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JSHarris last won the day on June 22

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About JSHarris

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    Advanced Member

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  • About Me
    Retired scientist, made the decision to build our own home a few years before retirement, then had the good fortune to be able to retire early and start the self-build journey. Started our build in late 2013, took far longer than anticipated to finish, but have now moved in and we are enjoying having a house with no bills at all (except for the blasted Council Tax...). The house pays us a modest income from the excess energy we generate, over and above the energy we use for heating, cooling, cooking, hot water etc, so we now have a healthy retirement holiday fund.
  • Location
    Wiltshire/Dorset Border

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  1. JSHarris

    window film install

    Pity about the timing, as we're heading over to Sark for a few days from tomorrow. Could have brought a roll or too over with me and had it forwarded on from Guernsey to save a bit of postage.
  2. JSHarris

    Save the world, install an LPG tank.

    Precisely linking cause with effect is pretty difficult with climate science, as I understand it. A more accurate way of referring to what we observe would be to say that there is a clear correlation between various factors, and the predictions made are based a fair bit on the strength of those correlations. Some will point out the golden rule of science, perhaps, that correlation doesn't equal causation, but then the same is true of many things that we cannot prove beyond doubt, yet can be pretty sure are true, nevertheless. There are also some factors that aren't fully understood, and some that have only come to light relatively recently. A good example would be the impact of ocean CO2 absorption. A few decades ago the thinking was that the oceans would just continue to absorb atmospheric CO2 as the concentration increased, so balancing out the effect of increased CO2 emissions as a consequence of human activity. That proved to be a false assumption, in that the way the oceans absorb CO2 isn't as straightforward as initially thought, and changes a fair bit, dependent on a host of factors that are separate from atmospheric CO2 concentration. Things are made more complex by the way that upper ocean CO2 absorption is partly driven by ocean turbulence and significantly affected by temperature, so as the oceans warm, weather becomes more variable and upper ocean CO2 absorption rates change, which then tends to drive temperature change, and so feedback to produce greater variability. The whole system is exceptionally complex and difficult to model with any degree of accuracy, which explains why practically all global warming predictions have such wide error bands. If things were as simple as saying changing the value of X will have this effect on Y, then it would be a lot easier to understand. Sadly it isn't, but what we are seeing are global changes that map consistently to human activity.
  3. JSHarris

    window film install

    I didn't manage to find a supplier who would just sell the external film when I was looking around. I got the impression that the manufacturers had pretty much stitched things up so that they would only sell to authorised installers. Installing the stuff seems to need a fair bit of expertise, together with some equipment. The people that did ours had dispensers for the rols, a large guillotine to slice the film off, and some thin stainless steel shields that they used to protect the edges of the window frames when they sliced the film to size when partially bonded to the glass. Fitting the stuff seemed pretty straightforward, they just thoroughly cleaned the glass and polished the surface, checking for anything that might be stuck to the surface, no matter how small (they ran wide blades over the glass). They then sprayed water onto the glass and applied the film, using a squeegee to smooth it down and get the air bubbles out. The film is self-adhesive, so not easy to handle once the backing has been removed, it took two people to apply most of the film to our windows.
  4. JSHarris

    Electric Vehicle Tariffs

    I can vouch for the BBC taxi bill probably being extortionate. When I was a guest on Kilroy they sent a chauffeur driven Mercedes to pick me up from home (just outside Salisbury) and drive me to Teddington Lock studio and back. All for five minutes on daytime TV.
  5. Units are never included in the data set, other than as a header to tell the CAD package what they are. All entities are just expressed numerically. Back when we first got CAD at work (AutoCad, running on a DOS PC, pre-Windows by a few years) we used the new CAD/CAM system in the workshop at our parent establishment for manufacture. Our drawing office designed a new form of Mk46 torpedo tail nut (which includes the motor exhaust valve) using the new CAD system. They were really proud of the thing, which was to be machined from stainless steel. It's dimensions were such that it should have comfortably fit in the palm of the hand. A few weeks later we had a phone call, saying that there was a truck with a delivery for us, and did we have a forklift available to unload it. Lots of scratching of heads, wondering what the thing was, until the pallet was unloaded. There, in all it's glory, was a beautifully machined tail nut around 3ft in diameter, weighing around 1/4 of a ton. The CAD file had been transmitted to the workshop minus the unit header, so mm had turned into the AutoCad default of inches, making every dimension 25.4 times too large...
  6. JSHarris

    Electric Vehicle Tariffs

    I thought that energy figure was just the total primary energy used by the UK divided by the population, wasn't it? If it is, then it seems to not be a million miles away from the only data I can find quickly, which suggests that the per capita energy consumption in 2014 (the latest year I can find data for) was about 95.4 kWh/day. MacKay was probably using older data, which may have given a higher energy use, plus the population may well have increased as well.
  7. Don't do what I did. This is our's in place (it's 2000 x 900 and weighs about 70kg): The stupid way I chose to fit this (it's a tight fit between the walls from left to right in that photo) was to slide the tray in place, spaced up on battens, then lift the right hand side up, propping it in place with a bit of 2 x 2. I then mixed up some mortar, spread it on the floor (being exceptionally careful to not nudge the prop), then I took the weight of the thing and pulled out the prop. I'd intended to lower it carefully on to the mortar bed, but this was not to be. I got it within about six inches of the floor then dropped it. By pure good fortune it happened to end up dead level in both directions, so I just left it and went home, thankful that it hadn't fallen on my head...
  8. Very few of my AutoCad drawings have dimension labels. There's not really any point in adding these except for drawings that are designed to be printed off and used as a paper copy. Probably 95% of mine don't have dimension labels, mainly because they are fairly pointless on a CAD drawing and also because they clutter up the drawing (unless put on a separate layer that's turned off so it's invisible).
  9. JSHarris

    Electric Vehicle Tariffs

    This map shows all the UK nuclear power stations, and most have long runs to population centres, much like those from offshore wind farms:
  10. If you only want to view the .dwg, then it may be that one of the free viewers will do what you need: https://www.autodesk.com/products/dwg/viewers (I've not used them, as I have a copy of AutoCad, but they look as if they may do the job)
  11. JSHarris

    Electric Vehicle Tariffs

    IIRC, some of us here had a lengthy discussion about David MacKay over on the other place several years ago, probably around the time of that video. It was great fun, as one of the combatants in the debate was convinced that the UK could just grow enough miscanthus to provide all the energy we need. At the time I spent a few hours calculating just how much arable land area the UK would need to grow enough sustainable biomass to provide our power needs. Unsurprisingly the result was more land than the UK has. Mind you, the same biomass fanatic refused to accept that you can't get more than about 8% efficiency from biomass (and frankly that's pushing it in the UK). One or two of us were making the point that PV panels are a great deal more efficient at turning sunlight into energy than plants are. The biomass plonker was having none of it, and insisted that growing plants in vertical racks would improve the conversion efficiency. His arguments reminded me of a former colleague, who started an argument one morning, accusing me of speeding on the way to work. He'd been following me, and, according to his logic, because he was driving at the speed limit I must have been speeding, as I was in front of him. Mind you, he was Cornish.
  12. JSHarris

    Electric Vehicle Tariffs

    Much the same would be needed for any form of generation, be it gas, oil nuclear or whatever, or any of the interconnect projects. They all need connection infrastructure, so any new generation solution is going to create similar scars on the landscape.
  13. JSHarris

    Length of time to put services in

    The only main services we have are electricity and telephone. For the electricity supply we already had a big supply cable crossing under our plot, that needed to be moved (it had no right to be there, anyway). I contacted the DNO (SSE) in January for a price to put in the supply and agreed a price with them in March. I paid them in full for the work in April, with an agreed start date for the work of June. After a great deal of hassle they eventually turned out to do the work at the end of August. So. the time from initial contact to getting the temporary supply on site was about 8 months (should have been about 5 to 6 months).
  14. JSHarris

    Electric Vehicle Tariffs

    Depends very much on what happens to the generation market. Right now, renewable generation is significantly cheaper to install than either fossil fuel or nuclear generation, so we're seeing a bit of a boom, even though most of the subsidies have now been removed. Wind generation, in particular, seems to be attracting a fair bit of investment. The reason for that investment is because the return on it is pretty good, and that return comes from the price suppliers are prepared to pay in the wholesale buy-ahead daily auction. Suppliers compete with each other to retail electricity, so there is an inherent commercial pressure to keep the retail price down. What I suspect may happen is that we see a greater range of half hourly and seasonal wholesale prices, as the grid gains a greater percentage of variable renewable generation. The chances are that this will result in significant wholesale price increases during periods at night with little wind, followed by more periods of negative pricing during daytime periods and strong winds. This volatility is likely to then drive a market for energy storage, and as that comes on line we're likely to see the variability even out, with a consequent reduction in the variation of wholesale energy pricing. As that variability reduces, the need for "smart" metering diminishes, too, as "smart" metering is intended to be a way to modify demand, or charge short period variable rate tariffs (which is really the same thing), in order to smooth the peak to trough ratio on the demand side. If I had to predict what we'd see next, then I'd suggest that we'll see a continued growth in renewable generation, combined with a significant growth in energy storage, be that batteries or pumped storage.
  15. Not sure it is, really. There's a farm building conversion a few miles from here that has an EPC of A138. The house is pretty poor thermally, not a lot better than building regs. It gets the very high EPC because two of the attached barns have roofs that are covered in PV panels. IIRC it has something like 30 kWp or so, and somehow that lot got included in the EPC for the converted house.