SteamyTea

All I can really comment on is my own system. I have a 200lt cylinder that is heated on E7. My incoming mains temperature is between 4° and 23°C (spreadsheet needs updating), the mean temperature is 11°C, the cylinder is heated to 50°C. The standing losses are now below 1 kWh/day. I use about 120 lt of hot water a day, but it is at 38°C once in the bath. So that is somewhere around 4.5 kWh/day. This currently costs me 36p/day. Delivery is done though a cheap (£100) twin impeller pump and a very cheap non thermostatically controlled mixer tap (never had small kids in the house, but had a disabled lodger who coped with it fine). The shower delivers 11 lt/min and the bath gets 20 lt/min I really can't complain about the set up at all. In the past there where problems with high losses and a lodger that thought the time to get out the shower was when the water ran cold). Occasionally I have had 4 people in the house, so just up the storage temperature by 15°, which stores another 3.5 kWh. This has always given enough hot water. When I am feeling really tight (and environmentally guilty), I just take short showers (30 lt) and get my usage down to around a kWh/day, plus the 1 kWh/day losses. When the time comes to change the cylinder, and it will come as it is nearly 30 years old now (I live in a very soft water area), I will possibly go for a smaller cylinder and secondary insulate it even better. An instantaneous water heater would reduce the losses (but no gas so would have to be electric) as would a Sunamp (but not to zero). I have thought that an ASHP may reduce the outgoings, as a 6 kWp one could easily recharge a cylinder in 4 hours, but is not really financially worth it. I would be better off fitting a couple of kWp of PV.

PD It is a bit of both from my understanding. You can't have more than a 1% volt drop between the meter (PV) and the CU (but really the main meter, which s usually close). This is more the case for ground mounted systems, or you could get the scenario where the modules, inverter and generation meter are several hundred yards from the load. The generation meter would count every joule being generated, but there could be large losses on the way to the load. It is true that voltage between the systems has to be within limits as well for reliability and safety.

You have to remember that if you intend to claim FiTs (or something in the future), there is a 1% voltage drop allowance (not the usual 5%). This is on the AC (it is to stop the meter showing higher readings than is reaching the CU). As for DC or AC cabling, that all depends on which inverter(s) you go for. If you go for micro-inverters, then you need to think about AC cabling (4mm), if DC to one inverter (somewhere cold), then just conduit for the DC cabling from the roof. It is not unusual to route this outside the building. Shame that you have been refused PP for PV. You could have gone roof integrated , saved some money and made a better looking install.

Don't leave. I am interested in this as to a certain extend I agree that the recommended air changes are low. What do you think we should be aiming for?

A combination of nuclear, large and small scale hydro, solar, wind and tidal, plus some geothermal. Just needs to be deliverable at 3p/kWh (wholesale price). That is the real challenge. In last weeks comic there was a bit about reforming natural gas into hydrogen, but leaving carbon behind, rather than CO2. That looks a promising idea, but does rely on natural gas. So let us frack away, it is going to happen anyway (for those that don't know, my BSc is in Environmental Science, specifically renewables, but I am a pragmatic person).

Abundant, reliable, flexiable and very cheap, non polluting energy sources is one way.

@Ferdinand I read this a year ago when we last discussed this (can't remember if it was on eBuild or GBF). http://www.emptyhomes.com/wp-content/uploads/2011/05/Empty-homes-in-England.pdf Just knowing about housing though is only part of the story. It has to be related to the age distribution in an area. But with around 600,000 (200,000 long term), we can easily house 1.2 to 1.8 million people (2 or 3 people per house). I wish I had more time to look at it again as it is an interesting economic area that needs a lot of unpicking.

The impact of demographics is massive. Yes, in away, bit it is why I said 'about' rather than 'exactly'. Many things have changed the demographics of both population and housing (if you can talk of houses having demographics). There are also more empty properties as a by product of a larger number of properties. We have also split many homes into two or more 'flats'. It is not all about new build. Our old mate Ed Davies, over at the other place, pointed out that each year the UK builds more metres2 new cars than new housing. We don't think of that as the same problem though. Yes, nor should it ever have been. Trouble comes about with local authorities interpreting national policy differently. This was once explained to me by my local MP (Matthew Taylor). He was doing a non partisan talk about energy and why it takes so long for government policy to be acted on 2 to 5 years usually. Was very interesting. Government should create policy based on the best available evidence, then the private sector should develop and then implement it. When I say Passive House, I mean anything of very low energy usage. With the official version of it, is that PassivHaus, don't they specify the energy rating of white goods as well? Which is going to far in my opinion.

I can see the advert now. New Wife Wanted replies You can have mine.

Isn't that like saying heat heat, or energy energy. Don't you mean thermal energy, or low grade energy, high entropy (or is it low, never remember, greater disorder).

Seems the way to go to me. Bit like an ASHP, they need to be oversized for the same reasons. Occasionally you have to 'accelerate' the heat transfer, you can't do that when it is already being driven close to the limit. It does make me think that going back to the old forced air heating systems has some merit to it. Just that now it can do the heating and the ventilation and hot have a huge furnace roaring away in the basement. Usually I think that combine different functions, that work at different times and at different temperatures (think Space heating and DHW) into one 'do it all' unit is a bad thing. But in this case, as they are not so different, I think it could work.

Not having a telly, I did not recognise Robert Llewellyn at first He has changed a bit. Has he had surgery?

Right. Addressing the 'small houses' issue. I live in a small house, 4m by 8m. It has a corridor for a living room, where the stairs are. The parking area is at the back, steps up to the front door. Upstairs the bathroom is wedged between the two bedrooms, one an OK size, the other tiny. Now someone 'designed' this. Technically it is well insulated, airtightness seems reasonable and it costs next to nothing to run (why I bought it as I was a student at the time and it is close to the college). So imaging that you park your car, come in the back door, where is the light switch, oh, other side of the room (kitchen). I have an ordinary sofa, nothing special, but it is too long to put across the living room, it almost hits the stairs, put it along the living room wall and you then have an even narrower corridor. You can put the TV under the stairs, it was 'designed this way' as the TV aerial point is there, but as it was 'designed' before flat screen where in existence, it would have 'stuck out a bit', right by the kitchen door. Now when I live on my own, I can cope with this, but when I had a lodger, the layout just don't work, it really does not. There is no way to get from the bathroom/bedrooms without passing though the corridor/living room. Could it have been improved, yes, if it had been made a bit wider, then the stairs could have been turned 90°. This would have acted as a separator between the front and the back rooms, making rooms truely individual rather than just a corridor. There was enough room on the plot (of 6 houses) to do this. And that is before we get onto the 'social' side of housing. Most individuals need some individual space, the larger the family, the more space they need. Men have sheds, women have kitchens, boys have bedrooms, girls bathrooms. Well it seems that way to me from looking at adverts. My old neighbours where a family of 4, two teenage boys, mother and father. They were crammed into 52.5m2 total internal floor area. This is just not right, but probably not unusual. It cannot be good for mental health to be crammed into such a tiny space. This may account for my current neighbours being a family of 3 (7 year old child), single, single, single, single, family of 3 (baby). Now an 'engineer' or economist, may well say that there is wasted space as there is at least 4 unused bedrooms. But this does mean that we can have friends to stay without putting them up on the sofa in the corridor. Having studied Economics (as well as other things), there is a bit of a myth about Supply and Demand. There are two ways to look at this. One, the normal methods quoted by 'industry experts', says that if there is a shortage of house, the price will be higher. The alternative is that if money is cheap, and it is very cheap at the moment, then the price of housing will be higher. So what have we done in the last 40 years. We have built more housing (there is no shortage of housing, just the distribution is not always right). We have allowed women to have there own mortgages since the late 1970's Hard to believe that they needed a second (male) signatory on the paperwork just 39 years ago. Then, a decade later we removed double tax relieve, pushing up property values and speculation that took nearly 10 years to recover from. Then, though financial manipulation the formula to work out affordability was changed from a simple multiply of of mean wage to median household income (this has, in effect, made more money available as not many people earn zero, but a few earn millions). Coupled to that is the way that banks have changed the method for lending money, they now work on a multiple of total household income, rather than multiple of major income plus minor income. Again this has increased the money supply to the housing sector. So take a simple 'old' method of a man earning £10k and the wife earning £5k, with a multiplier of 3. They could borrow £35k Now they can borrow £45k. This extra £10k (28% increase) is just sucked up by increased property prices, nothing to do with the supply and demand of the housing stock (we still have about half the number of houses as people). There has been no added value anywhere. So what can be done about it. First off, everyone that wants to buy a house should work out what they can realistically afford to pay back, (3 times income is pretty good), then, every Saturday morning, spend an hour going to estate agents and point out that their houses are probably at least twice as expensive as needs be, and probably 4 to 5 times as expensive, and would they tell the sellers that. You will probably get asked to leave the office, but if enough people do it, then the message will get driven home. This is especially true for first time buyers (and for every first time buyer there is a last time seller). The other things we can do is to stop thinking that the country has lack of room for housing. There is plenty of room. Urbanisation has only used up about 9% of the land area, housing is probably less than half of that, including infrastructure. So when a farmer wants to sell an acre of crap land for building, let them, it really won't affect your life. This has to be better than cramming in more and more people into existing towns and cities. This fixation with 'brown field' must stop. Turn a few of them green. I used to live in Buckinghamshire, where my Mother still lives. It is a nice leafy green place, popular with locals, London commuters and media celebrities. It has a population density of 404people/km2. Milton Keynes is a good place to live and work (I lived there and worked there once, better than Aylesbury or High Wycombe I found). Now I live in Cornwall, it has a population density of 150people/km2. So under half the density. Most new developments are opposed here because of pointless, uneducated arguments about overcrowding. We have plenty of space, so much space that we can accommodate 5 million visitors a year, ten times the resident population. Our infrastructure copes, no one gets hurts, all very pleasant in the summer. Last week there was a major accident on the A30, closed both ways as the helicopter had to land. It took me an hour to get the ten miles to work. It usually takes me 15 minutes. What it reminded me off was my old commute to Kingston Upon Thames from Aylesbury. The last ten miles could take an hour. It was just part of life. A time to sit back, relax and plan my day. I cured that problem by leaving earlier and getting to work by 7AM, leaving earlier when I could, only too just over an hour then. It worked well. The point of that is that there is no need to fear extra housing, or building larger houses, it does not affect the price, that is affected by income potential and interest rates. Small housing, at the lower end of the scale, is not good for society as it forces overcrowding and ghettoisation, under out current planning system. Commuting can be good if done right (we are starting to move to an era of lower emission vehicles). So if we start to build slightly larger housing, get rid of housing that is single bedroom because of the inherent restrictions, expand our towns and cities less, move people to the countryside, we can probably reduce overall air pollution, and almost certainly remove very high concentrations of it. This would reduce the need to 'filter out particulates' as much as we need to now, could help rejuvenate rural communities, disperse income and make for a better society. Not much of that has anything to do with the study of MVHR in Passive Houses. That is simple to solve, put in a larger unit with larger vents and ductwork. We really must stop working to minimums.

How do you fill it up? Is there an 'app' for that. https://www.rt.com/viral/362570-briton-wifi-kettle-tea/

Bugger, I have loads to say, but just in from work. I like a good rant.

Would that be 100W peak power? In reality you will get a lot less than that. Just had a look at my local weather station and today the sun has peaked at 157W.m2, currently at 91 W.m2. At those levels you will be lucky to get a usable 10W out of it. So by the time it has been though a charger, a battery, an inverter, you will have just about zero. As you are going for PV anway, you may as well use that as an off set. The 45 W 24/7 or a burst of 1.2 kW (by my thinking about 54 minutes run time) amounts to the same thing. It is the amount of mass that the pump has to shift that is important, not so much the way it does it.

https://www.gov.uk/guidance/waste-exemption-u4-burning-of-waste-as-a-fuel-in-a-small-appliance Just to remind people about burning waste wood.

If the stuff is being used outside, there should really be an RCD fitted, so one safety problem should be removed.

Can I come and watch

I tend to agree with this (not that I have on site experience of the trade). My house is one of the first 6 of their type built in the SW. They showed that there was not any problems with the design, then built thousands of them (they are ugly grey boxes, but I sit in it an look out, not the other way around). I think what the volume builders suffer from is lack of on site build quality control. Details like fitting insulation correctly, plumbing and wiring not to the drawing, fitting MVHR badly, and the big one, fitting windows and doors. The last one may benefit from better detail design to make installation easier, but probably the biggest benefit would be had from not having a pile of 'stuff' not sitting around getting covered in crap. It is hard to motivate a person to do a good job when you supply them with substandard goods to start with. So this comes down to training and management. Two things that the UK seems to have forgotten how to do. I worked in education for a while. I lectured in IT, but the courses were tailored to cover everything from first year plumbers, to Ma courses in Journalism. So I had an interesting spread of people, including a couple of Architects. I would often read the press, and hear on the radio, that the education system was not turning out students that where fit for the workplace. Not once in that time did a company come to me (apart from the NHS and Network Rail who had large budgets to dispose of) willing to pay for a tailored course. I wish they had, as I could have easily done a basic Mathematics and Science course that would allow ordinary people to appreciate what highly educated people where talking about (most science is pretty basic really). One of the problems is, I think (personal experience and a lot of prejudice), that you get some people that will justify a wrong decision and defend it to the end. If that person happens to be articulate (think Boris Johnson), many people are taken in. This is why the real sciences use data. Without it, or if it is not disseminated, society really cannot move on and probably goes backwards in some situations.

I agree with Mike George (I think). All I do is work out the chance and frequency of hitting a dew point condition and use that to calculate a risk. Trouble starts when you take data from one place (say the gap between my roof and the extra insulation on my rafters) and transferring it to someone else roof. They may not have the same orientation, weather or climate. I have a very moderate climate, only two seasons really (my winter is like early spring or late autumn, summer is like a late spring or early autumn) , very strong winds (at any time of year) that hit my house side one, so nip up into my roof nicely. I have higher than normal insolation (for the UK), but in a more spasmodic manner. Higher RH levels but very really cold enough to hit the dew point.

If you can't put a sensible unit on it, the term should not be used, ever. There has been long discussions about this.

I found moving from Hertfordshire to Cornwall improved the air quality in my home. Good only wikipedia has this to say about the fraction of air actually changed: https://en.wikipedia.org/wiki/Air_changes_per_hour I have heard this figure quoted before.

Andrew Bissell, CEO andrew.bissell@sunamp.co.uk 0795 774 8445

Have you read though this? http://www.ebuild.co.uk/topic/17614-sunamp-pv-vs-thermal-store-heat-loss-comparison/