Home Solar Efficiency Series # 4 - Step 2 | Estimating Home Energy Usage

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Once your home energy assessment is done, and you've made changes to maximize home energy use, you will want to estimate your energy consumption in both the warmer and colder times of the year. You will be able to approach a sound understanding of solar panel power capability, and how that applies to what you need, armed with your home energy profile. You will be taking a comprehensive look at all aspects of home energy use. The process of calculating home energy use could seem like a dreary task, but it's a valuable process that gets your brain thinking about energy consumption. We will keep this really simple by first explaining what we want to calculate, or what power measurement we are looking for, which is kWh's used. Using a Electricity Usage Monitor, which is used by connecting it between an appliance and a power outlet, is a useful tool to get a closer estimate of home energy consumption from home appliances, lighting or even a computer in stand-by mode. You can record energy use for a few days or a week and then average the total by dividing it by the number of days you recorded your usage. You want to know how many kWh's you use daily. Home appliances, small or large, will have labeling that shows how many watts, volts or amps it uses to operate. If you're not using an Electricity Usage Monitor you can calculate kWh's like this : use watts ( taken from appliance label ) X hours used ÷ by 1000 = kWh's used. For example, a table lamp using a 100 watt bulb for 30 hrs, would be 3 kWh's ( 100 x 30 ÷1000 = 3 kWh's )

Here's a simple step-by-step for this project:

1. Create a listed chart of all your home appliances, going from room to room
2. Over the course of a few days record how long you use appliances, air conditioners, lights etc.
3. Use a electricity use monitor, to get a closer estimate of energy usage for individual appliances
5. Calculating heating use is somewhat more complex and you can consult with professionals if you like, otherwise to get an estimated look at your home heating usage use this Heating Load Calculator
6. Add up totals for kWh's used to get an estimate of your overall home energy usage.
7. Keep this information safely on-hand to use in our next step in the Solar Efficiency Series - Solar System Cost and Power Capacities.

Useful Free Tools

• A Home Electricity Audit Form to print off, instead of writing down a list of your appliances
• This Watts Calculator will automatically convert amps, volts, or ohms to watts
• An Energy Cost Calculator

Electricity Measurements:
Unit = KWH (kilowatt hour: 1000 watts for one hour)
BTU’s = 3413 per KWH
Efficiency = 100%
BTU’s produced per KWH – 3413
To achieve 1,000,000 BTU’s, you need 293 KWH
Multiplier = 293