Saturday, January 28, 2012

January 2012 Reports

To conclude the month, the January 2012 monthly readings were all better than one year ago:
  • House 789 kWh (2011 829.0)
  • GSHP 531 kWh (2011 608.0)
  • PV 76 kWh (2011 65.3)
  • Sunbox 127 kWh (2011 94.0)
29 Jan 2012: Sunday night, and time for more meter readings, and consideration of what else is happening. Chancellor Osborne went to Beijing, and while it's possible that London may be the location for the RenMinBi to be traded globally, he also agreed to sell Thames Water to the Chinese. What the hell do they want that for?... London is perpetually being dug up to replace rotten old water pipes. Meanwhile, US and UK warships were 'testing' the Iranians by driving warships through the Strait of Hormuz. President Obama delivered his final State of the Union address, of impeccable logic, which left Republicans seated and unsmiling, and having to use tortuous spin-language to find any criticisms. Close to my interest, it was somewhat shocking that three buildings in Rio de Janeiro collapsed suddenly (one was 20 storeys), in a heap of dust and rubble - presumably a mixture of bad construction and gas explosion, perhaps. While I have been skiing in the humble resort of Kasberg, the great and powerful have been assembling in the resort of Davos for a major economic summit - I doubt if they found time for skiing.  Solar storms have produced effects on earth, with the Aurora Borealis being seen as far south of Yorkshire and Arizona! Meanwhile, what have my meters been doing? It seems we are back in the business of breaking records...
  • All time Low Records: House annual 4,586 kWh, GSHP annual 2,579 kWh, GSHP FLEQ (full load operating hours) 1,174 hrs.
  • All time High Record: The PV harvest is 3,395 kWh, Sunbox clock 2,496 hrs. The Sunbox energy capture is nearly a record, at 3,071 kWh. The PV is so agonisingly close to 3,400 kWh, I wonder if it will touch that. Feb 2011 was very foggy, so it might happen if Feb 2012 is better!
  • Ground temperature is 10.4ºC. (was 10.6ºC a year ago.)
28 Jan 2012: Well, I am back after a week's holiday in Austria (ArchiCad Winter School), and I expected the week's meter readings to be higher than usual because I have to leave the system on 'autopilot', i.e. I don't expect my wife to know how to check and tune it daily. However, the weather has continued to be kind (despite the hyperbolic speculation told by the Daily Express) and the house averaged under 25 kWh/day and the GSHP under 18 kWh/day. The News roundup and Weekly summary will be done on the 29th Jan, but at the moment it looks likely to be another set of records, with the house and GSHP below 4,600 and 2,600 respectively for annual figures.

20 Jan 2012: The meter readings are on a Friday because I am taking a short winter sport break. The biggest news story of the week continues to be the aftermath of the Concordia shipwreck. As if that wasn't enough to remind us of the hazards of the ocean, the idiot Michael Gove (who has recently printed enough King James Bibles for every school which are sitting in a foreign warehouse with his name and foreword in them, but who nobody is prepared to pay for) proposed that a Royal Yacht should be built for £60m and presented to her Majesty to celebrate her Diamond Jubilee. It's to be a three masted square rigger apparently. Quite how an 86yr old woman and her 90yr old husband will manage this is beyond me. And it's to be paid for when thousands of public sector workers are made redundant, or have their pay frozen. Mohamed Ali reached the age of 70. I remember his fights in his early career. On Wednesday, the whole world came to a halt for a day, as Wikipedia, its greatest repository of knowledge, was blacked out for 24 hrs in protest against SOPA. And an old family favourite, Kodak is finally facing bankruptcy.... sign of the times - the digital era. And what about the Peveril Solar house meters? Well as January 2011 was mild, it's not surprising me that they have levelled off.

  • Very low: The House meter is 4,24kWr/yr, the GSHP meter is 2,628 kWh/yr.
  • Very high: PV meter is 3,390 kWh/yr, Sunbox meter is 3,058 kWh/yr
  • GSHP clock is 1,200 hrs (low) and Sunbox clock is 2,475 hrs (high)
  • Deep ground temperature is 10.3ºC

15 Jan 2012: The weather has turned colder, but sunshine has been good. Our PV has hit an all-time record. January last year had a mild middle period, so the electrical figures have, at last, begun to level off. Elsewhere in the world, there is almost too much to report! Stephen Hawking reached 70. North of the border, the Scots are all stirred up by their leaders to want to be a separate country and currency (really, will they vote for that?). The residents of the rural Chilterns are roused to anger by the thought of high-speed rail travellers getting to Birmingham more quickly than they can reach Waitrose in their Range Rovers. In the USA, New Hampshire confirmed that Mitt Romney is in the lead with the Reptilian party, but the hideous paradoxical spectre of 'libertarian authoritarianism' is emerging in the rise of Ron Paul - and in the next primary, they will be the only candidates.
  Closer to my teaching interest, the BBC reported that a boom in skyscrapers precedes a recession, but as we are in that recession already, it's not a new story - and the trend mainly applies to the USA. In China, skyscrapers proceed even faster than ever, with more built in the 11 years of the 21st century than in the entire previous history of building. I am sure that many of the skyscrapers in Dubai will spend their lives empty - their boom is over.
  Closer to the topic of this Blog, there was a midweek stampede to reduce Gas prices by 5%, starting with EDF, conveniently omitting to mention that they had hosting raised prices in November by over 15% - this seemed to be a cheap trick to get a day of free advertising on the BBC. Only one company, British Gas, dropped their electricity price. The high court decided that the Nov 2011 decision on Feed in Tariffs was wrong, but the government in the form of DECC seem to have decided to ignore that. Thousands of women are worried about their PIP breast implants, and the Phobos-Grunt Mars explorer crashed to the Pacific after getting no further than 385 miles from earth (expensive fail...) The entire week's news was overshadowed by the capsize of the Concordia, a ship the size of a town (if redistributed on flat land). I am not a naval architect, but as a sailor and a skyscraper cognoscento, I have wondered how much taller these cruise ships can get, with rows and rows of balconies, but now we know. They only need a small knock to capsize.

  • The Annual figures are levelling out slightly, with the House meter having an all-time record of 4,609 kWh, but the GSHP meter levelling out at 2,623 kWh (not surprising in the light of the recent cold but sunny weather.) (A year ago these were 6,145 and 4,078 respectively.)
  • Happy to say, the PV hits an all time record high of 3,392 kWh (a year ago it was 3,288)
  • Despite my suspicions about the energy meter under reading, the Sunbox meter shows a nearly all-time high of 3,081 kWh with a record high SB hours of 2,478 hours (even though I raised the delta-T to 7 degrees.)
  • The deep ground temperature has dipped a bit due to the recent cold snap, but it's above 10, at 10.5ºC. (what would it be if the thermal storage was boosted by some evacuated tubes!?)
8 Jan 2012: When will the winter come? we have had the solstice and the new year.... but we have roses blooming in the front and back garden, weeds in the flowerbeds that do not usually show until July, and not a single day yet where the daytime temperature reached freezing (and not many nights either). No scraping of wind screens or salt on the pavement! As for the ground temperature, we seem to have turned the corner of the winter. More sunshine to come (although we might still have the long promised very cold spell..)
Ground Temperatures over three winters.
(Sunbox started operating March 2010)

  Elsewhere in the world, we now have two satellites ringing the Moon, (Sir) Jonathan Ives (chief industrial designer for Apple) becomes a knight, and the cartoonist Ronald Searle dies. So does photographer Eve Arnold, a few days short of her 100th birthday. William Hague visited Myanmar and met Aung San Suu Kyi. Eleven was significant for some, 11 died in New Zealand when a hot air balloon crashed into electricity lines , but 11 Iranian sailors should be grateful to the US Navy after being rescued from Somali pirates. On a more Nottingham located context.... this house again achieves all time records, always falling - as much due to the mild winter as to the solar augmentation, I am sure.
  • All time Records still Falling: House 4,615 kWhGSHP 2,621 kWh, GSHP clock 1,198 hrs. (A year ago, annual was: House 6,225 kWh, GSHP 4,151 kWh, GSHP Clock 1712 hrs). 
  • PV 3,382.5 kWh (Nearly the highest ever! It was 3,283 a year ago) 
  • Sunbox energy 3,058kWh (I'm happy as long as it is above 3,000). SB clock 2,465 hrs. 
  • Deep ground temperature is 11.0ºC. A year ago it was 10.4ºC. 2 yrs ago it was 4.7ºC.
If this weather continues mild.... I fear to tempt fate... it seems that the two key annual figures could go below 4,600 kWh and 2,600 kWh by the weekend.... because only a short while ago I was writing that it would be a 'dream' if it would go below 5,000 kWh and 3,000 kWh.
1 Jan 2012: Another week of mild weather, with daytime temperatures in double figures. It is illustrated in the diagram below where the Red graph traces the graph of Degree Days, indicating the heating requirements for buildings in this region, using a base of 15.5ºC. The Blue graph illustrates, in a relative way, the workload of the GSHP in kilowatt hours, over the last three winters. The current winter has hardly happened at all, compared with the previous two.
What about the rest of the world?... well Kim Jong Il was laid to rest in a rather noisy and crowded way, Syria has become a lot more violent. We had Christmas and New Year - the London fireworks were particularly impressive. Germany announces that renewable energy is now the single largest source of electricity, and nuclear is in decline  [See Report] (the bad bit of this being that the second largest source is Lignite, otherwise known as dirty brown coal). Samoa decided to cross the dateline and miss out Friday altogether. The BBC declared a Panda to be on the shortlist of Females of the year. The best news is that a Swedish woman found her wedding ring, 16 years after it was lost, growing on a Carrot in her garden. What else? Oh, the Meters! Here are some annual figures:
  • All time Records still Falling: House 4,654 kWh, GSHP 2,669 kWh, GSHP clock 1,224 hrs. (A year ago, annual was: House 6,285 kWh, GSHP 4,206 kWh, GSHP Clock 1728 hrs). 
  • PV 3,378 kWh (Very high! I'm happy if it is above 3,300, it was 3,276 a year ago) 
  • Sunbox energy 3,039kWh (I'm happy as long as it is above 3,000). SB clock 2,456 hrs. 
  • Deep ground temperature is 10.9ºC. A year ago it was 10.1ºC. 2 yrs ago it was 5.0ºC.

Wednesday, January 25, 2012

Surya Layout with Tubes added

25 Jan 2012: This diagram shows schematically how the new tubes will be added to the existing system. I have done a more detailed diagram of the existing for myself which is too 'busy' with detail to put on here. This diagram gets across the essentials, good enough for publication.
aaarrgh, I have just realised that this is also wrong... with this, the ground
loop would be forced through the tubes if the Sunbox was not operating!
One problem has been deciding what to do with the 3 port valve. I needed it before because even with the pump in the loft not operating, the pump is sufficiently transparent for liquid to more round illegally. The early system had a 2 port solenoid valve to stop this happening. With the current set up, the whole lot flows through the Surya Sunbox when it operates, but we could not have this happening through the tubes which have smaller pipes. It seems that the system may have to have three solenoid valves. 
• The existing 3 port valve to divert flow up to the Sunbox.
• The Tubes will need a 2 port valve to stop liquid moving round these accidentally when the Sunbox is working. 
• If the Sunbox is not working but the Tubes are, there would be illegal movement of liquid through the Sunbox.

While writing this, I have realised that this diagram is also wrong! More thought is needed!

15 Feb Postscript: I have now updated the circuit diagram and got it working!

Monday, January 23, 2012

Graph of Underground Temps

23 Jan 2012: While I am in Austria, I have the chance to think about the project... (while speeding downhill on a blizzard..). It's time I updated the graph of ground temperatures now that I have observed 3 winters and two summers with detailed data.
I have noticed that when the winter comes, there is a rapid fall off in temperature... a steep slope, even if the borehole has been charged. This is a temporary effect because the heating activity is cooling the area immediately around the pipes. There is a nadir at some point, usually in January, and then things improve and there is a longer slower slope for the temperature to climb back up. At the nadir, the delta-t between the borehole and the larger surroundings is big enough to draw energy more quickly from the wider surroundings.
   The exact size of this phenomenon depends on many factors, e.g. whether you have a colder/warmer than usual autumn or spring, the size of the house and how much heating you have to give it, the depth of the borehole, the availability of alternative heating (e.g. biomass in main living space), the size of solar panels you use for charging, and even the nature of the surroundings for receiving spring and summer sunshine - a tarmac road or open field nearby.
Temperatures from Sept 2009 to Jan 2012
The Surya system started in March 2010. The right hand side of the graph
demonstrates the revised shape of borehole temperatures. A rapid decline
in autumn, with a long slow climb-out from January to midsummer.
Then a flattish top until the autumn heating season restarts.
  With Solar charging, there is still the usual steep autumn fall, but it pulls out sooner, and with January, the ground temperature might be rising already because of improving sunshine towards the February end of the month. Once the ground has reached an optimum in summer, it did not just continue rising, presumably because heat is moving outwards into the mass surrounding (which is precisely what one wants it to do). If it remained too close to the pipe, the ground temp would rise, but it seems to stick at just under 14ºC. If I tested it at teatime, it might be 16 or 17ºC, but the methodology is to test at midnight, some hours after both the Sun and the GSHP stopped adding or subtracting. So one has a rather long flat top to the curve until the heating season restarts in October.
  So, looking at the top graph again, the uncharged borehole would gradually get lower in energy levels until it reached a low enough temperature that the delta-T was pulling enough energy in from surroundings to reach a new equilibrium. Being at a lower temperature it makes the GSHP less efficient, in fact, it might cause owners to consider that it was malfunctioning. The charged borehole will have higher nadirs that last a shorter time, with a quicker climb-out to summer temperature. The peaks will not get literally higher, but they get wider at the top, e.g. they seem to consolidate - increasing the energy level by staying at about 14ºC but to a wider radius.

Friday, January 20, 2012

Student video on Sustainability

20 Jan 2012: Some students in first year of our department made a video about the Concept of Sustainability, and built it round an interview with yours truly! (includes mentions of the Peveril Solar house and of Tall Buildings).
   Im not sure what all the Flintstone stuff was for at the end... presumably to suggest that we have to go back to simpler energy systems when the fuel runs out...

Tubes, high in the sky

20 Jan 2012:  Another reason for my interest in Evacuated Tubes is that they will contribute to my Skyscraper interest, because I am envisaging high rise facades which can include these, high in the sky out, of the way of trees and adjoining houses, optimally angled and positioned.
   I would have to rethink my ideas on thermal storage, as the cost of the PCM required for a winter's storage for an entire apartment is excessive. My colleague Dr Boateng is ordering some of the same tubes from Kingspan this month because he is doing research into tubes with PCM storage.
   For short term use, Water is the best store, but once it is hot, it reaches stasis (and has other problems, such as evaporation). One reason for liking PCM is that it absorbs more and more energy without getting hotter. But cost is an issue.
Heron Tower, Bishopsgate, London
I don't think it is practical to have arrays of tubes transporting heat directly to a ground store 200 metres below during the day time - system losses would be too serious. But it is practical to have daytime energy transferred to large water stores at intervals up the building. Energy is immediately available for local Diurnial heating and DHW that same day to the apartments in the floors near the tank. During the night hours, surplus energy is purged to a deep underground store in extremely well insulated ducts for later retrieval. (rather like the Norwegians pumping water uphill to lakes to cope with surges in hydro-electric demand).
   Tall buildings need deep caissons, and it is even possible to consider that the caisson is built, with insulated edges (but perhaps uninsulated bottom), tubes are laid, and much of the fill is returned (instead of being transported off site). For an insulated ground store, the sizing of the store would be very important because it is finite. There is less demand for underground parking now in major cities like London, so the caisson (which is still needed) can have a purpose.
   Under the Heron Tower in Bishopsgate, London, there is a caisson, but for reasons of traffic management, they only have a small handful of parking spaces, the majority being for disabled access. (I've no idea what they do with the remainder of the basement, but tall buildings usually require storage, loading bays for service, M and E plant.).

Tubes: High temp / Low temp energy

Easy adding of Varisol tubes,
with included manifold
20 Jan 2012: Chris Wood wrote to me with the thought that for adding extra solar capture capacity, I might be better off with a Flat plate solar panel, not tubes. I feel that my existing Sunbox system is in some ways like a large low temperature, less efficient version (perhaps) of a flat plate collector, although mine have the advantage of working in the dark, indeed, all night in summer. I want to discover the contrast between High temperature collection (diluting into the ground loop for shorter hours) and the existing Low temperature (feeding the whole ground loop through the panel for many hours).
My sister-in-laws flat plate panels
     I also like the tubes because they are modular, in that you can have a space, and work out how many tubes can best fit that space - that makes them very versatile.
     Large flat plate collectors don't always fit to the space available, and are large black heavy rectangles. Tubes are also semi-tracking, in that being circular, they are more adaptable to changing solar altitude - for much of the day, there is always part of the tube that is more nearly incident to the sunbeam.

Thursday, January 19, 2012

Tall ships keel, not sink

Screen capture from BBC website
19 Jan 2012: Getting off the topic of Solar for a moment, I have been amazed at how high modern cruise ships have become, and even ferries seem high out of the water. They have shallow draft, to avoid running aground, and because tank tests must show they are stable. The Concordia is something like 14 storeys high, depending on how you count, and the draft is only 8.2m. Its impossible for the centre of gravity to be below the waterline, but the vectors from the CofG to the waterline are such that it cannot capsize, providing it is not punctured.
See this BBC page, with drawings of the ship tilting.

 They had great problems lowering the lifeboats because on the low side, the boats would be crushed by the capsizing ship and on the high side, the lifeboats would not release.
 We have all seen how the Titanic sank.... with a similar gash in the side, she gradually filled up and gracefully settled vertically into the water, taking several hours to do it, and allowing lifeboats to be launched both sides. This ship, and the Herald of Free Enterprise in the 1980s are so high that they capsize sideways when punctured, the capsize happening in a few minutes.

WTC collapse
If buildings did this, there would be a very different attitude to structure. The twin WTC towers in New York were fatally damaged, but they fell vertically, like a collapsing accordion, within their own footprint. Imagine if the impact of the planes had caused the buildings to either snap (and the upper part fall) or to fall over onto its side like a collapsing tree, or like this ship has done.

Varisol progress

19 Jan 2012: I am making progress with the evacuated tubes project. MG Renewables called round on Friday for a look at the site, and I discovered that back in early 2010, I had ready built in 22mm attachment points for a future solar panel or tank. I have had some correspondence with Kingspan Renewables who are interested in helping, and I hope to meet their representative in early February.

Do we need the extra heat?
  As this house needs more heat than the present Suryas can provide, I propose that it is worth expanding the solar capture and seeing how the tubes would perform. Let's imagine that the house needs 12,500 kWh annually for heating and DHW, and the heat pump is burning 3,300 kWh of power to do it, and the Suryas are putting down 3,000 kWh of solar thermal energy. That simple arithmetic suggests that 6,200 kWh has to come from the natural surrounding - that tells me that there is additional scope for putting down more directly injected solar heat. I also believe that there are system losses, for example the upper 3m of underground loop are not insulated and probably just lose heat to the cold upper crust. Some additional solar gain will compensate for those losses.

Kjellsson thesis on domestic solar charging

Front cover of Elisabeth's thesis
18 Jan 2012: I've had an email exchange with Goran Hellstrom of NeoEnergy, and he has sent me a copy of Elisabeth Kjellsson's PhD thesis 2009 on Solar Collectors Combined with Ground-Source Heat Pumps in Dwellings. It's great to find that this has been properly written up. It is on the internet, with this link above.
   It appears to be based mainly on simulation, using TRNSYS software, which according to her paper, "has the capacity to simulate the whole energy flow with the basis in the climate, heat losses, transmission, ventilation, domestic hot water and demand of cooling." I would like to meet them one day, perhaps at Ecobuild. It would be interesting to run TRNSYS with the actual size of this house and the local climate and the capacity of the GSHP and see how the simulation matches reality.

Could I simulate the Peveril house system?
  I tried writing my own simulation using GDL, and really ought to go back to it: I should spend more time on it. I burnt out, slightly, after a day, but realised at the time that a more systematic approach would be better than diving in and trying it without deeper systems analysis first. See:
   The biggest problem for me was in trying to predict how much natural heat will return to the borehole. This is influenced by several things, most notably which part of the year it is, and the delta-T between the borehole zone and the space around - this changes every week. To make it more difficult there are contours around the borehole moving outwards (rings) and contours depending on the depth of the hole (distance from the surface). In addition, if you have twin boreholes, the rate at which natural heat is restored to the borehole is non-regular. Between the boreholes, the solar heat remains longer, but in winter, the natural heat finds it more difficult to return. In winter and equinox, the solar heat put down on one day is closely around the pipe and will be drawn up the same evening, without flowing out to the surroundings.

a screen capture of my effort at animation.
This image was from running the simulation
without solar input.
   Another problem is that the COP of the heat pump changes as the solar heat is provided. One could calculate the heat withdrawn from the ground by taking the electricity used and merely multiplying that by a COP index, say, 3.0. Or one could calculate the heat by looking at degree days for the week, and relating that to the theoretical heating and DHW needs of the house.
   The simulation has to work with and without the solar input, and it has to work for varying quantities of solar capture. If I increase the area of the Suryas to 12 square metres there would be a point where it would lose more than it gained. This may happen when I fit the evacuated tubes.
   By comparison, a simple calculation based on inputs and outputs would be easy.
  Another problem was how to represent it. I showed the borehole as something like a giant pair of lungs, with inflation and deflation, based on REAL figures recorded from the meters. Perhaps if I just showed it as numbers first, that would be enough, and then consider the visual metaphor of bottles or lungs later. 

Tuesday, January 17, 2012

NeoEnergy, Sweden

17 Jan 2012: NeoEnergy, the Swedish company of Goran Hellstrom and Thomas Blomberg (whose lecture on solar charging is a key document in this science) have a very useful dynamic animation on their contacts page, demonstrating progressive underground cooling over the years of a borehole from which heat is drawn by a GSHP, but not replaced. It gets progressively colder each year, and does not have time to recover fully in the summer.
I hope they don't change the page address in the future, but if they do, here is a screen grab of the page.
I gather that Robin Curtis (a key speaker at EcoBuild 2011's seminar on GSHPs) closed his UK company Earth Energy and has joined up with NeoEnergy, and later with Mimer, also a Swedish company.

NeoEnergy also sell software called Earth Energy Designer (EED) for borehole heat exchanger design, and they provide other specialist testing and prediction services (click on Service List on their main site)
Their links page has no active links to any UK sites, which seems to be a pity. I will write to them.

Monday, January 16, 2012

Number of hits on the site

15 Jan 2012: I amazes me how many hits there are on this site, and where they come from. We are getting close to 50,000 page views (by the end of the month), with over a hundred hits a day consistently. The majority of callers are from the UK, with a sizeable number from the USA. Some may be regulars to hear about goings on at the Peveril Solar house, but Google brings in many random visitors. Because of the use of the word Surya, we get hits from India. The word Navitron seems to get a lot of UK visitors. There are also a surprising number from Russia, although the effect is exaggerated as the Mercator projection of the tiny map makes Russia look bigger than it really is. When Googling, the site comes up early with people using keywords like Heatpump and Solar.

Sunday, January 15, 2012

Sunny Winter days

PV maximum curve for January
14 Jan 2012: Today has been the coldest of the winter so far, the first day to have below zero temperatures overnight and below zero in the first hours of the morning. But later it was sunny and clear and windless, so by 1pm, it was possible to sit in the outdoor seating of Belle and Jerome basking in sunlight and enjoying a long hot cappuccino, on the coldest day of the year. This also gave us the highest PV score of the year, 4.9 kWh, and the last time we had a score this high was 19th November of last year.
    By this day last year, the Sunboxes had captured only 25 kWh and in the same time of the present year, this one has captured 67 kWh. So perhaps the insulated design has been worthwhile.
   During the cold part of the morning after the Sun had got up and was moving to the south, the temperature inside the SB was safely above 25ºC. The daily GSHP consumption for the day was below 20 kWh, which is unusual for such a cold day.

Energy meter will be replaced

14 Jan 2012: The energy meter I have been using (Sontex Supercal 539) is perhaps on its way out. Maybe the battery is going, and it has always annoyed me that it displays in Integers only. It regularly appears to display 'Err 2' which is an error message suggesting the need for replacement soon. It's not massively urgent, as it seems to recover later and show a reading in the afternoon or evening. I have noticed it occurs most when the flow temperature is freezing or below freezing.
    DMS metering of Pinxton, Nottinghamshire are specialists in energy flow metering, and are only 20 miles from my house. They advised me that the 539 is not ideal for use with this system as its volume measurement is based on a plastic paddle and that degrades over time when used with glycol. It temperature measurement is not very precise when the difference between the flow and return is in the range of 1-4 degrees. If the temperature comparison is also in integers, then the system will be under recording - Delta-T of 0.8 treated as zero, or 1.8 treated as 1 - who knows? Anyway, it will be replaced.
  I drove to Pinxton and bought a Sontex Superstatic 440. It is £ 100 more than an SuperCal 539, but it measures volume flow by electrostatic monitoring of the flow (no dodgy paddles), it measures down to fine decimal points (for greater accuracy), and it has an option to be mains powered, so it will never need a battery replacement. In addition, the electronic display unit can be detached and replaced if there is a fault, without requiring any change to the plumbing. It can measure cooling as well as heating. The plumbing bit can be up in the loft, but the display unit could be down in the 'linen cupboard' (reducing the need to climb the ladder so often).
  See the technical document about the SuperStatic 440
  If the slightly dodgy old Supercal is better on higher delta-T, I could re-deploy it on my proposed Evacuated Tube array. It won't be thrown away.
  I can't fit the new meter yet, as there are some special Tee pieces that I couldn't get from DMS and that Screwfix don't have either, so I have to go to a large plumbers merchant for them.

Wednesday, January 11, 2012

Radiators suitable for Heat Pump

11 Jan 2012: People often ask me how they could use a Heat Pump without tearing the floor up and laying an expensive underfloor heating system. Some people just like something warm to hug or to stand with one's back to on a cold day, or put a damp coat onto after being caught in the rain.  Underfloor heating just doesn't have this comfort (except for cats who love it!) Underfloor heating is invisible, and sometimes, if you can't see it, you don't feel it! If you have thick carpets, then expect even more delay before warmth comes through. For Retrofit, Underfloor heating is just about too challenging for anybody to take up.

I happened across this company, JAGA, who claim to have a whole range of suitable low temperature radiators, some for surface mounting, some recessed or flush with the floor.
Jaga have a number of products, but their 'Performers' range of radiators are suitable for the lower heating temperature from a heat pump. They even include one that can be a cooler if you have a reverse cycle HP.
    These are the first ones I have found that I would quite like! Jaga use the expression 'DBE' (dynamic boost effect) which is very quietly running fan assistance, but I would expect these to be virtually inaudible compared to MVHR. They would all need a power supply, but this can be provided in the same skirting duct or alongside whatever the pipes run through.

So, take heart. If you are planning to try a heat pump, then these radiators are the ideal way to avoid the disruption or the impossibility of installing Underfloor heating, and which could use your existing pipework for your previous central heating layout.

David Hill of Carbon Legacy has written to point out that Dimplex and Myson have fan assisted models for use with Heat pumps, i.e. a low temperature circuit less than 43 degsC,

Does anybody care to predict the future?

11 Jan 2012: There is an interesting article on the BBC website about predictions from the year 1900 by an american engineer John Elfreth Watkins. I am impressed by the astonishing accuracy of some of them, considering that for some, there wasn't a trace of the technology in sight at the time - digital photography, TV, mobile phones and more.
    Looking ahead from our time, we can expect that fossil fuel energy sources will have become truly rare, except for gas which is partially self renewing. If people will not accept solar and wind energy now, will they be forced to? Scandinavia shows us that district heating and extremely well insulated houses are possible on a large scale. If sun is all we have, we have to be smarter than we are now. I have seen advances (or reducing technology costs) even in the short time I have been spending writing this blog.
  I don't think I can come up with more right now, but this is a project worth thinking about. One is slightly deterred by one thing that Watkins didn't have to worry about but that we have lived with for 60 years, is imminent destruction through nuclear war or accident, making all our predictions go wrong. Another is that he expected american economic domination to be a permanent feature, whereas we are seeing the rise of China and India balanced with the rapid decline of USA spurred on by outsourcing of manufacturing, increasing decline of their cities, massive inequality of rich and poor, threats against Iran, and financial madness from the Tea Party tendency. The Euro isn't doing so well either!

Energy prices

11 Jan 2012: There's a lot of news this week about energy prices, with EDF leading , by offering a 5% reduction in GAS prices (and conveniently hoping that the public are forgetting their 15% increase last November.) The wholesale price of Gas has fallen by 9.2% since November, but the distribution costs are such that they can only offer 5%.
    Please note that Good Energy, are voted number one energy supplier in a survey by Which Magazine, for the second year running. They have had their prices pegged for several years, and into next year because? Because? Because the wholesale cost of their fuel is free. It is as free as the wind and as warming and pleasant as the sunshine. Thousands of Home-Generators like me are contributing to their portfolio of power suppliers.
Note that none of the big six figure here,
these are all small suppliers or brokers
If you wish to add to a petition to get other suppliers to reduce energy charges, consider this on line petition
          Or better still, switch to suppliers with a cheaper source of wholesale fuel! (we have been with GE since 2006, when we lived at the previous house).
    Sorry to sound like a grumpy old man here, but I would like to see Gas more expensive (providing that cost was justified, and not just putting profit into EDF's pocket). My first reason is that it is still so cheap that it maintains the drive to install thousands of gas boilers and it deters people from using heat pumps. Secondly, the cost of gas is 'bearable' enough for people to continue with insufficiently insulated buildings. 

Watery gravel layers

10 Jan 2012: I was asked about solar ground charging by a developer friend recently, for his house. He lives very close to the Trent river, and suspects that he has groundwater bearing gravel within 8m depth of the house. When Severn Trent were recently doing some anti-flood maintenance work, they had deep trenches which had to be pumped out all the time for work to continue.
  For him, I cannot see a useful way to charge with solar heat - the heat would be washed away. I would recommend a cluster of short boreholes, all taking advantage of the conductivity, migration and latent heat of the slowly moving water . This would be preferable to one deep hole trying to get far below that layer.
  He will have a trial hole drilled to test the depth. The gravel layer is probably too deep to lay a horizontal pipe in (within the curtilage of his property), so a group of shallow holes that reach the layer would cause least spoil. 

Why consider the tubes?

10 Jan 2012: I ask myself that too, but it comes back to the idea of =Research=. This house is performing splendidly, and if that is all it must do, then some would say: "don't change anything!" I don't have another house to play with, and I am desperate to know if a high temperature supply like evacuated tubes (ETs) will work better than my low temp Sunbox (SB). If it is a lot better, then I am better off changing direction slightly in future installations, and future lectures or conference papers.
This symbolises the concept. And when I drew
this I didnt realise how much more beneficial
two holes would be than one.
    The fundamental constant is the idea of STORAGE. I am completely convinced about that now, providing the soil is good. The technological means of achieving it should be subject to improvement.
     The Sunbox works off delta-T for much of the equinox and winter, and I have upped the trigger delta-T to 7 degrees for it to work. This reduces the hours of working, but makes it work better when it does, i.e. more efficient - more Kilowatt capture. The accuracy of the energy meter is better with a larger delta-T.
     Having a panel of evacuated tubes will actually reduce the effectiveness of the Sunbox because it may deliver enough heat that the liquid going down to the ground is warmer, and then delta-T activates the SB system less often. The thermal sensor that triggers the Sunbox is downstream of the place where hot liquid from the ETs will be introduced. At the moment the SB produces over 3,000 kwh/yr because it is working to a cold store. I shall just have to take that risk.
   In the summer there is no problem as the SB works on actual temperature, e.g. if the SB temp is above 20degs C. This trigger temperature can be raise if the ETs consistently raise this figure too easily.
    One key difference is that the SB works at 5 litres/min (at slow rate) but the ETs have a slower pump, with a recommended flow rate of 1 litre/min. With this slow rate of dilution, I hope that the effect on the sensor for the Sunbox will not cause too much loss of activity by the SB.
    At a 'mere' 2.2 sqm, the panel of ETs would be smaller, but if it can produce 2,500 kwh and the SB reduces to 2,500 kwh / year, that would still be satisfactory.
   Also.... The whole point of the experiment.... Will the delivery of higher temperature liquid actually raise the final summer temperature of the deep soil beyond 14 degrees? Will that have a more significant effect on the GSHP than the present SB system has had?

Where to put them?
I did a quick calculation with PVGIS and found that an array on the roof at 40degs pitch facing east will get about 16% more than a vertical array of the same size facing south but vertical. That helps to decide which location is best. 

Tuesday, January 10, 2012

Green Technologies

10 Jan 2012:  The need for the economy to make a transition to green technologies is eloquently explained in this Guardian article by Andrew Simms. 
There's a story here of lost opportunities, governments going back on promises, ideals which get dumped if they are not 'good for business'.... The green movement needs to keep plugging away, it ain't going to come easy.
This comes on the same day as the decision to go ahead with High Speed Train from London to Birmingham, Manchester, Leeds. Although one has some sympathy for the objectors, their claims are very similar ones made in opposition to the rail network 150 years ago - and while people continue to take jetplane flights from those cities to London, there's proof that there is demand for faster travel than presently provided (and to justify the expenditure, I hope that the government of the future will curb the great number of shorthaul jet-flights.

Varisol Tubes

16 horizontal tubes make better use of that space, and keep the
plumbing compact too!
10 Jan 2012: Looking at options for evacuated tubes (ETs), I discovered Varisol tubes (by Kingspan) as recommended to me by Gerry Kennedy of MG Renewables. From this page you can download an installation manual.
   These ETs are very happy being laid horizontal (with a 2º tilt) and are modularly connected, i.e. do not require a large boxy manifold, as each one has its own manifold component and they all connect together.
  Although I like the simplicity of the older type where you can just lift a tube out of the boxy manifold, these Varisols are extremely neat and close fitting, and get maximum capture from a square metre of tubes - which cluster closely, leaving no wasted space between.
showing how the tubes connect, with no
wasted space between.
   16 tubes, of a length 1950mm would give about 2.2 sqm of area.  They would occupy that 3m x 1.3m space with a bit of spare working space around.   Although these tubes would be facing East, I do not see an alternative. The South wall is busy enough already, and has the added risk of kids throwing a speculative stone from the field. The west roof is clear, but it faces 10 degrees north of west.
  I looked at my plumbing in the loft and found that I have already (how very kind and thoughtful of me!), provided dummy connections for future attachment of a second source of heat, either a tank or a solar panel, should it ever be thought of. It is downstream of the existing energy meter, so will not confuse my measurements of the amount produced by the Sunbox. The tube array can have its own energy meter, thermostat and pump.
  I am currently in correspondence with Kingspan Renewables, regarding these tubes.
In the foreground, there is a blue handled valve and
either side of that, a 22mm Feed and Return pipe.

  Logic: My main worry is that the three port Danfoss valve on the ground floor has to be commanded by one thermostat or the other. Logically, it seems to me that it should be the Sunbox thermostat that does that. On the good sunny days, I don't want it to be Either-Or, I want it to be Both sending heat into the borehole. If the SB has enough sun to kick off, then there will also be heat from the ETs. The SB works from air heat, e.g., at 0100 at night on summer nights, and in that time, we would not want to be sending liquid through the ETs. There might be cloudy bright days when the ETs have heat, but the SB does not. The risk is then heat wastage if ET heat is sent around the SB and is cooled. There are delta-T conditions when the SB is working, but there would be no ET action because the thermostat on the ETs would not command it. .... doh! It will all make sense as I think about it more. I have invited Gerry to call round for a discussion.
  At some future date, I have the option to fit a solar water tank up there, as the Kingspan tanks are 480mm wide including insulation and would fit easily through the loft hatch. Why not use a water tank now? well as explained earlier, the principle of delivering heat directly to the boreholes can been so very successfully proved that there is only a marginal benefit and a very high cost by adding a mains supply up to the loft and a large insulated tank. 

Sunday, January 8, 2012

Well perhaps no tank....

8 Jan 2012: I worked out that a 117 litre tank would hold 22 kWh of heat if it was raised to 60ºC (quite possible in summer with evacuated tubes) and then lowered at night to 15ºC by a few hours of circulating through the ground loop. With a specific heat of 4.186 kJ/kg K it's about half a kilowatt hour per degree change. However, I have to return to the key idea of the 'Surya' technology that I am using on the existing Sunbox is that it does not need a tank, and that the ground gives an excellent delta-T.
There is a 3m x 1.3m space on the east roof
    If the pipe diameter is large, it connects by the 'trickle and whoosh' serial loop design and if it is smaller pipe diameter then it can work on the 'trickle all the time' parallel loop design. Simples!
    If a water tank was getting into high temperature, the amount of heat it would store would decrease progressively as the delta-T decreased - as the temperature of the tank approached that of the panel. If the solar panel is receiving liquid at only 12-15ºC even in summer, it would perform far more efficiently than it would from a tank that was warming up.
  The next problem is that the space available on my roof is 3m wide by 1.3m high. I don't want to add more to the south wall because it could become 'target practice' for kids on the field behind, and glass tubes are tempting - and being vertical, they would be less efficient anyway. Putting them there looks neat - see the diagram - but most tubes are manufactured in a 1.6m length. The tubes could go on the west roof, but it is West facing, with a 10º tilt to the north - but there is a clear 1.6m high space on that roof. The inefficiency of its facing west is balanced by the high efficiency of an excellent delta-T to the ground.

   It's possible to buy an array of tubes reasonably cheaply - this diagram on the Navitron website shows a 30 tube array, with 1500mm tubes, 2.5m wide is about £700 including VAT.

Saturday, January 7, 2012

Well, perhaps Water then...

210 litre double coil
(Screwfix photo)
7 Jan 2012: I phone Zafer at PCM Products and got some idea of the cost of materials. It is clear that the best application for PCM is for passive cooling. The problem with using it for heating would be insulating it long enough for the heat to be returned later. The cost would be prohibitive for a sufficient amount to do what I want - in its cheapest form, the brickettes, it would work out to about £2000 per cubic metre.
117 litre single coil
(Screwfix photo)
  The amount I would need for significant thermal storage intended for heating is not worth it when I have a large thermal store already. My idea has pushed on to high temperature storage for no longer than a day, and for this a water tank would work just fine - water has high thermal capacity even in a small tank, and is easy to store water and heat in well insulated tanks.
   The area of south facing wall that I could fit evacuated tubes to is limited, so there is no point in having a tank bigger than 120-160 litres. One could store heat in a water tank by day, and purge it during the night to the deep borehole.
   I will do a drawing to show an initial scheme. Twin coil tanks are all too large (180-300). The benefit of a twin coil is that it could also preheat the DHW - but I am against that on health and plumbing reasons.
  There is a way to do what I am aiming for with a single coil tank. The solar panel circuit would fill the tank entirely (yes, that's a lot of glycol), and the ground loop would go through the built in coil, controlled by a thermostat and solenoid valves. The tubes can heat this up to something like 60ºC on a good day, and this would be dumped at night. I will work out the thermal capacity.

 Unfortunately, this might mean some shopping with Navitron (the first company who come to mind for evacuated tubes), but I would like never to have to put any business in their direction after experiencing the manically hostile management style of the user forum. Nearer home, our department is always setting up rigs with tubes, and if any of these experiments have completed, I could offer a home to the redundant tubes.
   Also, the loft hatch is 515mm wide and the standard tank with insulation is 520mm wide. It is possible to remove some woodwork to make enough width to get a tank up. 

Friday, January 6, 2012

Thinking about PCM again

5 Jan 2012: In the quiet times before the university term gets going, the imagination gets going to fill in the time and space. The Surya Sunbox system has been working splendidly, and still gets solar heat even in these wind speeds and temperatures. The thermal insulation and airtightness of the new construction has proved to be useful, at last.
But it is boring with everything working so well, what else can we do!? 
Wind turbine is out
I have tried thinking of every permutation, but what ever one thinks of is put off by our location. The only positions are on the south roof end, but that would shade our PV panels. At the north end, that would cause noise and coruscating shadow risk for our neighbours. It has been very windy today, but the tops of the trees were moving a lot, about 80 metres north of us, but around our house it was calm, due to the wind shading effect of Sharp Hill.

What about PCM?
I am thinking about this, especially as I have another skyscraper design project coming up, and we will again be considering the use of PCMs in that design. It would be great to have a mini prototype of the technology working here by the summer. I have been looking for wholesale Wax, but can only find it for candlemakers, and the like. Some companies are geared up to provide PCM products with precise phase change points. I have contacts
Article about PCM in World Architecture News,
See also, the link:
I would be interested in a small PCM store in the loft, and charge it up in the day to a higher temperature with heat from evacuated tubes, and discharge the heat to the borehole at night when the main Surya boxes are sleeping (using a time clock)

My more serious interest is the application to high rise buildings. I had students last year designing skyscrapers in New York.
See page 24 specifically. This was designed by three of my Masters students, with inspiration from the thermal storage ideas used on the Peveril Solar House - recognising that conventional borehole storage would be out of the question. The ground is 200m below, out of reach and is also blocked by underground car parking etc. So local storage with PCM would provide enough heat for the very well insulated apartments if heat was stored using high temperature collectors. This could provide enough for the entire winter, with topping up on sunny days through the winter, over very short horizontal pipe runs.

30 Jan 2012 Postscript: Ive been looking at the site of Rubitherm, a german manufacturer of just the sort of wax-based PCM that might be suitable. However.... as my present system runs at low temperature, it's not going to be a lot of use compared with the capacity of the soil under the house. I would love to use PCM creatively, but am still snookered.

Tuesday, January 3, 2012

Strongbow - strong signal

3 Jan 2012: The things you can do with a riveter!
Our BT modem lives at one diagonal of the house, but the laptop used by my wife is in the dining room at the opposite diagonal. It's not a very large house, 9.6m x 7.2m, but the diagonal is cubic.... the modem is upstairs and the dining table downstairs.
   The modem is low powered with only one aerial, and the signal reaches one end of the dining table, but dies off at the other end!
   This is an idea I got from a friend in Italy. It is a Strongbow cider can, cut to form a parabolic reflector with the reflector direction oriented diagonally across the house. The reflector is riveted to a small aluminium bracket, which is taped to the back of the modem.

Cheap and effective! and we now have improved WiFi cover to the dining room, right into the corner!

Sunny-Stormy New year

The asymmetrical bell-curve is caused by having a North-South
roof ridge, and by having Sharp Hill to the SouthEast.
The white line under the Sunbox is sunlight
reflecting off the underside of the box
3 Jan 2012: Today, the UK is straddled with stormy weather with patches of sunshine alternating with driving rain and squalls, and a lot of structural damage further north in Scotland. But the 2 Jan 2012 could not have been better for a winter bank holiday, sunny all day! This PV score of 4.02 kWh for the day was the best since 9th December, and there is a pleasing symmetry, as they are both 11-12 days either side of the Solstice. The Sunbox scored 9.0 kWh on both those days.

Solar Angle and Sun Seeker
  The roof ridge is North-South with a 10º azimuth-swivel to south, so our solar midday (sun running axially down the ridge) is 1240. The photo of the Sunbox is taken at 1240 when there is zero shadow either side. The solar altitude at midday solstice is 13.65º, and ten days after the solstice, it's clear from the bright white line of reflected light under the Sunbox that the solar angle at the highest point is still below the leading front edge, i.e. less than 20º (it is 14.65º). It will be 2nd Feb when the highest solar angle is 20º, and after that there will by more of the day when the inclined front face of the Sunbox is incident to the solar angle.
   Info on angles comes from the iPhone App called Sun Seeker, nothing to do with posh motor yachts. As you turn it, the iPhone always knows which way to point to the Sun, even during the night. I discovered, while researching for this posting, that the App has detailed functions that I hadn't been aware of before.

Left: Solar altitude each day
Centre: The house was photographed in Summer 2007
Right: The sun path is shown in a circular chart

Monday, January 2, 2012

Turbocharging thoughts

2 Jan 2012: Most of us use the expression Turbocharging in the context of motor car engines, although the expression is frequently used more loosely in other contexts, such as in the economy, sport or teaching. It's commonly used to mean "a short term burst of energy to improve dramatically the performance or quality of ........... above normal expectations". It normally involves the release of energy from an external source, such as a spinning flywheel (in the Formula 1 KERS system), water stored at high altitude (hydroelectric) or in theatre, getting an experienced actor for a few weeks to boost the amateurs, or in football, the brief novelty effect of a new manager, and all the players desperate to impress the new boss.
    In engines, a small turbine driven by the exhaust gases can inject fresh air to the combustion process, more quickly than normal air pressure would provide. This boosts acceleration. Just when you need more oxygen, the exhaust cases are moving faster, and the turbine is giving the engine that extra oxygen.
    In our case, we have a free high performance energy input that comes when the sun shines, and helps the GSHP work more quickly and more efficiently. Normally our GSHP is working from a large volume of low temperature stuff called the earth, which it then has to convert to higher temperature. It does this by refrigerating liquid that is sent below to retrieve heat by coming back about 3 degree warmer. If it does not have to refrigerate so much, but still gets as much heat as it expected, then it is working more efficiently. When we get direct sunshine on our Sunbox even on cold days, there is a short term boost - and I see this in the figures at the end of the day - reduced House energy (because the PV was reducing electricity import) and reduced GSHP energy consumption (because the workload was reduced). This works better on cold sunny days (analogous to the accelerating engine) because the GSHP is required to reduce the outgoing refrigerant temperature, and thus the delta-T between refrigerant and Sunbox is even better. As the GSHP discovers that the liquid is coming up warmer than calculated, it can refrigerate less severely.
    I mentioned it in an October'11 posting called Turbo charge and here are some figures to illustrate it, sampling from two recent sunny and cold days.

Sunbox temp26.7º27.4º19.2º22.0º22.1º23.3º
Up to SB from GSHP4.4º5.8º2.7º2.2º2.2º4.6º
Down from SB to BH6.0º7.6º4.1º3.4º3.6º6.5º
From Borehole In7.7º9.9º5.5º5.8º5.8º8.4º
Ext Air Temp9.2º9.0º4.1º4.5º5.0º5.6º
GSHP activityHeatingHeatingHeatingHeatingHeatingHeating
Weather Sunny coldSunny coldSunny coldSunny coldSunny coldSunny cold

  We can see the process here, whereby a significant proportion of the heat required is gained from the Sunbox. The GSHP is calculating outgoing temperature based on the temperature it hopes to get from the ground, but as it gets more heat than it expects, it can reduce the amount by which it refrigerates the outgoing glycol. By doing this, it is cooling the ground less, leading to future energy savings.
   The nature of 'turbo' is to be a short term burst of energy boosting the main mechanism above the normal levels of activity. If the sun shone every day, then that might become the new normality, but in real life, the weather is a mixture of seasons, containing sunny days and grey days. If the sun shone every day, we could dispense with the borehole altogether and manage with solar-air panels only.

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