My Beef with the Watt

This week's post comes from Sarah Kate of the VisibleEnergy team.

Second Congress of the British Association for the Advancement of Science, I have a bone to pick with you. What's my beef? The unit of measurement known as the “Watt.”

A Watt is another way of saying joules per second. A joule is a unit of energy measuring heat, electricity, and mechanical work. So what’s the big deal? Well, for starters, we’re defining a unit of measurement I don’t intuitively understand using another unit of measurement that I don’t intuitively understand. When was the last time you described something in terms of joules? Physics class in high school, perhaps? So to understand what a Watt is, we have to figure out what a joule is. A joule is the amount of work done by a force of one Newton moving one meter along the direction of the force. Now we’re in Newtons, and blimey, the metric system! A Newton is equal to the amount of force required to give a mass of one kilogram an acceleration of one meter per second squared. Are you kidding me? This is not productive; the farther away we get from the original unit of measurement, the less capable we are of conceptualizing it.

But wait, I’m just getting warmed up. What more could be wrong with a Watt? How about the fact that a Watt is a rate? That doesn’t seem so bad, does it? It doesn’t until you remember the terms used to express nearly all other rates… miles per hour, beats per minute, megabytes per second… are units per time. But Watts are already in joules per second, so at any one time, the building you’re in is using energy at a rate of X Watts rather than something like Watts per hour. That means that Watt-hours, a related unit of measurement, are actually a measurement of energy, not a rate of energy (one Watt-hour is equivalent to 3600 joules). Egad!

So here’s the analogy, building off of one of Luke's previous posts:

A car driving 100 miles per hour (rate) for 2 hours (time) travels 200 miles (distance).

A house using 100 Watts (rate) of electricity for 2 hours (time) uses 200 Watt-hours (energy used).

It’s embarrassing that this nuance took me months to finally grasp. Might I suggest switching to a new universal standard of measurement? I propose the Cheeseburger (a quarter pounder). The Cheeseburger represents 500 Calories (kcal) of consumption. My home consumes energy at a rate of 60 Cheeseburgers per day. I can picture this, and the rate is stated the way rates should be – in units per time. Stated this way, I can internalize my consumption, I can picture the mound of hamburgers. With Watts, I must rely on comparison in order to know anything about my personal consumption, and as the wise John Fortescue once said, “comparisons are odious.” And they’re even more odious when you have no frame of reference for comparison. Congress of the British Association for the Advancement of Science, please consider my proposal. If we’re going to help people understand their daily impact, meaningful, digestible units are a must.

At VisibleEnergy, we want to help people intuitively understand their consumption, so thankfully we don’t have to wait for the Congress of the British Association for the Advancement of Science to act. How many Cheeseburgers does your home use? Find out using our Cheeseburger calculator: