1. Next discussion group: “50 Ways to Cut Energy Usage in Your Home” will be held at the
Central Avenue Bakery, 174 Central Avenue, PG, on Thursday, April 6, from 7:00 to 9:00 PM.
The meeting is free and the public is invited.
How Do I Lose Energy--
Let Me Count the Waste
The average American home turns high quality energy into useless low-grade heat.
How? By using crude devices designed for energy that was once nearly free—but now that it’s
getting scarce and expensive, it’s time for a change. What do we do that wastes energy?
Lighting
Most lighting is still done with incandescent bulbs—a fine tungsten filament is heated by electric
current in a vacuum—so hot that it glows. The problem is, if you get tungsten hot enough so
most of the radiation it emits is visible, it melts or evaporates. So the vast majority of the output
of an incandescent light bulb is invisible infrared radiation that heats the bulb envelope and
surrounding surfaces. If you have the light on when you’re heating your home, and you have
electric heat, it doesn’t matter much. But in any other situation, you’re throwing away almost all
the power that goes into that light bulb. What’s better? A halogen light can burn a little hotter
than a standard bulb, because it uses a gas like iodine to react with tungsten that sublimates from
the filament and return it, rather than letting it condense on the glass surface. A compact
fluorescent bulb uses about a quarter as much power to produce the same light as an
incandescent bulb, and an LED-based lamp uses on the order of a tenth as much. However, LED
lamps are still quite expensive to buy, though the dealers say they are more economical in the
long run. By the way—any light that uses a flame as a light source is probably even less
efficient than an old-fashioned bulb.
Heating
Heating is required when the temperature indoors is unacceptably cool for the occupants or the
contents of a home. Once the desired temperature is reached, the only heat required is the
amount that is lost to the environment through the floor, walls, windows doors and roof. If they
don’t let any out, you don’t have to put any in. The key to keeping a home at a comfortable
temperature is insulation. And remember, you can buy insulation cheaply now, but you will
have to purchase energy dearly later.
There are several ways to heat a home, and each warrants a little discussion:
• Fireplaces range from the old, crude open box with a chimney, to sophisticated glass
-fronted units with heat exchangers, blowers and thermostats. The simple open fireplace
typically burns wood or gas, drawing air from the room to feed the flame, heating it to a
Newsletter Editor: Mark Folsom 831 648 1543 folsomman@redshift.net

2. very high temperature and sending it up the chimney. Almost all of the heat that gets into
the room is in the form of radiation, which is a pretty small fraction, while the bulk is lost
in the hot flue gas. Even more pernicious is the way the air consumed is replaced—it
comes into your home from the cold outdoors, under and around doors and leaky
windows—and may cool your home more than the fire heats it. Of course, the most
sophisticated fireplaces can be as efficient as a modern furnace.
• Wood stoves can also be relatively efficient or very wasteful. The most wasteful are
those that burn the wood rapidly and hot, with a lot of hot gas going up the chimney.
More efficient units burn the wood more slowly and extract a greater fraction of heat
from the flue gas. However, cooler smoke can condense more readily on the chimney
walls, sometimes leading to increased danger of chimney fires.
• Electric resistance heaters, such as the electric baseboard type, are very efficient with
respect to converting electric power into heat—but there’s a huge heat loss at the power
plant: about two-thirds of the heat energy of the fuel used to generate the electricity is
discarded as waste heat. That isn’t because the power generators are perverse, it’s a
consequence of the laws of thermodynamics—heat engines can never turn all of the heat
in a fuel into power. However, if the power plant can find a local use for its waste heat, it
isn’t wasted, and could be used as process heat for some industrial process, or as space
heat for homes or businesses. This is called cogeneration.
• Heat pumps can make the overall picture even better. The special thing about electricity
is that it’s 100% available (meaning that all of it can be used to do work, unlike heat),
and can thus be used to operate a motor at nearly perfect efficiency. And the really neat
thing about a motor is that it can be used to take heat from the environment and pump it
up to a higher temperature—so all the electric power goes into heating your space, and
some heat from the cooler environment is added in as well. It reverses the principle of a
heat engine and instead of dumping low-grade heat into the environment, it takes low-
grade heat from the environment and upgrades it a little bit to heat your home. How
much it can get from the environment for each unit of electric energy depends on the
temperature of the environmental heat source and the temperature of your home—the
smaller the difference, the better it gets. That means that, if you can take heat from a
source underground, instead of the cold winter air, you get an extra bonus of efficiency—
and savings.
• Furnaces can range from around seventy percent into the nineties. If yours is old and
decrepit, it will cost you dearly as fuel prices rise—as they surely will. The problem with
a conventional furnace is that it converts high-quality energy (high temperature flame)
directly to low-grade heat, without exploiting all the power that a really hot flame makes
available. When concentrated energy is converted to diffuse energy, the process is
irreversible—its availability is lost forever. I’m not aware of any small-scale
cogeneration plants that are available commercially, but they would be good to have—
you could heat your home with 2/3 of the energy and use or sell the rest as electricity.
• Solar heat is available on sunny days at about 1000 watts per square meter. If you can
store some of it in a big thermal mass when it’s available, it can help keep you warm at
other times.
• Hot water heaters in the US have traditionally had a big tank full of water that’s kept
hot all the time. They continually leak heat into their surroundings—heat that has to be
replaced with a flame or an electrical resistance heater. Fortunately, on-demand heaters
Newsletter Editor: Mark Folsom 831 648 1543 folsomman@redshift.net

3. and solar water heaters are available now as alternatives. Leaving hot water running
longer than necessary can waste a surprising amount of energy.
• Dehumidifiers extract moisture from the air and collect it as liquid water. In the process
of condensing, the water gives up a lot of heat, which is put into the dried air, which is
thus warmed a bit, as well.
Cooling
Almost all space cooling is done by refrigeration—a heat pump is used to extract heat from one’s
living space and dump it somewhere in the environment, along with the work it takes to do the
pumping. The bigger the difference in temperature between your living space and the sink where
the heat is dumped, the more power it takes per unit of heat removed. Humidity contributes a
great deal to the air-conditioning load, because the water vapor gives up a huge amount of heat
upon condensing to liquid. Again, if you have a nice cool cave or a big cool underground mass
where you can dump your heat, you can get rid of it more efficiently than trying to get the hot
summer air to accept it. Heat always tends to flow naturally from warmer places to cooler ones,
and always requires work to make it go the other way.
Cooking
There are many ways to heat food, and most also involve heating the surrounding air. Each has
its characteristic ways of wasting energy, and many can be used more efficiently with a little
thought.
• Ranges--A gas flame that curls up around the bottom of a pot or pan will mostly heat the
air nearby—as will an electric burner that’s too big. If the space heater is in use anyway,
it might not make a lot of difference, but if the air-conditioner is running, the extra heat
will just load it up further. And—if you turn on an exhaust fan to draw air out of the
kitchen, an equal amount of air will be drawn in from outdoors to make up for it. If the
outdoor air is cool, you may have to heat it and if it’s hot or humid, you may need to cool
it.
• Ovens usually vent into the kitchen and lose heat through their walls as well.
• Microwaves are usually quite efficient, but often don’t produce very appealing results,
especially when cooking meat dishes.
• Crockpots and slow-cookers are often better at holding in heat than regular pots and
pans, but very long cook times can aggravate heat loss.
• Outdoor cooking may or may not waste heat directly, but it has the advantage that it
doesn’t burden indoor climate control and ventilation.
Refrigeration
Keeping food cold or frozen is a great way to keep food and beverages fresh, but it comes at a
high cost in energy, more so in a warmer home. Each time a refrigerator door is opened, cool
dry air is lost and warmer, more humid air replaces it. That new air has to be cooled to the
temperature setting of the refrigerator and the moisture condensed out of it—often in the form of
frost in the freezer, which then is melted and drained away. Big refrigerators generally use more
energy than small ones, and old ones use more than new. Uprights use more than chests.
Holding the door open while staring in uses the most of all.
Newsletter Editor: Mark Folsom 831 648 1543 folsomman@redshift.net

4. Entertainment
Televisions, VCRs, DVRs, DVDs, computers, stereos, game consoles and the like all draw
power, often even when they are dormant or turned off.. Though their contribution to energy use
is not usually as great as heating, air-conditioning or refrigeration, they can add up if not
managed well.
Resources for further information:
• C. Crane & Company—for LED lighting
http://www.ccrane.com/lights/led-light-bulbs/index.aspx
• Energy Star—for high efficiency appliances
http://www.energystar.gov/
Newsletter Editor: Mark Folsom 831 648 1543 folsomman@redshift.net