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Everything posted by Jeremy Harris
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Wow !..........so much to learn and so little time !
Jeremy Harris replied to Canoehq's topic in Introduce Yourself
^^^^ Definitely this! Couldn't agree more. We can all give advice based on our own experience and knowledge, but your house must be your own, and meet your needs first and foremost. Our views will be coloured by what we each prefer, and where we are each prepared to make compromises, and that may well be a million miles away from what you're seeking. We're also scattered all over the UK and NI, living in a fair range of different weather patterns, from members up in the Northern Isles and Hebrides who battle with high winds and rain, to those of us like me, down in the South and living at the bottom of a sheltered and very warm valley. All these things will colour the advice we give, even if we try not to let it. -
Wow !..........so much to learn and so little time !
Jeremy Harris replied to Canoehq's topic in Introduce Yourself
I had to fit solar film when we found that solar gain was too high, as have one or two others here. It works, but it's not as effective as solar reflective glass, you can tell there's film on the glass and it was more expensive overall than if we'd have fitted solar reflective glass in the first place. External blinds or shutters can be very neat and effective. Worth designing in, as then they can seem invisible when retracted. One or two here have then fitted, and have described how they look and work in other threads, so might be worth seeking those out. Retrofitting external blinds is possible, but never looks quite as neat. If not done yet, then I think that an early run through SAP would be a great benefit, to see how far off you are from meeting the regs. Having bifolds will make things worse thermally as they will inevitably end up with poor sealing after a while, reducing airtightness and increasing heat loss. Have you considered something that will be significantly better thermally, like lift and slide doors? You can still get large openings, but without all the intrinsic issues that beset bifolds. -
Wow !..........so much to learn and so little time !
Jeremy Harris replied to Canoehq's topic in Introduce Yourself
Welcome. As above, you're going to need to do a massive amount of work to mitigate overheating. Stopping heat getting in is far, far easier than trying to get rid of it once it's in, so I'd suggest making sure that the arrangement of brise soliels you have will be effective for all sun angles, consider using solar reflective glass, or perhaps Sage glass, and look to see if you can fit external blinds or shutters. The latter can be very effective, more effective than probably any other solar gain reduction method. There are lots of threads here on dealing with overheating through glazing, but I don't think we've yet seen a house with that much glass, so your challenges may well be significantly greater. Not sure what you're considering as a heat source, but a heat pump would seem a good candidate, as it could be run in reverse for most of the year to remove heat from the house. Floor cooling using UFH pipes works well, but with the amount of solar gain you're going to get I would consider fitting lots of fan coil units run from chilled water from the heat pump as well. Both these systems could also provide winter heating. Out of interest, how have you managed to meet the requirements of Part L1a with that much glazing? -
Visibility splays across unregistered land
Jeremy Harris replied to edsr's topic in Party Wall & Property Legal Issues
Having access is a big plus, and removes much of the incentive for any of the companies that go around looking to acquire ransom strips, I suspect, as the value just as a visibility splay is a fair bit less than as an access strip, I think. One thing I've just thought of is if there is a requirement that you have to be able to ensure that visibility is maintained over that land. Sometimes LAs have written conditions that require there to be a legal agreement with the landowner to this effect (something along the lines of not allowing anything higher than 1 metre for a distance of X metres in front of a designated visibility splay line). Hard to deal with that if the owner cannot be traced, perhaps, and that may be where some form of insurance might work, perhaps with you undertaking to ensure the area is kept clear in order to satisfy the planners. -
I don't know if you've looked, but there are some simple, and ingenious, hinge arrangements that allow ordinary gates to swing up a sloping drive, like this rising gate hinge: It would be pretty easy to fix an electric opener to such a gate, such as these ones, for example: https://www.easygates.co.uk/electric-gates/automaticgates.asp. Our local farm supplies place stocks rising hinge sets just like the one used in that video. My guess is that they are probably a stock item, as needing a gate to open uphill seems to be a fairly common requirement.
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Visibility splays across unregistered land
Jeremy Harris replied to edsr's topic in Party Wall & Property Legal Issues
Interesting question. If the land has no known owner, or at least none that can be found after a reasonable search, then using it for a visibility splay does present you with some potential issues. I'm assuming that this is a new access, and that you need the visibility splays in order to comply with a condition imposed by highways (yell if that's a wrong assumption). The big risk is that as soon as someone finds out that you must be able to control visibility over that land there is an incentive to trace the owner and acquire it, in order to be able to ransom you for using it as a visibility splay, as the land has gone from having little or no value to potentially a pretty high value (could be worth a fair chunk of the value of your whole plot and build). The best example of this I can recall related to a company that traced the owner and purchased a narrow strip of grass verge in front of a row of houses somewhere near the New Forest (I think) a few years ago. That company demanded tens of thousands of pounds from each householder, decades after the houses had been built, to grant them the right of access over this narrow strip of land. It seems that the company involved are specialists at doing just this sort of thing, and are very adept at tracing ownership and acquiring land in these sort of circumstances. One option is just to go ahead, erect a low fence around the land, keep it tidy and acquire beneficial use of it, in the hope that no one will do anything. In all probability that may work, and if you can show that you've had exclusive beneficial use of it then you can probably claim adverse possession and get to keep it. As to whether you can get insurance to cover this I really don't know. I think you might be best advised to seek legal advice, as whilst you can ensure against most risks, there are definitely things that you cannot insure against, one being unlawful use. If, for any reason, your use of that strip of land was deemed to be unlawful (hard to see how, but I'm not a lawyer) then you may not be able to insure against it being blocked. The other point is whether it's just the visibility splays that would be on unregistered land or whether the access would, too. if so, then that opens up another can of worms, potentially. Being unregistered isn't the same as being not owned, it just means that the owner isn't recorded with the Land Registry. There is still a fair bit of land in the UK that isn't registered, I believe, as usually registration only happens if the land has been sold since registration became compulsory (around 40 or 50 years ago IIRC). We recently had a problem tracing the ownership of a strip of unregistered land in our village, that runs between the stream and a lane. It took well over a year to trace it back to a local estate, that thought that they had sold all of the plots in the village in 1915. For whatever reason this strip was missed out of the estate sale, and today it still belongs to that estate (so they have to pay to keep it tidy and control the weeds etc in the stream). -
I cannot get my head around the current thinking when it comes to preserving and protecting historic buildings. A lot of them were butchered during the Victorian era, and it seems reasonable to keep some element of that in terms of retaining the history of the house through the years, but frankly I find it hard to understand how really poor workmanship from the 1950s and 60's can be defended in the same way. There needs to be room for compromise, so that when someone comes along with a strong committent to preserve and renovate a building, retaining it's intrinsic character, but making it useful, so it can continue to exist for future generations, they are given the support they need by those controlling our heritage. It must be better to retain a slightly modified historic building in good order, than let it collapse and disappear because it's just too difficult to get the necessary consents. Many of our old buildings have been extensively modified and changed, as the needs of those living in them and using them have changed. The second house we bought was a cottage that had been originally built in 1678. with granite rubblestone walls, with very little properly dressed stone (just the corners).It had been rebuilt with solid brick front and rear walls around 1904, following a bad fire in 1903, so looked late Victorian from the front, with sash windows and a timber glazed entrance porch, with Victorian floor tiles. A bedroom had been divided at some time in the 1960's to create a small bathroom, and a single skin brick extension had been added, probably about the same time, to create a separate kitchen. You could still read all these changes in the building, from the clues in the stonework. I changed it further by digging out the ground floor (to install a Radon barrier) lowering the floor in the process to give more headroom. I also insulated a dry lined the single skin kitchen walls, and changed the windows and doors to new timber ones that retained the design of the originals, but were casements, rather than sash (it was a windy area, and the sash windows always made a lot of noise). Looking at the house on Google Earth recently it was still very similar externally to how it had been when we lived there 30 years ago, so the history and look of the building has been retained, by sympathetic repairs and renovation, even though it's not listed. That suggests to me that people who buy older houses like this don't, in the main, want to destroy the very character of the house that attracted them. I would suggest that someone that takes on a listed building is probably even more likely to want to repair and renovate it sympathetically, which is more than can be said for some of the horrors that the Victorians unleashed on our old buildings.
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SAP calculation STROMA alternatives on MAC OS
Jeremy Harris replied to Patrick's topic in Building Regulations
I'm pretty sure I've mentioned this before, but to be clear, although you can do the as-built SAP assessment yourself, the assessors have a "closed shop" where they, and they alone, are the only ones that are able to access the database and lodge the final EPC, using their unique assessor reference number. Without this, there is no way for anyone else to lodge the completed assessment and so get it recognised by BC, or anyone else. It's very like the Part P cartel controlling electrical work in England and Wales. As someone who used to teach apprentice electricians, and was a qualified electrician for a time, I'm perfectly competent to carry out an electrical installation that is compliant with the regs and Part P, but I cannot do this, as unless I was a member of one of the cartels that control access to the Part P database I would not be able to lodge the IEC. The cartels will no longer allow anyone that is retired from being a member, so even if I was prepared to pay their membership fee they still would not allow me in. Worth noting that Terry quickly found an assessor and was sorted within 24 hours of his post on this topic, with two offers of assessors that would do the job for him. -
I'm glad it's not just me that's noticed this. There are only two of us, yet we often find that the thing just doesn't have space inside for the stuff from just a single meal. The biggest single problem seems to me to be poor use of the internal space. The space allotted to cutlery seems large enough for a family of six or eight, yet the space allotted for pans and their lids is barely enough for a household of just two. Spaces for things like cooking utensils are also poorly laid out, and the internal racks seem to be just the wrong size for most of our plates, bowls, pan lids etc. Just changing the layout of the racks would make a significant difference. It would be really great if someone could come up with better designs for these. For example, putting the cutlery rack down one side would free up room in the centre of the lower rack. Removing some of the near-vertical elements from the racks would allow pans to be placed more sensibly, Adding simple open trays to hold cooking utensils would be another good feature to have.
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SAP calculation STROMA alternatives on MAC OS
Jeremy Harris replied to Patrick's topic in Building Regulations
I'm definitely not trying to "suck you in" or anyone else. We're all free to read, or not read, anything, just as we are free to contribute, or not contribute, as we wish. I had genuinely forgotten about the issue Terry had, but it seems there was a resolution a day or two later: where both I and @PeterW gave the details for the assessors we used to try and help Terry out. It doesn't seem to have been a glitch in the software, just a local difficulty caused by assessors in his area being very busy at that time. I did call around two or three assessors, but that had nothing whatsoever to me having done the design stage assessment. I'm pretty sure that never came up with any of them; if it did then I don't remember it, and I'm certain I'd have commented on it as a possible issue, back in 2014 when I had our as-built SAP assessment done. When I rang around to get our as built assessment I'd done what everyone needs to do (or have done by someone on their behalf) I'd prepared a pack that contained all of the data that needed to be inputted into a SAP worksheet (could have been any product at that stage), together with supporting evidence (things like the air test chit, window and door specs from the supplier, etc). What happened was that, whilst on the 'phone to the assessor, when talking about the supporting information that I could email to him, I mentioned that I also had a Stroma file, and that if he also used FSAP, would that help make things easier for him. It was the assessor who said it would, and asked me to send him that initially, and he'd take a look at it and come back to me if he had any questions. I then just repeated my experience, nothing more, nothing less. As our US friends are fond of saying, YMMMV. Perhaps we should make it compulsory that every one giving any information here should always caveat it with YMMV. I've just taken it as read that there is so much regional variation with just about everything associated with self-build, from the way planners work, through to the ways local trades work, and even the way the utilities behave, that it would be very common knowledge that there is a great deal of regional variation in this lark. -
SAP calculation STROMA alternatives on MAC OS
Jeremy Harris replied to Patrick's topic in Building Regulations
I'm unaware of the problem Terry had with the Stroma software, TBH. If I had known of it I'd have highlighted it as a potential gotcha with that software package. Out of interest, what was the glitch he found with it? We're all entitled to our view, and to express that view, be challenged on it, and defend it. Why should I, or anyone else, change our view just because someone disagrees with it? Readers and contributors to this forum are free to take heed of, or ignore, anything here. Not only do I have no control over that process, I most definitely would not wish to. All I will ever do here is put forward ways that people can do things, or research how to do them. If they choose to do the same, then that's their decision. If they choose to ignore it and do something else then that's also their decision. It's just about informed choice, and providing as wide a range of information as possible, from as many contributors as possible, so that people can choose which path they wish to take. -
We used a towed water tanker on site for a few weeks. Easy enough to fill up and tow to the site, and most hire places have them. They aren't usually OK for potable water, though, so to get around the need for that I bought a couple of caravan type water containers (about 20 litres, I think) and filled those up at home and dropped them over to the site for tea and coffee making etc. Worked OK, just a bit of a faff shifting water around for a few weeks. Mains water wasn't a realistic possibility for us anyway, as we're so far from the nearest main. It was a lot cheaper to drill a borehole (but that was itself a long saga).
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SAP calculation STROMA alternatives on MAC OS
Jeremy Harris replied to Patrick's topic in Building Regulations
With respect, I'm an ordinary person, entirely self-taught when it comes to building-related stuff, so I feel perfectly entitled to give my honest opinion as to what can be done by someone who wishes to take the time to research and learn. I fully understand that some may not want to do this, and may prefer to just stay in the dark, consider this stuff to be something beyond them, and pay to have it done for them. That's fine, that's their choice, but if we don't at least make it clear that there are ways to do stuff yourself, rather than pay someone to do it for you, then what use is a self-build forum? We may as well just become a review site, sharing recommendations for professionals to hire. In the case of a SAP assessment, all of the data the assessor uses comes from the self-builder anyway. If you hire an assessor they will not ever visit the house to see what was used in its construction, they will take your word for everything. I cannot see the difference between sending a set of drawings, together with fabric build up schedules, an air test report, specs for the MVHR, hot water system, heating system, controls, glazing etc to an assessor and putting that same data into an application yourself as a backstop check that the design meets your own expectations. I refuse point blank to stop suggesting ways where people can do relatively straight forward jobs themselves. I believe that the more people know and understand about their projects the better equipped they will be to make sound judgements, and if some disagree with that ethos then they are free to just ignore it, aren't they? By the same token, if someone just wants to pay professionals to do the whole of their build, then that's fine. There are just as many pitfalls from taking that approach though, as some here will probably attest ( @lizzie springs to mind with the problems she experienced with using a professional project manager, professional (and expensive) window supplier, professional (and expensive) MVHR installation, to name just a few). -
SAP calculation STROMA alternatives on MAC OS
Jeremy Harris replied to Patrick's topic in Building Regulations
We had no problem doing this. I used the free version of the Stroma FSAP software to check the design and produce the design stage assessment, and I just updated this to reflect the as-built changes and emailed the file to an assessor who checked my work, produced the as-built assessment, lodged it on the database etc. The fee for the as-built only work was modest, about £100 plus VAT. There's no requirement for an assessor to do the design stage assessment, I get the feeling from chatting to BC that it's primarily a sensible check done at the start to be confident that the design meets or exceeds the requirements, so really an assurance tool (albeit a very important one). Nothing happens to the design stage assessment, it doesn't get filed or lodged on a database anywhere, as fas as I'm aware. It's only the as-built assessment that has to be done by a registered assessor and lodged on the database as a record of the performance of the house when it was completed. The big advantage of doing the design stage assessment yourself is that you get to learn a fair bit about how SAP works, what makes a significant difference to the outcome, and what doesn't have much impact. That makes it a really worthwhile exercise, as it's usually relatively painless to change a few things at the design stage, whereas that may not be the case later on in the build. -
SAP calculation STROMA alternatives on MAC OS
Jeremy Harris replied to Patrick's topic in Building Regulations
Point of principle, really, at least as far as I'm concerned. In my case, it has little to do with whether it's cheaper to get someone else to do something, it has everything to do with the view that was embedded into me when I was a small boy: "Never pay anyone to do something that you can learn to do yourself" One of the greatest failings in our society is that we are gradually losing the confidence to do things that we are perfectly capable of doing, with a little bit of effort and application. Self-build is a perfect opportunity for those that wish, to spend some time learning and perfecting new skills. There isn't much in life so rewarding as looking back at something and knowing that it was your own efforts that made it happen. There's nowhere near the same sense of achievement from just paying someone else to do something. -
SAP calculation STROMA alternatives on MAC OS
Jeremy Harris replied to Patrick's topic in Building Regulations
I'll have a dig around, as when I first started looking at this, years ago now, I took the BRE worksheet and translated it to an Excel worksheet. Not anywhere near as easy to use, and it doesn't do any self-checking for valid values, plus it would have the figures in for a much older version of SAP, but I may still have it somewhere. Might take me some time to find it though, as it's around ten years old, so probably archived away from about three machines ago. I'll leave myself a note on my desk to see if I can find it and update it, and get back to you. Alternatively, I think that BRE may still have the basic worksheet somewhere on their site, and you can take that and just convert it to run in whatever spreadsheet package you're most comfortable with. -
The whole listed building thing needs an overhaul, IMHO. a few years ago now, near where we used to live, there was a lovely old barn, that was falling into disrepair. Like many old barns, it wasn't suited to modern farming practice, yet was listed, so there was nothing the farmer could really do about it. He tried a few times to get listed building consent for change of use, to light industrial and domestic, but failed. In the end he just let it fall down. He was then fined for allowing it to fall into disrepair, but went on the offensive in the local paper, pointing out that he'd tried to save it three times, and each time he'd been turned down. His final line was that the £2000 fine he received was excellent value, as he'd spent far more than that trying to get consent to restore the barn for some useful purpose. My in-laws used to live in a listed town house in Chichester, and they quickly learned just how expensive and difficult it was to do many jobs that most would take for granted. In their case, one of the really absurd conditions was that a very large, 1960's single pane window (literally the size of a show window) on the first floor, at the rear, couldn't be replaced with smaller paned windows in keeping with those in the rest of the house. Apparently the big window had been fitted before the building was listed, as a means to get the piano into that room. They were quite happy to get rid of the piano (it came with the house, as it needed a crane to get it in or out) and wanted to replace the window with something more like that which had originally been there, before it was butchered in the 1960's. Sadly this proved to be a hurdle to high to jump, so the house was sold complete with the piano and the ghastly big window.
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Accessible House Questions
Jeremy Harris replied to Ferdinand's topic in General Self Build & DIY Discussion
Exactly what I found with the toilet I moved over to the left a bit. I just explained to the building inspector the reason, showed him the notes covering all the suggested changes to the house that my mate had drawn up, and he was more than happy to allow it. Not even a hint of an objection from him. My experience was that most building inspectors seemed to be well-endowed with common sense, and were happy to take a pragmatic view of something that met the need spelled out in the regs, even if it didn't meet the letter of the suggested means of compliance in the approved documents. And, FWIW, As a trained professional, I have no hatred at all towards anyone, be they trained professional or not. -
Accessible House Questions
Jeremy Harris replied to Ferdinand's topic in General Self Build & DIY Discussion
My friend reminded me that sometimes really small changes, that would seem to be of no consequence to an able bodied person, can make all the difference between being able to access an area or not. A point in question was that issue of the spacing of the toilet away from the wall. Building regs requires that the side of an accessible toilet, with oblique access, must be at least 400mm from the centreline of the toilet to the nearest wall. I moved ours over by 50mm, as that then makes all the difference between being easily able to use the adjacent wall for support well and not. Seems a small change, just 50mm, but as my friend said at the time, small changes make a huge difference, not just physically, but also in terms of confidence. Accessibility is as much about the person feeling secure through any manoeuvre as it is about providing enough space, handholds etc. Steve's classic demonstration of that is in the pub. He will don leg irons, lock them at the knee, and use crutches to get around and stand at the bar, His reason for doing this is entirely practical, even though it's a bit uncomfortable. Standing on leg irons at the bar people don't accidentally spill beer over him, something that apparently happens all the time if he stays sat in his chair. His perennial joke is that he's the only one of us who won't fall over when pissed, as he's had decades to get used to being legless... -
Accessible House Questions
Jeremy Harris replied to Ferdinand's topic in General Self Build & DIY Discussion
I agree, it is a heck of a challenge, but the alternative is that sometimes the less able will just impose loads on items that were just never designed to take them. I'll admit to an interest in this, as my late father was a wheelchair user for the last decade of his life, and converting our 1930's built house so that he had a degree of independence was a nightmare. Even the doorways all presented significant challenges, being too narrow for a standard width wheelchair. I also have a paraplegic friend, who visits fairly regularly, so I did ask his advice as to what would make things easier. The changes I designed in that made the most difference were making all the doors 33" wide, having dead flat level thresholds everywhere in the house (also makes cleaning easier), and providing wide turning spaces, so it's easy to just twizzle a chair around where needed. Some minor changes were to breach building regs in the downstairs WC, as if we'd put the loo the specified minimum distance from the wall it would have made a wheelchair transfer harder (I explained this to our building inspector, with a note from Steve, our expert in the day to day use of this stuff and he accepted it) Apparently it's easier if the loo is a bit closer to the non-transfer side wall, as that helps by being able to be leant against. I changed the way some doors open on Steve's advice, to make it easier for a wheelchair user to grab the handle and open the door, without the door then partly blocking access. The other main change was increasing the size of the 90deg wheelchair turning space outside the back door, at the top of the gentle access ramp. The larger this level turning area can be the better, apparently, as one issue is that wheelchair users may like to be independent, but they inevitably find that able bodied people "hover" around, taking up space where they need to manoeuvre. Finally, thinking ahead to the future, I included sections of 1" thick plywood in the stud wall up behind the plasterboard alongside the stairs, to allow the easy attachment of a stair lift. I also made sure there was more space than really needed at the base of the stairs, so the lift rail and seat can extend well beyond the base of the stairs and remain out of the way. There's also a power point there, in the form of a fused outlet, for a stair lift power connection. One thing I didn't do, and wish I had, was pay more attention to task lighting. There are areas where a little more light would make things easier. I'm finding that as I get older and need to use reading glasses from time to time, I also need a bit more light to see thing close up more clearly. I've already increased the brightness of the LED strip lighting under the kitchen wall units, and need to do something similar in the bathrooms, and above my desk. -
My experience was that nothing was sent by any third party to BC directly, with the exception of the Part P installation certificate that was lodged on the database that BC can access and the final as-built EPC which was similarly lodged on the database that BC can access. Everything else came through me, and was forwarded on by me to BC if needed. No structural calcs were sent to BC at all.
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Accessible House Questions
Jeremy Harris replied to Ferdinand's topic in General Self Build & DIY Discussion
One thing I thing would be useful would be to have a neat and inconspicuous way to turn the glass edge of a shower panel into a grab handle. The same goes for the edge of washbasins, it has to be fairly easy to just slightly alter the edge profile and improve the strength of the washbasin fixing, so they do double duty as grab handles. Ken McCloud touched on the poor design of disabled living aids on this weeks Grand Designs. He went so far as to try getting around in a wheelchair to see some of the challenges it posed. He was also pretty disparaging of some of the stuff specifically made for the purpose, that would look more at home in an institution than a home. Not sure I'd trust him to come up with better designs, but it might have got a few other people thinking about this. With building regs changing to try and make homes more future proof, it seems only logical to extend this to the design of multifunctional every day items. -
TIDAL RISE +FALL GENERATION
Jeremy Harris replied to scottishjohn's topic in General Alternative Energy Issues
He went to the same school as my youngest brother. -
That's without any foundation in fact, I think you've decided to just makes stuff up for reasons best known to yourself. Not the first time you're made grossly false assumptions about me, or my motives, either, it's getting to be a habit of yours, for reasons I'm wholly unaware of. I've nothing against anyone, least of all architects, and have written here, several times, that I felt that having an architect's input into our design would have been helpful. I have always done precisely the opposite of placing "blind faith in delegated responsibility". I resigned as head of UK marine radio, radar and nav aid type approval on a point of principle over this very aspect of the way EU regulation was changing the way that critical equipment approval was being allowed with no proper independent inspection. I do accept that this is the way that things work though, much as I may despair of it as a process. I described the process I used, in good faith. It was valid, accepted and fell well within the rules under which building control bodies are required to operate. I checked carefully to make sure that what I was submitting was most probably what was needed, and have shared everything, warts and all, in the hope that it may be of use to others. I provided no guarantee that what I did was a universal panacea, just put it forward that it is perfectly possible for someone with zero experience of the system to do some homework on what is required and manage it themselves, so saving some money, if they wish. Ultimately, this is a "self-build" forum, with an inherent implication in that term that "self" means doing stuff oneself. I very strongly believe that we should encourage people to do as much work themselves as they feel comfortable with, and provide information to help them make a choice as to which approach to take when facing any particular challenge. I am not going to sit here and suggest that someone must always use a professional service for everything, when I know full well that there are plenty of tasks that can be done on a DIY basis if the person is prepared to learn new skills and apply them.
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TIDAL RISE +FALL GENERATION
Jeremy Harris replied to scottishjohn's topic in General Alternative Energy Issues
Depends on time. A mouse might be able to muster enough power to move this mass over a few lifetimes, an elephant would do it a lot quicker, as it's more powerful. If we assume that there is 12 hours to lift the 5,000 tonne mass 8 m, and that the rate of lift is constant (it won't be for a tide, but this keeps things simpler) then the potential energy needed to achieve this is given by Work done = 5,000,000 kg * 9.80665 m/s² * 8m = 392,266,000 J Power over that 12 hour period = 392,266,000 J / (12 * 60 * 60) = 9,080.23 W So very roughly, ignoring efficiency, the potential energy is about 392.266 MJ and the power over 12 hours would be about 9.08 kW. Allowing for 70% efficiency, the mean power generated would be around 6.356 kW.
