Eco house

view - South side

view – South side

Eco house from the end showing garage door

Eco house from the end showing garage door

Check Google images for tiny house, small house, eco-house, pod, green living module or just a modern house. See anything you could imagine building then living in? I wonder.
Here’s the Original Twist idea of a simple modern looking house which, by using blocks or ICFs for the first floor and SIPs on top, is quick and correspondingly cheap to make. It is also quite small which leaves something in the budget for all the latest mod cons like the home cinema, a nice car in the integrated garage and of course the eco kit – 24 solar panels and the heat pump pod in the garden.
The actual building is conventionally cubic, clad in vertical wood, with all the metalic looking curvy edges added on later. They conceal wires and pipes and might be made of polystyrene or zinc covered forms. The south side is nearly all glass which adds to the feeling of space and allows for enough solar gain to take us into, or past, passivehause territory.
Small it may be but it is huge inside with the main living area 6m x 10m and a similarly massive room downstairs, both with cavernous ceilings. The raised bed platform gives a visual separation from the seating area and also makes the staircase to the lower floor neater. The change of levels gives a dramatically high ceiling to the kitchen/breakfast room below.
The main seating backs onto the big step and faces the partition wall which neatly houses a huge 4K TV, and all the usual kit, beneath a roller tapestry. This prefabricated wall incorporates storage on the reverse side and integrates all the home automation gear, security and communications.
To convert the living space into a dining room the table comes up from the floor – (see magic table on http://www.originaltwist.com)…… the TV disappears, the bed tips up and away and the sofa glides back into the recess behind it; fanciful maybe but it makes excellent use of the space and easily accommodates large dinner parties. The sofa mechanism is quite simple with the sofa parking on top of the cover door when it is deployed.
With all the clutter cleared away there is plenty of room for dancing with the ‘bar height’ raised platform making a safe place to put food and drinks. This house really is an entertaining machine.
There is a doorway either side of the big screen; one for the upstairs loo and the other to the kitchen. The generally high ceilings allow for an extra bedroom over the upstairs kitchen, accessed by a stairway along the back wall. It has to be very light and airy looking to preserve the cube like look of the main structure.
The house is suited to be built on a sloping site so access to the first floor would come from ground level and ideally via a glass entry vestibule to the front door on the wall opposite the big glass south wall.
Downstairs the large breakfast room enjoys a wrap around conservatory and incorporates a second small integrated kitchen. Doors to the rear lead to a couple of bedrooms, a loo and the garage.
The daily grind won’t seem so bad when you start with a cuppa in bed watching the morning news then a shower (in the small shower-room on the bed level) before going downstairs to a sunny breakfast before nipping through to take your Porsche off to work.
Of course the eco-technomologicalness will be state of the art. The 24 Sunerg hybrid solar panels actually dictate the size and shape of the roof and the red trim panels are fixed directly to the panels (PV and wet solar are all 2m x 1m). 4 of the panels on the steep roof will be wet to give a massive 8sqm to feed my own twin tank heat bank design – my speciality. The other 20 panels use micro-inverters to give a nominal 6kWp and a real 2-3kW in the winter to run the little air source heat pump which also does some neat heat recovery from the house and uses some ground heated air too. I have a whole book soon to be published on the full setup along with lots of cool tweaks to make the house a wonderful environment.
At the moment this is just an exploratory sketch but with serious intent. Local councils are being encouraged to make space available for self build houses and after a bit of polishing this design might gain some followers. Value for money would be very good if the drawings were all available and various trades all lined up and ready to make the next one. Practice makes perfect.
What next? Comments and criticisms would be good and then a list of the interested suppliers to put underneath here. If you are interested in owning one of these just let me know on the form and I’ll let you know how it develops.

Suppliers please step up:
Architects to draw it all up and polish the detail
Builders who like ICFs and SIPs
SIPs supplier (note the curvy roof)
Curved trim supplier – polystyrene.
Engineer for raising table and gliding sofa
TV partition wall
ASHP supplier
Solar pod for ASHP
Panels and micro-inverters
Power router
Panels – I’m set to import these.
Heat banks and design – that’s me.

Magic disappearing table

Now you see me

Now you see me


Now you don't

Now you don’t

You’ve been one of eight guests for dinner in a very modern eco-house. You all dined on a lovely heavy wooden table standing on four polished steel pillars; all very much in keeping with the modern house. You help to clear away the last plate into the kitchen and when you return 10 seconds later the table has completely disappeared. What? Your hosts were in the kitchen too so where has it gone?
OK, here’s the secret of the Original Twist magic table, and strangely, to make one table disappear you need 2 tables.
To start with imagine the original floor – for me, wide lime-washed oak boards – and this is where the table starts off; at this moment it is the floor. Underneath there is a small pit just big enough to accommodate the 4 steel pillars the bases of which screw into a rectangular frame which is raised and lowered by screw jacks and an electric motor. To go techie for a moment, there is an upper frame too with big DU bushes in blocks to steady the legs. When the floor/table is raised up you don’t see a hole in the floor because immediately under the first table there is a second identical floor section with 4 holes through which the legs move. When the legs base frame comes up to the top of the pit it pushes the second floor up to exactly the right height and the illusion is complete. The table has appeared from nowhere and the floor is exactly like it was before.
Hygiene would be an issue but with a rubber backed rug over the floor the table will never have been walked on and double protection would be afforded by a tablecloth as well.
Servicing can all be done from above and would be even easier done from below if the pit had a side hatch accessed from the floor below.
There is more to this concept that the sheer theatre of it. The easy removal of a substantial table makes grand entertaining in a downsized house all very possible without having that old hat idea of a largely unused dining room.
There is a business waiting to be started here. Precast pit and frames etc waiting to be fitted to the floor. If you are interested please contact me on the form below.

Air Source Heat Pumps and the Renewable Heat Incentive.

The Energy Saving Trust heat pump survey in 2009 found that many users were not impressed at all. The follow up in 2013 improved the results but the final average system COPs of 2.45 (air source) and 2.82 (ground source) were still way below the headline figures quoted for these machines which are going over 4 these days.
What is really good about heat pumps is that they can deliver more energy than they consume in electricity.

The power multiplier

The power multiplier


So a small one would be just like this diagram; working on the power of an electric kettle but delivering the power of 3 to your hot tank – a COP (Coefficient Of Performance) of 3 then. By contrast your immersion heater delivers and also consumes the power of an electric kettle so it has a COP of 1.

Heat pumps are all sold with an industry standardised COP. This is misleading to say the least and the reason why optimism is defeated by experience. Far from being a fixed figure the COP actually swings widely depending on outside air temperature and temperature delivered in the home. The COP plots here show how a kick is engineered to give a good headline figure; that kink in the graph is exactly at the publication point.

A sneaky kink

A sneaky kink


You might buy a machine with a quoted COP of say 3.75 but while making domestic hot water on a cold night it will be working at less than 2. There are benign swings however and given a sunny winter day with some warm air to chew on an ASHP can see COPs almost up to 5.

Gas per kW.hr costs almost exactly a third of electrical power so after adjusting for efficiency a gas boiler is similar to a heat pump with a COP of 3. Many people in the survey would be comparing their new heat pump to a gas boiler; a formidable opponent when running on cheap gas. A gas boiler is much more powerful than most heat pumps and delivers at usefully high temperatures so a heat pump must have an overall COP of over 3 to justify a hefty purchase price and compare favourably.
To be fair the Renewable Heat Incentives state that heat pumps are suited to people without access to town gas. So for them heat pumps are suitable but perhaps the performance could be lifted further?

To winkle out some ideas we’ll take daily temperature data for January in Guildford (http://www.wunderground.com/) and relate that to a COP matrix made from the published data from a modern ASHP (inverter drive scroll, r410a, delivering to under floor heating at 35 degrees).
We will be looking to lift the COP by running the ASHP at the warmest ambient temperatures possible.
A look at a January temperature trace shows:
There is usually a 5 degree swing between the mean night time temperatures and the daytime mean.
Night time temperatures are flatter and longer than the sharper daytime peak at 1-2pm.
The morning transition from lows to highs is halfway there by 10am.
Temperature rises coincide with sunrise, not surprisingly.

Relating the above to the COP matrix:
Running a 7hr shift from 10am gives an average COP of 3.86 – much better than gas.
The equivalent night time shift only gives a COP of 2.92 – but almost as good as gas.
If the pump has to make hotter water for radiators these day/night figures drop to 2.7 and 2.11 and for 55 degree hot water making 2.3 and 1.85– gas beats this hands down.
Storing daytime running means that delivery temperatures probably need to be around 50 degrees leading to an average COP of under 3 although bigger storage tanks improve this.
ASHPs can be smaller if they run continuously day and night on an average COP of 3.4 – still 13% better than gas.
Direct electrical heating is often used to boost hot water making (COP = 1) and this can lower the average COP. If we can avoid this practice and run predominantly in the daytime it should theoretically be possible to get a COP of 3.35 (7hrs day, 2hrs night, 2hrs hot water).
Transmission: Put 100W/square metre through your floors and your feet will be uncomfortably hot so somewhere near half that will be a good yardstick for calculating the power you need to heat the floors then leave some surplus to top up a tank.

Conclusions
A small ASHP can run considerably more efficiently than a gas boiler in a modest well insulated house. Fan-coil units in bedrooms and underfloor heating elsewhere are essential. The heat pump should run in daylight except maybe for a boost before dawn to guarantee morning showers and take the chill off the floors.
I should just mention one little thing in favour of the heat pump; the RHI incentive of 7.3p/kW.hr pitched to pay for the heat pump itself after 7 years. You’ll need to spend another £4,000 on proper tanks to integrate any other sources such as a wood burning stove and a combination like that would be a joy for anyone living out in the middle of the country.

Of course if you make your own electricity, or you want to be green, then a heat pump is already the answer.

Military Drone – Quadcopter

Quadcopter/puck ready for launching

Quadcopter/puck ready for launching


Quadcopter launcher

Quadcopter launcher


What will a future military quadcopter look like and how will it be deployed?
The Original Twist concept looks like a fat Frisbee or puck, at least it does for the first few hundred metres of flight with not an arm or propeller in sight.
Transportation: The propellers and arms are all tucked safely out of harm’s way, folded into the base of the puck. The folded puck can then be handled roughly and easily stacked up in racks.
Launching: Here lies the real Original Twist. As you will see in the launcher description below, the robust pucks can be flicked out like clay pigeons at the astonishing rate of 1,600 a minute. There is no battery power used for taking off, getting under way and reaching height which is a good thing. Neither is there a warning howl as hundreds of drones start up, just a line of discs silently darting across the sky to a location away from the launch site and therefore no giveaway of the origin. At the end of the launch trajectory the propeller arms flip out and the journey towards the enemy continues using onboard GPS. The propellers sit at a slight angle to the body so that when in flight the puck is perfectly aligned to the airflow. Reduced drag with some lift from the domed top allows a good range of at least 12 miles which allows one launch vehicle to cover an area of over 400 square miles.
Attack: The quadcopter/puck bodywork is made of moulded plastic explosive so they are very much like intelligent flying bombs. They can, for example, fly to a given location and using infra-red cameras locate human sized heat signatures for immediate targeting; no sniper will be safe from being blown out of his hiding place. Pucks can communicate with each other and with the host computer using a meshed network where signals are passed down the line. Other pucks can be programmed to cluster into a much larger bomb before simultaneously exploding.
Tactical use: The near silent deployment can have a myriad of other uses. Surveillance from on high or with sound and vision lying on the ground, simulated radio transmission sources to attract enemy fire, diversionary attacks from various directions and overhead flares to light up the enemy. They can even provide ‘Shoot me’ targeting information to overhead drones and airborne weaponry.
What could be more demoralising to the enemy than intermittent attacks from the air at no significant cost or risk to the other side? The biggest fear will be a ‘Cluster puck’ attack where several successive droves are launched and are resting on the ground nearby in preparation for a massive orchestrated attack.
A set of pucks with an affinity for vehicle wheels could be launched and without any difficulty a whole convoy of vehicles could be stopped in its tracks, or what’s left of them!
A major comfort to troops in hostile territory will be escorted manoeuvres. Protection from ambush is provided by pucks flying apparently random recce patrols but in fact checking ahead for any heat signatures.
Drone warfare will cause a change to military clothing; a wetted and cool outer shell being necessary to avoid being ‘seen’ by a drone’s camera. Even so, once terrain has been optically scanned any changes in position will highlight potential targets. If a drone flies over your hiding place it is likely that you will be attacked by the next one if you move. Computers and drones together make awesome weapons and there is no doubt that ground based warfare is about to enter a new era.

The puck launcher

Imagine a Landrover carrying a few thousand pucks in racks and on the roof a 6 foot diameter Catherine wheel spinning at 600rpm (car engine tickover) and flicking out up to 30 pucks a second at a launch speed of 120mph. The pucks are introduced into the calm middle of the wheel from an overhead magazine and then nudged sideways into the 3 radial arms where they queue to be released onto the extended launch ramps where they accelerate out to the open edge and away. They gain spin from the friction side of the launch ramps which initially swing out under centrifugal force to make the diameter bigger. The curved channels enable more pucks to be in the queue and also ease the centrifugal force at the end of the curve where the release catch is situated.
The loading magazine is itself fed by conveyor that has passed through the arming station. Here a fresh battery, much like a small puck itself, is fitted into the middle of the puck at the top while the mission computer installs targeting instructions via blue tooth.
No other system will deploy quadcopters this fast and it may even be necessary to slow it down.
Pucks not on suicide missions will return to land on a wide conveyor belt on top of the launch vehicle and from there mechanically re-folded, de-batteried and added to the stack heading for the launcher. In this way it will be possible to have hundreds of drones permanently out on various tasks. Separating the charging function makes long term storage very much easier and every puck receives a freshly charged battery just before taking off. Once deployed returning pucks can be re-batteried and launched back into the fray on a continuous basis.
With theoretical launch rates of a mind boggling 1,800 a minute there would never be time for a person to decide on the mix of missions being fed into the pucks just before they are launched. To do this efficiently the mission computer receives more generalised commands from several operations directors and these are collated and then automatically programmed onto the pucks.

Of course the puck concept is perfect for aerial launching too – no need for the launcher, just eject boxes of them to glide under low power for great distances. You would never see or hear the plane that launched a mass of pucks at you and it would be 100 miles away when the pucks arrive.

So to anyone who is not smelling the coffee yet here’s the question: Would you commit troops to a ground action where they can’t move, can’t hide, where attacks come relentlessly from every direction, where vehicles aren’t viable and all these things are cheaply applied by an enemy who, barring one launch vehicle, is immune to retaliation?

CNC router – Slide box and tool changer

Aluminium slide box

Aluminium slide box

tilting motor mount

tilting motor mount


Slide box: The basis is a wrap around box of thick aluminium plates enclosing the beam.
Each of the 4 plates has a unique function. The top and bottom plates are for the slideways, absolute location; Turcite blocks for the heavy downward loads and vibration damping, ball bearing rollers only for lateral location.
The vertical drive sideplate supports the entire drive mechanism – see picture. The drive motor sits over the top of the slide box and drives the big pulley on the outside. All the rest is inside the web of the RSJ ending up with the toothed belt driving onto the rack with a caterpillar drive to give more tooth contact. This plate is at the back of the machine and also supports a pair of Desoutter AFDK drills which just need a pulse from a 4mm air pipe to set them off on an automatic drilling excursion.
On the other side the front plate supports a swinging plate that holds a pair of angled router motors that are alternately selected with a push from an air cylinder; the cheapest alternative to a tool changer you’ll ever see.
The tool changer: The top pivot point is in line with each router motor axis so that they both swing into exactly the same position. The pneumatic pusher cylinder is mounted inside the box and pushes a peg that goes through a slot – neat huh? Between the motors a round steel plug is pressed into the plate and one of a pair of electromagnets pulls this to lock the plates together (better solutions in comments please).
So there we have a heavy duty industrial quality router with 2 tools and 2 drills; about £20,000 worth if you had to buy one. One could earn a comfortable living with one of these. Not a lightweight project but still DIYable especially if some of the complex parts are tested in MDF first and then self machined in aluminium or Tufnol to finish. Don’t get bogged down with cutting, welding and drilling heavy frames; the steel suppliers have all that kit and will make to your drawings in no time.
Levelling the beam: There must be a few ways to do this other than sending it away for precision grinding.
A small steel block with a laser on it will show a dot moving up and down a target to reveal the bumps which will respond to a light touch of an engineers scraper.
When the beam is true the finally added hardened steel guide bars will provide the perfect flat finish.
Panels: Professional machines come with expensive steel panels. As the central box chassis needs to be stiff and straight use MDF panels bolted to the steel to make it neat and strong too. Hammerite paint on MDF is remarkably durable and will keep it all looking very tidy.
Bellows: With a rectangular box sliding on the RSJ there will be no problem in adding bellows to make the machine the ultimate in tidiness and this will be no bad thing for the unlubricated Turcite slides.
For further reading try following http://www.mycncuk.com -a fount of CNC knowledge- and please criticise or add ideas for improvements in comments.

CNC router – Caterpillar drives

enclosed reduction drive click to enlarge

enclosed reduction drive
click to enlarge

Differential belt drive

Differential belt drive


Driving both sides of a wide beam or gantry present some awkward problems. Coupled long ball screws are expensive and prone to whipping if too long. Synchronised stepper motors on each end don’t always step in time and crabbing can occur. The caterpillar drive shown here for the slide box on the X-axis is intended to enable a timing belt to engage with a rack with the arrangement incorporating a low cost reduction drive.

There are 2 slide boxes at the extremities of the X-axis beam and they are driven by similar caterpillar drives except they are belt driven from pulleys on the rear drive shaft. Note that the pull on the belt is in the same direction that the slide box moves and that there is a differential action with the belt moving much faster.
With a couple more pulleys the belt can be made to lie, and slide along, beds rather than flap in the air.
Eventually the belt tips will wear out so regular belt replacement will be required but at least the system makes for an economical start and a rebuild with ball screws can come at a later date.

DIY industrial CNC router

CNC heavy chassis

CNC heavy chassis


Just think; if you had a CNC router you could start on the Original Twist 3-wheeler, make some furniture, maybe even earn a good living with contract work.
Cheap computers and software have brought CNC machining within range of the DIY brigade and Youtube reveals some totally heroic machines made in plastic and MDF with frames in off-the-shelf extruded aluminium beams. Time to join a mass of DIY enthusiasts and knock one up yourself?
I’d like to continue in this spirit but head towards something much bigger and heavier without increasing the cost to anywhere as much as that of a professionally made router.
Size: In order to machine round the outside of an 8’x4’ sheet, or bigger, we’ll need a long and strong X-axis. A heavy steel RSJ should resist the tendency to sag under the weight of two 4.5kW router motors and two drills. The neat thing about an RSJ is that it is not only cheap but the ‘I’ section enables us to put drive gears and the drive rack neatly inside the web.
Torsional rigidity is not a strong point but is easily enhanced by welding a heavy tube or two inside one of the webs. Steel can pick up vibration so filling a tube with heavy chain and oil will make a cheap but effective damper. You only get really smooth finishes on a machine that is well damped.
Z axis: You could buy an off the shelf Z slide and hang that off the X axis for a conventional and simple layout but the logic of that is debatable. When machining flat boards etc there is very little Z movement so it would be better to put the Z under the Y table so that the two major movements – X and Y – are as light as possible. The Z frame is raised like a garage car lift with 4 chassis mounted screw posts rotating to drive ball nuts on the frame. Unlike the continuous chain of the garage hoist a short timing belt for each screw connects to one of a pair of drive spindles which are both driven by a central belt and the stepper motor. This way we get reduced belt stretch and a built in reduction drive. This layout enables a much bigger Z travel – 3D modelers note – and makes a fast and responsive machine with a tidy uncluttered look. Air balancing means there would be no heavy lifting for the Z stepper motor.

This unusual configuration has a lot of advantages. The rough sketch doesn’t show the tractor drives or the box slides; one for the tool head and 2 to hold up the X-axis beam; they are described in detail later.
The rear mounted drive shaft drives the two differential caterpillar drives that power the Y-axis.

The advantages.
Size: Scaleable to industrial size. Pictured as 2m x 4m here.
Visibility: Whole work table visible without moving obstructions like gantry legs.
Safety: Work table has no sideways movement. No pinning accidents.
Space saving: No sideways movement of table so roughly half the footprint.
Convenient: Router motors present themselves right to the edge of the table.
Accurate: Very solid construction gives accuracy and good machining finish.
Neat: Hollow beams accommodate wires, lights and minor control panels.
Responsive: Weight of Z-axis is removed from the X and Y axes.
Large Z-axis: Big range possible – good for carving.
Short Y-axis: Single stepper motor drives both ends of X-axis beam so no crabbing.

Snags?
Weight: Chassis needs heavy welding skills and great accuracy.
Z-axis: Quite elaborate 4 pillar lift mechanism with guides.