Rotating, driveable house

It’s a house Jim but not as we know it

Planners usually allow you to build a pod within the curtilage of your house. This one follows the rules but it comes on wheels. So what’s the point of that? Well for a start there are no foundations to worry about, just a bit of hardstanding will do. Then there is the ability to drive it; 6 powered wheel units (electric or hydraulic) enable you to go for a trundle, down to the pond to watch the sunset for example. Steering is done from the glazed conservatory at the front or from outside.

With the wheels steered inwards the whole house can rotate on its axis to track the sun, making full use of the 6kW photovoltaic array. So yes, it’s all off grid and only needs to dock occasionally to empty some tanks and to refill others.

Is it worth all the bother? Absolutely, for rental to eco enthusiasts this is a thrilling bit of kit. Imagine their delight when their pod comes round the corner to pick them up and take them to some lovely spot – all filmed from various points to give them a memento of an amazing experience. You can charge a lot more for that than if you were just offering a shed.

sun tracking solar panels

If you want to use this on your piece of land you might put a 3-point hitch on the back and call it a tractor – great to sit in a comfy chair while you mow the lawn!

N.B. Based on the rules and with proper panel dimensions this is a preliminary sketch to see what it might look like. The wheels could be a bit chunkier.

The space invaders look is intentional.

 

 

 

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Grid Parity – PV goes mainstream

Grid Parity – we’re there – sort of.

Grid parity for Photovoltaics – when PV panels make electricity as cheaply as the grid does. It was inevitable that the lines for falling panel prices and rising energy costs would cross and grow wider apart from then on. On the production side this was reached a while ago; renewables beat power stations. For domestic consumption my definition of real grid parity is when it pays to borrow the money to buy the kit that replaces the mains supply. Well we are there now and the implications of this seemingly innocuous bit of news are profound; we are entering the era when it actually makes sense for some people to ditch their main supplier and go off-grid. The off-grid scene is no longer the province of hippies and eco warriors, it is now yours.

Last year grid parity still looked a way off but there’s been a change. Panel prices have fallen to a level in line with the second hand ones I was on about last year, £105 for 275W for example. And the big event is the arrival of a price busting bit of control electronics.

5kW inverter/charger

All In One Outback Inverter MPPT SPC III combined charge controller and inverter. This controls the charging of the batteries and supplies 240v ac in a computer friendly sine wave. The 5kW version comes in at around £1,000 and enables Bimble solar to offer a full off-grid kit for £4,533.50 with batteries and 14 275W panels (3.85kWp). N.B. Note the rather low input power. While we recently featured a quite useable 1.2kW system, which runs lights and a fridge and the odd extra, this 5kW one will at least spin up some home appliances but compared to the mains its utility is a bit light weight.

Of course parity depends on the price of the electricity being replaced and whether the PV electricity generated is used. Surplus power can be routed to an immersion heater, car charging or aircon so it is possible to have a system where every Watt is banked.

So. Starting with a £5,000 investment for the kit. Sainsburys Bank wants £91.05 a month for 5 years to pay it off. After 5 years you should enjoy free power for another 15 years or so and freedom from rising prices too. This apparent no brainer deal is tempered slightly by the fact that after every 7 – 10 years the batteries will need replacing; the ones on our sample kit from Bimble cost almost £1,000. That sounds a lot although £12 a month put aside has it covered.

 Italy

In expensive but sunny Italy, where a Kw hour costs a third of a Euro, our 14 panels should generate 4,355Kw hours or about €120 worth a month. So yes, in Italy, grid parity has arrived and freedom from price rises for many years will make this a sound decision; no more complicated bills and compulsory TV licence either.  Anyone building a new house or renovating should give off-grid serious consideration from the start. This is mainly suitable for ex-pats not paying tax in Italy; tax payers should still check out the grid connected route now that there are substantial price falls in panel prices.

 

England

Back in cloudy England our panels will be less punchy and electricity only costs about 14p per kW.hr. The chances are that after 5 years you would still be out of pocket by about half the investment and needing another 4 or 5 years to break even, and there will have been a £1,000 battery hit too. Even so, that leaves another 10 years or so of free electricity and with prices likely to have doubled by then this isn’t at all a wrong move. So yes, grid-parity is here but not the hugely compelling no-brainer that will start a mass exodus from the grid.

 

Grid connected system

Almost shocking price falls make a grid connected system worth a look. The kit does away with batteries and charge controllers; just panels (say 14 at £105) and an inverter (4.2Kw Growatt Inverter 4200 MTL-S Dual MPPT £515). So £1,985 plus fitting gives a chunky (but day time only) power source which, according to The Energy Saving Trust, will give annual benefits of £370. Sainsburys want £70 a month for a £2,500 loan which is too expensive (24% apr) so you’d need to look around or use your own money for a tax free return of 14% for 20 years. Your capital is sunk but even so this is a good return and ahead of grid parity.

If on-grid takes your fancy then you need to call your local MCS approved suppliers to see if you can get registered before 31st March 2019 when the FITs scheme ends.

Now that the lines have crossed, PV deals of all sorts can only become better as time rolls on – watch this space. Note that off-grid systems are surprisingly simple and fairly DIYable whereas on grid systems need a certified expert to install.

PV – overclocking

You can improve the performance of computer chips by overclocking them and, although there is no particular similarity, the same name is used for overpowered PV systems.

Usually charge controllers and/or inverters match the input power of the panels, but as most of the time the panels do not make their full power it pays to have a bigger array – maybe 30% bigger, say a 6kW system with an 8kW array. On those rare sunny full-power moments the electronics will limit the excess input power by what is known as clipping. Most of the time though the system runs in the more efficient part of the power curve turning bad production days into something useful.

A further tweak that really suits overclocking is to tilt up the panels to a winter biased angle. Panels look at the sky and overall light levels so 45 degrees is a good winter angle. This tilt fattens the shoulder months and tempers the power in the summer where the peaks would be clipped anyway.

So the overclock and tilt concept gives much better utility at the expense of overall production but this doesn’t matter where there is no FITs return to consider.

PV overclock and tilt

Dotted red line – where clipping tends to limit production; not a straight line in practice.

Blue line. kW.hrs per month produced by a 6kW array with a 20 degree tilt – no clipping.

Grey dotted line. 8kW array still at 20 degrees – not a great winter gain, high summer clipping.

Red line. 8kW array at 45 degrees – big winter gain, minimal summer clipping.

Note the significantly wider shoulder months and winter production almost doubled.

N.B. Tracking panels grab morning and evening rays so they absolutely love overclocking.

The sun tracking garage loves overclocking.

 

 

 

Solar thermal panels – a bad week?

Our overclocked array almost certainly knocks out the viability of solar thermal panels ( the wet ones with fluid pumped round.) A few more PV panels now have a similar cost to a full solar thermal set up. In winter, when we need to finesse all our kit, the wet panels are often connected to a hot tank so they don’t even run at all. Meanwhile PV panels will still be involved in the plot by running a heat pump (output 3 x input) or an immersion heater. PV plus heat pump is the future. In the summer the PV panels will be over producing so there is no need for another system.

The only way to justify wet panels could be to run my ‘solar stripper circuit’ as on the eco- heating system here. I’ve been running this circuit for years and it is wonderful to see the solar panels running almost every day of the year even when paired with the log burner.

Wood burning stoves – a bad week?

The Government Clean Air Strategy had some bad things to say about stoves and they were right. A stove running cool and with wet wood will emit a lot of smoke with particulates to match a diesel truck. However – properly designed stoves, running hot and burning dry wood, are so much better; the stoves I supply can even be used in London.

Trees are generally good for the environment but when they die or are used for some purpose there will inevitably be wood to be disposed of. If left to rot there will be no particulate emissions but there will be no return for the grower and less incentive to plant more. Any clampdown on stoves could lead to less tree planting and wood going onto bonfires – both disasters. As open fires, both outside and in the home, generate huge amounts of particulates it looks as though stoves are actually the answer, with all that lovely heat and light helping to keep the air clean.

I know that the open hearth is still a popular feature but this particulates argument adds another reason to upgrade to a stove. The other reasons being that open fires burn about 5 times as much wood for the same heat and when it gets really cold the replacement air can make an open fire go negatively efficient. Air conditioning in winter!

That’s all for now. If you need advice, a stove or a heat bank in UK, France or Italy please contact me.

Heating News – December 2018 – Zombie Apocalypse Edition

Heating News December 2018

Zombie Apocalypse edition.

We’ve covered the heating of old farmhouses so much already that if you are not in a house that is warm, cosy and cheap to run then you haven’t been paying attention. What about the Zombie Apocalypse though? If there is a power cut, all heat pumps, gas and oil boilers and most PV systems don’t work so a wood burner will be handy when the grid gets hacked, whether by Zombies, Russians or just bad weather. Connected to a heat bank that wood burner will provide heat, cooking, functioning radiators so not just a nice thing to have but maybe even a life saver.

But enough about that. Not everyone has a leaky old house with a siphon attached to their wallet. The other end of the spectrum – a Passivhaus – is pretty astonishing with heat losses so low that just by turning on the lights, TV and computer would pretty much cover the heating needs.

 

insulation matters

This diagram shows how energy demand falls as insulation values rise. The Passivhaus demands are so low that heating is hardly needed. It’s not just running costs that are trivialised. The actual build costs are reduced because there is no need for under-floor heating and no powerful heat sources to drive it. Usually a small heat pump using no more power than an electric kettle will be more than adequate.  This is offset by the cost of extra insulation but the savings are there forever and the Government RHI will pay for the heat pump too.

So what is a Passivhaus?

It’s all about insulation and airtightness. Insulation of walls floor and roof have to be slightly better than current UK regs, but not by that much, and the building must be a bit more airtight than usual but again not by that much. Heat loss is measured by U values (which we’ll examine below) and airtightness is measured in air changes per hour. Basically a fan blows up the pressure to 50Pa for a maximum of 0.6 air changes per hour and then the same again but with a negative pressure. A Pascal is the pressure of one Newton/sq metre so a bit like a minced apple spread across your desk.  50Pa is very low so with careful building and lots of tape the standard is achievable. Sealed doors and windows will close with more of a ‘schmwuk’ noise than a clunk and the house will probably feature triple glazed windows and mechanical ventilation with heat recovery MVHR. Passivhaus gradings relate to how much renewable energy they give back so for the top tier ‘Super’ the roof will be heavily covered by solar panels to make 120kW/m2/annum (footprint). The overall target U value for a Passivhaus is 0.15W/m2K so lets see how that compares with traditional practices.

U-Values

This value relates to the ability to flow heat energy across a surface so it is measured in Watts per square metre and takes into account the temperature difference across the surface, so W/m2K. So a Passivhaus with an external shell of 800m2 and U=0.15 would need 1.2kW when the outside temperature is 10 degrees colder. This ties closely to the Passivhaus limit of 15kW.hr/m2/annum (on the footprint) for total energy consumption.

Traditional practice U values  W/m2.K

Brick wall                          2

Cavity wall                        1.5      Note: this is 10 times worse than the example above

Insulated cavity wall      0.18

Concrete                             1.5

Single glazed                    4.8 – 5.8

Double glazed                  1.2 – 3.7

Triple glazed                     < 1

Wooden door                    3

Note that some popular modern building methods are not really up to scratch and need extra insulation to get towards Passivhaus. Eg Durisol insulated concrete forms 0.15    Structurally insulated panels 0.14. Adding extra layers of insulation is needed and to get the final U value you add the reciprocals of the U values of the layers then take the reciprocal of that for the final figure.

Current SAP rules

Wall      0.18

Floor   0.13

Roof    0.13

Glass   1.4

No doubt you have noted that glass is a five lane highway for heat loss especially on the North side of the house. South facing glass is different because it behaves just like a solar panel and gives back much more than it loses. For example the daily solar insolation average in Kw.hrs per square metre (Brighton) is: Nov 1.7, Dec 1.14, Jan 1.43, Feb 2.17. The obvious conclusion is that lots of south facing glass is often good enough to heat the house especially if accompanied with high thermal mass floors/walls and covered at night with shutters and curtains.

Now we have a house that barely needs heating and sells power to the grid but there will be days when some heat is required. The bills here are going to be so low that the choice matters less, but for a small house I’d go for a low powered heat pump because:

Heat pump power

The RHI payments are good, it’s ecologically sound, it runs on similar power to an electric kettle and the PV panels will run it free on most days.  Air conditioning can be incorporated when partnered with fan-coil units. N.B. There is no RHI for aircon enabled heat pumps so a separate chiller unit would be required.

What about a wood burner? – well of course, we love them and there is the Zombie Apocalypse looming.

DIY fan-coil unit

DIY fan-coil unit

No underfloor heating, no radiators, it has to be fan-coil units. There is a full description of the Original Twist version here.

It’s a cheap and easy DIY project.

 

1st year with Google Home and Chromecast

Verdict: So good we have 3. Main uses, TV control, intercom, encyclopedia, alarm.

Radio? They’re obsolete

Remember when a DAB radio with preset buttons was a Christmas present favourite? Well those days, in a flash, have gone. A Google Home will tune in practically any radio station; all you have to do is ask. Turn up the volume? “Hey Google, turn up the volume”  “Hey Google set an alarm” So it’s a radio but, of course, so much more with your Spotify playlists to hand, and via Chromecast, control of the TV, Netflix, YouTube … etc … but you know all that. It’s just fascinating how as an almost inconsequential aside this device has consigned an ubiquitous bit of kit to history. Will the next generations even know what a radio is.

That’s all for now. If you need advice, a stove or a heatbank in UK, France or Italy please contact me on the form below.

DIY fan-coil heater

DIY fan-coil unit

Fan-coil unit

You might be surprised to know that if your house build is anywhere near Passivhaus standards then minimal heat demand makes underfloor heating a waste of time and money. Well, that’s a big saving so bring it on but what to do instead?

Underfloor heating did away with horrible radiators, and we don’t want them back, so that just leaves warm air blowers such as kickplate heaters – i.e. water powered puffer heaters.

On the walls without plaster theme here I proposed a kickplate heater, in the lower cupboard part, to give an occasional guff of hot air and for slightly under £200 you can do just that. However these neat little units aren’t perfect. They have to shift a lot of air through a small aperture so they are intrinsically noisy, draughty and the heat exchanger, or a filter, can clog with dust and pet hair fairly quickly. Larger versions are available but they aren’t so neat and they are much more expensive.

So here’s the Original Twist alternative which is cheaper, quieter and more reliable.

cupboards with fan-coil unit

Lets assume that the low cupboard bit of your wall is made of typical 720mm x 300mm kitchen carcass units. A pair of them 600mm wide with a large slot cut out of the inner sides allows a 1000mm x 500mm x 70mm double radiator to fit inside (£48.14 Screwfix). Each of the top shelves is fitted just low enough to mount a 140mm fan from a computer (£10 – 20 Amazon etc) and these gently blow air past the radiator and out of the bottom. You can decide where the air inlet goes: probably top front but a wall panel channeling much warmer air from ceiling height is worth a thought.

This unit also does air conditioning when paired with a suitable heat pump hence the length of plastic guttering under the radiator to catch any condensation. N.B. The Renewable Heat Incentive does not support heat pumps with integrated aircon but you can still get it if you use a separate chiller unit.

You might want to kill airborne pathogens. There is plenty of space in the box for a pair of UV lamps but if you do fit them then avoid or wrap PEX water pipes because UV will kill them too. Fitting UV tubes in the top sections with the fans underneath is the way to go.

Controls:  The fans are switched on automatically when either hot or chilled water arrives at the radiator. An ESCO solar controller does all that for £45.50 or about half that with a frost stat and a 2 pole thermostat. You’ll also need a variable resistor for speed control. The fans are 12v so you’ll need a power supply and, like the fans, these are cheap PC components. Remember that the LED strip lights in your integrated beam floor could be 12V and might like to share that power supply.

And that’s it really. A few simple components all easily obtained and making the perfect, reliable fan-coil unit. When turned down to essentially silent the fan pair will move about 100cfm and the heat output will be between 1 and 2kW depending on the water supply temperature.

You might wonder why all this effort gives you anything better than the radiator fitted as normal. The answer is that heat pumps don’t work efficiently at the 60c normally used with radiators. While under-floor heating is the best at low temperatures a fan-coil unit works reasonably well at 40c. The only reason our unit has a radiator is that with all the fins in a double radiator you get a high surface area for not much money. The heat delivery couldn’t be more different. A radiator wafts hot air straight up to the ceiling where it tends to remain – with replacement  air moving across the floor as a cold draught. A fan-coil on the other hand, blows warm air across the floor where it mixes with cooler air in the room and gives a faster and more comfortable heating experience.

insulation matters

Have a look at this chart on heating costs for various house types to appreciate why a Passivhaus with a small heat pump and some fan-coil units could be the way to go. You’ll see that the ASHP can meet the Passivhaus demand for almost no cost. Indeed if the ASHP is connected to PV panels then the running cost of the house will be close to zero if not better.

 

 

 

I guess you might be in a state of shock now. Thousands saved on your heating strategy, the government is going to buy you a heat pump and air-conditioning can be a simple addition.

For more money saving shocks check out more building ideas on LIST OF POSTS.

 

 

Kenya – Turi reunion

Kenya reunion
December 5th 2018 – Wednesday
12pm  pub, Chelsea

Kenya watu at the Surprise

Well that was fun – Please get in touch for the next one, maybe next Summer.

Were you at school in Kenya circa 1955 – 1965?  Turi maybe. Come and meet some old friends next time.
Where are you?    Susan Casson, Gill Neville,  Arthur and Alice Brown, Simon Jefferson, Geoffrey Peatling, Gail Nichols, Pippa and Fiona Mills, Charlotte Gaitskell, Paul Skinner, John Sutton, Timothy Upton, Janet Lloyd, Robbie Godkin, Elspeth McPherson, Richard Lowenstein, Liz Phelips, Johnnie Sherwood, Jane Faber, Alan Riley, Fraser Roberts, Belinda Foxon, Susan Kennedy.
Let me know if you can come .. contact form below.
Salaamu
Patrick Littlehales

Silent gaming PC

Silent gaming PC by Original Twist

silent PC heat sinks

What a great time to build a gaming PC. The Intel core i5 8400 presents the sweet spot in terms of performance for money and as it has to have a new motherboard the Gigabyte Z370N WiFi Mini-ITX is a great, and near compulsory, match. The board even has two M.2 slots so you can have SSDs without the untidy wiring.  Near to the previous core i7 performance for less heat (and less money), the 65W CPU is even easier to cool with heat pipes.

You might remember the Original Twist silent PC and now this is a gaming upgrade with more space and probably the biggest heatsink tally on the planet.

As before, the corner extrusions are ‘off the shelf’ aluminium extrusions as are the heatsinks where the supplier offers a CNC machining facility for the 6mm heat pipe channels.

fanless pc assembly

This section across the lower half shows a Mini-ITX board, HDPLEX 300W AC-DC and GTX 1060 GPU in position with plenty of room to spare. The heat pipes from the core i5 go above on the same heat sink, same for the GTX 1060 although it could use the space in the centre extrusion for its pipes. With CNC machining it is just as easy to have splayed channels as parallel ones so bending and fitting the pipes will be easier than usual.

 

The case is like a tall chimney so there will be good airflow across all components, a clear advantage over flat cases with horizontally aligned motherboards. The vertical alignment of the heatpipes gives optimal performance; around twice as good as horizontal ones. By sticking the tails of these pipes slightly below the CPU block there will be more water running back down the pipes – another performance tweak which takes the potential capacity to over 100W.

9 pipe CPU block

Heavy duty gamers and clockers will scoff at 100W so just for them ….. a 9 pipe copper CPU block with the pipes running up into back to back heatsinks. i.e. the pipes are clamped between an additional section of heat sink inside the case. So, 9 long pipes running vertically to doubled up heatsinks and the chimney effect even stronger. Actually there’s easily enough room on the heatsinks to fit 11 pipes from a 6 + 5 CPU block – how much power have you got?

The corner extrusions are ready for m6 screws to hold on the open top and bottom plates and the feet, which could be rubber doorstops (well why not?)  The perspex side cover over all the connections can be laser cut once the pattern is fixed and that job can be subbed out quite cheaply.

Fancy building one? Fancy buying one? Register your interest below – opportunity knocks.

More on this topic in LIST OF POSTS

Cool fireplace design

On the theme of substituting alternative wall finishes for plaster here is a large brick fireplace that looks absolutely stunning with a wood burning stove and adds a bit of ‘wow’ to any room. Shown here, part finished, the brick construction is a structural part of the house with the essential offset from the main wall allowing the exposed brick to be part of the room behind. You were going to build a wall anyway so here a little bit of thought yields an expensive looking fireplace doubling up with a characterful wall on the other side.

Perfect fireplace for a wood burner.

A few dimensional suggestions: The front buttresses are 225mm or one brick wide and thus the wood sections are 225mm square. The width between buttresses of 1.6m gives room for logs to be stacked by the stove and the 1.5m height between the floor and the main cross beam works well.

fun with the band saw

The Zampi (Italian: paws) profiles go like this:

Draw a centre line, mark the radius from the corner, draw a 30 degree angle from the corner, the big curve follows from the centre line intersection.

Double click for a closer look.

 

 

You might be going to use a flexible flue and this will need supporting above the stove. A steel ladder frame that can be slid forward and back a bit will make lining up the stack and the stove really easy. Between this and the stove fit a removable flue section to make cleaning easy.

A big stove like the 14kW Clearview shown here is best connected to water or it will make the room far too hot. To get a simple gravity feed put your tank on the other side of the wall and inside an airing cupboard. That’s another lot of plastering avoided and the core of your heating system done. BTW – I’m happy to advise on tanks and stoves and to supply them too. There’s a contact form below.

P.S. Here is a 2m wide version drawn with the non plastered wall theme – i.e.with low cupboards that can incorporate the DIY fan-coil heater.

Inglenook fireplace

Like what you’ve read? Find more essential reading on my e-book

‘Dream House – Down To The Details’ 101 things you should have thought of.

Heating for your eco-house

For more straight thinking, this time on heating, have a look at the ultimate Eco heating system which integrates heat pumps stoves and solar.

You really should get this right and there are many wrong turns where multiple energy sources are integrated.

More on this topic in LIST OF POSTS