In considering how to replace a furnace diagnosed with a cracked (thus dangerous) heat exchanger last week, I discovered that this month, by my calculations, and in my case, the cost of incremental electrical energy for home heating ( $0.0506 per kWh) fell below the cost for heating by natural gas($1.52 per 100 cubic feet ~ $1.48 per therm).
Even assuming an extremely efficient furnace/boiler with an Annual Fuel Utilization Efficiency (AFUE) of 96%, and an efficiency of 99% for electrical resistance heating, 1 million net BTUs of heat cost me $15.42 (gas) and $14.98 (resistance electrical). (The electrical power used by the blower is the same in each case.)
Using electricity to power an air-source heat pump during periods when outside air temperature is appropriate cuts the cost in half ($7.44).
This should give folks interested in home automation and control pause for thought. (Environmental considerations add yet another dimension to ponder.)
For example, leaving lights turned on 24x7 and the fridge door open both have the potential of _reducing_ my total bill from my utility during the heating season.
And the additional cost of a gas burner compared to a electrical resistance heating element is _never_ amortized by the lower price of gas.
And so on.
Lotsa balls in the air at the same time.
... Marc (still lookin for the 'rithmetic mistake ...) Marc_F_Hult
Leaving the fridge door open does what? Causes the compressor to run constantly and food to spoil? You are using the compressor to generate heat, colder on the shelf side of the fridge, hotter on the back and top. A big toaster does it better and doesn't have expensive parts to wear out.
Leaving the lights on is exactly the same as running a resistance heater or as the heat pump folks call it "emergency heat". Except that the light bulbs burn out and all the lights help keep you up at night and fade colors.
Use a well to provide heat to your heat pump year round. Well established technology.
Assuming you can tolerate the luke warm air that a heat pump puts out.
On topic, zoning is probably a useful area for home automation.
I think Marc was just trying to be humorous! With the energy cost situation
*temporarily* upside down, the spill heat from from leaving something like the fridge door open is likely to reduce the demand for more expensive gas or oil because the open door and ever-running compressor would help to heat the house via cheaper electricity. As you point out, there are other, hidden costs.
With gas and oil as pricey as they are, it's almost an economic certainty the price of electricity will rise.
It does give rise to an interesting question: Does it pay to have two types of heating systems if there's a tremendous flux in availability of fuel sources? How would that be manageable from an HA standpoint?
Why not just rule out the cost side and pay for it up front with today's dollars and not tomorrows.
Many live well on alternative energy. Solar with home automation is a great way to go. Many states have subsidies to help defray the costs. If you plan to live in your home for more than 6-8 years, it will pay for itself.
The best setup I have seen is a zero energy home. It produces more energy during the day and the meter spins backwards, at night you use more than you generate, so it spins forward. Ideally at the end of the month the end result is zero change. I have seen some home make money from the electric company. Works better in Florida than Fairbanks in the winter, but even in Seattle it is a viable source. My mother lives this way 1 hour outside of Seattle.
Pair this with a well programmed home automation system, florescent lights and a electric based heating system and you are doing well. In addition get a 30 gallon tank for the roof, with a on demand heater for back up and your covered, conserving all around.
That's a hard choice for many people. You need to be in a house for a long time to recoup but you need to be able to move around the country to move up in most companies. Where do you make that cut? Ideally, the government should make sure that whoever does the work gets compensated for it fairly with tax credits and other stimulants.
I'm not so sure. The last time I looked, solar had an awfully long payback time and most people said it was a labor of love of the environment more than a love of cost saving. That was only a few years ago. Maybe the swing in energy costs has made solar more favorable than it was.
Really? Tell us more. I always thought Seattle was in one of the zones where solar was really an iffy proposition because of the number of cloudy days a year. What were the up-front costs? Would it work for a high-wattage geek as well as your mom?
That's the lynchpin. If the Feds were really sincere about becoming energy independent, we would see serious assistance in the purchase and installation of solar systems.
In the example of the upstairs furnace in my house that died, my current thought is not to replace the gas burner at this time. (Estimates I've obtained for a high efficiency gas furnace + AC + heat pump are $10-12K :-(
I may end up with four heat sources in the same air handler ("furnace"):
Natural gas burner Heat pump Resistance ("strip") heater Hot water (via water-to-air heat exchanger)
The hot water in turn could be derived from the currently existing boiler in the basement, and(or) another heating plant which might be in an out-building burning a solid fuel.
My first repair will be to re-examine insulation and other energy conservation measures.
The second repair/conversion will likely be to put a water-to-air heat exchanger in the housing that previously contained the electrostatic air filter. This is practical because the heat source for the air handler in the basement is already from a big ol' Weil-McLain boiler via a heat exchanger so I 'just' need to get the hot water from the basement to the attic -- easier said than done in a house with solid brick interior walls. (I got to be pretty good sweating 1-1/4 copper pipe when I redid the heating in our stone Victorian house in Minnesota starting 20+ years ago during the _last_ energy credit hoopla.)
The exercise of installing the water pipes will also provide the incentive/opportunity to replace the last length of aluminum wiring in the house, add a second floor load center, and re-commence the hardwired lighting of the second and third floors.
Managing this from a HA perspective will be interesting in part because near-monthly changes in energy costs will be the norm for the foreseeable future. So a 'thermostat' in the scenario I've outlined needs to have energy cost inputs and competition include in the real-time calculations. I say "competition" because not all energy sources are available _ad_libitum_ at all times. For example, I will not upgrade the 200amp electrical service. So that
200x240 VA source for all house electrical is a boundary condition. And so on.
Add humidity control, geo, summer AC needs, etc and this is looking to be a very long term project. The HA software (CyberHouse) I sue was the only HA software that I am aware of to integrate electrical energy cost and energy management -- done via a Cutler Hammer Advanced Power System:
The 'Feds' are (ultimately) you and me. And we will soon advance another part of a baby step:
I will wait to spend real money on my system until January 1 2006 when these small, new Federal Tax credits go into effect. It may be that HA projects that increase HVAC efficiency could be partially funded with this mechanism -- commercially available high efficiency HVAC clearly can. Only $500 for conventional residential, but every bit helps.
ROTFL. Good humor is a great improvement to what Dave brought to this topic last time 'round in c.h.a ;-)
But mountain-top removal is a reality in Dave's home state of Kentucky, not jist in thet far-way furren land called West Virginee.
(FWIW, I am a Board member and Chair of the Issues and Policy Committee of an environmental group that is suing the US Army Corps of Engineers in Federal court to end this heinous practice in Kentucky.
A discussion of the Faustian bargain of low-cost electricity in exchange for environmental and health devastation caused by irresponsible coal mining practices can be found here:
Resources Council on "Electricity and Environmental Politics" Posted: June 7, 2005
And then thar's thet fassinatin third-order concern of how long fridge appliance bulbs will last under a new National "Open Fridge Policy" ...;-)
Well, if there is an "except that" clause , it isn't "exactly the same" , is it? ;-)
Well, it _was_ hot stuff when I started as a practicing as a ground-water hydrologist 35 years ago ;-)
Ah ... but you don't _have_ to tolerate that if you design and implement additional heating sources in the same air handler and do a better job of controlling/automating them than is standard HVAC industry practice. That's part of where we are getting to in this thread.
The other parts of your post are also on topic IMO.
But yes, 'zoning' is part and parcel of home Heating Ventilation Air Conditioning (HVAC) automation.
Note that controlling electrical heating sources is, in several respects, easier to accomplish than controlling the mechanical equipment required by conventional heating by managed convection of hot water and(or) hot air. 'Zoning' with electrical sources of heat energy becomes a challenge not primarily of the mechanics of physically running ducts and dampers and so forth but also of information management -- including energy costs -- and design and implementation of real-time decision algorithms in (really) smart 'thermostats'.
On the topic of keeping warm for less than the cost of burning dollar bills in a franklin stove, humor is good.
I think its a given. Nuke and coal can help, but they have other issues.
Commercial plants have done this for ages. Typically with oil and natural gas.
I had a brother in law with two furnaces. He was a tree surgeon and got lots of free firewood. He had one wood fired boiler and a backup oil boiler. Set the thermostats at different points and life was good.
From a home auto view, you could switch control between boilers pretty trivially. Not much of a leap to control a heat pump at semi-warm temperatures and a real boiler when the heat pump is not feasible.
The obvious question is can you extend the zone controls to heat only the rooms you care about? Use some learning system to predict which rooms you care about at which times of day, motion detectors to allow over riding, etc.
All seems doable. Then you have to ask what is the load of heating a room from 60 to 72 when someone enters, does that actually net out a savings over keeping the room (with furnature, etc.) at a constant value.
ROTFL. Top Dog Dave top posts and takes credit -- more than three decades into the era of significant mathematical computations of global heat budgets that account for the relative proportion of solar energy that is absorbed or reflected. I'll read the hardcopy of the journal _Nature_, in which this article was published when it gets to my house. Lay accounts often pull out a theme of topical interest and distort its significance for news purposes.
FWIW, As best as is now understood, the major factor in the anthropogenic effects on climate from burning coal in modern generating plants is carbon dioxide. About/very roughly 7% of all anthropogenic CO2 release from energy production worldwide is from burning of coal in US.
There is real work by real people doing constructive work on these real issues. For example, regions of the world that have sedimentary rocks from which coal is mined also tend to have thick sedimentary rocks into which carbon dioxide captured from the burning of coal could be injected, thus sequestering the CO2 from the atmosphere and biosphere much as natural geochemical deposition of the sedimentary rock limestone and dolomite does. This the case in Kentucky where Dave and I live and where most of the coal that runs our computers is mined.
There are significant (home automation) choices in all this that I am personally pondering at this time (hence the thread.)
A home heating system that burns coal pellets in the back yard releases as much CO2 as burning the coal in a modern coal-fueled power plant, but the home system typically releases more particulate matter and sulfur. Here in Kentucky, home use of coal and other solid fuels is making a comeback. I know someone locally who just added a coal-pellets to their home heating system and is thrilled with it.
The use of pellet-like fuel for residential heating is not a new idea. Forty years ago I lived in an apartment in Spain that heated by a system that fed almond shells from an electrically operated hopper to the firebox to heat the boiler. No X-10 though ... ;-)
However dirty they may or may not be, coal and other pellet fuels are legal (in most place in the US), available, practical and much, much cheaper than energy sources from utilities, so -- as they say -- I'm 'conflicted' ;-)
The end is in sight for my hardwired lighting project. So the next five-year HA effort might be to develop a HVAC system and overall energy strategy that is low enough in cost so that I can afford to stay in the house when the price of petroleum-based fuels doubles and redoubles again.
One of the next steps may be to build a mathematical energy budget model of the house, as much for the challenge as for a tool for decision-making in design and operation. This might also be a good start in graduating from an automated house to an autonomous house.
Not heating a room that isn't used saves energy. No argument there. The challenge is that most people use lots of rooms, some one regular schedules (dinning room at meal time) and others at very irregular schedules.
A underheated (or overheated) room has not only the air to heat, but also all the furnishing, floor, walls, etc. Getting all of it up to temperature quickly is not easy. Oversizing the furnace, ducts, fans, etc. is not a clear winner.
What you want is enough sensors to know what rooms you will be using, and get them conditioned before you get there.
The earth's survived years and years of darkened skies from various mega-eruptions like Krakatoa. I'm betting on improvements in solar technology that at least keep up with the incremental darkening of the skies. I hope. :-)
That seems to sum it up. The Feds are the ones to take the lead on this because they can allocate long-term funds to underwrite the development of solar energy. This is where a purely "free market" model fails. IMHO. There are some things like the interstate highway system and the broadcast spectrum that need the backing of an agency dedicated to long-range planning. Too bad Sen. Stevens is so drill happy.