measuring home energy useStaying warm, cooking food, bathing, and driving to work are essential functions in our daily lives. Remove for a moment the stove, the hot water, the heated cozy home and your car and we see the vital, integral thread of energy in our daily lives. Electricity has been invisibly supplied in the background for decades, taken for granted perhaps. Yet energy convenience has been provided at a cost to our human health and the well-being of our natural environments.

Transitioning our homes from reliance on environmentally damaging energy systems that burn oil and coal for example, to sustainable energy, begins with a fundamental understanding and appreciation for home energy management. Time, personal effort and money will be wasted if home energy efficiency is not given adequate attention prior to doing any renewable energy home retrofit.

To begin we can measure energy used at home with the help of a few simple tools and some basic math. The information you collect will help you understand and map how you use energy on a daily basis, and give you a clear picture of how much energy you use on a monthly and annual basis. This is invaluable information you will use when evaluating what a solar system can supply to your home in terms of meeting your energy needs, and how much that system will cost to install. We like to remind our readers that solar installations can begin with a modest system that meets some of your energy needs. In North America, we are conditioned to the idea of bigger and faster, but most of us still live on a budget and approaching a new solar installation that's smaller to start out with suits many of us. Residential solar systems can be expanded very easily as your budget allows.
What you will be recording for this home project is how many watts of energy you use at home, to then calculate your kilowatt hour use (kWh), and the associated cost of operating each appliance.One kWh is 1000 watts and is the universal standard used in electronics. When it's time to calculate your solar system requirements to see what system costs are and what system energy capabilities are you'll be prepared with a close estimate of kWh's you use at home. For this project you will need some paper, a pencil, a clipboard and a calculator. Later you can throw this information into a spreadsheet if you like.
  1. Go through your home, room by room, and make a list of all your appliances, fridge, stove, lights, vacuum, clocks, computer etc., leaving room on the page to record corresponding power use and cost information. Consult the labelling on your appliances which should tell you how many watts are used per hour and record this on your list. Power measurements of some appliances may be displayed as amps, volts or ohms. Use this Watts Conversion Calculator if you need to translate amps, volts or ohms into watts, which then can be calculated into kWhs.
  2. Home energy management ultimately brings us closer to lowering our energy consumption, which is cost effective time well spent. With your list in hand, we can now gain further insight on what you spend each month on power by using either or both of these free tools, Energy Cost Calculator and Home Electricity Audit Form. This will show you how much it costs to run each appliance in your home based on the cost of energy your currently pay for. Record the results on your list.
  3. Any appliances you can't evaluate with the free online tools just mentioned, can be measured with a reasonably priced power monitor.  It will provide you with the most accurate measurements of energy used by appliances and identify problems. We recommend the P3 International P4400 Kill A Watt electricity usage monitor, which connects directly between an appliance and a power outlet. It not only measures power used by an appliance in kWhs, but also measures voltage and potential issues with outlets, line frequency, and will identify appliances that are guzzling the juice and costing you more than needed. This can lead you to explore upgrading to energy smart appliances, which has long term value in reducing energy costs and improving home energy management.  Find Energy Star products here.
  4. After appliances you need to determine energy consumed for heating requirements in the winter and cooling needs in the summer. Base your cooling needs on estimated usage in a 24 hr period, to determine how many kWhs you use at home per month when running an air conditioner and/or fans. Climate plays a huge factor in energy cost so estimate your usage on climate in your area and required cooling needs. Professional help is useful to determine heating energy demands because many factors, like insulation, weatherstripping, types of windows and even what you home is built from factor into both heating & heating loss, and home cooling energy demands. Home energy assessments are being offered for free in many areas so check out what's available where you live. If you don't want to get an assessment done, you can still get an estimate with the help of this Heating Load Calculator. We looked around for a good calculator and feel this one is clear and easy to use. Heating is measured in BTUs (British Thermal Units) and this information should be readable on your furnace.  Record your results as well as heating and cooling costs based on what you pay your provider.  Add your totals.
You now have a list of how much energy each appliance in your home uses, what it costs, including your heating and cooling numbers and your total overall home energy use. This serves as a home energy map which you can use to then reduce energy consumption by replacing old appliances, removing redundant ones, or by making improvements to home insulation and weather stripping for example. Consider small things like power saving devices and power smart lighting you can use around your home. The best results of this project is simply your own awareness of how you use energy and thereby how you can save energy.  It shows you also what you have control over through good home energy management. In planning a residential solar installation you will now really appreciate the energy a solar system can create for your home, having clear insight of your home energy needs.