Friday, September 30, 2011

New Sunbox versus old

30 Sept 2011: One question that the followers of this blog will want to ask is: "Do the newly designed Sunboxes make a difference?" Well, that is a question I want answered too.

What I can say is that from August 9 to Sept 30 in both years, the 2010 solar harvest was 492 kWh. For the same period in 2011, the harvest was 529 kWh. This is about 7% improvement - but that is a margin of change that could easily be varied by seasonal differences.
    Apart from the recent cold weekend (when the heating was on briefly), the weather is so warm that we are still in Summer conditions. This performance has been solely based on summer collection, i.e. inter seasonal storage with the low speed pump. (There is a brief moment of delta-T realtime operation when the water is re-heated every so often).
   The figures will continue to look good for a while because the weather forecast is for a week of sunny weather with which to close September and start October. We have had two days running of a daily harvest of over 20 kWh, which is a first time ever.
   The previous boxes managed to break the 20 kWh barrier 5 times in 17 months, and the new ones have broken that barrier 4 times in one month, including an all time record of 22 kWh in a day.
    The real test of it has to be over a longer period, with some part of that time occurring in the Winter when the GSHP is driving the glycol through the panels, based on delta-T.
     So far it does look like a slight improvement, and after a few more months have passed by, I shall post graphs comparing the performance. When there are chilly winds blowing, will the insulated construction yield benefits? When we are deep into the heating season, will the larger air volume (heating up when the Sun shines) make a difference?
   You will hear from it on this blog! And if I am wrong to have changed them, you will be the first to hear too!

Thursday, September 29, 2011

September 2011 Reports

29 Sept 2011 Postscript: Having had four days with sunny September days, we scored a good sequence of solar capture on the sun boxes (daily amounts of 15, 16, 20, 21, 22 kWh in successive days, the best sequence ever recorded). I did another deep ground test at midnight and the result was 13.6ºC. There is more sun forecast until the end of the month. I can see that unless we have a sudden outbreak of snow, we will have more record low figures for the house and GSHP meter at the start of October.


25 Sept 2011: Thanks to the holiday, we have again broken records, as expected.
  • The house meter is down to 5,265 kWh
  • The GSHP meter at all time low of 3,286 kWh
  • The Sunbox clock at a high of 2,356 hrs
  • Meanwhile, the PV annual is 3,302 kWh and the Sunbox annual is 3,012 kWh.
Let's hope that the next few months see us managing to stay in sight of those figures (last winter, the GSHP annual swooped up to over 4,000 kWh!). As a sign of the coming season, I note that the deep ground temperature is 12.9ºC, a slight drop on that of early September.
Ground Temperatures Aug'09 to Aug'11
   One question that the followers of this blog will want to ask is: "Do the new design of Sunboxes make a difference?" Well, that is a question I want answered too.  I've written a little bit about this, elsewhere in the blog.


18 Sept 2011: We have been on holiday from 14th -23rd September, so the house and GSHP consumption will be much reduced. But this reduction is normal for all households, and was for us in July 2010. Both of our annual figures have dropped below another threshold as a result, the house consuming 5,282 kWh and the GSHP consuming 3,298 kWh. As the PV is nicely balanced around then 3,300 kWh mark, this is satisfactory.

11 Sept 2011: Nottingham had a cold snap at the start of the week, and I had to go to Liverpool for 3 days, so in deference to my wife's preferences, I put the heating to "On". When I got back I was glad to see that there had been a balancing mini-heatwave, and it didn't actually come on at any time because the external thermostat didn't think it was quite cold enough and the internal temperature stayed good enough for it to stay off. Deep ground temperature is holding up at 13.4º (no heating yet to deplete it), and the GSHP again scored an all time record low consumption score of 3,315 kWh
   I'm forecasting that by the end of the month, the annual GSHP should be below 3,299 kWh! Try me!
  (A year ago, annual was: House 6,108 kWh, GSHP 3,996 kWh)

4 Sept 2011: The week has been average to dull for this time of year, including 3 days running of grey grey grey skies. We've only broken one record this week, which is the smallest ever GSHP consumption at 3,317 kWh for the year. If the autumn continues warm (i.e. not at cold as last year) the figures will get even better. Deep ground temperature is 13.4º
  So far I haven't been able to think of any improvements to make to the boxes (sans scaffolding) but I might go up the ladder and drill in two safety hooks or eyes, one at each end, so I can clip a carabina in when going up the ladder. I had thought to add this to the Sunboxes, but the scaffolding came down too quickly.
The final appearance of the house, with scaffolding removed

Tuesday, September 27, 2011

New schematic diagram

27 Sept 2011: I decided to draw a revised schematic diagram for the plumbing as I am working on another paper (for China) and need a better illustration. When I explain the system to people using the blog, I have found that I do not have a diagram that states it clearly enough. So here is a new diagram.
The thermostat decides if conditions are right to open or close
the solenoid valve and switch on the little pump

Sunday, September 25, 2011

Solar charging in Bulwell

The house will appear in this gap
25 Sept 2011: Earlier in September (7th), I spent a couple of hours with a heat pump expert Mo Kelly of Sasie, and his colleague Simon. They are building a Code 6 house in Bulwell, Nottingham (built to Passivhaus standards are far as possible), and it will use Solar Earth Charging. It is designed by Mike Siebert of Ecologic.
   They wanted me to know what is proposed so it can add to my research, but also, were keen to test out the ideas on me. They are building their own heat pump, so that it will be air source in summer and ground source in winter. They haven't yet settled on the type of collector they will use for the solar heat, but with ground charging this is less important - it does not have to be high temperature (like tubes). Perhaps they will use an adaptation of my sunbox!

Rendering in ArchiCAD by Mike Siebert
    The site is between two terraced houses, so it is too small for a horizontal ground loop and they wish to avoid using a conventional borehole. With Solar charging and exceptionally well insulated buildings, there are other opportunities to try besides a borehole. In the centre of the plan, underneath the ground floor, they are proposing an uninsulated pit 2.4m x 2.4m x 2.0m with a large amount of horizontal slinky ground loop pipe buried in a helical stack - back filling carefully with the spoil that comes out.  The building will be like a thermal tea-cosy, nursing the heat that is buried. Surplus heat will move outwards into the volume around the pit, under the house. This size of pit isn't big enough for an entire winter, let alone a month, or even a week, having a capacity of about 8.5 kWh/degK (CWood). However, it will provide diurnial assistance to the GSHP as a thermal buffer. If the heat loss of the building is very low due to Passivhaus design, it may be sufficient.
  At the moment, the building is not clear of the ground, all that can be seen is foundations and ground insulation. So there is time to make decisions. Simon is an expert on data collection and circuit design, and will be planting thermal sensors in many places in the ground under the house.
  I hope to be able to report on this in future months.
 (See comments below from Chris Wood, and I have amended the text above to include his observation)

27 Sept Postscript, email from Mo Kelly: "just to be clear our main heat delivery for the house will be what I describe as my Mono Energy System, the main components of this will be PVT panels tied directly into the HP the 2 main benefits of this is an all year round PV energy collection and between 10 and 15% better performance and night time usable primary source for the evaporation process of HP. I will update you on my plans for the overall storage of excess energy."

Wednesday, September 14, 2011

Progress at Stanton

14 Sept 2011: John and Rachel are making progress with the sustainable building project, which includes this idea to solar charge the slab to their new conservatory. They sent me some photos.

Underslab and slab edge insulation in place.
Blinded hardcore and membrane under the insulation
Reinforcing mesh laid and approx 100 metres
of underfloor heating pipes cable tied to reinforcing mesh
Concrete now laid, pipes coming up to surface
 Now that the pipes are down, the decision of how much to heat it can be tuned based on performance. If there is an array of evacuated tubes, it would get too hot in summer, so Chris Wood and I have suggested that the tubes are primarily heating a water tank, and that some of that spare heat is drawn off to provide warmth to the slab - using a time clock and thermostat to manage it. There is no thermal link to the larger ground below, the heat is entirely contained within the 300mm slab.

Rushcliffe BC consider, then reject PV

14 Sept 2011: I see that Rushcliffe BC are running a brief consultation process, but you have to be quick, I gather that comments have to be in by 19th Sept.
Actually, it seems that all the Local Authorities in Nottinghamshire have agreed to issue identical policies, except Erewash BC who seem to be applying slightly tougher standards or sooner targets for achieving certain standards (good for them).
   It's good to see that the authorities all agree and are avoiding some US-style split on doctrinaire grounds where it becomes obligatory to deny climate change if you want to continue in the party.
   I quickly scanned the document and can't find anything to disagree with, they seem to be intending to continue on target to meet 2016 standards etc.

Rushcliffe fell at the sustainable hurdle....
   Having said that, it is a pity that a proposal was discussed in the Rushcliffe cabinet last week to instal PV on some of the RBC buildings, and eventually the whole proposal was turned down without so much as agreeing to a single pilot project. (click the link to read the Evening Post story). They considered it Solely on Payback considerations, without once valuing the benefit of producing clean electricity without burning coal and emitting carbon.

Why mention this here?
The personal angle on this is that I did the powerpoint illustrated report for RBC outlining the costs and returns, and showing how the panels might fit and look on the buildings. I gather from a witness that the powerpoint was not shown, that a civil servant had converted it into a dry document just listing the financial equations without mentioning the qualitative aspects.

Monday, September 12, 2011

Paper for China

One thing I need to add to this diagram is that
we buy our energy from Good Energy who are
100% Renewable, so that does, in a sense,
cover our 'cooking, ironing, lighting, power' etc.
12 Sept 2011: The Istanbul conference has come and gone, and my head of department very kindly delivered my powerpoint to the conference. He wrote to say that it had been well received.
   Apparently, the conference hotel was about 1.5 hours drive from the old city and situated next to an expressway, so in terms of travel and tourism, I didn't miss anything. However, the learning content and networking is something you can only get by being there.
   Unfortunately, for family health reasons, I can't do extended trips abroad, so I shall have to ask my colleagues to deliver papers for me in future.
   I am working on another paper for the Ningbo CSET conference in China at the end of October, and there is a chance now to report more fully on the early performance of the new Surya-3 sun boxes.
  I've been asked to reformat the original paper into the right publishing template (to include data from my most recent summer sunbox rebuilding programme) for the Journal of Low Carbon Technologies.

Calculating Annual amounts

11 Sept 2011: During the 'old days' of 2007-2009 when I didn't read meters obsessively, I could only estimate from the electricity bills, but the House averaged an annual of 8,500 kWh and the GSHP can only be estimated at 4,800-5,400 kWh - probably the higher of those figures if you include the floor circulating pump - this alone is probably more than 300 kWh (and I shall know by the end of the year as it now has its own meter.) The PV is probably responsible for reducing the house consumption by about 1,600-1,800 kWh, annually, since October 2009.

Depending on the weather and lifestyle factors, there are swings in the ANNUAL AMOUNTS (re-calculated every Sunday).Weather affects PV power, and heat loss, and Lifestyle is things like baths or showers, visitors, birthday cake making or ironing or holidays.
  • The PV annual swings between 3,240 <-----> 3,340
                and currently the amount is ----- 3,299 kWh
  • The Sunbox annual swings between 2,980 <-----> 3,090
                and currently the amount is ----- 3,024 kWh.
  • The GSHP annual swings between a worst last December of 4,245 kWh and currently the amount is an all time low of 3,315 kWh, and is likely to be below 3,299 by the end of Sept. Unless we have another extreme December, I expect the average swing to be between 3,300 and 3,600 when things settle down.
  • The House annual meter swings between a highest last December of 6,300 kWh and a lowest of 5,295 kWh, and currently the amount is 5,308 kWh. (considered since August 2010 when we had precise weekly figures on annual consumption.)
Another thing one can calculate is DAILY AVERAGE kWh of key devices:
  • Oct 2010-Dec 2010
    - Housemeter 23.6,
    - GSHP meter 16.4,
    - PV Roof 3.49,
    - Surya 6.66
    (remember how cold that autumn-winter was!)
  • Jan 2011-Mar 2011 
    - Housemeter 21.3,
    - GSHP meter 15.3,
    - PV Roof 4.7,
    - Surya 5.68
    (much milder weather)
  • April 2011-now, mid Sept 2011 
    - Housemeter 6.3,
    - GSHP meter 2.15,
    - PV Roof 14.64,
    - Surya 10.7

Monday, September 5, 2011

Solar Charging for Office building

This view is from the south
4 Sept 2011: I had an interesting approach from the prospective purchaser of a 6 storey office building, nearby. The building is 1960s, with single glazing, the original boilers (gas), some very inefficient perimeter radiators. On the plus side, it has a sound concrete frame, the windows are sound, it doesn't leak.
     The tallest part, the core with lifts, stair and boilers and mobile phone masts are all at the south end, but there is unshaded surface at the north end. There are two storeys of shops below the 4 storeys of offices. There is an car park on the west side.


He has the idea of eco-renovating it, with boiler replacement and insulation. Having visited my house and discussed heat pumps and solar charging, and all that goes with it, we have prepared a plan for improvement of the building, and for making it very energy efficient, if not carbon zero altogether, expanding the technology of the Peveril Solar house to be applied to an office building.
   This would include about 120 sqm of PV array on the roof, 50 sqm of solar thermal panel charging a cluster of boreholes in the car park below, two replacement ground source heat pumps for the original boilers (pipes all using the existing vertical ducts). We would also be able to dump summer heat gains of the building into the ground, either with different boreholes, or perhaps sufficient for it not to require solar panels at all!
   The windows are single glazed but in good condition, so could be upgraded with a programme of secondary glazing, floor by floor, and the small area of walls below the windows can be insulated internally. The roof element can be insulated with an inverted roof method. With such improved insulation, there is a risk of heat gains that will have to be dealt with, e.g. by underground thermal charging.
   I have suggested taking down the suspended ceiling to use the floor slab as thermal flywheel, and instal a number of zonal MVHR units as there are currently no ventilation ducts. ('Warehouse chic' ?). There are acoustic problems with and exposed slab, but one can suspend absorbers in the air space that allow thermal air circulation.
   I need to do some before-and-after heat loss calculations so see if the combination of insulation, PV, MVHR, solar charging and GSHP would get close to the ideal of zero carbon. It would be wonderful if we can!

Postscript October 2011: We have a PhD student in the school ready to take this on as a practical case study, his main topic being the enveloping of office buildings as a retrofit measure. He is more interested in the insulation and re-glazing than in the heat pumps. 

Solar charging a Conservatory

4 Sept 2011: I had an email and call from John, one of the West Bridgford Ecohouses group. He and partner Rachel are doing major extensions to their house, and this will include a 20 sqm conservatory. He has been reading my blog and got interested in the idea of solar charging. They've no intention of using a heat pump, the idea is to dump heat into the slab under the conservatory. It will then be comfortably keeping the conservatory warm or tempered in the winter. The conservatory slab is to be totally new build, 300mm of tiled concrete on 150mm of rigid EPS foam.
   The storage capacity of the slab is only a day or two, so the idea is to use sunny days and sky infra-red during the equinox and winter months to just lift the temperature a bit in daytime. (During the summer it would be too hot, so either the solar panel will be closed off, or its heat will be diverted to a water tank). All the electrics and plumbing conundrums have been tackled on the Peveril Solar house and I will be able to adapt the thermostat and other elements to suit his installation.
   The conservatory is a good source of fresh air for a MVHR (Heat Reclaim) system, which they are likely to use. For the rest of the heating, the house will be very well externally insulated and will need little heating if the MVHR works well. For evenings, there is a source of firewood so they intend to use wood burning stove.
  John is such a can-do man (even has his own digger and dumper truck) that buying a commercial flat plate panel is out of the question - it must be self build! We talked about building a sun box type structure, using the same plastic panels that I already used, but as the panels are not intended for summer use, they may get too hot with stagnation. We discuss metal radiators, easily available second hand. We finished with a discussion of using his underfloor heating piping (or copper) used with the aluminium spreader plates (for underfloor heating), and then boxing them up with a cover made of the polycarbonate that was in the conservatory they took down. (This is the same stuff that I have used on the Surya-3 Sunboxes.).

PS. There is an interesting comment below from Chris Wood. He is approving the idea, but because this is intended for winter and diurnal use only, he is identifying Vaccuum Tubes as the best mode of collection  because they have a fast pick up (and of course are not affected by cold air temperatures). I note that they are also scaleable. If you have a large manifold to start with, you can add more tubes. We have plenty of tube arrays set up in the school if John wants to call in and view.

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