Energy Efficient Homes.

Energy Efficient Homes.

September 3 2020

The United States is the second largest producer of carbon emissions in the world. 329 million Americans produce 4.8 gigatons of carbon emissions per year, or 14.6 tons per person. By comparison, China’s 1.4 billion people produce 9.3 gigatons of carbon, or 6.5 tons per person. So what can each of us do to help reduce our nation's damage to the environment? A big part of global emissions comes from burning fossil fuels to produce the electricity that we use in our homes. The average US household uses around 11,500 kWh of electricity every year, or about 960 kWh per month. Depending on where you live, a kilowatt hour of electricity costs between 6 to 20 cents. An average electric bill is around $140 per month (960 kWh x .15) or $1,700 per year. Utilities separately charge for the cost of making the electricity (usually a natural gas or coal fired generation plant) plus the cost of building and maintaining the grid, plus taxes.

Most appliances (AC, fridge, microwave) run on electricity. Your electric company charges you for the kilowatt hours (kWh) you use. A kWh is 1,000 watt / hours: ten 100-watt lightbulbs running for an hour. Your carbon emissions also include appliances that run on natural gas and fuel oil: water heaters, dryers, and furnaces. For natural gas, consumers are charged by their utility per “therm” -- equivalent to 100,000 British Thermal Units (BTUs). Fuel oil is sold by the gallon.

US household energy consumption has dropped 38% since 1980 due to more energy efficient appliances, along with better insulation and other efficiencies. High efficiency light bulbs use around 10 watts per hour, 90% less than our old 100-watt incandescent bulb. A standard fridge in 1980 used 2,000 kWh per year -- today you can find “energy star” refrigerators that use as little as 350 kWh per year. Furnaces and AC compressors are 30% more efficient than models from just ten years ago. TVs, computers, dishwashers and washer/dryers are also vastly more efficient. Replacing old but still working appliances may make sense. Smart thermostats like Nest can save 10-15% on heating and cooling costs by closely fitting indoor temps to your needs and by adjusting them remotely through the internet. You might be able to switch to cheaper renewable energy by electing to take power from groups like Green Mountain Energy.

Putting solar panels on your roof may also be cost effective. A typical house needs a 6,000 watt system which costs around $16,200 (at $2.70 per watt). These costs are before a current federal tax rebate of 26% and incremental state incentives in some places. Net metering provides a credit when your house produces more power than it uses against when it needs to draw power from the grid. Depending on your price of electricity a $12,000 up front investment for a solar system could save $1,700 per year, or a 14% annual cash return on the investment (much better than the 0.7% annual return on a 10-year US Treasury bond).

You can run all your home appliances on electricity you make, as well as charge your electric vehicle. Electric powered air source heat pumps can fulfill all your AC and heating needs, eliminating your bill for natural gas or fuel oil. Cost effective technologies to retrofit heat pump systems on old houses now using fuel oil and natural gas furnaces are increasingly available. Costs for battery storage to get off the grid or to use as power backup are increasingly affordable. Taking charge of your energy usage is not only worth it but a service to your community and to our kids and grandkids.

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