Well, now you know why I got a C in physics.

I guess one could purify the basic question this way: Does 100% of the heat energy generated inside a closed, heavily insulated compartment (part of a theoretical appliance, let's say) get transferred to the outside of the compartment? I'd think that some of the heat would be lost (transferred as kinetic energy) in exciting the molecules in the insulation, plastic shielding, etc., and never make it outside the compartment. Heat CAN be absorbed, can't it?

My water heater, like most water heaters, is on all the time. It's heavily insulated, and the outside of it feels cool, year after year. I know the heat is going into the water, but as a space heater the water heater is useless. That's my basic quibble with the poster who started this forum.

Energy cannot be destroyed, but it can be altered. Heat is only one form of energy, and when it encounters resistance not of all it makes it to the other side as heat---I think.

I know I'm just guessing here, so I'd love to be educated on this specific point by someone with the right educational background.

Let's put it this way, if the insulation were to absorb heat and never give it back up to the surrounding environment, it would slowly heat up and eventually melt, and then vaporize. But that doesn't happen.
Thermal insulation doesn't work by absorbing heat... it slows the transfer of heat from one side to the other. The insulation does warm up some, but it is re-radiated from the other side of the insulation.

Basically, heat always goes somewhere. If you had a 100% insulated house, and NO heat ever escaped, and the only heat source was your own body heat... it would eventually build up inside that house, and you would die from the elevated temperatures.
Some people have built houses so tightly, with such good insulation that body heat alone was sufficient to keep the house warm in Winter. But the hardest part with THAT, is that you HAVE to have some air exchange, not only to bring in fresh oxygen, but also to de-humidify the air (because you also perspire into the air, raising the humidity). Highly efficient heat-exchanging ventilators (where the cool, dry incoming air is prewarmed by the moist, warm outgoing air) can help with that, but still represent a loss in heat energy from the system.

More practical, however, is a house that has good insulation, but the combination of body heat, appliance heat, and passive solar all combine to keep the house comfortable in Winter. This can be achieved with intelligent design, and the use of thermal masses that can absorb heat during the daytime, and re-radiate it at night. Thermal masses are not insulators. They are usually stuccos, masonry, specialized cement, or masses of water.
To be really energy efficient, the use of high-efficiency appliances is ideal, where the heating comes exclusively from body heat and passive solar.

Another thread also mentioned how passive solar can be used for cooling during warm seasons, too. Truly intelligent design can create a 4-season passive solar heating AND cooling system.

I slightly disagree. All of the materials you suggested as "thermal masses" are categorized as ceramics, which (in general) are decent insulators, when compared to metals. That's why coffee mugs are often ceramic.
Modern insulation for homes is styrofoam (polystyrene), a plastic, which is a better (cheaper!) insulator. I have about 14" of blown insulation in my attic. Works great.
I believe insulation is the biggest money-saver in home energy heating and cooling efficiency.

JW

I think today's homes and buildings are too sealed off from the outside air. A lot of human illness is traceable to this. So there's a big trade-off right there for all that wonderful insulation.

I heat my place entirely with wood (of which I have an infinite supply from my land) and leave the windows partly open all winter. If I don't, the place overheats! On days with no wind, a downdraft sometimes puts a little smoke into the house, which is my own heating-related health bugaboo. Still, I feel I'm healthier overall not inhaling people's recycled germs and formadelhyde fumes from carpeting etc.

Not too sure about that. Most office buildings are pretty sealed off, and it doesn't look like the people who work there are dropping like flies.

It's not the plastic that is the insulator, but the air bubbles trapped in the plastic. Air is a poor conductor of heat, unless it's moving (convection). Most insulation is a medium that traps tiny pockets of air. The best insulator known to man, aerogel, is 99.9999% air.

When speaking of insulators and thermal masses... we're actually talking about two different qualities, though there is some correllation between the two.

Insulators are materials that transmit heat slowly.

Thermal masses are materials that have a large heat capacity (the ability to store thermal energy).

The stucco, masonry, and cement I refer to are moderate insulators, but we don't insulate our homes with them, do we? If they were good insulators, we would. But they're actually not so good insulators. Sure, metals transmit heat faster, but masonry is much worse than fiberglass matt at insulating.

Intelligently designed homes will contain a lot of thermal masses INSIDE the external insulation envelope. The external insulation envelope reduces the transfer of heat into the home during hot seasons, and out of the home during cold seasons. During cold seasons, passive solar gain is a great thing... but only works during the daytime, unless you have some means of storing the thermal energy gain. It does you no good to have an 80 degree home at 3 PM, if it drops to 55 degrees at 3 AM. The air in your home is really bad at storing that solar energy you got during the daytime, especially since you have to recirculate your air, exhausting stale, moist air out of your home, and bringing in fresh air.

This is where thermal masses come in. Using thick plaster, stucco, masonry, and cement inside your home, where the solar gain can be stored up is intelligent design. All that thermal mass will be absorbing solar during the daytime, keeping your 3 PM temp to a comfy 70 degrees (instead of 80), and then re-radiate the thermal energy into your home at night, keeping it 65 degrees (instead of 55).

The fact that these materials are good insulators means that they will re-radiate that heat slowly... all night long... which is a good thing.

Edit: Oh, and the reason your coffee mug is ceramic is because it's a thermal mass. It will keep your drink warmer longer than a metal mug. Most people brew teas and coffees at around 140 degrees F. When you pour your drink into your coffee mug, the mug will absorb a lot of heat from the liquid, bringing it down to drinking temp (about 110 degrees) in a reasonable time. But once the temp of the mug and the liquid are equalized (around 120 degrees), the liquid has a tendency to cool faster than the mug. The mug will then slow the cooling of the liquid inside it by re-radiating heat into the liquid.

Have you ever wondered why they call it HVAC?
Heating, Ventilation, and Air Conditioning?
Most people understand the Heating and Air Conditioning part. It's all about keeping us at the right temperature, right?
Well... we've discovered that Ventilation systems are extremely important to both our comfort and health.

Modern buildings ARE sealed up pretty well, but they still need to provide proper ventilation. Mostly, this is done with an Air Exchanger. An air exchanger brings in fresh air, while venting stale air, but it runs the incoming air through a heat exchanger with the outgoing air. In Winter, this is done to pre-warm the incoming air, and reduce the amount of heat that's being vented with the stale air. In Summer, the opposite is true.

Well, I didn't say they were dying---just sick. Haven't you heard of "sick-building syndrome"? In a former life I worked for years in sealed office buildings and heard nothing but complaints from all my coworkers about their respiratory problems and frequent colds, which they started when they started working in those buildings. Also, it's possible that cases of cancer may be traceable to long-term inhalation of chemical fumes from carpeting and insulation etc. Of course, the relationship is hard to prove, but it's common sense to me.

When we still had an electric water heater (came with the house and replaced it with LP gas when it started to leak) I installed a timer (cost about $40 I think, for the timer) to turn the water heater "on" at 5:30AM so I had water to get ready for work in the morning, "OFF" at 8AM, then "ON" again at 5PM and "OFF" at 8PM. If I need hot water at other times, I could manually turn on the water heater.

This could be an inexpensive way to reduce water heating cost if you have a fairly new electric water heater.

Now we do the same thing, but have an LP fired water heater with electronic ignition, so I can still use a timer to turn it off and on as needed. Next step is to install those solar water heating panels that are sitting stacked in the shed.

Jim

I am going to be replacing my fridge soon. I've heard that fridges that don't have freezers in them consume a lot less energy. anyone know or have any comments?

Peanut, I love your puppy. is it yours or just a picture you found?

I dislike wired in fire alarms because one of the first things that can and sometimes does cut out in a fire is your power supply. no power, no alarm, no surviving.

I helped a friend build a house recently. Toward the end I installed some of the 10 or 12 smoke detectors in the house.

Every smoke detector had a 9-volt battery and a warning to change the battery every year. To me that sounds like disposing of a dozen 9-volt batteries every year even though they may have not have farted a single milliamp-hour.

But I don't suppose this waste really pertains to the thread.

(My own smoke detector uses a rechargable NiMH battery.)

I have tracked down a pump that uses 45 watts and will do the same job as my current 1hp pump. I will get the plumbing on it setup this weekend and provide some numbers. I'm currently hoping this will drop the energy usage for about $30/month to about $2/month giving me a 5 month payoff on grid power. The fact that it's feasible to run this pump off of battery power for outages and trickle charge those batteries through solar also makes this a great investment in my mind.

I watch my home's electrical consumption and it ranges from 595kwh to a high of 780kwh (during a long heat spell - a/c unit - ugh!).
However ... this month in rang it at a whopping 1,190kwh
I have no idea how it spiked to this level - I will have to monitor this situation closely.

The wife and kids are rather wasteful. The eldest toddler thinks the fridge is a play toy. The wife thinks it's her job to keep all the lights on in the house. I came home one night and I swear that the inside of our house looked liked the 4th of July. The wife said to my daughter recently not to play in the fridge because ... "Daddy is on his electricity kick again"

I gotta keep fightin' the good fight

Strider et. al., y'all are doing a great job trimming usage.


For most households, the biggest power users are: heating/cooling, followed by the fridge and the clothes dryer. Of these, heating/cooling can be dealt with via insulation etc., the fridge can be improved somewhat by fine-tuning (reflective layer between coils & cabinet, regularly vaccuuming dust from coils, etc.), and the clothes dryer can be done without in most cases (use clothes lines or drying racks, use the dryer only when you need to sanitize a load if someone's been sick, or when you need something dry immediately).


I got four of those Kill-A-Watt meters & gave three away to friends who are fellow geeks. (Eventually we're going to sell those on our website, and also offer them as premiums to clients who buy phone systems from us.)

I live in rental housing so my fridge came with the place and it's a truly obnoxious energy-hog. 323 watts while running; average 4.8 KWH/day. Part of the problem is it's large & crammed into a space where it gets almost no ventilation. Adding a PC-type fan (2 watts) and dryer-duct to force-ventilate the space behind the fridge reduced consumption to 4.4 KWH/day, saving of (extrapolated) 127 KWH/year. However what I'd rather do is replace this beast. That however will require dealing with property management...

The washer that came with the place is a conventional top-loader of 9 to 10 # capacity, uses 500- 800 watts while running, and total of 0.26 KWH/load. At 6 loads per month would be 1.56 KWH/month. This unit is presently only used for items that don't fit in the new one (below), which is rarely.

However this year I got a high-efficiency twin-tub (Danby DTT-420), 4 - 5# capacity, which uses 27 - 250 watts while running, total of 0.06 KWH/load, and at 12 loads/month works out to 0.72 KWH/month. This unit does all my washing except for occasional large items.

The dryer came with the place, is 220 volt, can't measure; but used rarely if ever (I switched over to indoor clothes lines which work fine). I have seen pictures of a micro clothes dryer that's sold in England (basically a scaled-down version of a conventional tumble-dryer) that uses 600 watts and holds about 2 - 3# of laundry (i.e. a pair of pants and a shirt, or a few pairs underwear & socks). This could be quite sufficient for those cases where one needs a few things dried immediately for whatever reason, or sanitized if someone is sick. It would basically serve as a backup to clothes lines.

The microwave (Emerson) uses 980 watts at full power, a typical cycle for nuking dinner is 0.2 KWH, and at 30 days/month this comes to 6 KWH/month. This unit handles most of my cooking tasks, i.e. I rarely have to use the electric stove/oven (220 volts, can't measure). This microwave uses 1 watt in idle mode (clock) and is easily unplugged when not in use.

The vaccuum cleaner (old Kenmore 2-speed) uses 500 watts on low speed (perfectly adequate for most cleaning) and 700 watts on high speed (rarely used); typical housecleaning cycle is 0.32 KWH, once per week, works out to 1.28 KWH/month.

My main computer (Apple laptop iBook G4) uses 20 watts while running and 2 watts on standby. This is typically on more than 12 hours/day.

My secondary computer (HP laptop ze-4600) uses 35 watts while running and 6 watts on standby. This is typically on 1-2 hours/day.

Both computers have about the same screen size and options.

Household PBX (yes, an office phone system at home; more about which below), Panasonic KXTDA-50 with KXTVS-125 voicemail: 27 watts, which works out to 19.2 KWH/month. (Panasonic has worked hard to reduce the energy consumption of its high-end PBX products, to about 25% of what it was in the previous generation of these systems.)

There's a bunch of network equipment plugged into power strips under the shelves it's mounted on; I'll need to put this stuff on an extension power strip to measure its usage.

The fan in the attic hatch uses 100 watts and is on at most 1-2 hours a day. The fan in the hall uses about 60 watts on "high" and is on at most 2-4 hours a week. The 6" desk fan is on at most an hour a day and uses about 17 watts. The 3" desk fan is on 4-5 hours a day and uses about 6 watts. When I come in after being in the field, and the house is hot, I'll turn on the 100-watt attic fan for an hour, and then turn it off and switch to a smaller desk fan to keep cool.

General strategy for cooling: use the bigger fans to get the temperature down to tolerable, and use the small ones pointed at me to keep cool. Most fans today are "generic" manufactured, and marketed at various drugstores, hardware stores, etc. under house brands. Taking off clothes helps a lot: if you can get by wearing underwear or shorts or a bathing suit or whatever at home, you'd be surprised how cool you feel regardless of the actual temperature.

TV: 5" diagonal B&W (Daytron "generic brand"), used a couple hours a year on average; the rating plate says 15 watts; with a quick test with a channel showing a baseball game, the meter shows 10 watts actual use. Zero on standby, it's an older type that turns completely off.

Radio: Baygen Freeplay (windup/solar/AC), when plugged in with its AC adaptor shows 0 watts when idle (0.01 amps) and 1 watt when playing at normal room volume. Typically used less than an hour a day.

There are a few other things that need to be measured e.g. clock-radio in bedroom; I'll get to these eventually and might end up replacing them or putting them on switches.

Just an update to remind everyone to keep at it.

the bill for the last two months just came in
1990 kwh used in 59 days
1.41 kwh /hour used down from my all time high in winter of 2.26 kwh/hour and shaving another 5% off of my previous low of 1.49 kwh/hour

Thats lowered my bill from $187.43 for 57 days to $120.4 for 59 days (flat rate 6.050 cents/kwh) so thats just over $60/month which isn't half bad for an all electric house that I'm just getting started on making more efficient. This price doesn't include the other fees and tax which add $7.60/month this time. Every watt saved is also saving on not needing to pay those fees which have dropped from $30.77 on the first bill to $15.23 on the last.

The only real money spend was on replacing all bulbs with CF bulbs and that bit of insulation on the back of the fridge. I'd guess that cost me about $150 to do. The real savings have come from reduced usage.

I should be getting the pump switched over to my new one in the next week or so. That should show up on the bill in late september as a savings of about 1000 kwh I hope.

Add in the woodburner for this winter and I hope to get a $30+ fees/month bill in late september. That would be 1/3 of my starting usage and low enough to make alternative energy feasible.