The One Billion Ton Opportunity Cont'd - Part III: Household Energy Use


UPDATE 3/16: Two measures added--delay retirement of personal computers by two years and use dryer more sparingly (line-dry in the summer).

Today, my colleague Matt Eisenson continues his blog series on the NRDC-Garrison Institute "Behavioral Wedge Project" (see here and here for the first two blogs in the series), our effort to see if Americans could reduce greenhouse gas (GHG) emissions by 1 billion metric tons of carbon dioxide equivalent (MtCO2e) emissions below business-as-usual (BAU) by 2020—roughly 1/7th of U.S. annual emissions today—through a series of small and simple personal actions and changes to their behavior as consumers. In today’s blog, Matt focuses on the next of four categories of emissions: household energy consumption.

As of 2009, emissions from household energy use in the U.S., including both electric power and local fuel combustion, are responsible for approximately 1.2 billion metric tons Mt of our annual GHG emissions.  The U.S. Census Bureau projects that the U.S. population will grow from an estimated 310 million today to 340 million in 2020.  If the average number of people per household remains near 2.6, there will be around 130 million households in 2020, with projected GHG emissions of at least 1.3 billion MtCO2e.

We have identified measures to cut these household emissions by 380 million metric tons (MMtCO2e) below BAU in 2020, roughly a third of the present amount, and more than 25% of the anticipated future baseline (adjusted for population growth).

Figure 1: Proposed measures for reducing emissions from household energy use.


We assume in the baseline scenario that energy consumption per household will remain flat and behaviors constant.  For the most simple actions (e.g. swapping incandescent bulbs for energy-saving compact fluorescents and adjusting temperature settings), we accounted for the projected growth of households.  To determine the impact of upgrades and weatherization, however, we measured only the impact on existing appliances and infrastructure, and used conservative present-day EnergyStar standards (in reality, the standards in 2020 will likely be more stringent, so an upgrade in that year would have a greater impact than our estimates suggest). The Energy Information Administration’s (EIA) Residential Energy Consumption Survey provided a detailed inventory of appliances in use, and EnergyStar’s online calculators offered sufficient depth to account for significant factors such as age and size.

The chart below shows the share of total projected emissions reductions achieved through each of our recommended household energy saving measures:




Efficient Heating and Cooling

The simplest and cheapest measures for weatherization—patching leaks, sealing ducts and installing attic insulation—can cut the costs and associated emissions of household temperature regulation and ventilation by up to 20%.  If only half of U.S. households achieved these savings by 2020 (a modest target considering generous government funding for more rigorous weatherization programs), the resulting emissions reductions would total nearly 85 MMtCO2e.

Today, over 70 million out of 115 million of the country’s households set their winter heating thermostat above the recommended level of 68°F, and almost 25 million use a setting over 4°F above this level.   In summer, more than 2/3 of all households with central air-conditioning set their thermostat below the recommended level of 78°F.   Each degree lower on the heating thermostat equals energy savings of 3%, and each degree less cooling saves 6%.  If the average household turned down the heat settings by 2°F in winter and turned up the cooling settings by 2°F in summer, those households would save 6% on heating costs and 12% on cooling costs, reducing GHG emissions by over 35 MMtCO2e in 2020.

The Rocky Mountain institute estimates that installing a programmable thermostat and using recommended nighttime and daytime (away-from-home) setbacks could save 450 kg of CO2e per household per year.  (Some studies have estimated potential savings of well over 1 MtCO2e per household per year in many parts of the country).  Currently, fewer than 15% of households follow this efficient energy-saving measure.  25 million households own a programmable thermostat, but only 15 million reported using its setback feature, according to EIA.  The remaining 85% of households can save over 45 MMtCO2e in 2020 by following suit.

Improving Water Heating Efficiency

Heating water is energy-intensive.  Fortunately, it is both easy and cost-effective to improve water-heating efficiency.  Ninety percent of the energy consumed by a washing machine goes toward heating the water.  With most modern detergents, however, hot water is necessary only for the dirtiest loads, if at all.  Efficient showerheads, which include all of those manufactured after 1992, provide a superior, more concentrated stream and limit flow to 2.5 gallons per minute (GPM); older showerheads often allow more than 5.5 GPM.  Faucet aerators, similarly, regulate water flow and also reduce splashing.

Washing clothes in cold water, insulating one’s water heater, and setting its temperature down by 20°F (from the unnecessarily high default setting of 140°F), as well as installing efficient showerheads and faucet cap aerators, will cut emissions over 60 MMtCO2e by 2020. Nearly one third of those savings comes from washing laundry in unheated water, one of the easiest and most practical measures proposed. 

Upgrading and Using Appliances Responsibly, Reducing Standby Power and Using Efficient Bulbs

Upgrading one’s refrigerator and dishwasher to EnergyStar-approved models over the next 10 years (in line with the product’s natural expiration date) will save approximately 55 MMtCO2e annually by 2020, almost 40 MMtCO2e of which is for the refrigerator alone.  An EnergyStar dishwasher will save water, energy, and money compared to washing by hand; each product will pay for itself, and save an additional $50-75 over its lifecycle. 

**NEW PARAGRAPH**: On the flip side, we need to address our inclination to upgrade our gadgets too often.  We replace our computers every four years, although they are built to last longer.  EPA estimates that we would save around 25 MMtCO2e if we simply delayed retiring our PCs another 2 years.  And, to round it out, we overuse our appliances.  In the latest RECS, we found that over 85 million households used a dryer regularly, of which the vast majority, 72 million, used one all the time.  If these households started using a clothesline or rack in the summer alone, we would save 35 MMtCO2e (based on RMI estimate that a household can save 780 pounds CO2 per year adopting this change).

Comparable savings opportunities exist for those appliances not in use.  The average household computer is left in “idle” mode for an unconscionable 6,000 hours a year, drawing 44 watts per hour more than a computer in hibernate.  With at least 170 million home computers projected for 2020, the energy savings potential of setting computer defaults to hibernate mode exceeds 25 MMtCO2e in that year.  Many devices, including DVD players, cable boxes, and video game consoles, consume more electricity in a year just being plugged in to the wall than in use.   These “phantom” or “vampire” energy losses from standby consumption account for at least 5%,and as much as 15%, of total household energy use.   Assuming the low-end estimate of 5% in energy losses, cutting standby electricity consumption by a modest 1/3 would reduce GHG emissions from home energy use by 15 MMtCO2e in 2020. 

There are approximately 25 million extra refrigerators in American homes, more than 75% of which are more than 10 years old and almost 30% of which are more than 20 years old, according to EIA.  These refrigerators, especially the older, inefficient models, place an enormous drain on household energy use and their owners’ wallets.  The average small-to-medium size refrigerator (15-18 cf) built in the 1980s draws over 1700 kWh according to EnergyStar’s Refrigerator Retirement Savings Calculator.  Unplugging such a refrigerator could save as much as $200-300 per household per year.  If all 25 million secondary refrigerators were unplugged, we would avoid over 15 MMtCO2e emissions in 2020.

Compact fluorescent lamps (CFLs) require less than ¼ the energy of a traditional incandescent bulb to produce the same intensity of light, and often last up to 10 times as long.  If we assume the average household light bulb is on for three hours per day  and every home replaced six 60-watt interior incandescent bulbs with equally luminous 13-watt CFLs, we would save approximately 25 MMtCO2e in 2020.  Additionally, 30 million households leave an exterior bulb on all night, every night.  If these households replaced one exterior 100-watt incandescent with a 23-watt CFL, we would save 5 MMtCO2e emissions in 2020.  Finally, at least 1/3 of all lighting in the United States is wasted.  According to EPA's 2009 inventory, residential lighting accounted for over 100 MMtCO2e of emissions.  If we could cut this waste by 50% by 2020, we would save an additional 14 MMtCO2e after subtracting the savings from switching to CFLs (or 18 MMtCO2e without switching to CFLs).

The next post, coming shortly, will focus on food and offer some surprising—and hopefully inspiring—information about the potential impact changes in our diet could collectively have on the climate.  In the meantime, if you’d like to reduce and track your own carbon footprint by implementing some of these ideas, join the Simple Steps community by going to “My Simple Steps.” 

This project is collaboration between NRDC and the Garrison Institute’s Climate, Mind and Behavior (CMB) Project,  working to integrate emerging research findings about what drives human behavior into new thinking on climate solutions.  It envisions a "behavioral wedge" empowering people to eliminate a gigaton of GHG emissions by simply changing our behavior, starting now, even as we continue to work on other fronts to achieve institutional, regulatory and market changes.  CMB is convening leading thinkers and practitioners in the fields climate change and environmental advocacy, neuro-, behavioral and evolutionary economics, psychology, policy-making, investing and social media, working together on ways to shift behavior on a large enough scale to realize this potential 1 gigaton emissions reduction.