Is underfloor heating really worth the effort

[EcoPower]

Its a fair comment re the cost / efficiency of Solar PV. My view is that the cost of the technology will not decline much if at all purely because of supply and demand - there's a lot of demand.

In its place it is effective and worthwhile - in its place. Horses for courses.

The buy back rates are genuinely 0.55 centimes per kWh from EDF for roof mounted panels - as a rule of thumb it will take something like 10 years to get your money back.

You have to take a view I guess.

Marc

[Gluestick]

[quote user="EcoPower"]

Its a fair comment re the cost / efficiency of Solar PV. My view is that the cost of the technology will not decline much if at all purely because of supply and demand - there's a lot of demand.

[/quote]

As has been mentioned herein before, the actual cost of the latest Photo-Voltaic cells is dropping rapidly all the time, mainly owing to mass production from China.

As with most technology areas, rapidly expanding demand lowers unit costs: also as leading edge technology enters the mainstream and as more emerging economies are able to address what were previously demanding manufacturing processes, then prime unit costs fall quite dramatically.

This has been the case with all semiconductors; eePROMs are perhaps the best example.

What has not dropped in price thus far, are the associated control systems and the added costs for the System Integration.

Integrating solar to other prime energy sources has been something of a Black Art: same with geothermal: this is now rapidly changing, however.

Rather like evacuated solar, more and more suppliers and installers are entering the field fostering competition and creating commercial downards price pressures.

PV will go precisely the same way as volumes are ramped up.

One of the core problems to date has been technological break throughs - e.g. film circuits -  and each break through requires significant front end laydown costs, which have to be amortised. And product (and technology) life cycles have been very short as new concepts have emerged thick and fast.

It is identical with each type of technology, but particularly so with semiconductors and silicon: in the early stages product life cycles are low and performance improvements come very rapidly as technology changes: and the entry costs are too rich for all but the biggest: however, once a market segment stabilises and offers serious volumes then the second tier technology manufacturers enter. PV has been the same: originally it was the big boys, such as Motorola, TI etc. Now Korea, China et al are manufacturing in volume.

If one considers the basic PV arrays which are used for example in maintaining yacht batteries, the power outputs and acquisition costs have risen and fallen, respectively, quite dramatically during the past ten years.

This will continue into the mainstream of both domestic and commercial energy applications.

 

[EcoPower]

Gosh - what a response and your points are well made.

My belief re cost of PV stays the same however and this belief is based predominantly upon economics and the product life cycle.

My opinion is that we are only at the middle of the introduction phase in the product life cycle so still growth and maturity to come, but I suspect even this will change as new technologies are introduced thereby distracting manufacturers from focusing on current core products and how they position these in the market.

As you rightly note, many of the manufacturers are based in China and the costs of shipping are increasing all the time.

Additionally the costs of shipping also affects the manufacturers regards the supply of raw materials.

I am told by colleagues in the far east that the cost of labour is also increasing as it did in Korea some time ago so this will affect the 'bottom line'.

To further confuse things the export (buy back price of electricity rates) is expected to change (reduce) as is happening in many European countries and now also in the USA who are the largest consumer of this type of technology.

Because of this the race is on for prospects to buy their PV systems to beat this expected reduction in buy back rates which will only serve to put a big 'blip' in the product life cycle curve.

I think you are absolutely right when you mention the associated control systems and as I'm sure you know this area is strongly dominated by just a couple of manufacturers. If we saw a change here then that certainly would affect matters favourably.

It's a difficult call but I still believe that the cost of PV will not change significantly in the near future and there are many variables which affect in this equation.

All that said I sincerely hope you are right as it can only help all of us.

Regards

Marc.

[Gluestick]

As with all technologies, things move on, Marc.

At present, it seems Gallium Arsenide offers certain advantages over Silicon.

It is impossible to say where the market is, currently, as whilst parts are perhaps in the middle of their cycle (my earlier example Yachts e.g.), others are in their infancy, as different technologies or combinations of technologies emerge.

What is clear, is the new urgency driven by insane fossil fuel prices, themselves driven by greed of major oil companies.

Original PVs used Selenium: later realisations used Silicon: and then Gallium Arsenide was hailed as the new wonder substrate for a range of semiconductor devices. And now a combination of elements  and compounds are being exploited.

http://www.copper.org/publications/newsletters/innovations/2007/05/solar_energy.html

Early realisations were mainly in specific application areas such as SatCom and of course, the Apollo Programme and NASA kick-started serious apps of PV for various space exploration projects, and particularly the moon landings.

PV research was really going ahead rapidly when I was working for a short time in Silicon Valley, Calif.,  in the mid 80s.

What has happened, as I suggested before, is that Thin Film Technology now allows very cost-effective production for both fixed and mobile arrays.

Indeed, in California, amongst other places, commercial buildings are constructed where whole glass "walls" are faced with thin film PV arrays.

Personally, I think the next 20 years will force ever-cheaper PV, Solar Heating and renewables (such as Bio-Mass etc) as well as huge advances in insulatation and "House Conditioning" environmental controls (sort of upmarket VMC with effective waste heat recovery) as natural fossil-based fuel costs rise out of sight, driven by rapidly increasing demand from Asia.

New houses will have whole roofs of thin film PV arrays as a normal planning constraint.

Interesting to me how rainwater recovery and underground storage tanks in France are quickly becoming common now: we talked about this, with Grey Water Recovery, on this site, some years back.

It will be a very exciting period!

Anyone working in the Renewables area like our own Pool Guy, is in for a boom era.

http://photovoltaics.sandia.gov/docs/PVFSCGallium_Arsenide_Solar_Cells.htm

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

 

[EcoPower]

Quote: What is clear, is the new urgency driven by insane fossil fuel prices, themselves driven by greed of major oil companies.

Oh how true.

To compound matters, governments (the taxman) enjoy ever increasing revenues from TVA, VAT, etc levied on these sources which does dissappoint me.

To rub salt into the wound, today Centrica have ''suggested'' energy prices will again increase due to continuing rises in Oil and Gas costs.

Bearing in mind that Shell & BP are some of the biggest players in the Solar PV market one wonders whether this goes conflicts with their main source of revenue?

I suspect Thin Film Technology may have a positive effect on the market but I believe the main USA source has some very nicely guarded patents on what seems to be a very slick production method so I wonder where they will position these products?

Amorphous PV seems to be the current 'in thing' which is understandable.

My colleague in Spain tells me new builds have to employ some form of solar energy system within the construction, but the vast majority of products used to comply with this requirement is Solar Thermal Syphon purely because of cost.

I do hope you are right about decreasing prices for PV.

Yes, interesting times ahead indeed. I hope I'm around to see it.

Marc

[Gluestick]

Marc:

Oil companies such as Shell and BP have a sort of token investment in alternative technologies.

For me, this is simply a sop to the green lobby, whilst they continue to rape the globe's resources.

http://greenroofs.wordpress.com/2007/05/24/solar-power-to-enhance-green-roofs/

http://www.suntech-power.com/

Whiulst the USA leads certain areas of semiconductor research and development, increasingly Asian companies such as Samsung are spending far greater proportions of Gross Revenues on pure research and development. Asia now leads the world in silicon laydown and fab.

We have a current sort of pre-conception that PVs and indeed Evac Tube Arrays need to be mounted on roofs: they don't, of course, and if one has the space, ground mounted arrays, with sun-following servo motors are superior: difficult to rotate your house from AM to PM!

One of the great management gurus I studied, Theodore Levett, told the story of the board of a US railroad corporation assembling for a meeting in the 1930s.

before the formal board meeting commenced, the President asked the members to consider and answer one salient question: "What business are we in?"

After a due pause, one Director said, "Why! We're in the railroad business!"

"Wrong!" said the President, "We're in the transportation business. And because we think we're in the railroad business, well that's precisely why we're going bankrupt!"

The new kid on the block was the airplane; and increasing numbers wanted to fly from one end of the States to the other, rather than take days on a train.

Oil and gas companies are in the energy business: it ought to have been such as Exon with their obscene wealth who led the charge into solar, fuel cells and other new energy areas. Simply because they did not, they, like many other major corporations will gradually vanish as fossil fuels exhaust: and I for one will be cheering! Same happened with such as British Steel: they were in the materials business and ought to have invested heavily in the good days in such areas as ceramics: like Japan did! Modern automotive engines will probably (Extra High Temp - Lean Burn) have ceramic bore liners and pistons, able to withstand the incredibly high working temps.

With energy, cheap supplies from the Mid East has led both Europe and the USA into a sort of cloud cuckoo land of profligate over-consumption: larger and larger gas guzzlers like the appallingly gross Chelsea Tractors; and homes and buildings where the solution to cold is to throw increasingly large amounts of heat into the building and let it escape through windows, doors and roofs.

 

 

[EcoPower]

Interesting comments especially regards the pre-conception that solar has to be mounted on a roof.

Perhaps this is in part due to the net metering rates for electricity via PV which is 0.55 centimes for roof mounted PV and only 0.30 centimes for ground mounted so everbody automatically thinks 'the roof it is then''.

Unfortunately, as you rightly eluded to previously regards system components, the cost vs return of a commercially available tracking system is questionable. Mind you, for solar thermal todays controllers can accomodate orientations other than solar south with reasonable efficiency.

Here's an interesting snippet:

In France, for instance, dwelling and office buildings output around 90 million tons of CO₂ per year, out of a total of 385 million tons. The aim of the national “Climate 2004” plan is to divide France's

emissions by four by the beginning of 2050, and promote the use of

solar and other renewable energies. However, few economic players seem

interested, whether they be consultants, research departments,

manufacturers, or installers. “In the 1970s there were as many as 60-70

manufacturers of solar thermal collectors. There are considerably fewer

today,”

If I had to place a long term bet it would be on hybrid-thermal (PV/T) systems - but it's just going to need the right level of investment from industry / government. I believe it's a French chap leading some of this research?

Lastly, I couldn't agree with your last point more - this point will in fact be the first article in a series for a national newspaper. Whole house energy audit and efficiency plan etc.

Have we strayed off the subject of the initial post a little?

Will this be the longest thread on the forum?

Marc

[Gluestick]

Marc:

Personally, I feel this is critically important!

When Mrs Gluey and I bought our French house, heating oil was circa 30 cents/Litre: now it is circa three times the cost. I am amazed at just how many people are not using their CH systems, simply because they cannot afford the cost.

Thus those planning on moving to France should factor into their TCO (Total Cost of Ownership), alternative heating systems.

Fortunately, France has a head start on most with its extensive nuclear programme: additionally, Pas de Calais is sprouting wind turbines like Dragon's Teeth!

Not being a full-time resident, as yet, whilst I planned on oil-fired CH, I have prevaricated, gone through pretty deep research into wood pellets and other bio-mass energy sources and am now probably focused on electricity on cheap rate (Heures Creuse) charging a large thermal store, with evac tube top up.

I've discounted UFH from ground source as whilst it's good for a new build or barn conversion (e.g.) the sheer dislocation cost for an old established property is not really viable.

We have gone over this a number of times: worth a search through this forum area.

What is really needed to galvanise solar, is a government looking at the much longer term, rather than the next election: that said, France has been far more forward looking than most European states, hence the forward planning and investment in trains and the TGV, the peage and autoroute systems and of course, nuclear electricity.

Difficult for a state to go head-to-head with its own asset, however now that France the state has severely diluted its own shares in both Total and Elf-Acquitaine (since the 80s/90s) no reason for a major push into solar, with seriously significant tax credits and grants (plus EU funds) for R & D.

With copious solar energy from Paris, going  South  I have a feeling that France like Spain, Greece and Portugal will soon take the initiative.

 

[jxedwards]

Gluestick,

I tend to agree with you on most of your comments.

However before you wish the demise of XomShellBP Oil Co ACME Inc please wait another 3/4 years til we have finished our place!!!!

 

Back to the subject based on our UK conservatory experience UFH a big thumbs up and will be installed in Le Presbytere in the next 12 months using either a Rayburn or Villager wood burner as the source.

John

[EcoPower]

I admire your passion for the subject and wish all customers did a similar amount of research.

It's a very contraversial subject, but I have to admit that one of the reasons we tend to like Electric UFH is because of Frances substantial use of Nuclear for electricity production - i.e. very low carbon footprint when compared to coal etc.

As regards the oil situation we too have friends that are not using (or at least severely limiting) the use of their oil fired central heating systems. That said, (and its genuinely not intended as advertising), we WILL have a product guaranteed to reduce Oil / Gas / LPG consumption dramatically very soon. The friends I mention have volunteered to be our resident data collection site for this product.

The purpose of mentioning this is that we would like to try and obtain either TVA relief or Tax Credits for customers on these products and ADEME etc are not playing ball. It is obviously not in the interests of the Oil / other companies and we certainly won't be taking on BP, Shell, etc etc.

So, any ideas or help in this matter greatly appreciated. It really is in everybodies interest.

The idea of a thermal store is probably sound as you suggest the solar will provide a 'top up'. For this I agree - but only as a 'top up'. A thermal store of any significance is large both in size and volume so too much for solar on it's own.

I also agree re Geothermal. It is costly and disruptive - vertical bore holes seem to cost much more here than in the UK which greatly surprised me.

Personally, for a new build or conversion I would opt for a Canadian / Provencal well before GSHP/ASHP.

Very cheap to incorporate and if driven by a Solar PV fan system then a real winner.

As for TCO then insulate, insulate, insulate - in that order and if you need it to be eco friendly then sheeps wool, recycled paper etc etc.

I actually suspect some of the incentives will be reduced soon vis a vis the anticipated reduction in net metering prices and the tax credit scheme ending in 2009 - that said even this is something of a scam and suppliers are certainly not telling the truth about these.

ADEME cannot (will not?) comment on what, if anything will replace the scheme so we shall have to wait and see.

Again I hope you are right about France taking some sort of initiative but I remain sceptical. There are still many 'jobs for the boys' schemes which only serve to increase product costs with Qualisol being a prime example.

Regards

Marc

[powerdesal]

[quote user="Gluestick"]

Fortunately, France has a head start on most with its extensive nuclear programme: additionally, Pas de Calais is sprouting wind turbines like Dragon's Teeth!

Not being a full-time resident, as yet, whilst I planned on oil-fired CH, I have prevaricated, gone through pretty deep research into wood pellets and other bio-mass energy sources and am now probably focused on electricity on cheap rate (Heures Creuse) charging a large thermal store, with evac tube top up.

I've discounted UFH from ground source as whilst it's good for a new build or barn conversion (e.g.) the sheer dislocation cost for an old established property is not really viable.

[/quote]

GS,

We have spoken in the past at length about heating alternatives, I will be really dissappointed if you are a supporter of those "blots on the landscape" known as wind turbines.

Contrary to your focus on electricity, I am seriously tending towards log gasification backed up or rather supplemented by evac tube solar.

I totally agree about GS heat pumps, mainly on cost of boreholes, I could perhaps live with the dislocation although I am not sure SWMBO would appreciate the destruction of her veggie garden, albeit temporarily-ish.

I totally agree with "Insulation, Insulation, Insulation by Marc, but then I am a bit of an insulation bore, or anorak if you prefer.

[EcoPower]

Wind turbines - Blots on the landscape !!!!!!!

I like mine - it's just a little more interesting to watch than Solar. Even my wife who thought it would look out of place thinks it blends in rather well.

Still, each to their own.

I think you have really hit the keyword re Solar for any heating application - 'supplemented'.

That said, despite supplying such products I have my reservations about the cost vs return. Depends on your motives I guess.

Personally I like Biomass (wood) but then I would, wouldn't I. We do seem to have an abundance here in France

Marc

[Gluestick]

Steve:

I'm not a supporter of wind turbines (have stated that previously): I remain very cynical about total costs and personally doubt they can actually demonstrate a payback point on the capital cost, plus maintenance, plus land rents etc.

Apparently the Commune receives cash; as do the farmers who agree to have them sited on their land. There are also EU grants I believe.

The very scenically pretty areas around the Septe Vallees on the Cote d'Opal have been ruined by these awful objects: luckily, thus far, whilst we can see a bit of one from the front perspective, we see nothing from the rear (which is  one of the main reasons we bought the house, 'cos it's like looking out over the Sussex South Downs). More appear each and every time we return.

GSH: yes boreholes are expensive: Slinkies are not. However, I was put off by two realities.

GSH is not really viable with wet rads, rather than wet UFH. The capital cost is far too high.

I'm also looking at gasification: trouble is wood prices are rising around us, due to demand. Plus the capital cost for a decent wood gasifier is significant and you still need a thermal store anyway!

 

[powerdesal]

Sorry GS, I should have remembered that you were not a wind turbine fan.

I cant disagree with the wet rad / GSH comment, my thoughts entirely.

Whilst the capital cost of a gasifiation boiler is substantial, plus the heatstore of course, I think the economics are reasonable. The Atmos 20kw unit with a 2000l heat store seems a reasonable mix for my heat load although perhaps the 25kw unit may be a better option giving surplus scope for the future.

The total capital cost of c.GBP 5000 is not an unreasonable figure IMHO (for the system based on 20kw). Of course there are installation and ancilliary control costs to factor in. My theory of high output burn to a super-insulated heat store (akvaterm in an insulated "room within a room") with the CH pump taking from the heat store seems to indicate a recharge of not more than once per day or even once per two days if the days are not too cold.

Sunny winter days should give a reasonable supplement from evac tube solar.

I agree that wood prices are rising but gasification seems to be the most efficient way of using wood, which is after all a renewable resource.

The possibility of Heures Cruese(sp) top up also exists with a fitting to the heat store.

As has been said before, the basic requirement of any system is comprehensive insulation to keep the heat that you are paying for in the places that you need  it. Insulation has to be the most cost effective DIY thing anyone can do.

[Gyn_Paul]

I've trawlled back through this and other threads, not to mention the other relevant sites and I'm stumped. I know it's here somewhere but I just can't find it.

So someone PLEASE help me. I'm trying to calculate the size of thermal store which is practicable (cost/size/availability/etc), and need to work out something quite simple: How much heat can I store in/get out of a 2000L store ?

I'm thinking of the next size up Atmos (35Kw), and hoping not to have to get 2 x 2000 L stores to make the most of it.

paul

[powerdesal]

[quote user="Gyn_Paul"]I've trawlled back through this and other threads, not to mention the other relevant sites and I'm stumped. I know it's here somewhere but I just can't find it.

So someone PLEASE help me. I'm trying to calculate the size of thermal store which is practicable (cost/size/availability/etc), and need to work out something quite simple: How much heat can I store in/get out of a 2000L store ?

I'm thinking of the next size up Atmos (35Kw), and hoping not to have to get 2 x 2000 L stores to make the most of it.

paul[/quote]

A "quick and dirty" calculation shows that using a 'useable' temperature range of 25 degC (90 out, 65 return) some 58 kwhr of energy can be stored in a 2000l cylinder.

In other words, if your heat load is 30 kw, you have two hours - ish.

Specifically:  752400000 joules for 2000l raised from 0 degC to 90 degC, which is a bit academic really.

edit. Is there any way of doing superscripts on the message panel.-  ie 752.4 x 10 superscript 6  ?

[bejay]

[quote user="powerdesal"]

edit. Is there any way of doing superscripts on the message panel.-  ie 752.4 x 10 superscript 6  ?

[/quote]

For these purposes most people settle for 752.4 x 10^6. Otherwise you have to develop a Latex fetish ;-)

bj

[Tibblington]

I may be a bit late with this advice but I will pass it on all the same as there will be someone else asking a similar question.

Before you consider underfloor heating you need to consider the weather conditions where you are living because there is a deal of inertia in the system especially if the pipes are buried in the screed.  Generally speaking you can't expect a response time of less than 36 hours which is not a lot of use if you suddenly get a very cold snap followed by warmer weather.  Moreover if the system kicks in during this brief cold spell you have heat that you have created and don't need 24 hours later.  For those with properties in the north of France perhaps underfloor is worth considering but further south Charente, Dordogne and south of that I would NOT suggest under floor heating.  You need a system with less inertia and a shorter response time.  Ideally warm air as this has a response time as short as 15 minutes but otherwise we are talking about a radiating surface.  Both of these systems could be made to work well from a solar collector but you would need a substantially sized insulated water storage tank to act as an accumulator.

I have a very effective warm air system which does have a response time of 15 minutes - the plumber who helped with the installation was astonished how effective it was as he had never seen a system like it before.  I am running on oil but am going to install a solar collector to heat the domestic water 12 months of the year.

[Poppy]

We have electric (from EDF) underfloor heating in the form of a cablemat directly under the tiles on the ground floor and carbonmat directly under the wood on the first floor. There is insulation under both so we find it heats instantly and very easy to control. Our thoughts are that it was cheap to install and run and soooooo convenient.

[Jonzjob]

[quote user="Tibblington"]

I may be a bit late with this advice but I will pass it on all the same as there will be someone else asking a similar question.

Before you consider underfloor heating you need to consider the weather conditions where you are living because there is a deal of inertia in the system especially if the pipes are buried in the screed.  Generally speaking you can't expect a response time of less than 36 hours which is not a lot of use if you suddenly get a very cold snap followed by warmer weather.  Moreover if the system kicks in during this brief cold spell you have heat that you have created and don't need 24 hours later.  For those with properties in the north of France perhaps underfloor is worth considering but further south Charente, Dordogne and south of that I would NOT suggest under floor heating.  You need a system with less inertia and a shorter response time.  Ideally warm air as this has a response time as short as 15 minutes but otherwise we are talking about a radiating surface.  Both of these systems could be made to work well from a solar collector but you would need a substantially sized insulated water storage tank to act as an accumulator.

I have a very effective warm air system which does have a response time of 15 minutes - the plumber who helped with the installation was astonished how effective it was as he had never seen a system like it before.  I am running on oil but am going to install a solar collector to heat the domestic water 12 months of the year.

[/quote]

Carcassonne is not far from being as far South as you can get in France. We have LPG fired wet UFH that was installed when the house was built in 1982 so I assume that it is in a screed. We have no qualms about the lovely heating we have and in the 3 years we have lived her the only problem was with the old original very inefficient boiler. We now, since December last, have a new condensing boiler with the asociated control system and it was even better through last winter. We didn't even worry about switching the system of last spring because when it warmed up the heating switched off automatically.

As for warm air heating a heating eng friend of mine in England told me a long while back that it had fallen out of vouge because it had moving air and that on it's own caused a small amount of chill factor and the air temp had to be a bit higher to supliment this, thus knocking down the efficiency. A friend also had it in his new house in the early 70s and said that he would never consider it again because he had suffered with very dry eyes from the time he had the house.

I think that I will stick with my UFH right down here slightly further South than St Tropez thank you!![:D]

I nearly forgot to add that our warm up time is about 12 to 14 hours and we both LOVE the warm floors and the general feeling of comfort, not heat, comfort, through the winter!!!

[andyh4]

I am with John on this one.  Tibbington is right that the system does have a degree of inertia but the simple answer is to turn it off during the summer and if perchance there is a chilly evening, put on a cardi - instant solution!

[Gyn_Paul]

There is the added point that old stone buildings have an enormous thermal mass which produces an inertial of its own. The last couple of days here have seen (air) temperatures going up and down like a dog at a fair, yet the inside of my house has remained fairly constant on the ground floor (50 cm solid stone), but less so on the first floor (breeze block, air gap, terracotta blocks, plaster). The inside of the barns - uninsulated stone - all seem to be the termperature the outside was 24 hours earlier!

So my point is that short-term temperature variations have less effect on mass buildings than might generally be supposed.

My Aberdeen friend grew up in the 30's in a draughty stone house with the mantra "if you're cold, put on another layer, and have a mint-humbug" ringing in her ears!

paul