompanied by a cultural shift towards conservation, they are likely to waste more energy than ever before.

The trouble with sustainable living is that it requires a total lifestyle change. Life apart from consumerism can be difficult to imagine, so we resist. It’s much easier to just keep searching for the next big thing. We want to be environmentally-friendly, but we don’t want to give up our cheap energy, shopping sprees, fast cars, quick profits, and junk food. So we’ll be sure to see plenty of paradoxes for years to come.

  1. These technologies are an improvement, but they’re still not sustainable. Zero-emissions cars aren’t really zero-emissions; they still require electricity, which is produced by burning coal. Smart grids will save some energy, but we will just waste the savings by powering more gadgets. Lastly, even the greenest laptop will produce some e-waste, since electronics aren’t biodegradable.
  2. From Wikipedia’s summary of The Coal Question.
  3. If he had the potential to save 5 gallons, but only saved 2, then he wasted 3 out of 5 gallons, which gives 3÷5 = 60% rebound effect. An 120% rebound effect is equivalent to 120% = 6÷5. In other words, he had the potential to save 5 gallons, but actually wasted 6 more.
  4. Physics Professor David McKay writes that the Hydrogen 7, the hydrogen-powered car made by BMW, requires 254 kWh per 100 km – 220% more energy than an average European car. In other words, hydrogen cars are worse than conventional cars.
  5. Low-Tech Magazine explores LEDs and energy-efficiency paradox.
  6. From an abstract in The New Yorker.
  7. One writer argues that efficient heating and cooling has led to a rise in McMansions.
  8. Photo by nugefishes, CC BY; our own picture.