Eco-house delivered tomorrow morning and ready to live in by tea time? “Yes Sir, no problem, will that be the £130,000 ROOT2 or the ROOT2 MAXI for £170,000?” The smaller Root2 Eco-house comes in 3 towable modules that are parked in a ‘T’ shape with the gap in the middle covered by a hexagonal roof. The hexagonal living room under the roof is a spacious 4.5m wide and the fully glazed front side gives a modern airy feel to it. Each module is constructed in structurally insulated panels (SIPS) with smart double glazed PVC windows and doors. The roof, floor and end panels are wrapped in zinc to give a modern look and water proof durability. Being just 2.25m x 5.25m the modules can easily, and legally, be towed by most family cars. The ‘wet’ module goes in the middle of the ‘T’ and comes pre-fitted with a wood burning stove connected to a 475 litre heat bank which is also heated by wet solar panels (6sqm on the roof), an immersion heater and an lpg Vaillant Eco-plus gas boiler just in case. The wet module also houses a neat galley kitchen, a shower and chemical lavatory which can be exchanged for a normal one when a septic tank and soak-away is installed. Of course the wet modules wouldn’t be wet without water so a 1,000 litre tank is placed over the roof to give adequate supply and pressure. A trailer is available for fetching another 1,000 litres in an IBC if necessary. The other 2 modules together provide 2 small bedrooms, one double bedroom and an office – useful 50msq accommodation for a family of four. Under-floor heating is pre-installed throughout and quickly connected at the setting up stage along with wiring, made simple with Z-Wave wireless lighting and switching which also enables many functions to be controlled remotely on any i-pad or mobile phone. Root2 is a proper Eco-house with 42% of the build cost going into sustainable energy equipment. The other 2 modules at the sides have a total of 18 PV panels on their roofs to give a total of 4.5kW (kpa) and the power, stored in batteries, is handled by a Power-Router unit that also allows connection to the mains when available. While the Eco-kit incorporated might look a bit excessive at first it does allow the house to be placed very quickly on site in a fully working state and provides a most economical off grid user experience after that. The extraordinarily low price also comes without the need for expensive extras such as site preparation and various professional fees; a patch of land with permission for 3 caravans will probably suffice. Being a new house built by a contractor Root2 should qualify for the UK ‘Help to buy’ scheme and will enable many owners to enjoy comfortable living without a huge mortgage burden. No doubt some users might sell existing properties and release cash for holiday villas or ski chalets. Corporate purchasers will value the instant hassle free solution for housing workers on site with all the proper modern comforts of home. The ROOT2 MaxiThe maxi is built to the same concept but each module is 6m x 3m and the central hexagon is 5m wide. While ROOT2 is like a flat in size the Maxi is just like a house. ROOT2 Maxi is not towable and is delivered on a truck with a crane and in that respect can be installed almost as quickly. If you want a well appointed 5 bedroom Eco-house next week then this is the way to go.
Good COP bad COP
A ground source heat pump (GSHP) is more efficient than an air source heat pump (ASHP) but is this relevant, or even true, for central Europe where air temperatures are warmer than in England for example? Taking the daily high and low average temperatures for Perugia in Central Italy and converting them directly into COP figures for a modern ASHP gives a chart showing the performance envelope. The straight black line shows an approximation of GSHP performance. Note how the GSHP starts really well and declines over the season as the ground energy gets depleted. Even so it performs strongly throughout and has the ASHP licked overall especially at night when the air temperature falls dramatically.
That’s the simple story but can the ASHP fight back in any way?
You’ll see that the big red line at the top shows that every day there is a time when the ASHP will always be running a better COP so the ASHP could be elevated with a total commitment or even a bias towards day time running. This assumes adequate power and bigger energy storage with tanks of some 2,000 litres. A house with high thermal mass and heated concrete floors will store energy too.
This regime pulls the average COP for the ASHP a bit higher than halfway between the day and night lines so over the season the ASHP is a match for the GSHP; but the battle isn’t over yet. Time to introduce the solar shed.
The solar shed in its simplest form is a greenhouse for the ASHP and apart from adding a little sunlight to the equation it allows 2 extra sources of warmer air to be added. The ASHP fan blows air out of the shed and replacement air can come from vents leading from the house air exchange (bathrooms and kitchen for example) and also from large diameter tubes buried in the ground. The latter is old technology and has been shown to raise the air temperature by around 5 degrees C. The green dotted line on the chart shows the night time COPS being elevated by 5 degrees and as you can see the COP envelope is an easy match for the GSHP and draws ahead in the late season.
Finally some ball park economics starting with a €10,000 ASHP and the equivalent €20,000 GSHP. Assigning a typical bill of €2,000 to run the GSHP a standard ASHP would cost €2,500, at the very worst, and thus take 20 years before the total cost overtakes the GSHP – already a no brainer for the ASHP before we even start on economy measures. Increasing the storage to a 2,000 litre twin tank system would add up to €3,000 and that would be recouped in 6 years, which is useful, but the air recovery and ground heating systems don’t look feasible on top of that although eco-warriors might like to go the whole hog.
The conclusion is that Air source is the way to go in Southern Europe and big tanks are worthwhile if the quotes look reasonable.
What about England?
If you live in England you might be wondering how relevant this graph is to you. Comparing monthly average temperature highs and lows for Perugia vs. Horsham gives these results for the 6 cold months only:
Nights are only 1 or 2 degrees colder in England except for Jan and Feb when Italy is 1 degree colder so on balance there is no real difference.
The average monthly lows for both zones are just above freezing – i.e. no trick technology required for air source heat pumps.
Days are always warmer in Italy, 1 – 3 degrees. The swing between night and day is a little more and so air source heat pumps make more sense particularly if biased towards daytime running with big tanks.
For the 3 coldest months England is only a degree or two colder during the day than Italy so in COP terms they are in the same ball park.
The bottom line is that an ASHP is just as valid wherever you are, the graph holds true and it makes sense to run during the warmer day and store in bigger tanks. Running an ASHP on economy 7 at night is also valid of course and I’ll make comparisons when I’ve updated my models.
If anyone is into the nitty gritty of COPs and stuff I have prepared a COP matrix for a modern ASHP in Excel. You can select an air temperature and the target temp such as floor, rads, fancoils and read off the COP. Just contact me if you’d like a copy.
If you are starting a project and need advice on integrating wood, solar, gas and an ASHP by using a heat bank just let me know. I’ll be in England full time after Summer 2015.
The Original Twist bug catcher enables any bug in the house to be captured with a single press of a trigger. It works like a one shot Hoover with a spring loaded piston causing an air blast to move the bug from a wall to inside the bug viewer.
The bug catcher is a short clear plastic tube with a funnel shaped trap at the front to enclose the bug and a cylinder off the side where the bug ends up after firing. The side cylinder is also clear plastic and incorporates a magnifying glass for better bug inspection.
The firing sequence. The piston has to be pulled to the front with a pull rod until it locks on the trigger stop. The pull rod is then pushed back into the gun and only then does an interlock allow the trigger to be pressed. When the trigger is pressed a spring pulls the piston back into the body of the gun and the vacuum causes air to enter the funnel trap and blast the bug into the gun too. Perforations at the back of the gun regulate the back pressure air and a twist collar can set the power from ‘Kill’ to ‘Kind’. There is a small hole at the very back of the gun which allows air to escape from the damper chamber which is simply where the back end of the piston ends up coming to a soft stop.
Just as the piston comes to a stop it uncovers the entrance to the bug viewer; the bug slams into the angled face of the piston and is deflected into the bug viewer along with some of the moving air. The entrance port to the bug viewer has some bendy hairs which give way to the bug and air but spring back to prevent the bug climbing out. After that the bug can be inspected and ejected by removing the bug viewer canister.
You saw it on Original Twist first. If you wish to use this design please get in touch using the contact form.
Description: A frizbee that doubles as a speaker. It can record sounds or speech and replay them them with a time delay. A plug in the centre body enables a media player or phone to be attached when the frisbee acts like a static loud speaker.
Method: The plastic shell of the frizbee holds a central module that incorporates a driver (probably made by Peerless) working on NXT technology. This is what vibrates the frisbee to make sounds. The technology is not new and a licence from NXT will be required. A rechargeable battery and memory module are incorporated and a USB port for charging..
In action: Set the timer, record a message then throw the frizbee. It will deliver the message while flying overhead or when caught. A new message can then be recorded and the frizbee thrown back.
The Market: This could be the next big thing in toys. Potential sales are therfore in the millions.