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Measuring energy efficiency at home

November 30, 2019


I’m Jeff Siegel. I’m in the Department of Civil, Architectural and Environmental Engineering here at the University of Texas. And, we’re here at the UTest House, which is a house like any other house in the U.S. that was dedicated to the study of indoor, environmental and energy issues. So, we’re here at the test house and thought, given how important they are, we’d talk a little bit about windows. Now you can get windows that perform almost as well as the walls that are around them. Frames that are made of metal, like alumnimum, or steel are not as good as frames that are made of non-conductive materials, things like wood or vinyl. Two panes of glass, double-paned windows, are much better than single-paned windows. Making sure that they are good drapes or blinds on the window. The best feature of this house is that it’s like many other houses in the U.S. There’s nothing really that special about it other than all the instrumentation that we added to it so that we can study things that go on. Buildings in general in the U.S. are responsible for about 40 percent of all energy use. An obvious way to save energy would be to get a more efficient air conditioner. The problem with that is that’s, of course, very expensive and if you have an air conditioner that’s working fine, there’s really no reason to replace it. You’ll notice it’s very clean. There’s no leaves in it. That allows for better air flow. When you’re doing your spring cleaning get out a hose and clean off your outdoor unit. So, this is the indoor portion of the air conditioner. Around half of the homes either have too little or too much refrigerant in them. If your air conditioner doesn’t have enough refrigerant in it, the evaporator coil, which is inside this box will freeze up and turn into a solid ice cube, so not only are you gonna have terrible efficiency, but you’re not going to get very much cooling. Now, you can’t see the ducts in this house. The problem is those ducts leak. Because air doesn’t make a mess when it leaks, we don’t tend to think about them very much. A very easy thing to do is to seal your ducts. Sealing up the ducts can pay itself back in terms of how much energy you’ll save very, very fast. Often less than a year. Heating and cooling system is responsible for about half the total energy use in a typical house. So, little decisions you make at something like the thermostat can have a really big impact on your overall energy bill. People who are actIve in using programmable thermostats, especially people who aren’t occupying the house for part of the day, they typically save on their energy bill as much as 25 or 30 percent. So, this is part of a battery charger. They’re getting warm because they’re using electricity. And, so, sometimes even when there’s no battery in a battery charger, or the cell phone is in your pocket, not plugged in, they still end up using electricity. Standby power can be as much as six, 10, 15 percent in the typical American house. Electricity that you’re not getting any benefit out of, you might want to think about unplugging them when they’re not in use. So, by far the most common light in the U.S. is an incandescent bulb, and there’s really a dizzying array of different bulbs out there on the market. Let’s take our 100 watt incandescent bulb as an example, so that’ll use a 100 watts. If you switch to a halogen to get the same amount of light, maybe that halogen will use 75 or 80 watts. So, a little bit less. If you go to a compact flourescent, you’re probably looking at a bulb that uses somewhere around 20-25 watts so that’s four times less electricity. And not only that, but you don’t have all this extra heat generated that your air conditioner has to get rid of. And then if we’re looking down the road at what lighting technologies are around the corner, the one that I think will get used in houses soonest is LED technology. You might only use 10 watts, or so, of electricity with an LED light. Let’s talk in general about appliances. You’ll find very large ranges of how much energy they use. You might need a new washing machine. You’re going to decide between a front-loading washing machine, a top-loading washing machine, how big it is. Think about issues like water use, electricity use, maybe other fuel use that are important, too. And it’s really going to have a big impact on your bill, but it’s also going to have a big impact on things like outdoor air quality. If you have a house that uses electricity to heat it, in particular, then that’s electricity that’s probably going to be generated, to a certain extent, with coal or with other polluting sources. And so, you want to think about what the impact of this fuel is going to be on the cost of your bills. [ MUSIC ]

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