Asymmetrical Information

Along the same lines -- here's my question. Why is composting considered a good thing and burying yard waste in landfills a bad one? Doesn't decomposition release greenhouse gases (not only CO2 but methane)? And doesn't burying leaves and lawn clippings act as a carbon sink?

In northern parts, at least where it's far enought north that it snows, the roofs turn white in the winter anyway.

If a white roof had a palpable, measurable benefit beyond appeasing the Carbon Gods, wouldn't more roofs be white already?

I live in Minneapolis, and changed my roof from a dark to lighter color. My house is more comfortable in summer (I have no useful comparison on energy cost). Winter sunlight is much weaker, so the effect of the change doesn't seem to leave me colder.

Another consideration for roofing around here is the rate of snow melt and associated ice damming that can lead to water in walls and ceilings. A flat white roof might need different engineering to handle the snow load?

Interestingly, the very topic came up in one of the courses I have taken in mechanical engineering (I think it was fluid mechanics). The problem is that reflecting is not enough, because the rays are not exiting through the atmosphere into space, but are rather reflected back downwards. So, wouldn't it be better to optimize the urban heat island effect by painting the houses BLACK on the roof?
In the long run, it depends whether the summer is going to be longer or shorter than the winter (and sadly, Global average temperature doesn't help here, because there are large regional differences). Whatever is longer should give you a hint on what color to choose :)

On a side-note, the chinese are accidentially producing something I'd call a ray-hole. They are emitting tons of aerosols which reduce cloud cover and create a passage for reflected light rays. Perhaps this is a good way to go?

I'm not going to comment on the effect of surface albedo on overall energy consumption and the like, that is a bit over my head. But just from what I know about the thermodynamics of air conditioning systems, I guarantee you that all things being equal they are far less energy efficient than heating systems. Among all the creature comforts that we Americans have come to take for granted A/C is probably one of the worst energy hogs.

I would go one step further. Instead of painting the roofs white, I would plant rooftop gardens. They provide a cooling effect in the summer, plus the plants directly absorb the CO2 as they grow.

There are already some "green" buildings that are built this way.

Just off the top of my head (no time for serious analysis):

The cooling effect in summer will be much more pronounced than in winter, because the sunlight is greatly more direct in summer, and the days are much longer. The earth is tilted on its axis by 23.5 degrees (roughly) relative to the plane of the ecliptic; here in Northern Virginia (latitude 38.5 degrees, pretty close), that means that the sun gets to about 15 degrees of directly overhead during the long days in June, while in late December it is only 28 degrees above the horizon at noon. So there's a lot less sunlight to reflect in winter, and for less time each day.

It is also true that air conditioning is vastly less efficient than heating. Air conditioning doesn't eliminate heat, it just moves it out of the house, and creates a lot more of it in the process (all the energy used by the AC unit becomes heat). This adds to the urban heat island, increasing the ambient temperature and leading to more AC being used, et cetera.

I'm a scientist but not the right kind...

One thing I thought to point out: in many of the classic home styles of which I'm aware in the Northeast attics are often (not always) left uninsulated and cold: people use 'em like a cellar for storage, if they can access them at all --- and there's a lot of insulation between the attic and the rest of the house: essentially fiberglass packed between what would be the floor joists of the attic. So the idea of doing anything to the roofs of Northeastern houses to affect the use of heating is misguided, and meanwhile it's still a great idea for LA.

Although my wife and I were bitching about this this morning: the San Francisco Bay Area is a place devoid of the simple insulating practices (storm windows, windbreaks on doors, etc.) that are de rigeur in the Northeast, because, well, it never gets so cold (except rarely, like this year). The houses are freakishly energy inefficient.

No idea regarding energy savings, but New Scientist reported that painting the roofs of *all* buildings on earth white would cancel out global warming that has taken place since the beginning of the industrial revolution. But a model taking into account atmospheric effects may not agree.

http://www.newscientist.com/backpage.ns?id=mg18825273.000

That article seems to treat as a bit of a lark. Additionally, it seems to be someone's back-of-the-envelope calculation.

It'd be nice to think this was the case; it'd be a hell of a lot easier than planning to sequester CO2 in the North Sea.

There are some paints additives that do a fairly good job of reflecting heat without being white. Some sort of molecular behavior I haven't bothered to understand.

They are somewhat more expensive that common paints, some of the expense being a special mixer to put in the additives.

The answers are pretty much correct. AC is much less efficient than heating. And the lower sun in winter is going to supply less heat regardless of the color of your roof.

As pointed out, most houses are build to defeat heat gain/loss through the roof anyway. If there is a steady air flow through the attic then the temperature at the roof surface won't matter much within the house.

Sunlight can supply significant winter heat through the windows. The key is to have air circulation. Otherwise the South facing rooms become too hot and the homeowner closes the blinds and defeats the benefit.

I wish the GW situation was as simple as reflecting roofs. In the simplest model it is. Too bad that model requires an earth without air, oceans, ice, or clouds.

Assuming that global warming is actually occurring (and is not simply a wedge used by Marxists to force a worldwide government and cripple the economy), there are a couple of other fixes possible.

My preferred method would be to place a solar power satellite in the Earth-Sun L1 (libration) orbit, about a million miles away from the earth in the direction of the sun. A satellite placed there (which would be mostly a reflective sheet of aluminum a few atoms thick, stretching out to form a circle a little over 500 miles across) would block out 0.1% of the insolation received by the earth, and also produce as much electrical energy as all the commercial nuclear plants in the world combined - multiplied by 300.

Or we could just induce a nuclear winter by bombing the hell out of some desert somewhere.

While painting the roof white might not help the house, it may help the heat island effect in the city. All those black rooves with soffit vents and air flow are generating hot air that rises up above the city.

EI

Don't waste your time worrying about carbon. That's what we have plants for. (Carbon dioxide is ca. 0.05% of the atmosphere, by partial pressure.) Water vapor absorbs much more solar energy than CO2, but no one is bleating about that.

Just stay prepared for the next doomsday fad to sweep urban lefty neurotics. Y3K won't come for a long time, avian flu has (ahem) laid an egg, killer bees have buzzed off, the Alar fell very far from the tree, AIDS hasn't progressed beyond the shirtlifting/junkie set, so we have to wait for the next thing to doom us all. Maybe Godzilla will come out of retirement. Sometimes it seems as though the left must spend all of its time watching the Lifetime channel.

The sky is falling! Give me all your money or you're doomed, doomed I tell you!

No matter how much cats fight, there always seem to be plenty of kittens --Abraham Lincoln

What nonsense is this that air conditioning is less efficient than heating??

Typically, COPs vary from a low of about 1.7 to a high of about 3.3 for air conditioners.
(From http://www1.sedo.energy.wa.gov.au/pages/refriger.asp

Heating, unless it's a heat pump (basically an air conditioner) will have a COP of less than 1. A "high efficiency" furnance will have a COP of 0.9.

Energy efficiency is always tricky to discuss. Surely gas/oil heat has to be more efficient than electric cooling, since burning the gas/oil releases heat energy directly, where as electric cooling has mechanical steps. Of course when calculating energy efficiency for a society you also have to worry about the efficiency of getting the energy to where you want to use it.

In seconding some of the other comments, I thought that painting the roofs white was to reflect energy back into space to offset the increased absorption of higher CO2 levels not to actually reduce CO2 levels (or reduce the rate at which CO2 levels increase). And even if it did reduce the rate at which CO2 was produced, this would have to be a small effect, more than offset by the CO2 increases from development in the third world. So CO2 is going up no matter what the US does.

I would also point out that heating and cooling are pretty expensive, so I would bet that cost effective measures are pretty thoroughly used.

My favorite carbon fix: nuclear power

1) You are right, there is a winter heating debit
2) They should. I checked one website and they did.

The reading I did indicated white roofs were used widely until air conditioning, and still are in the Middle East. They went out of favor because they showed all the dirt, mold etc..

In addition to reducing cooling costs, white roofs, trees that shade asphalt etc can potentially reduce the temperature of a city like Los Angeles by several degrees, reducing the rate of smog formation...

Michigander is right for practical purposes. What people want is effectiveness, not efficiency.

Heat pumps, while cooling, are usually more effective than when they are heating. They will also usually be more effective than a furnace.

Heat pumps achieve high effectiveness by moving heat from where it is not desired while cooling. And by moving heat to where it is desired while heating.

Since heat pumps move heat energy instead of converting it to, or from, another form, the word efficiency isn't very useful.

Confusing? Look at it this way. If we built a huge furnace and began burning everything* we could, the Earth would heat up. That is efficient.

But if we could replace that furnace with an ideal heat pump it would just shift heat around. It wouldn't heat the Earth but it might heat where you were while others would be cooled elsewhere. The heat pump would have no defined efficiency.

*Don't confuse this with the greenhouse gases arguments. Apples and Oranges.

My question is, what is the effect of solar panels on rooftops in terms of cooling building in summertime? Would they be more efficient than painting rooftops white? Is the energy they absorb to make electricity be compared with the energy white paint reflects back into space?

Surely gas/oil heat has to be more efficient than electric cooling, since burning the gas/oil releases heat energy directly, where as electric cooling has mechanical steps.

Wrong! The "COP" stands for "coefficient of performance," which is the number of units of energy moved per unit energy consumed. It takes less than 1 joule of energy to move a joule into or out of your house with an air conditioner or heat pump. On the other hand, you must always burn more than 1 joule's worth of gas to move 1 joule into your house because your furnace has exhaust gases that are warmer than the air outside of your house, leading to heat waste.

(Also, the efficiency and total consumption of energy in either case depends on the difference of temperature between inside and outside your house; typically winter differences are greater than summer)

That said, the generation of electricity by burning oil or gas isn't terribly efficient; at best you'll get a COP of .6 and usually lower. That means that if you calculate overall efficiency from coal-fired steam turbine through the warm transformers and out your air conditioner, your air conditioner (or heat pump) may end up using more power than your gas furnace to move the same overall amount of energy.

But in any case the question can't be answered by resort to "Surely X must be true..."

It seems to me that if you wanted to change the energy use of heating and cooling for houses, the most efficient thing to do would be to build houses underground.

Two feet underground the ambient temperature in North America would likely resemble that of caves. There's nothing googlable about such a stat, but I'd guess 68 is reasonable. In such a case, you'd use the earth itself as a reflector.

I don't think I'd want to live in a Hobbit hole (unless it had a 60 inch plasma and THX) but it does solve a lot of problems.

If caves were a nice comfy 68 degrees, we wouldn't be living in houses. As I recall, cave temperature is about 55 degrees, which is a little chilly for year-round living. My wine cellar in the basement has three exterior "cave" walls; the other wall adjoins the regular basement. The temp hovers around 60 degrees.

First of all, I can't imagine what kind of paint would stick to our composite roofs here in the prairie states - how often would they have to be repainted? Can the roofing material withstand being painted, or will the paint decrease the life of the shingles?

Secondly, Rex is correct. Caves are around 58 degrees. I know because there are hundreds of limestone caves in this area, and they are used for storage of all kinds of things from Disney movies to government cheese.

Beth: I don't think painting shingles would work, but maybe they could be replaced with ones where the little gravel bits that form the exposed surface are white instead of some dark color. There's a question about that I don't know how to answer: AFAIK, the reason for the little stones is to protect the other materials in the shingles from sunlight. Would that be as effective with a reflective white gravel as with dark stones that absorb it? If white shingles last only half as long, any beneficial effects might be canceled out by all the emissions associated with replacing them (manufacturing, decomposition in landfills, transportation of the shingles and the work crew...)

White materials tend to let more light through, but I think it's the ultraviolet that does most of the damage, and so maybe there's a material that is dark to UV (absorbing and blocking it), while it's white and reflective in the visible and infrared bands that carry most of the heat.

Up where I live, we use air conditioning for 6 to 10 weeks a year, and heat for 8 months a year. Making the building absorb less solar heat doesn't sound like a good tradeoff at all in terms of individual energy bills. (Also, as has been previously mentioned, most houses have unheated or cooled attics, so roof treatments don't do much effect anyhow.)

1. painting roofs white reduces the *urban heat island effect*

ie this is about reducing the urban temperature so that *everyone* uses less air conditioning.

A little googling finds an article by the Berkeley team that invented this:

http://eande.lbl.gov/HeatIsland/PUBS/PAINTING

[quote]
White roofs retain their energy advantage surprisingly far north. Let's compare the solar intensity on a flat surface in June and in December at the latitude of New York City. By December, the length of the day has halved, and the sun is so low that it "sees" only half the roof area that it saw from on high in June. Moreover, New York is about three times cloudier in winter than summer. The three factors multiply: 1/2 x 1/2 x 1/3 = 1/12, so potential solar absorption on a roof is only 1/12 as great in December as in June. The bottom line: because so little winter sunlight ever makes it to the roof in the first place, it doesn't much matter what color it is. White singles therefore allow buildings to be much cooler in summer and yet be only slightly colder in winter (because only a relatively small amount of absorbed sunlight is foregone). [end quote]

(planting big trees has a similar effect on air conditioning load).

It does not, necessarily, reduce the solar absorption of the earth. *that* depends on how much greenhouse gas there is, and at what frequency the light reflects back at.

1. painting roofs white reduces the *urban heat island effect*

ie this is about reducing the urban temperature so that *everyone* uses less air conditioning.

A little googling finds an article by the Berkeley team that invented this:

http://eande.lbl.gov/HeatIsland/PUBS/PAINTING/

[quote]
White roofs retain their energy advantage surprisingly far north. Let's compare the solar intensity on a flat surface in June and in December at the latitude of New York City. By December, the length of the day has halved, and the sun is so low that it "sees" only half the roof area that it saw from on high in June. Moreover, New York is about three times cloudier in winter than summer. The three factors multiply: 1/2 x 1/2 x 1/3 = 1/12, so potential solar absorption on a roof is only 1/12 as great in December as in June. The bottom line: because so little winter sunlight ever makes it to the roof in the first place, it doesn't much matter what color it is. White singles therefore allow buildings to be much cooler in summer and yet be only slightly colder in winter (because only a relatively small amount of absorbed sunlight is foregone). [end quote]

(planting big trees has a similar effect on air conditioning load).

It does not, necessarily, reduce the solar absorption of the earth. *that* depends on how much greenhouse gas there is, and at what frequency the light reflects back at.

foxmarks

Welcome to Behavioural Economics.

Studies show when it comes to energy efficiency, consumers (and indeed companies) avoid in investing in measures which have a payback of *2 to 3* years

ie an Internal Rate of Return (tax free) of 30-40% per annum.

It's very difficult to square this with other studies which show personal discount rates of c. 10% (or lower), when making investments.

Why this would be so is a subject of debate:

- information problems - consumers and companies may not be aware of how much they are spending on energy, or the difference say between a modern fridge and a 1970s one (4 times the energy efficiency) (1)

- agency problems - tenants (eg companies renting space, or apartment tenants) may not be incentivised to invest in energy efficiency (they won't be around long enough to reap the returns)

- credit problems - poor consumers, certainly, and perhaps many companies, are cash flow constrained. They can't readily make investments in energy saving because they can't borrow

- Behavioural Economics - humans have different discount rates for different 'buckets' of their lives.

http://en.wikipedia.org/wiki/Behavioral_economics

see 'hyperbolic discounting' and Harvard economist David Laibson for some ideas.

The assumption that 'if white roofs were a great idea, everyone would have one' is akin to the famous Stigler-Friedman conversation 'there's no point picking up that $20 bill that someone dropped, because in an efficient market, that $20 bill couldn't exist'.

The reality is markets exist because clever entrepreneurs spot market inefficiencies that have yet to be arbitraged away, and arbitrage them.

(1) the fridge is also a wonderful example of how much there is to go for in energy efficiency with a little concerted effort. It's not widelly known by how much fridge efficiency has increased since the 1970s. By no means are we efficient users of energy as a society.

Another interesting example is a European washing machine (front loading). It uses something like only 60% as much energy, and less than half as much water, as a top loading American machine. I don't think Europeans have dirtier clothes than Americans?

But top loaders in the US are relatively rare, and relatively expensive.

While air conditioning is inherently less efficient from a physics perspective, don't forget that in many areas we're not necessarily talking about heating or cooling the same amount of heat. In New York, for example, air conditioning only very rarely is needed to cool more than 20 or 30 degrees Farenheit lower than the ambient temperature at the most. By contrast, in the coldest parts of winter one must heat over 60 degrees higher than the outside temperature.

Of course, there are issues of insulation versus airflow that confuse the issue. One reason why homes on the Pacific Coast don't have so many "energy efficient" things like sealed windows is that those are a lot less necessary when you don't use as much cooling or heating, and sealed windows can have other effects like increases in asthma.

Construction and house design can be optimized for different environments, too. Anyone who's ever been perfectly comfortable at 90 degrees in a beach cottage but boilingly uncomfortable in an (unair conditioned) upstate New York house at the same temperature knows this all too well.

Cobb - English beer is meant to be drunk at "room" temperature, when room is in the inside of a drafty stone castle - ie, an above-ground cave. Americans think that room temp is 68 or higher - a temperature at which English beer is not nearly so good as at real cave temperatures.

The problem with those efficient British washer/dryer units is that they don't dry the clothes, forcing you to run the cycle at least twice. This is not an actual savings, except insofar as it forces you to dry the clothes on racks instead of in the dryer.

I have seen the use of light grey shingles in southern climates, and they reportedly have the effect mentioned - reducing A/C costs.

Far better are underground or earth-sheltered houses, or houses with sod roofs or roof-tops gardens. There are two problems with these - making them watertight (which is doable), and getting people to live in them. While it is not universal across cultures, it does seem nearly universal in the US that people refuse to live underground - although with good design and plenty of windows, one can manage to have plenty of natural light and airflow. In fact, it is quite possible to build underground buildings where it is impossible to tell from the inside that one *is* underground. I once ran across an account where someone investigating the psychological effects of living underground asked a clerk in an underground store how they felt about it, and the clerk said that being underground was too dim and dreary, and said this while holding their hand above their eyes to shield them from the glare of the sun.

As for underground temperatures - these differ by latitude, but will be between 55 and 65 degrees Fahrenheit in most populated areas. This may be a bit chilly in the summertime, but it remains far easier to circulate some outside air into the house, or even heat the air inside the house a few degrees, than to use air conditioning to reduce the heat by 20 degrees or more. In the winter, of course, it is far more efficient to heat a house from a base of 55 or 65 degrees, than from the base of the air outside.

Using the same principle, Heat Pumps are available that exchange heat with the ground instead of the air, allowing them to be efficient even on the coldest winter days.

Underground houses do tend to have a problem with moisture, and may need a dehumidifier running most of the year.

Construction methods such as the use of monolithic domes (which don't actually need to be domes) look to be comparable to traditional methods in cost, but are much stronger and will last much longer.

In short, we already have plenty of ways to drastically reduce heating and cooling costs, as well as the use of energy. Many of them are quite comparable in cost to present methods, or have slightly higher initial costs but far lower lifetime costs. The biggest problem in reducing energy use is getting people to change their habits.

Underground houses do tend to have a problem with moisture, and may need a dehumidifier running most of the year.

At least some dehumidifiers are composed, ironically, do the equivalent of cooling the air and then heating it.

While air conditioning is inherently less efficient from a physics perspective,

Why do people on this thread keep saying this, especially after Michiganlander's link? Do you know something they didn't teach me when I was doing my graduate work in physics?

My post should read; some dehumidifiers, ironically, work by cooling the air and then heating it again.

For heaven's sake. Heat pumps and AC are very efficient (COP 3 to 4 is typical) as explained. An old gas/ oil furnace is 60-70% unless you have a modern one that's maybe 90%. However, the electricity that you use is about 33% efficient (that's why electric resistive heating is expensive even though an electric heater is 100% efficient; the product of the two is 33%). On the other hand a cheap COP 3 AC unit times 33% is 99% efficient and better than any modern furnace. Furthermore, the delta T in the summer is much lower. Ambient temp is 30C and you are cooling the building to maybe 23C. In the winter it is OC or colder and heating to 20C requires a delta T of 20.

Last winter people with electric heat pumps paid a lot less than people with nat gas furnaces due to the high nat gas prices. However, note that the efficiency of a heat pump drops toward 1.0 at sub-freezing temperatures, which is why they are not used in cold climates.

So, YES, AC consumes a lot less energy than heating. Maybe by a factor of 4 for a place like NYC with typical 30C (high) summer days and OC (low) winter days!

But someone correctly pointed out that the sunlight has little heating effect in the winter.

However, global warming being caused by CO2 is rubbish anyway.......

Valuethinker: You seem to support an assumption that when people do not choose "best" according to whichever standards are applied, those people are stupid (irrational). I suggest there are more factors in a choice beyond those measured.

I may have missed a proof in the comments, but the benefit of a white roof seems either vague (like my own roof) or non-material. This technology doesn't have the kind of obvious benefits as, say, a gas furnace over a wood stove. The efficiency benefits of a white roof are not so substantial as to control the decision.

It is more like Stigler and Friedman came across a penny rather than a twenty. Not so many people actually bother to capture that diminutive value. The total return has to be significant before the rate of return matters.

If lost pennies become connected to some doomsday scenario, I would expect much ado over the need to collect all stray coins, to the exclusion of other pursuits.

I bought a new front loader washer along with one of those nifty six foot tall dryers about a year ago.

Love the dryer. The washer? Well, it has become my mortal enemy.

I was all excited about saving the earth and Mrs. Fan was all agog about getting a new washer and dryer. "Look!" she said, "We will be able to wash eleventy pairs of jeans at once and we will be able to hang the kids in the six foot tall dryer after they have been playing in the snow all day!"

Turns out that the manual advises against hanging the kids in the six foot tall dryer, but I like it anyway.

The front loading washer which is suppose to save so much energy and clean water for all the recently iceberg-less polar bears has some computer encoded design that assures no matter what I do, all eleventy pairs of my jeans are tied into one giant KNOT.

The heat produced from my wrath filled tirades most assuredly heats up the air in the laundry room. As we tend to have cooler winters, this is probably an energy plus. However, factor in that I also wash clothes in the summer, that I am now forced to iron my jeans~ something I haven't done since Jimmy Carter mattered, er, at least since he was president, and now my children and the family pet hide every time they see me take the hamper downstairs, I'd say all in all, the front loading washer is an energy minus.

And my nemesis.

Jane

'front loader' does not equal 'washer dryer'!

These are 2 completely separate points. You are mistaken in your analysis.

I don't have a washer-dryer, they are unreliable. I do have a front loading washing machine.

But in North America my mother doesn't have a 'washer dryer' either, she has (separate) washer and dryer, as many do in England. There is (AFAIK) no difference in efficiency between a European dryer and a North American one (the key for efficiency is to have an installed vent to the outside world).

The question is one of washing machines, not washer dryers.

Foxmarks

I didn't say that people are irrational (necessarily). I suggested there is a hot debate about why they do seemingly irrational things:

- humans seem to discount different activities at different rates, why is not clear. Hence the whole subject of Behavioural Economics.

- there are rational reasons arising from agent-principal problems, information problems and capital market constraints (credit) why consumers and companies may not do the rational thing (ie apply the same discount rate to saving money, that they do to spending or investing it)

The research says that painting roofs would be a no brainer. Incredibly cheap energy savings-- read the article I cited from the Berkeley people.

We can imagine a whole host of reasons (starting with an aesthetic dislike of dirty white roofs) why individual building owners don't do it (what do I care about my tenants' electricity bills anyways?).

Your argument is very much in the position that there are no $20 bills lying around, because if there were, the market would be inefficient, and we know the market is efficient.

My argument is that would mean that you couldn't create a Google or a Microsoft. Because the market would have already anticipated that technology and positioned itself. There would also be no need for *any* active fund managers-- market efficiency would look after itself.

Yet plainly we do have new companies like Google and Microsoft being created, and we do have active fund managers. There are $20 bills lying around.

In the area of energy conservation there are lots more 'free wins' around, we just haven't grabbed onto them.

FLR

I love (not) throwaway lines like 'Global Warming being caused by CO2 is rubbish anyways'.

I presume from the above that:

- you agree there is Global Warming?

- you don't think CO2 is causing it?

There is an overwhelming amount of evidence and scientific consensus for both assertions. The doubt (such as it is) is about the relative importance of other factors (particulates aka aerosols, the water vapour cycle etc.) and the feedbacks-interactions between the two.

So it would be interesting to hear what you think *is* causing global warming.

FLR

Just another point.

Heat pumps work very well at sub zero (centigrade) temperatures: the largest installed base of ground sourced ('geo exchange' is the US term these days) heat pumps is *Sweden* (over 350k) which has very cold winter temperatures.

They also work very well in Canada as I can attest to from personal experience. This is on top of a ridge where, with wind chill, winter temperatures frequently reach -20 centigrade, and normally hover around -5 or so (low 20s Fahrenheit). In this situation, the only backup is a wood stove in the living room, the rest of the 4 bedroom 2000 square foot house is heated and cooled by heat pump.

I think you are confusing them with the (more common in the US) air exchange (or air source) heat pumps which do not require digging a long trench or a deep bore for the cooling/heating pipe, but are not particularly effective below about 0 degrees centigrade.

I've heard it said that air cooled heat pumps work particularly well in high humidity summer environments a la the US South East, but I don't have any direct personal experience with them.

No, I am not going to debate global warming.... the fact that it's Al Gore's pet project is enough fair warning that something is awry if you use your common sense.

I am not confusing anything.... Since I live in nominally the southern US the air exchange heat pump is very common and convenient as it works as the summer central AC in reverse. I was not familiar with geo heat pumps, but it makes sense in CAN and SWE. Nevertheless, any heat pump will have an auxilliary resisitive heating mode that is going to kick in at a certain low temperature, depending on the design. When it's doing that then it's a very expensive operating mode because it's cold as all hell and you are heating the house resistively.

In Sweden, historically, detatched houses used resistive electric heating, especially ones built in the 1970s when oil became expensive and electricity remained cheap due to hydro and then hydro/nuclear mix.... I suspect that the geo heat pumps are now replacing the direct electric heating because the price of electricity has gone up for a number of reasons. I found a reference on the web after a quick google noting that detached houses in 1990 had >50% direct electric heating. In the old days oil heat was the only alternative and that became expensive post 1973 and I am sure that they also slap some nasty taxes on heating oil these days to throw salt into the wounds.

Apartment buildings generally use district heating in Sweden.

But back to the original question, the answer to 3) is a resounding NO. Just compare your heating bill with your incremental increase in electricity during the winter.

1) and 2) I hope so but it's hard to measure and the sun does not heat much radiatively in the winter in NYC. So maybe zero is a fair approximation?

No, I am not going to debate global warming.... the fact that it's Al Gore's pet project is enough fair warning that something is awry if you use your common sense.

I am not confusing anything.... Since I live in nominally the southern US the air exchange heat pump is very common and convenient as it works as the summer central AC in reverse. I was not familiar with geo heat pumps, but it makes sense in CAN and SWE. Nevertheless, any heat pump will have an auxilliary resisitive heating mode that is going to kick in at a certain low temperature, depending on the design. When it's doing that then it's a very expensive operating mode because it's cold as all hell and you are heating the house resistively.

In Sweden, historically, detatched houses used resistive electric heating, especially ones built in the 1970s when oil became expensive and electricity remained cheap due to hydro and then hydro/nuclear mix.... I suspect that the geo heat pumps are now replacing the direct electric heating because the price of electricity has gone up for a number of reasons. I found a reference on the web after a quick google noting that detached houses in 1990 had >50% direct electric heating. In the old days oil heat was the only alternative and that became expensive post 1973 and I am sure that they also slap some nasty taxes on heating oil these days to throw salt into the wounds.

Apartment buildings generally use district heating in Sweden.

But back to the original question, the answer to 3) is a resounding NO. Just compare your heating bill with your incremental increase in electricity during the winter.

1) and 2) I hope so but it's hard to measure and the sun does not heat much radiatively in the winter in NYC. So maybe zero is a fair approximation?

Al Gore's interest in global warming is neither here nor there, particularly to a non-American. He was also interested in the Internet (although he never claimed to have invented it: that was a distortion skilfully fed to the Media)-- was the Internet a non-starter?

You can't discredit an idea simply by saying there is a politician whom you don't like associated with it.

Adolph Hitler (and Joe Stalin) were big fans of rocketry. Is NASA therefore a bad idea?

There is an overwhelming basis of evidence and peer reviewed science that 1). the climate is changing (warming) and 2). that the cause is human action. We really don't have anything better (or worse) to go on-- we make all our decisions on scientific matters on the basis of what scientific evidence tells us (there are other factors, but we do look at the scientific evidence).

The US passed the Clean Air Act because people and animals were dying of air pollution, and science told them it was a problem. Los Angeles had over 100 smog alert days a year in the early 70s. Science told them it was the result of automobile pollution-- should that scientific evidence have been ignored?

Ground source ('geo exchange') heat pumps work far better at low temperatures than air source ones.

http://oee.nrcan.gc.ca/publications/infosource/pub/home/heating-heat-pump/asheatpumps.cfm

if you look down (at the map of Canada) it shows you the regions where AS heat pumps are viable.

Contrast that with the diagram for Ground Source heat pumps:

http://oee.nrcan.gc.ca/publications/infosource/pub/home/heating-heat-pump/gsheatpumps.cfm

The difference being that an AS heat pump is dealing with the outside air (which can be at a very low temperature) whereas a GS heat pump is using the ground (55 degrees F constant).

(actually just skimming the cites above, winter ground temperature can be as low as -2 degrees centigrade. However your *air* temperature in that case could be minus 30-- hence the GSHP preference over an ASHP)

So when the outside air temperature is below 55 degrees, the GS heat pump starts to have an advantage.

AS Heating Seasonal Performance Factor - 5.9 to 8.6
GSHP HSPF - 9.2 to 11.0

(data from sources above)

On Sweden, the Swedes went for the technology because gas mains gas wasn't common (still isn't, AFAIK), and because they have a general incentive towards energy conservation (being a country that imports the bulk of its energy except for some hydro and biomass). The point of Sweden (I could have cited Switzerland which is also an adopter) is that in a very cold climate, they use (ground source) heat pumps. About 350,000 which would be something like 10% of residential units.

On question 3, your summer electricity bill may not be worse than your winter bill *but*:

- if we reduce the urban 'heat island' effect, then in aggregate we will all have lower bills-- a classic appropriability problem, we all do a good thing, we all benefit, but we all (or most of us) have to do that good thing to make that happen

There is a 'spillover benefit' or externality that benefits other people, if we do this good thing.

- as the original Berkeley research I quoted up the thread shows, the winter heating loss is more than offset by the summer cooling gain (because of the angle of the sun and the number of sunny days in a winter) *even* in New York City.

Valuethinker, I don't know where you got the idea that no one in America has front-loading units, but they're quite common here, especially among newly purchased machines.

Having just bought one of the things, I'm going to reinforce Jane's comment. I took a long hard look, swallowed twice, and spent approximately double the cost of my previous top loader on a new front loading washer.

But, there were two hurdles to overcome before I pulled out the checkbook.

First, there are some horror stories out there about certain brands, mainly earlier models no doubt, but still. An appliance that doesn't work saves me nothing, and the best top loaders are pretty good - I just didn't want to put a few hundred dollars in repairs into my 15 year old top loader.

Next, am I really going to save the $500 I overpaid to buy the front loader? If it saves me $40 a year in gas (hot water) and water, and if LG is reliable then I win.

Ultimately, it ALL boils down to economics - my apologies to the true believers.

My new roof is light colored. Why? Keeps the shingles cooler so they last longer.

Last comment. Every analysis I've ever seen ignores the impact of producing the new stuff. Did anybody account for the pollution effects of producing the light colored paint for the roof? Heck, does anybody even quantify the costs of washing out the cans so we can recycle them? Of course everyone cleans them in cold water, even in winter, right?

Jane

It wouldn't be the first time my rellies are behind the times... ;-).

When I priced these things (in Canada) I found the front loaders were among the most expensive machines. I concluded this was because they had an 'environmental chic' and were aimed at that market.

MarkD's comments seem to support mine.

MarkD

My guess is where front loaders are getting popular is where there are persistent requirements to save water (eg Southern California).

Your point about them being expensive supports mine. They are a fringe item (but perhaps growing more popular?) in North America, whereas in Europe they are (at least) 90% of the market. Actually I've never seen a European top loader.

I agree with you on economics *but* the problem we have right now is there is a massive unpriced economic externality-- what the Stern Report called the largest externality in human history. Emitting carbon is untaxed, yet it causes long term environmental damage. You can get a range for how much damage (Stern reckons as much as $100 per tonne of CO2, depending on how much you value the loss of future world GDP associated with global warming, other analysts (Nordhaus) have come up with much lower numbers, say $30/tonne).

http://news.bbc.co.uk/1/shared/bsp/hi/pdfs/30_10_06_exec_sum.pdf

This untaxed externality was once true of Nitrous Oxides, Sulphur Dioxide, Mercury and other pollutants. Over time, society has found that untenable. So too we will, in time, find the unrestricted emission of CO2 to be unacceptable. The scientific case for man made global warming is as certain as we can be about such things, the story now is what we are going to do about it, and how fast.

Essentially our (carbon emitting) energy is too cheap. We are not paying the full economic price for emitting carbon into the atmosphere.

A related problem, as I outlined in other posts, is that for reasons we don't entirely understand, human beings discount energy savings at rates of c. 40% per annum (2 to 3 year payback) whereas they apply far lower interest rates to other types of investments.

On rooftops, yes there will be a lifecycle cost but it's a fair bet that the cost of paint is reflective of the economic cost of making it (less the omitted carbon tax). If painting roofs saves 10% of summertime energy bills, then my guess is that would be a heck of positive net present value.

My thinking is say the average 1 bedroom NY apartment costs $100 pcm to cool for 4 months of the year. So a savings of 10% is $40 pa.

(a related issue is non appropriable spillover. We *all* benefit if city-wide temperatures are lower, but to achieve that we *all* have to paint our roofs white. There are severe 'free rider' problems in this).

Ignoring discounting, and assuming we have to repaint the roofs every 10 years, then that's $400 of savings, per apartment. Say we lose 1/12th of that in increased heating (the Berkeley cite, above), so $340 net.

That's a heck of a benefit, the cost would have to be very high not to want to grab that.

Jane,

I first heard the "paint the roofs white" meme in an article that attributed it either Greg Bear or Gregory Cochrane back at an Environmental Conference in LA in 1993. When they stood up and proposed it, backing it up with calculations that showed that if all warm climate cities (not just LA) did this, it would reduce "global warming" by more than the Kyoto protocols would, they were booed. Sorry about no links, but I am going on memory from my desk.

If we used white roofs, planted trees, used white concrete for roads, etc.; we would reduce ground level heat absorption and also lock up more CO2. Jerry Pournelle pointed out at his site that if what environmentalists wanted was CO2 mitigation, then we would be planting plants and sinking dead stuff in the Marianas trench to take the CO2 out of circulation for a while.

Since we are not, they are obviously after something else.

Oh, and the previous commenter who wrote that water is the #1 greenhouse gas is right - it is and it contributes to the glaciation cycle, but that is covered much better at so many other places.

Bottom line, white roofs, white roads, plant trees, and if we all put mylar bags around our cars in parking lots, that would do a lot too.

Underground homes consume too many other resources - and if caves were all that lovely we would live in them (except for AmerInds in the American SW, I do not think any people actually have - cartoons not withstanding)

Oh, and Jane, welcome to Maryland - but Silver Springs? (shudder)

Since air conditioning a building in summer is going to be less "efficient" than heating the building in winter, then I think the winter adverse effect of white roofing is going to be less than the claimed beneficial effect of summer cooling.

In addition, the areas most likely to be negatively in winter are likely to have white rooves most of the time anyway.:~)

There is one more effect that makes white roofs better in winter too. Everything radiates heat. The higher the temperature, the more heat is radiated. You can feel the radiant heat emitted by your electric stove, an incandescent light bulb, and the sun.

Dark items absorb radiant energy well and they radiate well. Light items do not absorb much radiant energy and they do not emit much.

Thus, it is better to have a white roof in the winter so that the house radiates less energy at night.

Oh boy, I guess Valuethinker has no sense humor. Just because a bunch of left-wing scientists feeding out of the same trough create consensus.... If you look deeper into the matter there is a lot of dissent among free thinking scientists who are not feeding from the government trough. What is amusing is that it is all based on rigged computer models and it has reached such a hubris that dissent is not tolerated. Pathetic...... I suppose when southern Greenland was indeed green 1000 years ago was due to CO2 emissions? It is outrageous anthropocentrism to think that mankind can dictate the course of the climate like this.

Re washing machines, European front loaders are better because they clean clothes and do not destroy them like stone age American washing machines. I don't give a rats ass about being "green". I bought the damn thing because it works better. I think people here are too old to remember the hubris of the 1970s. There is plenty of oil; the reason that oil and other commodities are expensive today is because of your government and its worthless fiat currency.

Two feet underground the ambient temperature in North America would likely resemble that of caves. There's nothing googlable about such a stat, but I'd guess 68 is reasonable. In such a case, you'd use the earth itself as a reflector.

There is already a type of heating/cooling system based on this. What it does is essentially run pipes several feet underground. In the summer water is cooled underground and then it cools the house. In the winter the water keeps the house from dipping far below the underground temperature. You still need some other form of heat and probably A/C (unless you like summer heat) but they don't have to do as much work.

On the other hand a cheap COP 3 AC unit times 33% is 99% efficient and better than any modern furnace. Furthermore, the delta T in the summer is much lower. Ambient temp is 30C and you are cooling the building to maybe 23C. In the winter it is OC or colder and heating to 20C requires a delta T of 20.

I'm not really following this? Are you saying it would be better in winter time for me to just turn my wall A/C units around and let them 'cool' the outside and heat the inside rather than using an oil or gas boiler?

Boonton,

No, not literally, because your wall unit is optimized for different temperatures, and because electricity may be quite expensive for you relative to gas or oil.

But it takes less than one joule (of electricity) to move one joule (of heat) from outside to in, so a heat pump/AC is more efficient than resistive electric heaters. Meanwhile, it takes more than one joule of gas to put a joule into your house because the exhaust is warmer than the outside air, so the AC is still probably more efficient even after you account for the cost of producing the electrcity.

Thus, the people who say "AC is less efficient than heating" are wrong.

(Random aside: the air in a cold house contains the same amount of thermal energy as the air in a warm one, since cold air is denser. So "heating" your home is really an exercise in shoving energy out the door.)

Rob,

Well the people saying it is less efficient are clearly right from a financial perspective otherwise why isn't anyone selling a winter electric heat pump to compete with traditional oil and gas furnances?

If we're measuring carbon I still suspect that such a system would end up being more carbon intensive after you calculate for the fact that you have to generate electricity and move it to the house for the pump to work.

For heating houses, a much better approach is to use the waste heat from doing mechanical work. For instance, an electrical generator running in your basement could also heat the house. You get the same heat as a byproduct of useful work. I don't really know why no one does this.

The purpose of the white roof is to prevent the house from getting hot, thus reducing the amount of energy used to cool the house. If you put a giant mirror on the roof, it would be more effective. If you could use an invisibility cloak to hide the house from the sun, that would be even more effective. Any method used to prevent the heat from reaching the inhabited parts of the house will reduce the energy needed to cool it. The impact of the reflected heat on the atmosphere is not really being considered in these analyses.

Well the people saying it is less efficient are clearly right from a financial perspective otherwise why isn't anyone selling a winter electric heat pump to compete with traditional oil and gas furnances?

The usual word for "more efficient from a financial perspective" is "cheaper." I have no quarrel with people who say it is more expensive to cool their homes than heat them. But at least one commenter said "from a physics perspective," and the rest didn't say cheaper, they said "more efficient," which generally implies a comparison of energy use, not price.

On the subject of accounting for the energy/carbon cost of producing the electricity, at least two commenters have addressed it; I was one of them. Bottom line: a highly efficient air conditioner will still move more heat per cf of natural gas burned than a gas heater, even accounting for losses in generation and transmission.

And heat pumps are sold for winter heating use. But as was pointed out up thread, air-exchange heat pumps don't work well at low outside temperatures (for engineering, not physics, reasons) and ground-exchange heat pumps require a substantial initial investment in the form of trenches or boreholes in your yard. In addition, they run on electricity, which may be quite expensive for reasons unrelated to efficiency or carbon production.

For instance, an electrical generator running in your basement could also heat the house.

This is called "co-generation" and it has numerous problems, such as the need for electricity without the need for heat (summer), the need for heat without the need for electricity (winter nights) and the excessively polluting nature of small engines. But in a cold climate it might be useful.

Rob Lyman

Good analysis.

I've looked at heat pumps in a UK and Canadian context quite closely:

1. in the UK they are not cost competitive with natural gas *if* you are on a gas main. About 5 million homes (and perhaps 1 million commercial sites) do not have access to piped gas.

They are very efficient from a CO2 perspective, even against using gas for home heating.

Heat Pumps are cost effective in this applications *but* there is the investment in digging a trench or a borehole, and not all sites are suitable.

If you both heat and air conditioning (which most commercial sites do, but very few homes) then a ground source heat pump is a no brainer if you are going to be resident for more than 10 years.

You can get a government grant to install a heat pump, and in Scotland, a particularly generous one.

The UK has relatively small numbers of installed heatpumps: there aren't many contractors who can do it, and the industry is really niche, the technology is not trusted (HVAC engineers are famously conservative).

2. Canada the case is even stronger, although parts of Canada you will need a backup heating source. But outside the Maritimes and the West Coast, most Canadians now install air con as well as heating.

Again for various reasons domestic gas is cheaper than electricity, so the heat pump sector has not expanded as much as it otherwise would.

Sweden has made a real commitment to the technology, and now France and Switzerland are. In the latter two cases it makes good financial sense (gas mains gas isn't that common so people use oil and even coal heat). But you also need an 'ecosystem' of manufacturers, installers etc. and a comfort and familiarity with the technology.

And you need a relatively high level of home ownership/ commitment to long term investment by the home owner. Most private landlords won't do that, and most householders don't have enough information/ don't want to spend $10k on their household heating system.

The Swiss, being the Swiss, don't have that problem-- they think long term by nature.

Dan in MD

The Kyoto Process including lengthy negotiations on just how to price CO2 abatement, and in particular internationally. I am not sure whether 'white roofs in the USA' was one of them (the CDM mechanism) *but* to the extent that it would reduce US electric power demand, that would contribute towards meeting the Kyoto Target.

Pournelle, as is so often the case with his analysis, is talking out of his hat without doing his homework. All of what he suggests *has* been discussed, and some will be implemented:

- Carbon Sequestration (Capture and Storage) is a leading candidate technology for large fossil fuel emissions

http://arch.rivm.nl/env/int/ipcc/pages_media/SRCCS-final/IPCCSpecialReportonCarbondioxideCaptureandStorage.htm

from the IPCC itself!

http://www.colloqueco2.com/IFP/en/CO2site/presentations/ColloqueCO2_Session1_02_Socolow_PrincetonUniversity.pdf

good summary (powerpoint) of sequestration potential

- biological sequestration is included in the Kyoto Treaty (planting trees as an offset)

The bitter reality is that there are, under current technologies, no easy options regarding dealing with CO2 emissions. The best policy is not to emit those greenhouse gases.

To scale the problem, of the 15 Socolow 'Wedges' (each accounting for a 1bn tonne pa abatement of carbon emission, v. the 15bn tpa 'Business as Usual' 2050 scenario assuming a normal extrapolation of current trends of economic and emission growth), 1 'wedge' is abatement via Carbon Sequestration (putting CO2 capture and geologic storage on 1000 large power plants). Another wedge is biological sequestration (planting forests, and halting current deforestation trends in tropical countries).

So that is 2 out of the 8 wedges we will need to hit any sensible target for CO2 abatement by 2050.

(others include doubling the fuel efficiency of the existing car fleet (which is assumed to quadruple in size between now and 2050), halving the amount of driving per car, building 700 new nuclear reactors, etc.).

FLR

- obvious logical flaw. Greenland was hot in 1000, and it was not due to anthropogenic CO2 emission therefore the fact that the climate is heating very rapidly now cannot be due to anthropogenic CO2 emission.

The logical flaw in that assertion is obvious.

- left wing conspiracy of scientists. I wish. The 'free thinking' scientists are by and large not climate scientists, some are in fact funded by the energy industry.

(even Richard Lindzen, who is a respected climatologist and is cited all the time, admits that he doesn't know: he has a thesis that increased cloud cover will abate global warming, but he admits he doesn't know that it will.)

What you have in the scientific community is massive and growing alarm. Not just in climatologists, but in glaciologists, biologists, oceanographers, atmospheric scientists, paleontologists, planetographers...

It is striking to which the scientific alarm is much greater than the general public alarm. Usually it's the other way round: physicists worry less about nuclear power than the general public, etc.

But on this one the position is reversed.

Well the people saying it is less efficient are clearly right from a financial perspective otherwise why isn't anyone selling a winter electric heat pump to compete with traditional oil and gas furnances?

That's exactly what my parents just installed in their house last fall. They wanted AC, and decided that to make that commitment, they might as well replace the 20 year-old furnace (heat exchangers do crack eventually, and then you you have CO problems; and obviously, this furnace predated modern high-efficiency units).

After researching their options (this is the Colorado front range, mind you, where you can experience 3 of the 4 seasons in any given day of the year), they went with a hybrid system that uses a 95% effecient gas furnace and a heat pump. When the system is set to "heat," the gas runs if the outside temperature is less than about 35F. Above 35F, the heatpump runs. And if the system is set to "cool", the heat pump runs as an air conditioner.

The local electric utility is so delighted that you have chosen to balance your electricity consumption on a year-round cycle, that they provide about $2500 of incentive rebates for installing a heatpump. The final cost of the heatpump + furnace system was about $1000 less than the cost of installing AC + furnace with no incentives.

So far this winter, their gas consumption has been cut in half as compared to last year, without a proportionate rise in overall electricity usage. Not a bad deal.

For heaven's sake, the Greenland example just shows that the climate changes "naturally". Most people are not aware of this and soak up the global warming nonsense without understanding anything about the topic. There was also something called the little ice age.

In any case Arctic cooling is a myth since data shows a strong warming trend from 19th century to mid 20th century and then cooling until the late 1970s and then an increase from there. Yes, global temperatures cycle. Imagine that? Remember the 1970s when the brilliant climatologists were up in arms about the coming ice age? We were also going to run out of food and oil by 2000.

Yes, Al Gore's videos of crashing ice flosw are impressive but is sheer propaganda in the vein of Dr. Goebbels, another proponent of national socialism. Sorry, I suppose the new trend is global socialism to combat global warming.

Now the crooks at Goldman and Morgan Stanley want to get their pounds of flesh in profits based on trading "emission permits".

FLR

It's a dead giveaway you are losing an argument when you start calling the other side 'Nazis'-- equating Al Gore to Dr. Joseph Goebels, for example. Why don't you call Dr. Nick Stern a Nazi as well (hint: he is Jewish)?

I haven't actually seen the Inconvenient Truth movie (it's a movie about Al Gore, btw, rather than one that he made). So I'll have to assume that it looks impressive as you say.

You have an obsession with Al Gore. You would do well to shake that. Can I suggest Sir John Houghton's book: 'Global Warming: the complete briefing'?

http://www.amazon.com/Global-Warming-Briefing-John-Houghton/dp/0521629322

He's not a Nazi either, by the way. He was chief meteorologist to the UK government. A devout Christian though, if that offends you.

It is a good non technical intro to the subject.

I love the idea of 'crooks' at Goldman Sachs and Morgan Stanley, too. I suppose they too are Nazis, particularly the Jewish partners at Goldman?

Worldwide measures to control emission of a pollutant are hardly socialism. The mechanisms provided for in Kyoto are tradeable offsets, the prevailing intent is to use emission trading schemes, a la the European Trading System.

(hmmm... answer truncated)

Just on straw men:

- there wasn't any great climatologist consensus on ice ages in the 70s. There were a couple of speculative papers, and Newsweek had a cover story

http://www.realclimate.org/index.php?p=94

- the medieval warm period is controversial, to say the least. If there was such an effect, it was localised to the North Atlantic, and was not global

http://www.realclimate.org/index.php/archives/2004/11/little-ice-age-lia/

On 'global socialism' the US successfully uses an auctioned permit system to regulate SO2 production. The costs of abatement were much lower than expected.

This is what is proposed for CO2. How is this 'global socialism'? I would term in 'pricing an externality'.

As to overall costs of abatement to stabilise atmospheric CO2 at 500ppm, the Stern Review reckons a cost of 1% of GDP in 2050. In other words, in 2050 (January 1st) world GDP will reach the level it would otherwise have reached in June 2049.

For all the criticism of the Stern Review, I haven't seen anyone attack that conclusion.

(the actual range in the Stern Review is -1% (ie net growth in the economy) to 3.5%).

Taking a worst case of say 5% of world GDP, that would mean in 2050 the world economy would be the size it would otherwise have been in 2048/ Q4 2007.

That seems to me to be a quite reasonable price to pay for insurance against the risk of destabilising the planet's climate *or* even the Stern Review's estimate of permanent loss of global GDP of 15-20%.

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