DoingHomework wrote:The result is that, for a given size the ES reading is meaningful. But a larger unit can waste more energy for the same rating.
Yes, but this is exactly how Energy Star is designed to work: it identifies the most energy-efficient models in every size class. It's not designed to identify the most energy-efficient model overall. That's what the EnerGuide label is designed to do.
The Energy Star label is designed to be a blunt instrument that simply identifies models that consume less energy than a specified threshold. It doesn't distinguish between models that consume way less versus those that consume just a little less. The EnerGuide label lets you sort all that out, but comparing EnerGuide labels across multiple models takes time, and most people won't take that time. The Energy Star label makes it easy, it's like a "made in the USA label" on clothing or a "Marine Stewardship Council" label on seafood. The people who developed Energy Star spent months talking with store salespeople and consumers to understand purchasing behavior, and concluded that a simple label would be most effective. The EnerGuide label provides a lot more information but as simple as it is, it's still overwhelming to most consumers and there's no practical way to know which model is most efficient without spending an hour walking around the showroom floor comparing EnerGuide labels. People don't have that kind of time.
If you're shopping for a big refrigerator but you want one that'll save you energy compared with other big refrigerators, you just look for the models with the Energy Star sticker. If you're shopping for the most energy-efficient refrigerator you can buy, you look at the EnerGuide label (which is available for all appliances regardless of whether they're Energy Star or not) to see how much electricity the unit consumes over the course of a year.
Energy Star recognizes that the vast majority of consumers don't go out shopping for "an energy efficient refrigerator." They go out shopping for a refrigerator that's big enough for their family, and that provides all the features they're looking for (ice and cold water dispensor, etc.). The Energy Star label just helps people find the more energy-efficient products in the size class that they've already decided they want. Again, there's no sacrifice involved: Energy Star isn't telling you that you should buy a smaller refrigerator if you want to be "green." It recognizes that we all face different realities and constraints. It just says "if you have to buy a huge refrigerator, you can save money over the life of the product by buying one with our label."
As for why the Prius comes with an air conditioner, that again is a demonstration that energy efficiency is not about sacrifice. If you sell a super-green car with no air conditioner but nobody buys it because it doesn't have an air conditioner, what's the point? To make energy-saving attractive, you want to show that energy efficiency can involve getting the SAME experience with LESS energy.
Energy conservation requires sacrifice: you turn down the thermostat in winter, put on a sweater, and shiver. Energy efficiency requires no sacrifice: you keep the thermostat set where you've always set it, but you use less energy because you've added insulation and energy-efficient windows to your home. There's an up-front expense but it's paid back quickly in energy savings. The paybacks are so well documented that there are companies that will actually perform energy efficiency upgrades to your home or business for free, and then you pay them back out of your energy savings.