Sunday, October 31, 2010

Climate Change Lecture

28 Oct '10: David NC went with two other Transition West Bridgford members to a meeting arranged by Derby Climate Change Coalition, for an excellent lecture on 'Zero Carbon Britain 2030'. Peter Harper, senior researcher at CAT (Centre for Alternative Technologies) is a joint author of a major report on this title, addressing the question of whether Britain can meet its future obligations (Kyoto, Copenhagen etc) by reducing its CO2 emissions, or going even further, to be considered Carbon Zero - by reducing emissions, and balancing the remainder by using renewable energy generation, nationally.
A full copy of the Zero Carbon Britain 2030 book is available free as a PDF on line.

David NC writes:   A more detailed report is on the WB Ecohouses Blog
and In this blog in a report here.

Thursday, October 28, 2010

East Leake Progress - Construction!

27 Oct'10: More progress at East Leake - despite the delightful attentions of the dog Charley who doesn't take it seriously and just wants to play throw and keep ball.
  Both front panels are up on their top hinged bolts. We have made a back panel for the upper part where it has to sit against the wall, but the wall leaves about an inch gap at the rear. This is now filled, using a thin sheet of plywood.
  We nearly got the bottom louvre in, but it was getting dark so quickly, and there were issues with bolts and washers. So I hope to be back there for some more work at the weekend.
  We decided that the roof can be bolted on, and does not need to tilt. There will be an upper flashing at the rear, to protect the plywood. We will have a top mirror to enhance the air temperature (there are already internal side mirrors).

31 Oct '10: Spent part of Sunday afternoon (after the clocks changed) to get the roof finished. This is now in place, but every time I went outside, it rained a bit more, so did mostly some light electrical work inside the garage while David H got on with the plumbing - finding suitable interfaces for the Sontex energy flowmeter and pump. When I talked some months ago about a 'magic metre' of plumbing, I wasn't far wrong. All these units have such long extensions, that it really does seem to need a metre of plumbing to put them all in line.
   We havent taken off the plastic film of the main sunbox yet, we are waiting till a good date for the 'grand unveiling' !

Tuesday, October 26, 2010

Sunny cold days in October - Sunbox performance

25 Oct'10: This has been an unusually cold October. Last year, evening temperatures did not go into single figures until November, whereas we have had weather in the last two weeks that has been definitely wintry. October day temperatures should be similar to May, but haven't been! The length of days is now less than 10 hours, compared with the 18 hours of midsummer. October gets 1/3 the insolation of June, but when it is cold, the PV does well. We have had several days in the last week with over 10-11 kWh of PV, but temperatures at freezing for much of the 24 hours with only a brief daily rise, not even touching 10º C.
  The Sunboxes have performed incredibly well, with days of 17, 19, 20 and 21 kWh, it has been a week of all-time high scores, hugely outperforming the best thermal harvests of mid June. On a day without sun, the harvest is never above 6kWh at this time of year - with a bit of sun, the harvest is never below 10kWh. This change can only be due to the mirrors. As there can no longer be doubt about it, this harvest encourages me to speed up installing of side mirrors. I was expecting marginal improvements, and the people on Navitron forum said that it wasn't worth the cost of the metal - how wrong that was.
  There is a tree to the southwest that is never a problem in summer, but cuts off the sun in the afternoon at this winter season. What with Sharphill to the south east making the sunrise later, the tree shortens the day even more than normal seasonal variation. I might have to make some long-reach clippers. These two day-shorteners makes our enhanced thermal harvest even more surprising.
  Once the side mirrors are up, I shall have run out of any more ways to boost these sunboxes. If only I could think of a way of fitting convector fins on the back of the existing black collectors.

What difference will this make to the performance of the Heat pump? This will really not show fully until deeper into winter, and the cold October is temporarily making our annual performance look to be worsening. But if I compare the recent daily consumption with days last year of similar evening air temperatures, then it is performing more economically. If I compare deep ground temperatures now with the same time last year (when the weather was warmer), the ground is better now.

Dr Chris Wood has posted some interesting queries, see the Comment below and my answer.

Sunday, October 24, 2010

Would side mirrors work?

23 Oct '10: The mirrors have been pretty successful. For little cost, they seem to be significantly boosting the performance of the boxes on sunny days. I haven't had a reading of the value 7, 8 or 9 for the last few weeks. If the day is cloudy so that they do not work, the energy capture is low, as one would expect, of 2-6 kWh during the day. If there is any sun during the day, the capture is always in double figures.

Like I did with the head mirrors, I shall allow a whole month or more to monitor the performance of these boxes with the foot mirrors. But in case there is proof that they are effective, going into the winter months, I shall consider going all the way and fitting side mirrors. Before doing anything, I fully 3d model it to see what it will look like - and anticipate manufacturing problems.
   These side mirrors could have some disadvantages, in that they act as shaders in the morning and afternoon, but if they are positioned on the corners of the boxes (see right), they could deflect morning sun into the box to stimulate an earlier start. During the peak hours of 1100-1400 there will be even more heat diverted into the boxes, through the front panels.
There is no way I can increase the number of collectors, or the area/volume of the boxes, so this seems to be the only way to increase their effectiveness.
Any Comments?

Thursday, October 21, 2010

East Leake Progress - Construction!

20 Oct '10: I spent all day at East Leake working on the construction of the second Sunbox. I know from the past that with Polycarbonate and Aluminium, there is no room for tolerances, things have to be millimetre perfect, and it's hard to bodge things if you drill in the wrong place. Aluminium is so strong, it won't tear if you have to drill a correct hole a short distance from a wrong one... but polycarbonate will tear if it is over drilled. The plumbing is mostly done, so its mostly a matter of building the external box, doing the final connection plumbing (leave that to last) and some electrics (thermostat and switches).
   Working in bitterly cold (but extremely sunny) conditions, the radiators are all up and plumbed externally, the Sunbox side and back walls are now fixed, the front panels are done, but not finally bolted on.
In these photos, I am getting help from Peter.
You can see that in the winter afternoons, there is a shadow from the house on the lower part of the box, which is a concern, but doesn't have the harmful effect of that happening to a PV panel. The upper collectors are still getting sun.

So.... the lower front panel is on now. This is still quite a laborous methodology, so if we try again somewhere else, we will use a flat plate solar panel, but modify its construction and plumbing.


More Progress is likely to happen next wednesday.


Cooling the Wall?

20 Oct: Someone on the Navitron forum asked if we are cooling our wall - and would this have the effect of cooling the house? (as usual, this question was asked with malicious intent)
    We are NOT intentionally cooling our wall. We are getting surplus heat from the wall in summer which gets up to 40degrees, and with that thermal capacity, continues to release some of that in the evenings. I would term 'cooling the wall' to be taking it below a comfort temperature like below 15.5, and if the temperature is this low the thermostat turns the box pump off.  The boxes need a temperature of over 18º to work, else, they need a delta-T of 5 degs.
    I have yet to see it work in deep winter, so imagine that when the thermostat is driven by delta-T and not by temperature, the heatpump might well be sending glycol up at 5 or 4, and the air in the boxes might be 10 or 11. In fact it was like that on some days this last week. 
  So Yes! with more thought, I recognise that it is possible that in Dec, Jan or Feb, the low air temp might cool the wall, even though the black collectors are a full 100mm distant from the wall. I will check that with my infrared thermometer, outside and inside, on cold nights.
Portable infrared thermometer
is a good way to test surfaces and
discover cold bridges
   However, most of the wall behind the boxes is in the LOFT Gable, so it is not taking heat from the inhabited part of the house even if it was. But the point is taken. Were the boxes to be fitted on the wall of a bedroom or living space, there could be a cooling risk.
   ON days like today, sunny but very cold air temperature, the air temp in the boxes would have been mid thirties up there, even when ambient air temp was about 5. So, overall, the wall probably benefits more than it loses.
   The next Sunbox that we are building is having a timber framed wall behind it, so no thermal mass to make use of. Side mirrors, not top and bottom. All part of the experiment. If if works satisfactorily without a wall backing it, then we could put insulation behind future panels. 
   It would still be substantially different from a standard solar thermal panel, but we are thinking for our next project (if there is one) is to use a standard solar thermal flat plate panel, but ask the manufacturer to supply one without the insulation backing panel.

Postscript: the people at Navitron Forum were alarmist idiots, as always. In the winter, the sunbox acts like a double skin facade over the wall, reducing the heat loss. Any heat taken out of the sunbox by the heatpump in winter is taken when the temperature in there is warmer than the air around. So even then, it is not losing heat from the house. In summer, it is cooling the walls, because they get up to 40º after a good day, but that is a good thing, and they have about 5 kWh worth of heat to release after sunset.

Wednesday, October 20, 2010

Foot Mirrors now up! Try datalogging!

The upper mirrors are fixed and optimised for winter
sun angles only, the lower ones are tiltable for all sun angles
20 Oct '10: First view of the foot mirrors. For the first two days after these were up, there was not a single sighting of the sun, but Wednesday was an excellent harvest! With the coldest air temperatures of the half year, but all day sunshine, we scored an All time Record, in fact, 21 kWh in the day, higher than the harvest on the hottest day of the year in June, averaging a previously unthinkable 2.3 kW for over 9 hours!
    I have thought about monitoring their effect specifically, rather than just hope and see (following the questioning on the Navitron forum, some constructive, but others bewilderingly hostile). I listen to all good advice, and if it's doable, I do it. That is how these whole boxes and collectors and the plumbing circuitry developed, by evolution and discussion.
    One of the first suggestions from there was that of putting in foot mirrors, because there was misperception of how the top mirrors would work when their edge was pointing at 60º.  These ideas gathered momentum. If the idea of mirrors is to boost winter performance, why wait till next May? Do it now! Get the kWh into the system now!

Considering their effect as a whole:
   I now agree that quite soon, it would be an idea to consider having say, the left hand sunbox mirrors disabled for a while (the upper mirror muzzled with dark cloth, and the lower mirror tilted back or muzzled too) and have the datalogger measure the flow temperature (the same to each) and then measure the different return temperatures from each sunbox (different pipes that unite in the loft before going to the energy flowmeter. This would be easy to do if I have long enough datalogger wires (getting these is a problem) and made easier by the fact that the liquid pressure and flowrate is the same through each sunbox. Being two, they each have a different interior air temperature.
   I was reluctant to do this earlier, as I am keen to grab every free kilowatt hour that is going, to establish a new low for the annual electricity consumption in 2010-2011. But there is a research case for doing it.
    Perhaps it's time to get my own little USB dataloggers, as I don't know if Blaise will have time in his final year of writing up. I can't get data out of the ones I already have without his help as he has the software on his laptop. I do have a spare old laptop that could be configured for use.

Sunday, October 17, 2010

Foot Mirrors built, but not up

16 Oct '10: The foot mirrors are built, but still on the ground - it is all very precision made down here, so I hope the assembly fits when it goes up. Next time there is daylight and a few hours, I hope to be up the ladder fixing them.

PS 17 Oct, they are up now, but as it was completed well after sunset (in moonlight by the way) there is no photograph as yet.
  The optimum angle of the mirrors is about 22 degrees tilt, directly facing south, which is also directly facing on edge to the optimum position that a photographer would stand in the field behind the house - so they are near enough invisible, which is exactly how I would like them to  be seen from that angle.
  Sunday 17 Oct was sunny but cold, and for a long part of the afternoon, the sunboxes were disabled by having the louvres and front panel propped open while I worked bolting on the brackets for the mirrors. Despite this, the earning was still 19 kWh which is one short of an annual record. How can this figure be so much higher than most days in May-June, if it is not for the mirrors?

Thursday, October 14, 2010

East Leake Progress

Dog, eat the ball not the radiators!
13 Oct '10: I travelled out to East Leake again to drop off some vital plumbing supplies, such as the pump, flowmeter, non return valve, solenoid valve and thermostat - also some miscellaneous plumbing bits that are surplus to my needs.
  These black collectors are stock single panel radiators with convector fins at the rear, and painted matt black on the south facing side.
  Hmm... I had better get back to my press drill and complete the work on the aluminium, ready for erecting the Sunboxes. There will be one difficulty of customization which is that the upper part of the sunboxes is against a shiplap timber wall, and we will need to scribe the two edges to fit. Also, along the top the roof will not meet the wall line because that is also not consistent as would be a brick wall..... hmmm again... its lucky I have some spare aluminium sheet in the garage, I feel a custom roof flashing design coming on.
The radiators need flexible hose connections.

Voltage Optimiser coming

13 Oct: I have decided to go ahead and instal a voltage optimiser. Starting off a while back the size of a fridge, they now seem to reduced to the size of a consumer unit and cheaper too, and I'll get a good deal on the installation cost. Let's see if it will make a difference.
The unit will come from a manufacturer called VPhase.... installed by a local company. hope it works.

http://www.vphase.co.uk/default.aspx

Our house is totally heated by electricity (i.e. the Heat pump getting what it can from the Earth and from Sunboxes) and the heatpump and the associated pumps are all motors. As this is where the greatest saving can be found, I hope that we might get at least the 10% that is offered, and perhaps more if we tune it down to 220 volts AC. The voltage in our house is a consistent 248 volts, way above the norm of 230 volts AC. All the devices we have, apart from the oven would work just as well at 220 v, but using 10% less energy.
  For people using Gas central heating, HW and cooking, the 10% saving is only of a smaller amount, the electricity they use for power and lighting. As our heating, DHW, cooking, lighting and power are all electric, 10% of a much larger amount seems to be worth going for.
  It's possible partially, to decide what to regulate. We will not regulate or interfere with the PV roof (would be illegal because the meter is governed by OfGem), and we will not change the oven (would make it be slower to heat) - the main culprit that needs regulating is the heat pump which is 2/3 of the total house consumption annually! All the things on the general ring main (computer, TV, fridge, modem, printer, power tools etc) would work just as well, but consume less.
  As usual, all results will be monitored and published.

Tuesday, October 12, 2010

Building the Foot mirrors

11 Oct '10: The dear old Press drill has been busy tonight, I have the aluminium today from the stores, and have been making the L-shaped brackets. I am applying much more quality control than I used to, clamping all the components before drilling so that the holes really do line up perfectly (there is little tolerance when using pop-rivets).
  Some people wonder what I mean by the 'turbo charging' effect' of the mirrors. I feel that I now have enough days of capture to have evidence.
 Looking at the figures for the captured heat in the days since the mirrors have been installed, there is something interesting about the way the figures are 'stretched apart'. Prior to the mirrors going up the heat capture was fairly evenly distributed numerically from 1 to 18kWh, with many days being in the range of 7-10 kWh.
 The 18th and 20th of Sept are exceptions because of weather events, (eg rain following sun)  but for the remaining days the figures on cold cloudy days are all below 6.0 if there is no direct sun and above 10 if there is some sun.  Even if there is a bit of sun for a part of the day, they make it safely into double figures, at levels that I was happy to get in summer with a far higher solar angle.

  The range of 7-10 has disappeared. So in the sense that 'turbo' means 'to boost', this suggests to me that when there is direct sun there seems to be a boost.
  Future weeks and months of recording will show beyond doubt if this is a substantial effect. By the end of the week, I intend to have the foot mirrors in place, adjusted in tilt angle to optimise for winter sun angles.
  I still don't see why this project seems to encourage derision and even rage from many Navi tron Forum users, when other parts of the forum are full of examples of people trying experimental things with strawbales, drainpipes, compost, barrels, electronics etc. As a teacher for many years, I have learnt better than to pour scorn on well intentioned efforts.
  Half a million people in India and another half million in Africa cannot all be wrong! One of my colleagues on the staff hails from Ghana, and thinking back to his childhood, he remembers his parents using a solar cooker, and using solar reflectors to enable hot water for washing.

Saturday, October 9, 2010

Tuning the IVT Greenline C6

9 Oct '10: Mr BoDidly on the Navitron forum asked a question about the IVT Greenline C6 heat pump, which is the same model as mine. 
Bodidly has a shallow ground loop that is in a groundwater condition and after heavy rain, the water rises to the surface, so this is partially a water source heat pump - the earth is in effect, warmed by rainwater. As it has a huge latent heat of freezing, that's quite an efficient source of energy for the HP.

There were some other good replies, and here is mine,
I have done seven things to my IVT:

1. The 'ChargingtheEarth' circuit with solar panels to recharge the earth store.
(This technique cannot be used by BoDidly, because he has active groundwater in the earth around his ground loop. His groundwater is charging the earth in effect, because water has a big latent heat of freezing.)

The following could all be done to any IVT heat pump and all have been done to mine with the approval of Ice Energy:

2. Insulate internally - There are internal system inefficiencies in the IVT that cause the expenditure on Hot Water to be excessive, that can be solved simply by taking as much of the casing off and insulating the tank. I used superthin insulation like Aktis, formed into pads. In Sweden, people tend to put their GSHPs into garages or outhouses, and the air temp falls to -20ºC so the HW tank is deliberately poorly insulated to stop the machine from icing up. My GSHP is in a heated utility room. I have had the casing off and super insulated it, and once it reaches the right temperature it stays above the target temperature for many hours. For example, today, it has not fired up yet because it was at a good temp at 10pm last night, and its is now 12 hours later and still no need to run.
(Take the front panel off your IVT, reach under and tap the bottom of the water tank.... what do you find? completely naked copper bottom!)

3. Insulate externally - Check that most pipes coming into the IVT are insulated, to reduce system losses. Even the Cold water supply pipe gets very hot, as there is a direct metal link from the tank to the exterior.

4. Fake Thermal sensor- A small fix to stop the heating circulating pump from running when the night temperature drops in spring and autumn night times - my wife cannot stand the sound of pipes running at night. We have a small resistor that imitates the signal of the exterior thermistor - my resistor fools the GSHP into assuming that it is 25º outside. A two way light switch can simply change from one to the other, and we turn it off at 10pm, and on again at 9am. The 4.7 kOhm resistor cost 17 pence from Maplins. I have now set up a simple Timeclock to turn this off and on, but it needed an Omron relay to operate the switch.

5 Timeclock - the IVT has an internal timeclock, and you can save night time heating by simply adjusting it with that timeclock to turn water and space heating off during certain hours. The IVT's timeclocks can manage Heating and Hotwater independently, turning off the heating, or turning down the heating at night.

6. Telecommand - if this is activated, you can disable the heatpump , e.g. at night with a method that was designed to enable the GSHP to be managed with a mobile phone or external controller. Again, we have a simple Light switch to turn the compressor off and on remotely, leaving the GSHP running. At the moment it is able to turn the Hot Water on and off, and we leave the Fake Thermostat to manage the heating.

7. Cylinder Thermostat - As the hot water frequently gets too hot - on the IVT it is sometimes reaching pasteurisation temperatures every day - I have fixed a standard cylinder thermostat to the metal surface of the water tank, and this can use the Telecommand to turn the Hot water off if it is overheating. The tricky bit is that the metal surface is not the water tank, it's the jacket around the watertank, and so you need to set it to about 72 degrees to get the water tank heating to stop at about 55 degrees. If your heat pump is of the type that has a pipe coil inside the tank, then adjust the temperature accordingly.

I could do these as a package deal, as a sort of travelling IVT 'vet' and I could turn up and run through the list 2-7.

Defrosting the Earth in shallow ground loops

9 Oct '10: There's been a discussion on the N-tron forum
http://www.navitron.org.uk/forum/index.php/topic,11137.0.html
about whether shallow ground loops can cause subsidence or ground heave through changing the moisture content of the soil, or freezing it. It started with a discussion of problems in the US where some reverse cycle HPs will dump heat below as a method of cooling, and can shrink the soil by drying it out. If the loop is under the building this could be very serious.
 (By the way, my system cannot shrink the soil as the depth goes down to 48 metres, the water content in 8,000 tons of soil will not be changed by shifting the base temperature from 12 to 14 during the summer, and moisture cannot escape so high.... The upper surface is tarmac and houses, and the house is not directly over the boreholes anyway.).

Coming back to the UK where the soil is used for drawing heat out, the main risk is of poor installation leading to ground freezing. This can be that the boreholes or slinkies were undersized, that the HP is trying to warm an oversized and poorly insulated house, or the owners think that because the heat from the soil is 'free', they can use it for a heated swimming pool and the like.

So, My advice on the forum was: 
If the ground loop is too small and shallow, then soil will be getting down to temperatures below freezing. If you continue to use the GSHP through into the spring, there is not enough heat to be drawn from the earth, so you will have some risks,

1. Frequent panics by the GSHP leading to it using its 1:1 immersion heater which triples the electricity consumption immediately. (this happened to me last March for one day, and average daily consumption went from about 23 kWh a day to 69 kWh in one day).
2. Frost heave in the area where the ground loop is planted if the soil around the pipes get below Minus Four degs C.

I advised him to read the thread entitled 'Mirrors' in the 'Ideas and Inventions' area. Or read my blog re chargingtheearth.
With a ground loop that is horizontal you cannot really "Charge the Earth" with heat, but you can use Solar-Air panels to provide a daily Defrost that will reduce the risk of ground heave.

For summer use, there's no way that the panels will shrink or over heat the ground in summer for two reasons:
1. The amount of soil relative to the input of the solar-air panels is small. But if the ground loop is small:
2. You have a simple OFF switch, so DO NOT pump heat into the ground loop during a prolonged hot summer if you know it won't stay there till winter.

If you know that the Ground loop is small,
1. Digging it up and laying another is virtually out of the question due to the high cost, and perhaps you don't have enough land to extend it.
2. Having a deep borehole drilled to replace it if you can get a drilling rig on to your site and have about 5 grand is probably also too expensive.
3. For a far lower cost than either, use a solar-air panel to supplement the ground loop and to defrost it in winter, and provide most of your HW needs in summer. The plumbing loop could be designed with a slightly different valving arrangement so that in summer, the GSHP only uses the sunboxes directly, if the Thermostat permits.

All of these are cheaper than repair to your house if it suffers subsidence or heave - even if the cause of the subsidence or heave is cured, the house continues to show the scars of the repair (uneven pointing, wobbly looking windows etc) that will for ever affect its resale value.

Foot Mirror in 3D

General view, with a single mirror.
8 Oct '10: The Foot mirror design idea is evolving, and I always make a 3D model of what needs to be built before ordering the stock metal.  This was a good idea here because the 2D model thinking was wrong.
  My original idea was for two louvres, to reduce the shading on the windows below, but at winter angles, they have the same problem that PV panels have when mounted on a flat roof - the front one shades the one behind. So it is better to have a single tilting mirror.
  The one above is already built and is 280mm, fixed at 60º angle.
This shows a close up detail of
how the bracket might work
  The foot mirror is still a parametric model, so I can change the number of louvres and the depth of the louvre, and the tilt angle. It would be best to be flat in the summer and angled forward in the winter on sunny days, and angled back on cloudy days. I can make them controllable either from below (on a long stalk) or from the bedroom window, using wingnuts (a tidier job).
  Actually, as drawn, the mirrors would prevent the top hung front panel from opening, so the mirror has to be lowered.
  One regret I would have about this, is that when I stand below the boxes and look vertically upwards, I would see the soffits of the foot mirrors, and not the boxes...

Friday, October 8, 2010

Annual capture per square metre

8 Oct '10: Mr A.L. on the Navitron forum attached great priority to the thermal capture per square metre per annum. He went to the extent of counting the bricks on the photos, and working out his own figures.

So I answered: (shortened version) The black collectors are Exactly ONE squ metre each, and there are four of them. The air volume enclosed by the plastic glass is near to One Cubic Metre, in TWO boxes, each 1.75m wide x 1.6m high x 200mm deep, supplemented by 1 sqm of alloy mirror above, and shortly to be supplemented by about the same below.
The black collectors are Polypropylene and flat on both sides, and do not have fins to help exchange heat with the air (Doh! ).  So my next prototype sunbox is using 4 off-the-shelf metal radiators, each precisely one square metre, single panel with a high amount of convecting fins on the back, all sprayed matt black.
   Over 8-12 hour pumping days, we are averaging 0.8-1.5 kW per hour of operating. Best recent day has been 1.75 kW / hour over 8.6 hours in sunny conditions on a coldish October day.

Metered capture so far is 2,160 kWh from 7 months of operating. Heat capture in wintry conditions is doing well (always in double figures if there is a hint of sunshine), so I dont expect us to fall short of the 3,000 by next Mid-March. At an average of over 10kWh a day, I would hazard a guess that we might make 3,300.  On this basis, my boxes' annual capture and bury might be about 825 kWh/m2.

Swivelling foot mirror idea

Mirrors here are shown tilted
for winter performance.
Red lines are swivel controls.
Blue lines midday sun angles.
8 Oct '10: I am sufficiently convinced by the performance of the mirrors in the last 3 weeks to take this further.
   I told the guys on the N-tron forum that I would probably fit foot mirrors next Spring equinox to bounce summer light upwards. I have access to cheap metals, so if an idea is possible, cost is not an issue about trying it out. Once an idea takes hold it is difficult to postpone it, and during a lecture, I started doing sketches for a swivelling foot mirror that could be workable for winter and summer. Once the sketch is done, the details of swivelling and control begin to crystallise. So why not do it in Winter? That is the time when I am seeking gains, even if only marginal gains. With my collectors arrayed horizontally, heat and foot mirrors will help, side mirrors will do nothing useful.

  The Top mirrors are not adjustable, because I didn't think I could make an adjusting mechanism that wouldn't rattle on windy nights or require more drilling of holes in the wall. So they are at a fixed angle of 60º, optimised for Winter sun. They are not useless in summer as the sun is only at 60º at midday, and there are times either side of midday when the sun will be lower and will bounce downward.

  The Foot mirrors would be best to be sloping about 10º forward in summer, so the 60º midday sun bounces back up onto the front glass. For winter it needs to tilt further forward to bounce heat upwards to the centre height (but not too high, to avoid reflection off the front glass). As the range from winter to summer is 46º, I suppose that the mirror angle should vary by 23º from one season to the other = 10º, 20º and 30º.
  Tilting the mirrors slightly back would be better on cloudy days to improve the daylight into the two bedroom windows below. I have shown the mirrors above as being TWO louvres, with a hinged control mechanism below, but this is a lot of work to make in detail.
  Next, I need to make a 3D model to test out the idea, and forecast sizes and swivelling modes.


Thursday, October 7, 2010

East Leake Progress

David and David and dog
6 Oct: I travelled out on the bike to East Leake and had a detailed couple of hours with David Hill, discussing the plumbing, electrics and construction for the mark 2.1 version of the Surya Sunbox.
   He will do the plumbing and electrics himself, and everything is very very accessible, with the Dimplex GSHP less than a metre distance from the Sunbox. There is only a light timber wall to drill through. With metal finned collectors and side mirrors and more airtight construction, we have high hopes for the new model. He installs PV systems, so has metres of fixing rail and can make the brackets and spray the metal collectors.
Photo shows that Sun will be good on this wall....
due south!
  The polycarbonate is on its way from Liverpool, and I have the aluminium in my garage, half of which is now drilled, ready to be riveted to the polycarbonate.
  Ice Energy will continue with their equipment sponsorship by providing the Sontex energy flowmeter and the AKO thermostat, and I am keen to use these as they are fully comparable with the metering and control for the Peveril Sunboxes.
  David points out that there may be some pretty smart (and expensive) metering and control units for solar thermal systems that we can use in the future, but for now, the research is not about them - it is about proving and measuring the effect of solar charging of the ground loop that supplies a ground source heat pump! David A of Ice Energy had checked some of these out last year, but they didn't have the dual mode of the AKO.

Energy foundations

7 Oct: I asked on the Navitron forum for ideas about Energy foundations, and some kind hearted people  have posted replies. Mr eccentricAnomaly provided this link:
http://www.greenershelter.org/index.php?pg=3

Mr Billi provided an interesting discussion of Passivhaus, including this weblink to a german site (but in english),
http://www.passivhaustagung.de/Passive_House_E/Passivehouse_measured_consumption.html
Billi made a fair point that there should be a renewable heat incentive for having an exceptionally well insulated house, and not just for installation of systems.
    Billi posted this picture from a Swiss website of an astonishing office building that has actually been built, that is storing heat underground, below the building.   I hope he will post the address of the site this came from as it is deeply interesting to me.
  Mr dhaslam (who is doing interesting storage experiments of his own with earth storage using straw bales as insulation) commented that there is a risk of putting pipes under the house for two reasons, one is swelling or moisture change in the soil (suggesting to me that we would need short piles) the other is the impossibility of access in case of an error. He also wondered whether Passive House really works in the British climate. Would we have enough capacity to store heat through cloudy times without needing something like a large swimming pool under the house?

Wednesday, October 6, 2010

Mirrors performance enhancement?

Standing under this, the light from the
mirror is blinding, but the camera light
meter flattens out the glare.
6 October: It is early to be completely certain, but I am recording a notable increase in performance - thanks to the mirrors? Winter is coming in, but when the sun shines even for a while, there is a notable increase in performance. Let's have a look at today, as an example.
   Today was sunny in the morning although with cold temperatures. Air temperature was 11-12º rose to a maximum of 18º during the day. Surface temperature rose briefly to 28º maximum when the sun shone brightest at about 11 am.
  The Sunboxes were working well, and maintaining an air temperature internally of 38º, a full 20 degs higher than the ambient air, and note that the air temperature is being chilled by glycol all the time. If I turned the pump off the temperature would rise above 40º
 The heat pump was sleeping (house warm and no hot water required) so the glycol was circulating.... it was coming UP from the deep borehole at 13.2ºC, rising to the Sunboxes and returning DOWN at 18.2ºC. - gaining 5 deg C on its 5 litres/min trickle around, and losing that 5 degs in the soil 48 metres down.
  Due to the air temperature continuing chilly, the heating was on, and during the 24 hours, the 6 kW heatpump burnt a total of 4.04 kWh.

The Sunbox pump ran for 8.6 hours and collected 15.03 kWh (on a day when 30 sqm of PV roof panels collected only 7.50 kWh).
   For the doubters, that is an Average of 1.75 kW per hour!
 (only a datalogger could tell me what the Peak performance was....)
 I am so convinced by the mirrors that I will add foot mirrors next March (to celebrate the Equinox). I am providing mirrors to the new Sunbox in East Leake. I bought the aluminium for that on Monday, and yesterday, I found an equivalent amount of the same thickness of shiny aluminium in a skip right outside my building at the University. It is amazing what people will throw away!

Navitron forum

Sept 2011 Pre-script: Why is this still the most frequently read item on my whole blog? Is it coming up on Google searches for the company name or something? Its a year old now, surely, not worth a mention? 
If you are from the Navitron company, GO AWAY!
Dec 2011 note: Why do I have a special antagonism for Navitron? Because for all of the last year, they took the trouble to detect the IP number I used from home or work, and had a custom page that would be displayed to me gloating that they were stopping me from logging on or even viewing the forum, with a completely spurious excuse that I had not bought heat pumps from them.
_______________________________
6 October 2010: I have had an entertaining time on the Navitron forum. I started a thread by mentioning the alloy mirrors, but there are many other areas of interest, such as FITs, PV, CHP, interseasonal storage, evacuated tubes, high rise buildings, wind turbines etc.
    It was alarming at first, a bit like walking into a bar in Tennesee or Montana with a gaypride teeshirt. Heads turn, who's the newbie? To the newby, it seems cliquey, with contributors who have attained immense 'seniority' through hundreds of postings, who really appear to resent a newby coming in especially if many of his ideas are already formed. If I had started a year ago as a totally nervous newby, I am sure that there would have been supportive ideas, and by now there would have been hundreds of postings as the project grew.
   Before the development of full blogging sites, a forum like this was the best place to report the progressive advancement of a research project. Gradually, people become more friendly and genuine, and the discussions can be very very informative.
  However, there remain moments when one is stunned by comments of utter malice, which seem so unjustified. The people who have been nastiest all claim to be 'moderators' so it seems to be running opposite their role which should be to encourage discussion. The abuse extends to criticising one's family, one's job, one's very existence!
     That is what you have to expect, I suppose, the rough with the smooth. I am sure that forums on Vegetarianism or Beekeeping can get just as mean, with fish-eaters, cheese-eaters and vegans slugging it out, or beekeepers insulting each other's queens.

The virtues of the Navitron forum are worth it to endure the initial entry ordeal.  Although one's confidence is dented by excoriating or just angry criticism, the ones who have been supportive or who have provided genuinely considered criticism have raised my faith in human nature. Many of the criticisms have led to me improving my website or checking my figures, or explaining things better.

I am not criticising Navitron as a company, and I am certain the products are good - some very innovative combinations of technologies. The forum moderators seem fiercely anti heat pump ('superannuated fridge'), despite Navitron being a supplier of low cost heat pumps. Several of the forum members are 'off-grid' and jolly good for them! People who can live off-grid in strawbale houses in a field in Wales are wonderfully brave, but living in yurts or haystacks isn't a solution for the majority of the urban population. It's research to refine the technology, land requirements and lifestyle adaptation requirement, but it's only part of the answer, not all of it.

February 2011 Postscript: I would advise anybody setting out on a research or sustainable energy project to develop their own website, such as this one. Posting items on a forum is a bit like writing letters to a newspaper, you have great difficulty in piecing the threads together later - especially when what you write is likely to be slagged off or deleted by capricious moderators.
For giving the above advice to a newby on Navitron, I was banned from the forum - proving the truth of what I wrote. I was NOT advising that they avoid using the forum, because it is excellent as an information source. But the project originator need to be able to write up the project where they will not have their confidence damaged by savagely malicious or manically capricious comments irrelevant to the project, as I have suffered - months of being slagged off.
   If you have a project to do, I cannot recommend Googleblogger too highly, it is your site, and you have a good historical thread of the progress of the project. Use the Navitron forum too, to share your finding with some of the good folk. But don't be surprised if a year's worth of discussion is suddenly deleted by a moderator who disagrees with you by just deleting everything you have written.
   The Navitron forum is not a safe place to make the only place where you record your design process, because it's not really a 'forum', it's a 'court' of some tiny-minded emperor moderators who don't welcome newcomers with projects they don't agree with. And as an architect, I will never specify Navitron products while I am denied access to the forum, and I will leave this highly negative review of the Forum on show until I am welcomed back. 

Monday, October 4, 2010

Drakes Landing storing heat underground

[Diagram from the Drake's Landing website]
3 Oct '10: One of the writers on Navi tron forum reminded me about Drake's Landing, a solar settlement in Okotoks, Alberta, Canada. It is an estate of 52 houses that have a large array of solar thermal panels on their garages. The heat is taken to a grouped cluster of boreholes that has a large energy centre on top of the boreholes, a district heating scheme, that sends the heated water back to the houses in an insulated duct. Each house has a local solar panel for topping up the water heating.
[Google Streetview image]
  It is reported that 80 percent of the space heating need is met by the project's boreholes and energy centre.
  I am thinking of how this could apply to the project I am working on in Surrey, about 90 houses. I still think that in the way that the British housing market works, ours would still be better off with a borehole each and a heat pump in each house, with no shared ducting required in either direction. We also do not have the large array of garages, and yes!, we do want to have most of the house roofs for PV. It's likely that a bulk order for 90 heat pumps would be cheaper than their combined district heating energy centre. (I know all the arguments in favour of district heating, but the Brits are peculiarly insular...) So, we are likely to go for wall mounted sunboxes, which I hope will be a proven technology by this time next year.
  Okotoks is almost precisely the same latitude as Surrey, but has a continental climate, somewhat arid in summer, and long very cold winters. We will still pursue the idea of Sunboxes driven by heat pumps... but don't let anybody try to convince me that the idea is not going to work. Drake's Landing has exceeded expectations!

Sunday, October 3, 2010

'Trickle' and 'Whoosh' explained

3 Oct '10: I have added more to the Glossary, as people here and on the Navitron forum are asking more questions about the system design, especially the plumbing. So, what do I mean by Trickle and Whoosh?


'Trickle' = Circulating glycol through the Sunboxes at about 5 litres/minute using the low power consumption pump in the loft.
'Whoosh' = Circulating glycol through the Sunboxes at about 18 litres/minute using the circulating pump in the heat pump. This only occurs when the heat pump is doing a heating cycle for DHW or Underfloor Heating.

'Trickle-and-Whoosh' = Plumbing arrangement with a 3 port solenoid valve so that when the Thermostat says Yes! the entire ground loop is diverted sequentially through the Sunboxes at 'whoosh'-speed, downloading any heat very quickly, chilling the sunboxes quickly, and then the thermostat says No!, allowing the valve to close again, and turn off the loft pump. It reduces pump power consumption. This is only possible if the pipe sizes are large and the black collectors support fast flow. Over the length of a day, the difference in total thermal capture is likely to be similar to Trickle while we Work, but collected in intermittent pulses. This is what we use on the Peveril Solar House. If 'Whoosh' occurs, it just pushes through the 'Trickle' pump.

'Trickle-while-we-Work' = Plumbing arrangement so that the loop through the Sunboxes is a parallel bypass to the existing ground loop, working at 5 litres/min and is controlled by a 2 port solenoid valve. This circulates whenever the thermostat says Yes!. When the heat pump is running a heating cycle, the Sunbox loop merely injects (dilutes) the warmer fluid at 5 litre/min into the fast flow, meaning that the thermostat sees a favourable delta-T for far longer, saying Yes! for 3 or 4 times longer perhaps. A non-return valve is required to make sure that the circulation goes in the right direction. This enables one to use narrower pipes and narrow diameter metal collectors, but will cause longer hours of pump consumption. This is what we will use on the East Leake house.

This T-w-w-W method is not so effective. Trickle while we Work will inject the heat into the circuit, but being diluted it is not going to catalyse the GHSP, it just contributes helpfully. With the Trickle and Whoosh system, the ground loop gets a larger amount of liquid coming down, sometimes at above the normal ground temperature, thus lining the earth around the pipes with greater than average warmth - a temporary and welcome uplift.

The main difference between using these Sunboxes and industry standard solar panels is that we don't need an intermediate tank. Those solar panels are very well insulated, so do not pick up anything significant from the air temperature, although they will get warmth from a bright sky. With an insulated backing, they do not have any thermal capacity of their own.

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