All tasks can be evaluated for their efficiency and waste production. Automobiles have high fuel efficiency when they go a long comparatively long distance on a comparatively small amount of gasoline than another, less efficient car.

Light bulbs we use to illuminate our nightscapes and interiors can be evaluated by how much of their energy actually goes to casting off light, and how much of it is wasted in the production of heat. Like our unfortunate biker, bulbs can be crippled by inefficiencies too, giving off equivalent amounts of light but wasting far more electricity than other bulbs of a more recent, more informed design.

Electrical appliances work the same way. Some of them waste more energy getting their work done than they have to.

It is a fact of physics that any task will produce some amount of wasted energy. Think about the warmth of your computer charger, for example. You want a charged laptop battery, not a feeble heat source. But in order to get power to your laptop, the battery charger must heat up. The point is not to eliminate all waste, because then nothing at all would get done, but to waste as little energy as possible- in short, getting the most bang for your energy buck.

Efficiency is measured as a ratio of amount of energy put in to a task to amount of energy performed by the task. It is expressed as a percent. For example, a 100-wattt light bulb typically produces the equivalent of about 5 watts of visible light, so the efficiency of the light bulb is said to be 5/100 = 5%.

Energy Uses

Our society allocates electrical energy as follows:
Residential - 16%
Commercial - 13%
Industrial - 22%
Transport - 21%
Electric power sector - 28%

Once that 16% of residential energy gets to our homes, here's how it breaks down:
Lighting and Appliances- 24%
Space heating - 47%
Air conditioning - 6%
Refrigeration - 5%
Water heating - 17%

The good news about the efficiency game is that, with a few exceptions, the most environmentally responsible decision is the most frugal decision too. For starters, you can try any one of the many suggestions at stopglobalwarming.org's informative site and see if you notice a difference in your electric bill or your car's fuel efficiency.

Here are some other simple actions, arranged by topic, that you can take to cut down on your (and by extension the world's) carbon output.

Light Bulbs

A worldwide switch to efficient lighting systems would shave nearly ten percent off of the world's energy bill. In light of numbers like that, the benefits of paying attention to energy efficiency in our daily lives – both for the environment and our budgets – are clear. And it’s such an easy fix there’s no reason not to do it. Here’s a brief description of possible lighting sources for your home, listed from least to most efficient.

Halogen lamps - these upward-illuminating fashion favorites are the world's least efficient way to light a space. Worse, they're hot- so hot, in fact, that extra air conditioning energy is often needed to offset their heat-generating power.

Incandescents - the oldest of humankind's lighting technologies, the standard incandescent light bulb is also one of its least efficient. This is easily demonstrable- just touch the bulb and feel almost all the watts burning away as heat. It is still, unfortunately, the cheapest to manufacture. But over the lifetime of the bulb, the cost of operation far outstrips the initial savings of the cheap bulb. Efficiency: 5%

compact fluorescents (CFL's) - Marketed in many places as "energy-saving" bulbs, these operate at an efficiency of about 20% or more. They also have the added benefit of being extremely long lasting. They cost more, but this additional cost is more than offset by their long life and low energy consumption per unit of light given off.

fluorescents - often used in public and commercial buildings, the best of these flickering white tubes have decent efficiency ratings (up to 60%), but other types are a dismal 10%, only slightly better than incandescent light.

Did you know...?

***Consumer lighting is not the only cause of unnecessary waste. A lot of the world's most inefficient lighting is used in mercury vapor lamps to light our night streets. While we don't have direct access to making these decisions, we do have a say in our city governments. Exercising your power and your clout to change your city’s lighting scheme might seem futile at first, but with a concerted effort alternative, high-efficiency lighting systems can be put in place at little taxpayer expense. The real value is in getting a public dialogue about lighting efficiency started.*** Maybe cut this? It’s a tad vague. If we could go into it more it’s a really good point. Any ideas? Any case study to quickly mention?

Other Appliance Tips

Tips for Saving Energy (from the U.S. Department of Energy)

- water
* take showers, not baths. a typical bath uses approximately 30 gallons of hot water, while a 5-minute shower with an efficient showerhead will use about half of that. Don't believe it? Next time you shower, close your drain and see how much water you collect.

*Fix leaky faucets – dripping can waste up to 95 litres of water per faucet per month

* Keep the freezer full. This increases the heat capacity of the freezer- meaning it's easier to keep cold once it's cold. Don't do this for the fridge; the fridge needs air circulation to work, and overfilling it can actually make it less efficient because you're blocking the air flow.

* Keep refrigerators and freezers out of direct sunlight, and allow at least 5 centimetres all around (or as recommended by the manufacturer) to allow heat to escape from the compressor and condensing coil.

* Allow hot foods to cool before putting them in the refrigerator.

* When using the stove, be sure to put lids on pots in order to keep the heat in the pot, which enables you to use lower heat settings!

* Microwave ovens use up to 75% less energy, so whenever possible, use a microwave instead of your stove or oven.

* Using a dishwasher can actually be more efficient than washing dishes by hand, assuming you use the dishwasher once for every 3 to 4 times you would wash dishes by hand.

* Wash your clothes in cold or warm water. A whopping 85-90% of the energy used by washing machines is for heating the water! You can save a lot of energy by lowering the water temperature.

* Clean the lint filter after every load. (A clogged lint filter can increase energy use up to 30%, and may be a fire hazard!)

* Get some fresh air! Consider using a clothesline to dry your laundry.

* Front-loading clothes washers cost a little more than conventional washing machines, but they use roughly half the water per load, and are more effective at squeezing the water out of the clothes – which lowers the electricity costs for drying them!

*Computers and related components use electricity even when they are not in use. Plug each computer component into a power bar that can be shut off, to avoid wasting electricity with the ‘standby’ power feature.

- heating and cooling
Fans should blow air downards during summer. This circulates air against the gradient of heat, which is heat --> up. Blowing up will just make a room hotter, allowing a reservoir of hot air to collect near the roof.

* keep blinds and shades closed when it's hot. Keep sunward windows un- shaded when it's cold.

* replace furnace filter often

* plant leafy trees on the sunward side of your house. In the summer they'll shade you.

* If you can afford it, install a programmable thermostat with a built-in timer. The money saved will soon pay for the expenditure.

Energy Star Appliances

ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy. It is a rating system of appliances: manufacturers must meet strict efficiency requirements to earn the seal. As is the case with most efficiency-and-economics issues, the cost of Energy Star appliances is high but tolerable when viewed in light of both their social/environmental benefits and the money consumers who use them can save. Americans, purchasing ENERGY STAR appliances, saved enough energy in 2005 alone to avoid greenhouse gas emissions equivalent to those from 23 million cars — all while saving $12 billion on their utility bills.

New homes can also earn Energy Star certification.

Fuel Efficient Cars

Put economic pressure on automakers to produce more fuel efficient cars by purchasing them. Low-yield clunkers like SUV’s will cease to be produced once consumers stop buying them. Hybrid cars are another fuel-efficient option. Nothing helps lowering the greenhouse output of our society more than reducing the amount of gas you have to buy to get somewhere.