National Energy Use of Consumer Electronics in 1999

Karen Rosen, Lawrence Berkeley National Laboratory

Alan Meier, Lawrence Berkeley National Laboratory

Stefan Zandelin, Lawrence Berkeley National Laboratory

**ABSTRACT**

The major consumer electronics in U.S. homes accounted for nearly 7% of
U.S. residential electricity consumption in 1999. We attribute more than
half of this figure (3.6%) to televisions, videocassette recorders, and
DVD players, and nearly one-third (1.8%) to audio products. Set-top
boxes currently account for a relatively small fraction of residential
electricity use (0.7%), but we expect this end-use to grow quickly with
the proliferation of digital set-top boxes, which currently use 40% more
energy per unit than the average TV set. In all, these consumer
electronics plus telephony products consumed 75 TWh in the U.S. in 1999,
half of which was consumed while the products were not in use. This
energy use is expected to grow as products with new or advanced
functionality hit the market.

# Introduction

The U.S. Department of Energy (DOE) keeps records of how the nation uses
energy, and draws on this information to forecast energy consumption and
develop energy policies. In 1999, the DOE commissioned several studies
to determine energy consumption of electrical products that they had not
previously studied in detail. In particular, the DOE requested annual
energy consumption estimates for common consumer electronic devices,
including audio and video equipment, set-top boxes, and telephony
products. This paper combines and expands on the findings of these
investigations (Rosen & Meier 1999a, 1999b; Rosen, Meier & Zandelin
2000), and includes some newer products not included in previous
reports.

Previous U.S. studies have investigated energy use of consumer
electronics products. The Annual Energy Outlook 2000 (EIA 1999) included
TVs. One of the first comprehensive investigations of the energy use of
small domestic appliances in the U.S. was undertaken by a graduate
student at the University of California at Berkeley (Sanchez 1997). The
results of the Sanchez study were used in several subsequent reports
(Sanchez et al. 1998; Wenzel et al. 1997; Zogg & Alberino 1998). Other
reports have included power level measurements without regard to total
energy use (Huber 1997; Meier & Huber 1998).

This report presents national energy use estimates for several products
not addressed in these previous studies, including digital TVs (DTVs),
DVD players, digital cable boxes, and component stereo systems. In
addition, this report includes power levels and usage of all the
commonly used modes, whereas previous studies addressed only one or two
modes. The original database on which many of these previous studies
were based has been expanded to include a greater variety of models and
ages of products. In the case of TVs and VCRs, our database was
sufficiently large to allow us to adjust average power levels to reflect
actual distributions of age, manufacturer, and screen size in the U.S.
stock. Finally, we updated stock estimates to represent the number of
products in the U.S. in 1999.

# Data and Analysis

The ideal approach to estimating energy use would involve a national
metering program under which all products in a statistically
representative group of homes would be metered for a year. These
measurements could then be extrapolated to the whole country. This
approach would take years to complete. Instead, we resorted to a
bottom-up approach combining direct measurements and survey data as
follows:

1.  Determine the products to be included in the study

2.  Determine the modes that contribute significantly to energy use for
    each product type

3.  Estimate typical usage patterns, i.e. how much time the product
    spends in each mode

4.  Collect power measurements for the most commonly used modes for each
    product

5.  Estimate the number of units in the U.S. residential sector

6.  Estimate annual product energy consumption in the U.S. residential
    sector

Below we describe this approach in detail, following closely the steps
outlined above.

## Products

This study includes the energy use of the consumer electronic products
shown in Table 1.

Table 1. Consumer Electronic Products Included in this Study

+------------+---------------------+---------------+------------------+
| **Video    | **Audio Products**  | **Set-top     | **Telephony      |
| Products** |                     | Boxes**       | Products**       |
+------------+---------------------+---------------+------------------+
| Analog TV  | Component stereo    | Analog cable  | TAD              |
|            | system              | box           |                  |
| Digital TV |                     |               | Cordless phone   |
|            | Compact stereo      | Digital cable |                  |
| VCR        | system              | box           | Cordless/TAD     |
|            |                     |               | combo            |
| DVD player | Portable stereo     | Digital       |                  |
|            |                     | satellite box | Cell phone       |
|            | Clock radio         |               | charger          |
|            |                     | Game console  |                  |
+------------+---------------------+---------------+------------------+

NOTE: TV = television; VCR = videocassette recorder; DVD = digital
versatile disc; TAD = telephone answering device (answering machine).
TV/VCR combos are included in the analog TV category.

These were the most commonly owned consumer electronic products in the
U.S. in 1999. Other products, such computers and other office equipment,
will be considered in future studies.

## Modes

The term "mode" refers to a device state, and implies that the user has
a choice of settings. Most products have many modes, and each usually
requires a different power level. An accurate estimate of energy
consumption includes the energy use for each mode. This entails
identifying common modes, then estimating average power levels and usage
for each.

Different types of products have different operational modes. Typical
TVs have just two, but an audio system may have a dozen or more. Because
this study covers a variety of product types, we define operational
modes of the products considered in this report very broadly and limit
the number of modes to those that account for a significant portion of
product energy use. The definitions we used are summarized in Table 2.

Table 2. Common Consumer Electronic Modes

  -------------- ----------------------------------------------------------
  **Mode**^a^    **Description**

  Active         The unit is performing a requested service, e.g. record,
                 play, talk, etc.

  Charge         The battery charger provides current to the battery

  Idle^b^        The unit is on but not Active

  Standby        The unit is plugged in and appears off to the user

  Disconnected   The unit is unplugged
  -------------- ----------------------------------------------------------

^a^ These definitions were manufactured for the sake of convenience in
reporting power levels and energy use for this study. They are not
"real" in the sense that they may not be found in the dictionary or
product literature. Similar studies may define more or fewer modes, or
create different names or descriptions for the same modes.

^b^ Idle may occur (1) after the user switches the unit on but before
requesting a service, or (2) after the service ends (e.g. end of tape)
but before the user switches the unit off. Some consumers never switch
units with idle modes off.

In Table 2 and elsewhere, we use the terms "on" and "off" to indicate
that the product has a system power switch, and that the user can
control changes between these two states by directly or indirectly
toggling the physical or electrical position of this switch. Products
without a system power switch are always on unless disconnected from the
power source.

The product modes considered in this study are as follows. We consider
Standby and Active modes for TVs, clock radios, cable and satellite
boxes, and TADs. We consider Standby, Idle and Active modes for VCRs,
DVD players, and all stereos, but record modes are not included in the
Active modes for stereos because they are used so infrequently (CEMA
1996). We consider Standby, Charge and Active modes for cordless phones
and cordless/TAD combos, and Standby and Charge modes for cellular phone
chargers.

## Estimating Usage

Of the three types of data needed for a bottom-up estimate of energy
consumption, usage is usually the most difficult to acquire. Unless
resources are available for a survey tailored to the needs of the study,
the best sources of usage data are existing surveys, often conducted by
market researchers. Unfortunately, these surveys tend to deal with
household behavior instead of per unit usage. For example a typical
survey might publish the time household members listen to radio
broadcasts instead of the time household members listen to a clock
radio. This becomes a problem when more than one product is capable of
the behavior being studied. Existing methods allow the use of such
survey data to create upper and lower limits on per product active usage
estimates (Rosen & Meier 1999b).

Typical U.S. homes may contain several units of certain product types,
and usage values are likely to vary from one unit to the next. For such
products, calculations of average household energy use should utilize a
distribution of usage values instead of average usage values, thereby
avoiding the false appearance that, for example, homes with three VCRs
watch movies three times as much as homes with only one VCR.

A more difficult problem involves the time that the product is *not*
used. Market researchers survey product usage, but do not inquire about
the state of the product while it is inactive. As a result, these
surveys are not helpful in estimating usage patterns for the Standby and
Idle modes, which are critical for accurate estimates of unit energy
use.

Estimating usage patterns for this investigation involved a variety of
data sources and assumptions that varied from product to product. In
general, Active usage values were based on consumer surveys, while the
remaining values were estimated from anecdotal data or best guesses.

## Collecting Power Data

Power data may be collected from many places. Retail stores often allow
measurements to take place during business hours, provided the customers
are not inconvenienced. Where power measurements of older equipment are
desired, visits can be made to repair shops and second-hand stores,
where available. Data can also be collected at residences, but this can
be very time consuming. We adhered to the following steps in collecting
power data:

1.  Identify the operational modes to measure

2.  Plug the power cord of the unit into the power meter

3.  Record the Standby power draw before switching the unit on

4.  Record the power draw, in watts, of the unit in all other modes
    studied

5.  Switch the unit off, and confirm the Standby mode power consumption

We used a true RMS wattmeter that was custom-built for measuring low
power levels (0.1W minimum) with high accuracy (±0.5%+0.1W). This meter
displays average power every second. Where readings fluctuated, we
visually estimated the average power draw based on the readings.
Readings typically fluctuate only one or two tenths of a watt.

## Estimating Average Unit Power and Energy Consumption

To calculate the average unit power consumption (UPC) for each product
type, we weighted the arithmetic mean of the measured power levels to
reflect average usage as follows:

$\text{UPC} = \sum_{i = 1}^{M}{{\overline{P}}_{i} \cdot T_{i}}$ (1)

where *M* is the number of modes, ${\overline{P}}_{i}$ is the average
power draw in watts of the product type in mode *i*, and *T~i~* is the
percentage of time that the unit is in mode *i* such that Σ*T~i~*=100%.

Average annual unit energy consumption (UEC) was then calculated as the
product of the average UPC in watts and the number of hours per year
(h/yr) as follows:

*UEC* $= (\text{UPC}) \cdot \text{8760}\ \frac{h}{\text{yr}}$ (2)

where *UPC* is the average unit power consumption calculated using
Equation 1.

## Estimating the Number of Units in the U.S. Residential Sector

Because taking a national census of products is impractical, an accurate
count of the existing residential stock is not directly available. Two
methods can be used to estimate the residential stock count of a given
product nationwide. One method involves estimating penetration by
counting the products in a representative number of homes and
extrapolating to all U.S. homes. The other involves combining historical
sales/shipment data and average product lifetimes in a stock turnover
model.

**Estimating stock from penetration statistics.** Penetration statistics
are often available as a result of market research surveys or service
provider subscription records. Penetration values present a serious
problem to energy analysts because they represent the shares of homes
with *at least* one of the product in question. It is unknown whether
that respondent has one unit, two units, or perhaps three or more units.

To correctly estimate stock from penetration data, the number of units
per unit-home[^1] must be a factor in the equation, as follows:

$\text{Stock} = (\text{Households}) \cdot (\text{Penetration}) \cdot (\frac{\text{Units}}{\text{UnitHome}})$
(3)

![](media/image1.png){width="4.475694444444445in"
height="2.5381944444444446in"}**Stock turnover model.** It is possible
to construct a stock turnover model where number of units sold or
shipped and average product lifetimes are available. For this study, we
used a simple model -- the "4/3 Retirement Function" -- which assumes
that stock retires according to the function shown in Figure 1 (Koomey,
Webber & McMahon 1998).

> Figure 1. The 4/3 Retirement Function

This method should perhaps only be used where ownership surveys are not
available, due to the uncertainties associated with product lifetime
estimates. Where possible, it may be desirable to use both methods for
comparison purposes.

## Estimating National Energy Consumption

National energy consumption values for all product types were calculated
as follows:

$E = (\text{UEC}) \cdot (\text{Stock})$ (4)

where *UEC* is calculated using Equation 2 and *Stock* is calculated
using Equation 3.

# Results and Discussion

Using the methods described in the previous section, we collected a
database of over a thousand product measurements. Table 3 shows average
measured power levels in watts (W) and estimated usage patterns for the
consumer electronic products included in this investigation. Also shown
are the average annual UEC values, calculated using Equations 1 and 2.

Table 3. Usage, Power, and Unit Energy Consumption of Consumer
Electronics

<table>
<colgroup>
<col style="width: 23%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 12%" />
</colgroup>
<tbody>
<tr class="odd">
<td><h5 id="product">Product</h5></td>
<td colspan="2"><strong>Standby</strong></td>
<td colspan="2"><strong>Idle</strong></td>
<td colspan="2"><strong>Charge</strong></td>
<td colspan="2"><strong>Active</strong></td>
<td><strong>UEC</strong></td>
</tr>
<tr class="even">
<td><strong> </strong></td>
<td><strong>W</strong></td>
<td><strong>Time</strong></td>
<td><strong>W</strong></td>
<td><strong>Time</strong></td>
<td><strong>W</strong></td>
<td><strong>Time</strong></td>
<td><strong>W</strong></td>
<td><strong>Time</strong></td>
<td><strong>kWh/yr</strong></td>
</tr>
<tr class="odd">
<td><h5 id="analog-tv">Analog TV</h5></td>
<td>4.6</td>
<td>84%</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>75</td>
<td>16%</td>
<td>140<sup>a</sup></td>
</tr>
<tr class="even">
<td>Digital TV</td>
<td>8.8</td>
<td>84%</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>177</td>
<td>16%</td>
<td>320</td>
</tr>
<tr class="odd">
<td>VCR</td>
<td>5.9</td>
<td>77%</td>
<td>13</td>
<td>24%</td>
<td></td>
<td></td>
<td>17</td>
<td>4%</td>
<td>74</td>
</tr>
<tr class="even">
<td>DVD</td>
<td>4.1</td>
<td>72%</td>
<td>15</td>
<td>24%</td>
<td></td>
<td></td>
<td>17</td>
<td>4%</td>
<td>64</td>
</tr>
<tr class="odd">
<td>Component Stereo</td>
<td>3.0</td>
<td>65%</td>
<td>43</td>
<td>16%</td>
<td></td>
<td></td>
<td>44</td>
<td>19%</td>
<td>150</td>
</tr>
<tr class="even">
<td>Compact Stereo</td>
<td>9.8</td>
<td>72%</td>
<td>20</td>
<td>18%</td>
<td></td>
<td></td>
<td>22</td>
<td>10%</td>
<td>110</td>
</tr>
<tr class="odd">
<td>Portable Stereo<sup>b</sup></td>
<td>1.8</td>
<td>51%</td>
<td>4.9</td>
<td>13%</td>
<td></td>
<td></td>
<td>6.1</td>
<td>6%</td>
<td>17</td>
</tr>
<tr class="even">
<td>Clock Radio</td>
<td>1.7</td>
<td>99%</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>2.0</td>
<td>2%</td>
<td>15</td>
</tr>
<tr class="odd">
<td>Analog Cable Box</td>
<td>11</td>
<td>78%</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>12</td>
<td>22%</td>
<td>95</td>
</tr>
<tr class="even">
<td>Digital Cable Box</td>
<td>23</td>
<td>78%</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>23</td>
<td>22%</td>
<td>200</td>
</tr>
<tr class="odd">
<td>Satellite Receiver</td>
<td>16</td>
<td>78%</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>17</td>
<td>22%</td>
<td>150</td>
</tr>
<tr class="even">
<td>Game Console</td>
<td>1.1</td>
<td>78%</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>7.9</td>
<td>22%</td>
<td>23</td>
</tr>
<tr class="odd">
<td>TAD</td>
<td>3.2</td>
<td>99%</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>3.6</td>
<td>1%</td>
<td>28</td>
</tr>
<tr class="even">
<td>Cordless Phone</td>
<td>2.6</td>
<td>35%</td>
<td></td>
<td></td>
<td>3.6</td>
<td>60%</td>
<td>3.1</td>
<td>5%</td>
<td>28</td>
</tr>
<tr class="odd">
<td>Cordless/TAD</td>
<td>3.1</td>
<td>35%</td>
<td></td>
<td></td>
<td>4.5</td>
<td>60%</td>
<td>4.2</td>
<td>5%</td>
<td>35</td>
</tr>
<tr class="even">
<td>Cellular Phone<sup>b</sup></td>
<td>1.0</td>
<td>75%</td>
<td></td>
<td></td>
<td>5.0</td>
<td>5%</td>
<td></td>
<td></td>
<td>9</td>
</tr>
</tbody>
</table>

a.  UEC values shown here assume that all units are used equally. When
    the propensity of consumers to watch larger TV sets is taken into
    account, UEC increases to 150 kWh/yr (Rosen & Meier 1999a).

b.  Time does not sum to unity because this product is disconnected part
    of the time.

We estimated the number of units in U.S. stock using both ownership
surveys and stock turnover models. In most cases, the two methods
resulted in similar stock estimates. Where results differed
significantly, we chose the estimate that seemed more probable. Our
final stock estimates and national energy consumption estimates, by mode
and total, are given in Table 4.

Table 4. Number of Units and National Energy Consumption

  -------------- --------- ----------- ---------- ---------- ---------- --------- -------------
  **Product**    **Units   **Standby   **Idle     **Charge   **Active   **Total   **Share of
                 in 1999** Energy**    Energy**   Energy**   Energy**   Product   U.S.
                                                                        Energy    Residential
                                                                        Use**     Electricity
                                                                                  Use in
                                                                                  1999**^a^

                 M         TWh/yr      TWh/yr     TWh/yr     TWh/yr     TWh/yr    \%

  Analog TV      220       7.3                               23.5       30.8      2.7%

  Digital TV     1         0.1                               0.3        0.3       0.0%

  VCR            130       5.2         3.7                   0.7        9.6       0.9%

  DVD            3         0.1         0.1                   0.0        0.2       0.0%

  Component      75        1.3         4.6                   5.5        11.4      1.0%
  Stereo                                                                          

  Compact Stereo 50        3.1         1.6                   0.9        5.6       0.5%

  Portable       70        0.6         0.4                   0.2        1.2       0.1%
  Stereo                                                                          

  Clock Radio    130       1.9                               0.0        1.9       0.2%

  Analog Cable   40        2.9                               0.9        3.8       0.3%
  Box                                                                             

  Digital Cable  3         0.5                               0.1        0.6       0.1%
  Box                                                                             

  Satellite Box  13        1.5                               0.4        2.0       0.2%

  Game Console   54        0.4         0.0                   0.8        1.2       0.1%

  TAD            77        2.1                               0.0        2.1       0.2%

  Cordless Phone 87        0.7                    1.6        0.1        2.5       0.2%

  Cordless/TAD   35        0.3                    0.8        0.1        1.2       0.1%

  Cell Phone     70        0.5                    0.2        0.0        0.6       0.1%

  **Total**                **28**      **10**     **2.6**    **34**     **75**    **6.7%**
  -------------- --------- ----------- ---------- ---------- ---------- --------- -------------

^a^ Based on the 1999 U.S. residential electricity consumption of 1122
TWh/yr (EIA 2000).

According to Table 4, 37% of consumer electronic energy consumption (28
of 75 TWh) occurs during the Standby mode alone, and more than 50% (38
of 75 TWh) occurs when the products are not in use.

## Video Products

In the video product category, TVs clearly require the most energy per
unit. According to Table 4, the digital TVs we measured use more than
twice as much energy as the analog sets. This difference exists because
the average digital TV is about twice the size of the average analog
TV.[^2] When compared to sets of similar size, digital TVs do not
require significantly more Active power. The higher average Standby
power is also somewhat misleading, because the variance was very high.
Excluding outliers, the average Standby power of the measured DTVs was
nearly two watts lower than that of analog sets measured.

While the Active energy use of TVs will continue to increase if the
preference for larger screen sizes continues, Standby energy use is
likely to decrease as a result of national and international energy
efficiency programs targeting this mode. Implications for overall TV
energy use are uncertain, but in the long-term, advances in low-power
display technology may cut TV energy use to a fraction of its current
total.

VCRs and DVD players are nearly identical with respect to energy use.
Both spend the vast majority of time in Standby and Idle modes, where
90% of the average UEC occurs. We do not expect VCR energy use to change
dramatically because the VCR market is mature and because VCRs will
eventually be replaced by digital recording technologies. If DVD players
replace VCRs, there will be no significant change in energy use. On the
other hand, if DVD players supplement VCRs, as is expected for the near
future, household energy use will increase.

## Audio Products

Among audio products, component stereos are the most power-hungry, with
compact stereos taking a close second. Portable stereos and clock radios
are among the lowest energy consumers in our study. Both have average
annual UEC values under 20 kWh/yr.

National audio energy use may increase significantly as a result of the
growing popularity of home theater systems. While some homes have always
used stereo systems for television sound, advanced home theater setups
involve multiple sets of speakers, requiring more amplifier power. In
addition, a proper home theater system also includes a subwoofer, which
has its own amplifier.

## Set-top Boxes

The power needs of cable and satellite boxes in Standby and Active modes
are considerable -- and nearly identical. Because this significant power
use (11-23 watts) is continuous, cable and satellite boxes often use
more energy than the TVs they supplement. Digital cable boxes have
particularly high UEC values. At 200 kWh/yr, these units use more than
twice the energy of an analog box and 40% more energy than the average
TV set.

The number of cable and satellite subscriptions has been climbing
steadily throughout the nineties and is expected to grow even more
quickly with the introduction of new broadband and interactive TV
services. There are currently no digital-cable-ready TVs in the U.S.
stock, so each TV set, analog or digital, must have a set-top box to
receive cable programming. This implies that, even without cable
subscriber growth, the switch from analog to digital cable boxes will
increase annual cable household energy consumption by over 100 kWh *per
TV set*. What is more, only half of existing cable subscribers have a
cable box, so the switch to digital cable has the potential to increase
cable box energy use by a factor of eight -- i.e. twice as many existing
subscribers (all of them, not just half) need twice as many boxes (one
for each TV) that use twice as much energy. On the bright side, however,
we believe that digital cable boxes will become more energy efficient as
the market matures.

If all goes as the Federal Communications Commission plans, by 2006
every TV in the U.S. will be replaced by a digital TV or supplemented by
a digital set-top box, or both. While the switch from an analog TV set
to a DTV set of the same size will not increase energy use, the addition
of the accompanying set-top needed for high definition TV will. More
importantly, market research surveys show that a majority of people plan
to purchase or rent digital-to-analog converter boxes instead of
replacing their analog TVs (De Sonne 1998). This means that nearly every
home will have at least one digital set-top by 2006, whether a digital
satellite box, a digital cable box, a digital-to-analog broadcast
converter box, or a combination unit. The implication for residential
energy use is staggering. Assuming only one set-top box per home, U.S.
set-top energy will more than triple by 2006 to about 20 TWh/yr.[^3]

To date, game consoles have very low or no Standby power needs. Active
power needs of units sold before 1999 were also relatively low,
resulting in an overall UEC of only 20 kWh/yr. If future game consoles
require permanent cable, satellite or wireless network connections, they
are likely to use as much energy as digital set-top boxes.

Some of the newer set-top boxes not included in this study are
remarkably power-hungry. For example, one of the new personal video
recorders has no power switch and consumes 60 watts at all times. At
this rate, such a device would cost its owner about \$50 in electricity
bills every year. Another new product, a combination HDTV/satellite
receiver box, used over 30 watts in all modes. The proliferation of such
devices could have a noticeable effect on U.S. residential electricity
use over the next decade.

## Telephony Products

Electronic telephony products use very little power -- typically less
than 5 watts regardless of the tasks they are performing. But because of
the sheer number of them -- over 250 million in the U.S. -- total energy
consumption adds up to 6 TWh/yr.

# Opportunities for Future Energy Savings

The three factors that contribute to the national energy use of consumer
electronics are power, usage, and number of units. A reduction in any
one of these factors will result in a reduction in national energy use.

Power levels can be reduced through better product designs and the use
of more efficient components. Products that do not have Standby
functionality can be designed to draw zero watts by properly
implementing a hard-switch. The use of efficient power supplies is one
of the simplest and most effective ways to improve the energy efficiency
of consumer electronics, while other power savings can accrue through
power-saving chips and displays.

Time in higher power modes can be diverted to lower power modes using
existing power management techniques. For example, the battery chargers
commonly used for cellular phones supply current to the battery only
when the battery charge is low. In other cases, entire systems could be
powered down during periods of non-use. Where this involves separate
devices (e.g. a set-top box that switches off whenever the TV is off),
protocols must allow for power management across a network.

Reducing the number of consumer electronic products in the U.S. would
certainly reduce the national energy consumption of consumer
electronics; however, this method is unlikely to be popular with
manufacturers or most consumers. A similar effect could be realized by
reducing the number of appliances that are connected to the grid by
using switched outlets (e.g. those on receivers or power strips) or by
unplugging units that are rarely or never used.

Although existing technologies allow product designers to make
significant energy efficiency improvements in consumer electronics
products, market forces alone usually do not motivate them to do so.
Regulations and government-sponsored voluntary programs have the
potential to realize significant energy savings in the near future. For
example, the U.S. Environmental Protection Agency's Energy Star Home
Electronics program, which sets voluntary Standby[^4] power limits for
TVs, VCRs, audio equipment and set-top boxes, has the potential to
reduce the energy use for this group of products by 15 to 20
percent.[^5] In Japan, regulations targeting both Standby and Active
modes of TVs may reduce TV energy use worldwide.

Unfortunately, other trends may outweigh these savings. For example,
energy-intensive set-top boxes, only present in about half of U.S. homes
in 1999, are likely to become ubiquitous within the next five to six
years. Other trends, such as the increasing popularity of home theater
systems, not only replace existing equipment with more powerful units,
but may also encourage consumers to use their equipment more often.

We believe that now is the time to address energy efficiency in consumer
electronics. While this study shows that the energy use of existing
consumer electronics is significant, we believe that this is only the
tip of the iceberg. The explosion of devices designed to take advantage
of the deregulated communications market is underway, and measurements
of some of these early products show alarming power consumption levels.
We should therefore act quickly to encourage manufacturers to consider
efficiency in this group of products that has not heretofore been
properly addressed.

# 

# Limitations

With the exception of TVs and VCRs, no effort was made to ensure that
the data samples were representative of U.S. stock. This may have
affected average power estimates, for example, as result of regional
model or manufacturer bias. In addition, many products measured for this
investigation were new. This may underestimate total energy use by
neglecting energy efficiency improvements; i.e., older units that are
less efficient were not counted. On the other hand, older units
sometimes have less functionality, and are therefore less
energy-intensive. Excluding such products from our study may
overestimate energy use.

# Conclusions

Consumer electronics have become a significant power drain in U.S.
homes. Combined, televisions, VCRs, DVD players, audio products, set-top
boxes, and telephony products account for 75 TWh/yr (6.7%) of
residential electricity consumption. The largest energy consumers are
TVs at 31 TWh/yr, followed by component stereo systems at 11 TWh/yr.
Figure 2 shows the energy use of each of the products considered in this
study.

> Figure 2. National Annual Energy Consumption of Consumer Electronics

![](media/image2.wmf){width="6.002777777777778in"
height="3.6319444444444446in"}

![](media/image3.wmf){width="5.947222222222222in"
height="2.8833333333333333in"}By taking power measurements of the most
commonly used modes and estimating typical usage patterns, we calculated
the contribution of each mode to total appliance energy use. Figure 3
shows the average contribution of the Standby, Idle, Charge and Active
modes to total consumer electronics energy use.

> Figure 3. Contribution of Modes to Energy Consumption of Consumer
> Electronics

More than half of the electricity used by consumer electronics is
consumed when the products are not being used, namely, in the Standby
and Idle modes. Simple design modifications have the potential to cut
this energy use significantly.

*Acknowledgements*―This work was supported by the Assistant Secretary
for Energy Efficiency and Renewable Energy of the U.S. Department of
Energy under Contract No. DE-AC03-76SF00098.

# 

# References

Koomey, J., C. Webber, and J. McMahon. 1998. *Projected Regional Impacts
of Appliance Efficiency Standards for the U.S. Residential Sector*.
LBNL-39511. Berkeley, CA: Lawrence Berkeley National Laboratory.

\[CEMA\] Consumer Electronics Manufacturers Association. 1996.
"Consumers Making Modest Use of Recording Technologies." *CEMAcity
Gazette.* December 30.

De Sonne, M. 1998. *HDTVs --- It's Where the Buyers Are: Consumer
Interest, Set Availability, Set-Top Converters*. Washington, D.C.:
National Association of Broadcasters.

\[EIA\] Energy Information Administration, United States Department of
Energy. 1999. *Annual Energy Outlook 2000*. Washington, D.C.: U.S. DOE
EIA.

Huber W. Standby Power Consumption in U.S. Residences. LBNL-41107.
December 1997.

Meier, A., and W. Huber. "Results From the Investigations on Leaking
Electricity in the USA." LBNL-40909. Berkeley, CA: LBNL.

Rosen, K. and A. Meier. 1999a. *Energy Use of Televisions and
Videocassette Recorders in the U.S.* LBNL-42393. Berkeley, CA: LBNL.

Rosen, K. and A. Meier. 1999b. *Energy Use of Home Audio Products in the
U.S.* LBNL-43468. Berkeley, CA: LBNL.

Rosen, K., A. Meier, and S. Zandelin. 2000. *Energy Use of Set-top Boxes
and Telephony Products in the U.S. (Draft)*. LBNL-45305. Berkeley, CA:
LBNL.

Sanchez, M. 1997. *Miscellaneous Electricity Use in U.S. Residences*.
Masters Project. Berkeley, CA: University of California at Berkeley.

Sanchez, M.C., J.G. Koomey, M.M. Moezzi, A.K. Meier, and W. Huber. 1998.
"Miscellaneous Electricity Use in U.S. Homes: Historical Decomposition
and Future Trends." *Energy Policy* 26 (8): 585-93.

Wenzel, T., J. Koomey, G. Rosenquist, M. Sancez, and J. Hanford. 1997.
Energy Data Sourcebook for the U.S. Residential Sector. LBNL-40297.
Berkeley, CA: LBNL.

Zogg, R. and D. Alberino. 1998. *Electricity Consumption by Small End
Uses in Residential Buildings*. Prepared by Arthur D. Little, Inc. (Ref
34732-00) for the US DOE.

[^1]: A "unit-home" is a home that has at least one unit of a given
    appliance.

[^2]: The median screen size in our sample of DTVs was 50 inches, while
    the median analog TV screen size was only 25 inches.

[^3]: Based on preliminary average power levels for digital-to-analog
    boxes (5.5W Standby, 40W Active) and HDTV converters (8.5W Standby,
    48W Active).

[^4]: The Energy Star Home Electronics program does not address Active
    power levels and does not require automatic shutdown of units
    accidentally left on.

[^5]: Assumes 100% replacement of stock at current Energy Star levels.