Wednesday, August 31, 2011

Powerpoint for Istanbul

The 'virtuous pentangle' of technologies
31 August 2011: The SET 2011 (Sustainable Energy Technologies) conference is taking place in Istanbul this weekend, and I am meant to be there, but can't travel at the moment. So a colleague will show my 15 minute powerpoint. I did this diagram to illustrate the interactions of the systems on the Peveril Solar house. The talk is limited to strictly 15 minutes, and I had to script it, so that the speaker (on my behalf) would be able to get through it without getting confused or running over time. I have put it on line, so that you can see it, please click the picture above. The picture below shows the performance of each component, the key ones being the equal balance of the PV roof and the GSHP consumption.
  Having only 15 mins, I have to keep it short, so some things like the mention of 'panic' mode are a form of shorthand for the slope adjustment on the heat pump that causes it to use Additional Heat. This has been one of the key things for reducing the consumption. There was a worst ever day in Feb 2010 when the GSHP used 69 kWh in a single day!
I am certain that there will be variations during the winter, but at the moment, these are in pleasing equilibrium. One single bad day in the winter can use 30 kWh of GSHP energy, and generate 0.1 kWh from the PV. As we progress week by week, I re-compute the annual, so it is setting against a similar week before, so I hope that the fluctuations will not be too large. Last winter, in the severest part of December, the annual for the house rose to 6,300 kWh and for the GSHP to 4,245 kWh ! If we have a mild autumn and winter coming up, the figures will be getting very interesting! 

Tuesday, August 30, 2011

Surya3 complete and scaffolding down!

Final photo of the Surya-3 before
I descend the ladder for the last time
29 Aug 2011: The scaffolding is due to come down, so I found time during the Monday bank holiday to finish off everything I could think of :
 • gave the boxes a good coating of Turtle Wax (so they would reject water droplets better), and
 • fixed extra machine screws along the top edge of the front panels (to improve stability of polycarbonate under wind or ladder loading)
 • fixed a strut at the top centre line of both front panels so that they can take the pressure of a ladder leaning on them,
 • added a few more screws and rivets here and there to make them more airtight,
 • strengthened the hinges at the top of the front panels.
At about 5.30 pm, my Riveter broke, and luckily Screwfix were open on the Bank Holiday. Managed to get a better one and fix the extra rivets in before dark. The new one has a swivelling head!

The scaffolding is being taken down
quickly, and soon I can get a photo
of the clean wall!
30 Aug 2011: 9am promptly, the scaffolder, Richard Pearson, was at the front door to request taking down the scaffolding. I was glad to see it go, so that I can photograph the final boxes just in time to complete my powerpoint for SET Istanbul - which has to be done by 30th August, today!
  I cannot recommend Pearson Scaffolding too highly, they have been quite excellent. The scaffold was strong and safe, all the tubes and boards are new, and Richard was very flexible to allow for my complicated life, which meant that a job that I thought would take only a week took 5 weeks. Phone 07804-794374 if you need a very good and reasonably priced scaffolding for your building project.

Monday, August 29, 2011

Weather Station up

Framework on its mounting,
but not wired up yet
28 August 2011: While the scaffolding is up, I thought I would fit a weather station and it arrived last week. I have had an enjoyable weekend getting it done and up, and it is working.
   If you order one of these, you have to have a good think beforehand of where and how you will be able to fit it. Even if you know the general location, the immediate problems of what it will fix to are there. I couldn't really decide of finalise until I was up on the scaffolding, looking at the immediate site. The main thing is to get the Anenometer in a clean airflow, above the ridge, and clear of everything, including the TV aerial. The Raingauge is near it, but below - that also needs to be in clear space where it isn't over shaded, and not picking up dead leaves etc. The Anenometer has to be oriented very careful so that its North and South align to the true compass angles.

Framework on the work table. The two
units sit on a 38x38 angle
Having wondered where I would drill for anchor bolts, I found that the TV aerial bracket has 4 very solid anchor bolts, well able to take sideways wind loads from my framework. It means that I won't have to drill any more holes in the wall. I also went through my aluminium box, as I wanted to do it with minimal cutting - I managed to do it with no cutting, apart from tiny trimming and mitring. The entire framework is built from recycled metal from the old sun box, or from offcuts. The precise dimensions are thus fortuitous (dependent on the size of the previous sun box, and the angle keeps it well away from the ridge. Finally, the wires had to be led through the body of the Surya-3 Sunbox, led through to a Thermometer and humidity meter sheltering out of direct rain or sunlight below the soffit of the sunbox. I can easily replace the batteries once a year, as the unit is positioned adjacent to the bedroom window.

This is a Lacrosse 1600, and setting up was very easy. Once the batteries are in, the transmitter in the thermometer sends a signal, and the display unit is like a small iPad with buttons. There is a 'Set' button for progressively setting Time, Date, Units etc.

One thing that this may teach me, is whether a small wind generator would be worth fitting. Although there are no buildings south-west of us, we are in a dip, and the main smooth airstream is passing about 50metres plus above the house. At the height of our ridge, it already seems that the wind is too variable and reduced to be useful.

Sunday, August 28, 2011

August 2011 Reports

28 August 2011: Last report of the month, and as usual, some records. I think there has only been one weekend when there wasn't one record or another. The House meter is near to its lowest ever, the GSHP figure is a record, at 3,318.7 kWh, and the PV is close to last week's record. The Sunbox clock has scored a record high at 2,345 hours, and the annual figure for the Sunbox energy is creeping back to its previous highest figure of May 2011.
  The deep ground temperature is disappointing - I have watched it climbing though the summer and hoped it would pass 14.0ºC, but it has dipped slightly to 13.2ºC - at about the time it dipped slightly last year. Hmmmm.... One thing I can say is that in the period 9 Aug to 28 Aug, there has been a performance benefit, but it could be seasonal. 175 kWh in 2010, and 193 kWh in 2011.


21 August 2011: Three records broken this week, it's been sunny and dry, good for record making. The house consumption is good at 5,309 kWh, but the GSHP consumption is a record Low, at 3,323 kWh. The PV roof achieved a record High, at 3,342 kWh. The two systems crossed each other decisively at 3,330 and kept going. I know that all this could be upset later in the winter, when the daily house consumption can exceed 40 kWh in a day and the GSHP sometimes 30 kWh in a single bad day.
     The third record is the Clock on the sunboxes - this has touched 2,230 hours. I'll discuss this in another posting.


14 August 2011: Well the boxes have been closed in most of the week. I am disappointed that they are not hotter inside - the hours of running seem to be longer, and heat is being put down, but the kilowatt equivalent is not as high as I hoped. Our power scores for the week are average. No records broken this week!
   Although the hours of heat pump use are very low at this time of year, I see that the deep ground temperature remains stolidly fixed at 13.5ºC, and wish it was just a few tenths higher.

7 August 2011: Well the Sunboxes are still not sealed in, so I am still unable to see how the new design will turn out - I hope that only a couple of days are required. I will run them in their new form for another week after that before taking down the scaffolding, so that I can be sure that all airtightness and maintenance issues are covered. The metering records are improving again, with consumption lowering, and after the sunny weeks we have, I can announce an all time record for annual PV generation :- 3,331 kWh in one year. The Ground Temperature is still 13.5º and I am sorry it hasn't got higher - but as I found last year, there seems to be a process of consolidation so the heat distributes more evenly within the thermal cylinders around the boreholes - the test of which is how well it performs in the heating season. Because I always wait till midnight to do the test, the ground has time to cool after the day. If I tested it at 6pm, I would get a string of temperatures above 14º or 15º.

Tuesday, August 23, 2011

Solar Security light

22 Aug 2011: I got one of those Solar Security lights from SolarCentre, the EVO 36. I got it free on a special deal through Rushcliffe and am not sure if I would have lavished £49 on one of these... but as we are a solar house, it's adding to the solar-ness of our existence here. I go into the back garden a lot and use it as a sort of workshop too, so some free light is always valued, and we now have a bright LED based light in the back garden.
    The 2 watt PV panel is on a long metal stalk which I knocked up from spare aluminium. It gets a good view of the South sky, as the wall is facing east and is shaded by the eaves above and a high hedge opposite.
   The panel is swivellable, so it can be optimised in the winter. I haven't actually seen it on yet, as it has to be allowed 3 days of daylight to charge up the battery cell.
28 August Postscript: Well I have seen it now, and it is very bright, very responsive, and turns itself off quickly when one has moved away. LEDs always seem to have this cold light with harsh shadows. But it's a security light and is doing a great job for our back garden!

Monday, August 22, 2011

Surya 3 Finished!

22 August 2011: Well, I declare these finished. I did a bit of draught proofing today, and have inserted a V-shape mirror above the 1-watt night lamp. I am leaving the scaffolding up in time to fit the Weather Station when it arrives. From now on I test it.
   Unfortunately, my mind is already working out an improvement. I don't have the time or the willingness to undo all my recent work now, but it's a project to try next year, or on someone else's house. The thermal capture from the naked panels in the sunshine of July was impressive, and it would be good to be able to open them up to the sun in the day and close them at teatime. I thought about it at the time, but decided that panels opening with a bottom hinge would be too dangerous in wind conditions, and make it difficult to do regular maintenance.
   Talking about it with Mrs NC at teatime, I thought that I could construct a big Sliding Front model, that would be closed most of the time, but the user can reach up with a boat-hook and slide it down on good sunny days. I will make an ArchiCAD model of this quite soon.

Clock and Pump Speed

22 August 2011: The annual total for the Clock on the sunboxes was a record this week - this has touched 2,230 hours. This is a variable amount, because I could make it do more hours by working with a smaller delta-T and trigger temperature, and fewer the other way. But then the kilowatt-hours per hour would be poorer. I have a balancing act between them. The overall annual efficiency (measured as the power capture) of the Sunboxes over the year is 1.3 kW -  it seems to be about 1.8 kW during the winter (when the GSHP is driving the glycol round fast) and 1.1 kW during the summer (when the glycol is trickling round at the slower rate).
Should I run the pump at the faster speed? perhaps.... There is a choice of 30W, 46W and something higher, perhaps 60W. ....thinking about it....

Perhaps, Yes!  I should have a policy of running it faster in the five summer months and slow in the seven months of the heating season Oct 1-May 1. I will try this for the final part of August, and for the first half of September. My daily and weekly measurements will reveal if this works. The majority of the pumping time is when there is power from the PV roof, and if the 'chillers' cool the sunbox space more quickly, then good! the valve will close until the air temperature builds up again.
September 2011 Postcript: Later, NO! I changed it back to 30W, the slow speed. I have an instinct about this. If the pump runs too fast, the volume flow is greater but the temperature difference between the pipes at the point in the illustration is too close, making it too difficult for the SuperCal energy meter to pick up the difference. Slow speed gives us more accurate readings.

Sunday, August 21, 2011

Link to Sunny Portal repaired


21 August 2011: For a month we have had no luck with connecting our Sunny Webbox to the Sunny Portal that shows our PV performance.
    For those just arriving on the blog, we have had a live link from the SMA invertor of our PV roof to SMA's datalogging site on the web, so that the hourly and daily performance is converted to graphs and we can then display them with a browser or on a smart phone. We have had this from November 2009 to the present day.
    There's nothing wrong with the webbox or the cabling, so it was a mystery - emails with SMA's team hadn't made anything better, other than to check the cabling. SMA had been helpful by suggesting that I could downlood the figures directly from the webbox, and send them as a CSV file to SMA and they would put them on to Sunny Portal manually.
    It's important to be on this site, to add to the international community of power generators. If you go on to http://www.sunnyportal.com/ and click on publicly visible sites, you can find us by doing a word search using 'Peveril' as the key.
     Im glad to say that it is all working again now, thanks to Paul of EvoEnergy. Paul spent a bit of time investigating the IP numbers of the BT modem, our wireless router, the webbox and did some reconfiguring of those. It is possible to do this. I suspect that part of SMA's site maintenance has been firewall improvement, and I wonder if other people have been cut off too if the firewall blocked conflicting IP numbers. One of the difficulties for Paul was not knowing if it was working until a day later. There is no feedback, nothing appears on the site immediately, but we had a green tick box icon instead of a red no-entry button at this end, so this looked hopeful.
   If you get it working (or think you have got it working), just walk away and leave it overnight, you have a reasonable chance that the following morning, the graphs will all be updated - and they were!
 It is good to see this, especially as we are having something of a bumper sunny August so far, and twice this month, our PV roof has reached records for best annual performance. 

Electricity consumption reduced

Good Energy
21 Aug 2011: We all know it's been a good(ish) summer, although gardeners could have done with more rain. Our PV meter reached its highest annual figure 2 weeks ago (of 3,330 kWh) and this Sunday, it's likely to be touching a record annual maximum of 3,340 kWh, judging by the figures for August.
    We had a bill from Good Energy, the 100% Renewable energy supplier with over 3,000 small home generators like us on their books. Because I haven't send in a reading recently, the bill was based on 'Estimated use' - I have of course been on their website and entered the correct figures for consumption and generation.
    Their estimate from 16th May to 16th August was for 1,193 kWh. Remember that our house is using electricity for DHW and for cooking, which in other houses is usually done by gas. They must be assuming about 12-13 kWh/day over summer.
    I was pleased to see that the real figure for the same period, for DHW and cooking and normal house use is actually 565 kWh, less than half the estimated figure! (averaging 6.25 kWh/day)
    The Saving alone is equivalent to £80 pounds, and during the same time, the Feed in Tariff has racked up an income of £620 pounds!

Saturday, August 20, 2011

Beetroot inspire the next step

19 Aug 2011:  The sunboxes are finished, so I am looking for ways to re-use the material from the previous sunboxes. These are the two front sheets of 6mm PC glass from the old ones, each 1.75m x 1.54m.
   So there are two ideas, I need a side GATE for the house, so I fancy making it of polycarbonate with the slenderest of aluminium framings. The remainder is enough to make a large CLOCHE, and you can see the beetroot lined up, egging on Mr Makita to make a start on the cloche for their descendants to follow, while they sit in the fridge waiting to be eaten...
One Idea I had was to use them to surface part of the South wall, eg with a 50mm cavity, a sort of heat gathering wall.... but the brick walls are so well insulated, I don't think it would make a difference and besides... I need the Gate and Cloche more!

Deep Temperature: I always do my ground temperature test at about midnight, but just for a change I did an impromptu test at 8pm after a sunny day. After 20mins circulating, the deep temp was 14.0º. It usually relaxes back to 13.5º once it has had the evening to disperse a bit.

Friday, August 19, 2011

Bonnet-Stays

Bonnet-stays made in the back garden...
18 August 2011: I'm so finished with the work on the boxes that I can't think of much else to do to them - except take readings now and through the winter. When open, they are very stable and proof against slamming in wind. There may be a tiny bit of draught proofing. One thing I am doing is putting more machine screws (fine gauge bolts and nuts) in places where I previously used rivets, to strengthen the bond between polycarbonate and aluminium.
... and now installed in the sunboxes

Wednesday, August 17, 2011

Surya3 - view from the hill

16 August 2011: I took a walk up the hill to look down at the house. It really does look weird amongst the conventional houses, although I am glad that the house 4 doors down the hill has a full PV roof now, and one just to the right of this photo has had a full PV roof in the last month or so - all ones that I suggested PV to!
Closer up, one can see that the boxes are complete now, and the TV aerial is no longer so high that it is overshading much of the PV roof beyond. I have worked through the checklist of things to do, and only the 'bonnet-stays' are left to do now. I am ever-grateful to Pearson Scaffolding who are willing for the scaffolding to remain up a little longer, so I can observe and test, and think of other small refinements. Most of my refinements now are to do with draft-proofing, or with techniques for future maintenance, such as hinging and locking.

Surya3 - unfriendly to pigeons

16 Aug 2011: The previous set up suffered a bit from pigeon poo, so these panels now have a fine 'crown of thorns'. The rivets, with two eyes and a 'nose' make it resemble a rather angry robot with very long eyebrows.
  It's made with galvanised wire and some aluminium angle section, and a few rivets.....

Tuesday, August 16, 2011

Nightlight glowing

15 August 2011: Got my first photo of the house at night, with the 1-watt lamp to indicate that the pump is working. There is now a metal reflector covering the visible brickwork and it scatters the light better. I am thinking that perhaps I should have installed 2 lights, facing opposite directions. It's useful in the dark on the scaffolding having that light shining! But really, two lights would be too bright.
  That TV aerial has to be lowered! I practised getting up the small ladder, and it is easy to reach the adjusting bolts.

22 August Postscript: The lighting is a bit too localised and vertical, and I don't want to add another bulb. First, I restored the vertical aluminium reflectors which stop you seeing the brickwork (as above). Then I have now found some old mirror glass and have put a V-shape above the lamp, so that the light is dispersed in two directions. Looks great!

Shut that door!
My next project after this is to build a side-gate for the house, re-cycling the solid polycarbonate. I don't want to have to store these large sheets through the winter. It's got to be used for something useful or ornamental!

Monday, August 15, 2011

Weather Station coming

15 August 2011: The house has scaffolding up, so there will never be a better time to put up a Weather Station. I've ordered a LaCrosse weather station 1501 from Weather Weather Weather. This has sensors on the outside, and a wireless link to a hand held unit indoors.
   The temperature gauge contains the batteries, so I'll position this in the shadow under the Sunboxes where I can reach it from the bedroom window. The Wind gauge can go right up to the house verge, in the airflow. There'll be more reports after it arrives.

Sunday, August 14, 2011

Surya 3 Progress - nearly finished

The detail for the centre section. the complicated hinges
were a 'workaround' for a mistake I made in getting the
height calculated.
14 August 2011: Managed to get the Indicator light fully wired up and it now comes on faithfully after Sunset if the loft-pump is running. I've been doing some draughtproofing, hinge modification and panel strengthening (as listed below).

13 August 2011: Well the long ride is nearly over! the Surya-3 Sunboxes are nearly airtight, with all panels and metal trim on, and just a small amount of draught stripping and electrical to do. What else is there to do, before the scaffolding can come down?

The one-watt GU10 light is mounted on a
transparent shelf at the very centre of the
sunbox assembly.
Well one thing is true, I haven't had to change the plumbing one iota, it is perfect. So for the boxes:

  1.  I need to get the indicator light wired up - it will come on when the sunbox pump is running, and using a photocell, it will only do this at night. It is only a one-watt GU10, and is in a place where I can easily replace the bulb using a ladder, if I have to. It will make the external boxes glow in the dark in the winter, and I suppose walkers on the hill will wonder if I am growing something suspicious in the boxes!
  2. I am going to add bird spikes to the centre section as it took only a day for the centre section to be splashed with bird poo. 
  3. I have a bit extra draught-proofing to do here and there.
  4. The TV Aerial can be shifted downwards to avoid casting a shadow on the PV panels.
  5. I need to fix opening stays to keep the front open (like you have to hold the bonnet of your car open). 
  6. I need to strengthen the panels by adding machine screws here and there, as it is clear that rivets don't hold the 1mm polycarbonate skin securely if pressure is placed on the panel.
  7. I need to modify the main hinges slightly to make the panels open more easily.
  8. The light is working, but it needs mirror reflectors in the box to bounce light about. The light looks great, but it is illuminating brickwork, and needs to illuminate metal!
Really... that's it. I can't think of anything else!


Saturday, August 13, 2011

Second Anniversary

13 August 2011: The metering process and the idea for this blog and project started exactly 2 years ago this week.
See the first month's worth of postings.
   This coincided with the decision to have a PV roof, and it became necessary to record meter readings so that we could compare the 'before' and 'after'.
   The drawing here is the first sketch that I did, and it is extraordinarily close to what I have finished doing, even though I have had a number of deviations before returning to the true path of the diagram. In fact, after all my experiments with the building of the new Surya-3, I might one day finish up using a conventional flat plate panel!

Friday, August 12, 2011

Surgery Ideas

11-Aug-11: Surgery: I had a visitor on Weds evening, John, a doctor who is trying to build a Carbon Zero surgery building. He has some very ambitious ideas, and when I see these, I can't help feeling that my system is already pretty cost effective. It's amazing what people will do to avoid using a borehole, even if the alternative solution is likely to cost more. But I am never one to discourage someone from trying, and there is merit in the idea, if it will store enough heat to obtain the heat passively without needing a heat pump. Basically, he is building something along the lines of the Surya-3 sunbox, but on a giant scale - making half the length of the entire building roof space as a large sunbox.
    I don't think it will get as much heat as he hopes, and larger scale thermal storage projects have always assumed that it takes more than a year or even two to get to steady state, the working temperatures they need to get the inputs and outputs balanced. I shall be interested to advise and assist on this project. It will need monitoring, as any experiment is worthless unless records are kept of its performance.
    I've been email-discussing with him for about a month and a half, and some of John's ideas have influenced my design on the Surya 3 boxes, in the use of Triple wall Polycarbonate, the angled front and the creating of a larger volume of air that is heated by Sun. This was the first time we met.
   I shall be happy if I get regular air temperatures in the Surya-3 boxes on sunny days of 35º-40º (as I was getting with the previous boxes) and hold this heat for longer. John is hoping for air temps of perhaps 55-60 in his version of the sunbox.
   If he will allow me to, I shall post some images at a future time.

Surya Progress 11-8-11

9th August - right hand roof fitted
11 Aug 2011: A bit more finishing progress made with the left hand rooflet fitted, and the upper part of the middle section fitted. The boxes are nearly air tight so I am looking forward to the next sunny day to see how they compare. I need to buy a bit more flashing to be fully finished.
    I shall be gutted if the new designs do not work better! Maybe I should simply have re-fronted the old boxes - but having paid for the scaffolding, I feel that I had to do the more thorough job! I won't really know until August of next year, when I have had several months of readings to compare with the previous panels - it takes a year to be sure.
11th August, the left hand roof fitted



Tuesday, August 9, 2011

Surya Roofs nearly on!

Photo taken 7 Aug '11, and on
the 8th, additional small sections
were added.
8 August 2011: I didn't have a lot of time to spend on the sunbox construction today, but what I did have was useful. The right hand roof is permanently fixed now.
   Since this photo, the central and right hand metal shrouds (protecting the insulation around the exposed pipes) have been fixed. I only have the left hand rooflet to fix now, and the system can be tested. It is too early to take the scaffolding down, as there are refinements needed to the central portion to make sure that the boxes can be maintained from a ladder, and can be disassembled non destructively if future maintenance is required. When both rooflets are in, the central portion needs metal trim to line through with the trim on the lifting front panels.

Monday, August 8, 2011

Another IVT user!

7 August 2011: I went to an Open Day at my sister in law's house, in aid of Save the Children, and we braved the rain and a hundred mile drive to see the vegetables, PV and solar panels... and plenty of cakes and hot dogs. I had the pleasure of meeting a couple who have just installed a GSHP, and it turned out to be the identical make and model of the one I have - IVT Greenline C6 from Ice Energy!
    Truthfully, John and his wife are the first people I have met who have a heat pump (other than David Hill who I am doing a project with) - theirs is the same model, but has a horizontal ground loop in the adjacent field.
    I ran through a list of the tunings that I have done to mine, and have offered to do a round trip to their house soon, with my electrical tools and do some of the tunings. Nobody else (including Ice Energy) has such a comprehensive list of tuning possibilities now that David Atkins seems to have retired.
   There must be ways in which solar charging can be used (less efficiently) with a horizontal loop, but first, there are simple things that can be done to any heat pump - insulating the water tank, setting the time clocks for heating and hot water, turning off additional heat, setting external switches for the same two, and fitting a Elster Meter to measure the power consumption.

Saturday, August 6, 2011

Surya 3 Progress 5.8.11

Right hand Sunbox has its front off. These are to be hinged
for future maintenance. 
5 August 2011: Good progress again, although I always finish when it is so dark that I can't take an end-of-the-day photo. I really seem to be almost finished! In the two weeks of this build process, I have noticed the changing of the times of sunset and absolute darkness. I have resisted using an outside light in darkness, or I would go on deep into the night and annoy the neighbours with drilling and angle grinding.
  There are so many people walking past, taking their evening walk that I often lose time chatting with them, me on the scaffolding with hat, goggles and knee pads, and them with their dog gambolling around while we chat.
This shows the new partition walls
clear and strong.
Both front panels loosely
fixed so that I can resolve the fitting
of the centre infill zone.
This shows the new partition walls
clear and strong.
Detail of the space between the boxes, which has to be filled in. The parts had to be custom cut, measuring precisely to the existing cantilever walls. This could not have been done easily if I had stuck with the previous partition walls built from triple wall it would have been impossible, so it was a good thing to make the change three days ago. If doing a totally new box, I would not have had this complexity.

6 August '11 addendum: Saturday: Shopping and Nottm Forest match today and when I got back it rained! However, between the rain and nightfall, I had the satisfaction of being able to complete an entire rooflet with mirror, and get it fitted up, fitting perfectly. 

Thursday, August 4, 2011

Retrovent in the future

3 August 2011: While I was at Ecobuild 2011 in March, I took an interest in MVHR, or Mechanical Ventilation with Heat Recovery.
   The house is well insulated, but it is a prime maxim of the Passivhaus concept to use MVHR because the insulation levels are so good that only the ventilation heat loss remains to be dealt with.
    In our case, even with quite pessimistic assumptions, our ventilation heat loss is probably 50% more than the loss through roof, walls and windows. Some of this is lost through coming and going through doors, the rest is leakage, or windows left on trickle vent or left open. One only counts heat loss during the heating season, the windows are open all the time at this time of year.
   I have spent months thinking about Whole House MVHR like the diagram below - because it is more efficient, and is the way it should be done in a new building.

  After much thought and diagram drawing, I decided that the whole house solution will not work because we have underfloor heating and it is too risky to have vertical ducts passing through the first floor. I had to do this to get my Sunbox pipes down to the Heat Pump and that was a nightmare of plumbing, to avoid the floor heating pipes. It would be possible to do a Box-in-the-Loft solution for the bedrooms only, but that seems to be a project for the year after.
    I shall have to compromise and go for a Room-at-a-time solution, and the only room worth doing on this basis would be the Kitchen-Dining combo.  This is our 'Winter Snug', and the one we most want to retain heat in whilst having good ventilation.
Illustration from Homeventilation website

At EcoBuild 2011, the Retrovent from Envirovent seemed to be the most advanced product for single room heat recovery and ventilation, so I decided that I must research this and get a quotation for installation.
   It seems to be very low energy (3 watts in normal ventilation mode) and hopefully, it will reduce the workload of the heat pump by maintaining good air temperature.

13 Sept 2011 Postscript: I have now paid for the Retrovent and hope it will be installed by the end of September.

It all hinges on.... hinges!

3 August 2011: A good day for progress, although not without setbacks, and having to endure working outdoors on the hottest day of the year so far.
   Having got the new party walls in, I focused on fixing the HINGES, and got those in during the morning. The next thing was to fix the FLOORS in permanently, and I managed that - see photo - using bolts not self tapping screws. If they ever need to be taken down, it will be with a scaffold, and whoever does that can undo bolts safely.
  The floors have reflective metal floor surfaces, so heat bounces up at the black panels when the sun angle is high. There is a light slot of 400mm between the wall and the start of the metal, so daylight comes through to the bedroom windows in summer.
  While working on the scaffold in hot Sun, it was possible to feel the flow of cool liquid through the black panels and to identify 'hotspots' where the velocity of fluid is slower. Along the top line of the black panels, it was almost too hot to touch! It is impossible to avoid slow hotspots somewhere, but the arrangement that I worked out with David Atkins in 2009 seems to be the one that has least wasted space.
  As often happens with such hot weather, it had to break and there was a period of heavy rainstorm passing over which stopped me working outdoors, but meant that I didn't have to water the garden later.

Later, I tried fixing the large front panels. All the hinges are identical, but I was dismayed to find that I had somehow got the height of the first hinge wrong by 20 millimetres, but I had manufactured and final-fixed all the remaining 3 to that exact size and position, millimetre identical, but still 20mm too low. As they are all firmly fixed in by bolting or riveting, I could not raise the position of the hinges. I had to 'bodge' by making 4 identical adaptors, little aluminium flats riveted to the original, but providing a new bolting position 20mm higher.
  So the finished product is serviceable, but not as elegant as the clean detail in the photo shows. Nobody looking at it from the ground will notice, but for me, it will always be an annoyance because I 'know' that it was a bodge.
  The first front panel is now fitted, and has been stripped of the protective plastic, and looks beautiful. It makes a nice airtight fix to the sidewalls and floor, and hinges conveniently.
  Photograph will follow when there is daylight.

Tuesday, August 2, 2011

A bit of Re-manufacturing

the old and the new parts on the floor
with the triumphant Mr Makita surveying his work
2 August 2011: I have been concerned with making a large hinge for the front panels, and there is a need for a strongpoint to fix the middle hinges to. I decided to re-manufacture the middle walls, re-using some of my 6mm structural polycarbonate. These are thinner and strong enough to take the tightest bolts.

  This was quicker than expected because the aluminium parts were already cut to length, and only minor re drilling was needed. All the rivets on the old partitions had to be drilled out. I was recycling the 6mm solid PC rooflets from the previous sunboxes - I wish I had thought of doing this earlier.
By the time this is re-bolted it is dark, but
more will be done in the morning!

Meanwhile we are having good daytime and evening temperatures (how nice if it could stay like this all year!) and there is no urgency to get the covers on - we are having daily scores higher than the same time last year. But if I haven't finished by the time that the heating season starts, then the scores from unboxed black panels will fall compared to boxed in ones (I assume)

No PV recording at the moment

1 August 2011: I am sad about one piece of technology that is not working so well. The Sunny Portal Webrouter of the Photovoltaic invertor is not sending data to the Sunny Portal, or maybe it is being sent but they are not processing it and displaying it. Therefore, I am getting no daily bell-curves of solar performance, no monthly reports etc. Luckily, I am still recording daily readings from the OfGem meter, so I know the daily and monthly performance. The invertor stores about a months worth of data, but after that it is lost, so I need to get on to their technical support. Typically of so many companies now, there is not a trace of a contact email or phone on the Sunny Portal website. I will have to try SMA's website.
  I haven't changed anything and tried not to stress the cables.... the correct lights are showing on the house router.

Monday, August 1, 2011

Surya 3 progress - hinges!

31 July 2011: The overall shape of the sunboxes was completed almost a week ago, but the difficulty is in the details - as in everything! I could easily seal them up and be finished in a day, but then would need scaffolding for any further modifications. The intention is to have the large panels able to hinge at the top and be sealed only with some self tapping screws on the lower rail which can be reached from a ladder.
   I managed to get the two big front ones to the top of the scaffolding on my own (ropes, duct tape, patience and strength). Any further cutting on them will be done atop the scaffold, I am not taking them down again!
   The detail photo shows the problem. I put this decision off until now as my detail drawing was perfect for the general plan and sections, but as usual, there are three dimensional problems at the corners - the same applies to buildings! Here I have to make and fix two hinges, despite the difficulty of a 200mm gap to work in, making drilling difficult.
  

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