How Your Home Uses Energy

Chances are, if you live somewhere, you use electricity and you pay for it. I’m sure there are some exceptions – you might live off the grid (or in a van down by the river). Electricity is something that we take for granted. We pay our bill every month and that’s the end of it. If you’re interested in learning some electricity basics and how your home uses energy, take a look at this post and comment or email us if you have questions!

Photo by Leon Contreras on Unsplash

Energy vs. Power

Real quick, before we continue talking about how your home uses energy, I want to differentiate the terms energy and power. In terms of your homes usage, energy is how your usage is listed on your electricity bill. You pay for electricity by the kilowatt-hour (kW-h). Power is the amount of energy an appliance or light bulb will use in a period of time – measured in watt (W) or kilowatt (kW). This is the rate at which energy is transmitted. So think of energy as total amount (you’re paying for total energy used monthly) and think of power as the energy doing work (lighting your house, cooking your food).

How Power is Supplied to your Home

Most residential power in the United States is supplied by either 120-volt or 240-volt, alternating current (AC) electricity. Your power company monitors the amount of energy you use in terms of kilowatt hours (kW-h). They generally have a set, or variable rate that they bill you per kW-h. So, what does all of this mean? How do you know how much power your TV or fan use? If you don’t already have a good understanding of what I’m talking about, or how all of this works, read on. I’m going to try explain all of this in a way that is helpful to the average home-owner.

Basics of Electricity

To kick off this conversation about electricity basics and how your home uses energy, I could start in many places – I mean, we could begin at the electron! But let’s assume that we all understand electricity is the movement of electrons between atoms. This is more likely to happen in the atoms of some materials (conductors) than other materials (insulators). Copper is an example of a great conductor, hence why it is used for residential wiring.

Voltage, Amperage, and Ohms

Voltage is the measure of how much force is behind the electrical current (those moving electrons) moving through your conductor. It’s analogous to pressure in a water pipe. Amperage is the amount of electrical current available in the conductor, or in terms of the water pipe, how much water is in there. Electrical resistance is the measure of opposition of amperage – this is measured in ohms. Anything appliance or device that uses electricity provides resistance.

Energy and Time

Electrical energy can be measured by joules. One joule is equal to the energy dissipated when 1 ampere of electrical current passes through a 1-ohm resistor for 1 second. Now, if you look at how many joules are supplied to a source, you can measure that over time – or say joules per second – this gives you a watt. The watt is a measure of power. One watt is also equal to 1 ampere being “pushed” by 1 volt. So, the watt is your base unit of power. We’ll take it one step further to equate this to your power bill – multiply the power used by time again, and we get the watt-hour. Measure the watts in thousands and you have your kilowatt-hour.

If you broke all of these terms down by their units, you would see that watts (power) is energy divided by time (J/S). Then we multiply the watts by time again, so we actually land back on energy (J/S X hr. = J).  

More specifically (1000 joules / seconds) X 3600 seconds = 3600000 Joules = 1 kW-h

I didn’t get that; can you try again?

Sure! An appliance draws an electrical current over time (kW-h). The kW is the power being supplied – the kW-h is how much of that power was used by the appliance (how much power = energy).

Why are different voltages supplied to my home?

For some larger appliances around your house, like your clothes dryer or air conditioner, 240V electricity is more efficient. These larger appliances usually have large electric motors or heating coils and require more power over time to operate. Watt’s law shows that Power = Voltage X Amperage – so, with higher voltage (that push), you can get more power our of the same Amperage. Your normal appliances, light bulbs, ceiling fans and such are all powered by 110 volts. The outlets for 240V is much different than 110V so you can’t mix them up.

Let’s put our new found knowledge into practice!

Grab a lightbulb from your laundry room, or wherever you keep the extras, and look to see how much power it is rated for. If its an incandescent, it’ll probably say 40 or 60 watts. An LED, much less, probably 8 or 10 watts. This means that when the light is ON, it’s using that amount of power. So, if you have one LED light bulb that uses 8 watts of power and it’s on for 1 hour, you have used 8 W-h of energy. If you leave that same light on for 1,000 hours, you have used 8 kW-h of energy.

The same goes for toaster ovens, your TV, computer, and any other electronic device you own. Now go check everything you own! Multiply the power rating (watts) by usage time and figure out how many kW-h you’re using! Well, that sounds like a lot of work – maybe just let the power company keep track of that.

Saving money with your home’s energy use in mind

This does come in handy when trying to decide if adding that garage refrigerator is worth it. You can do a quick cost analysis of how much it will cost to operate and discuss with your significant other if it’s worth it in order to keep a larger selection of beer on hand. Once you have the kW-h energy usage determined for the refrigerator, multiply it by the rate that your power company charges you for electricity. You can usually find this on their website or on your bill. According to the U.S. Energy Information Administration, the average kW-h cost Americans $0.145 in March of 2022!

How does your region compare? Are power prices rising like gas prices in your neck of the woods? Did this article help you understand how your home uses energy?

Let us know, we like to complain as well!

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