Do It Yourself
ReNew articles to make home more sustainable
A house built of straw
You’re unlikely to go from building newbie to strawbale expert after a four-day workshop, but you should come out with basic skills, a better understanding of the process and the ‘right’ questions to ask. Enga Lokey explains.
THERE are many good reasons to choose to build with strawbales—better thermal performance, non-toxic material, agricultural waste product, low embodied energy, very high levels of insulation, beautiful curved walls, etc. But once you have made this decision, it may be difficult to find an architect, engineer and builder to provide the assistance you require in working with this unique medium.READ MORE »
One of the best ways to give yourself the knowledge and skills necessary for a successful build is to do a strawbale workshop. If you have no prior architectural or building experience, a workshop won’t prepare you to undertake your own project from start to finish unassisted; however, you will be able to gain enough understanding to ask the right questions of the professionals you choose to employ and also gain basic strawbale building skills yourself.
What should you look for and what should you expect from a workshop? At the most basic level, participation in a workshop should provide you with enough of an understanding of what you are getting yourself into to confirm your convictions or prompt a reconsideration of your building plans. Additionally, most workshops will give you hands-on experience with some of the unique aspects of building with bales, such as alternative framing techniques, bale tying, stacking walls and corners, prepping for render and rendering.
There is a huge variety in the offerings available. Before signing up for a workshop, ask yourself what you are looking to achieve and what level of participation you plan on having in your own project. The more you expect to do yourself on your own house, the more detailed and precise your level of understanding needs to be. Are you just interested in understanding the process so you can decide if this is the type of house you want to build? Are you interested in the theory and principles of good strawbale design? Do you want to participate in every aspect of the building process or just help with the bale walls and rendering? Asking yourself these questions will make it easier to pick the correct one. Some of the major differences between courses are discussed below, followed by a chart that tries to summarise the various options on offer.
Read the full article in ReNew 136.
Wicking beds: Irrigation from the ground up
Seven years ago, when permaculture design consultancy Very Edible Gardens began, they had no idea what a wicking bed was. After repeated queries from clients, they started to research and experiment. Dan Palmer, co-founder of VEG, shares the fruits of their labour.
Prior to our foray into wicking beds, all of our raised vegie beds were either unirrigated or set up with drip irrigation. But then someone whispered these words to us: “Wicking beds… We want wicking beds.” So we started setting up wicking beds in old bathtubs, and using plastic liner in standard raised beds. We set out to learn by doing, our initial intention to prove to ourselves that wicking beds didn’t work. We gave it a pretty good shot, learned a lot in the process and refined how we went about them—a good example of iterative design, where you keep doing what’s working and improve what isn’t, then repeat.READ MORE »
What is a wicking bed?
Invented by Australian Colin Austin, the wicking bed idea involves the prevention of water loss from your garden bed through the use of a waterproof liner or layer. This creates a reservoir of water beneath the soil and means that, instead of watering from above via drip irrigation, a hose or a watering can, the water wicks up into the soil from below.
This keeps the soil nice and moist. You prevent the weight of the soil from squashing all the water out by having the water sit in a layer of small stones, sand or similar, which can accommodate the water while bearing the weight of the soil. You prevent the soil from dropping down into gaps between the stones or sand particles with a layer of something that lets water wick up, but stops soil moving down. The last essential piece of the wicking bed puzzle is that you need a designated overflow point so that the soil layer doesn’t get flooded and kill the soil life and plants by rotting their roots.
Read the full article in ReNew 135.
Double glazing on a budget
Double glazing can be very expensive, but with a bit of care and patience you can add double glazing to existing windows without breaking the bank. Alan Cotterill shows us how.
Built in 2002, my four-bedroom brick veneer house has stock standard powder-coated aluminium windows and doors. With my previous efforts to retrofit for energy savings and thermal comfort (see ‘Efficiency on a budget’ in ReNew 130), I had already fitted effective shading for my windows in the warmer weather. As I understand it, this is a prerequisite if double glazing is not going to be counterproductive in summer. But for winter, double-glazed windows insulate and thus hold in the heat much better than a single-glazed pane. Thus, I embarked on a project to retrofit my windows with a second (acrylic) pane.READ MORE »
For the additional panes, I used 3 mm cast acrylic sheet accurately cut to size commercially by The Plastics Factory. They cut 34 panels within a tolerance of 1 mm to my requested dimensions. Accurate measuring by myself was of paramount importance for this! Buying direct from a wholesaler meant a good saving; in fact, the cost was around half that of uncut sheets from local retail outlets.
I adhered the acrylic sheet to the aluminium surrounds of each panel of glass using highly flexible silicone sealant. The reasons for this choice were two-fold.
Firstly, the linear expansion rate from a change in temperature is significantly different between the acrylic sheet and the aluminium frame, with the acrylic expanding at three times the rate of the aluminium. With a 1200 mm edge and a temperature change from 0 to 40 °C, the acrylic would expand nearly 4 mm more than the aluminium frame. Flexibility of the sealant would cater for this to some extent.
Secondly, if a glass panel needs replacing down the track or a return to single glazing is desired, the silicone sealant could be scraped off (although still a tedious, fiddly job!)
Read the full article in ReNew 135.
Small things matter too: Simple reuse DIY projects
In everyday life we are surrounded by materials that are usually thought of as rubbish. But most can be reused for other purposes with a little DIY effort.
By Lance Turner.
We hear a lot about reduce, reuse and recycle and, while most people make an effort with basic recycling, the first two parts—reduce and reuse—are really more important.READ MORE »
Reducing is simply a matter of choices—if a product comes in too much packaging or non-recyclable or environmentally damaging packaging materials (read plastic), then simply look for an alternative that is better packaged.
While it’s great to be able to reduce your waste load by careful shopping, some products are simply not available in anything other than plastic or plastic composite packaging. You can opt to simply not buy the product at all, but a particular product may be a requirement, for example, for health reasons, or it might be required for your job.
Given that most people will end up with at least some packaging that local recyclers don’t take, the best option is to try and reuse the material. This has two advantages—it reuses rather than recycles, and it offsets the purchase of new materials/products that would otherwise be bought for that purpose. It’s not just packaging that can be reused, there are many other sources of useful materials, from pallets to old electronic devices.
So just how can you reuse items that might otherwise seem like they have no use? In most cases, just a small amount of effort and DIY skill is required. On the following pages we present a few ideas that are simple and effective, and quite obvious once you see them.
Read the full article in ReNew 134.
Storage, study, sleeping: Container convert
Tammi Jonas is definitely a convert to container homes. Motivated by reuse and sustainability, their light-filled container conversion has also proved a joy to live in. Here she describes the conversion process.
In May 2011, we had a moving/storage/accommodation challenge. We needed to move all our material trappings from Melbourne up to our new farm near Daylesford, but store them for four months while we traipsed across America, and then accommodate our growing (vertically, not numerically) family in a small three-bedroom house on the farm. The obvious solution was a shipping container for all three jobs.READ MORE »
That’s how we came to buy a used high-top 40-foot (12 m x 2.4 m, 2.9 m high) container (from eBay) rather than simply hiring one to do our move. It cost us $2500, plus $500 to get it delivered to us in the suburbs and then hauled up to Daylesford.
The day the container arrived, we watched in trepidation lest the truck’s cranes broke the low wires overhead. Then we filled it up, to the top, grateful we would have an enormous shed at the other end to supplement our new little house.
Our intrepid truckie, Bluey, arrived to collect the now-heavy container, and drove it through the rain and up our slippery, narrow driveway onto the farm. I held my breath the entire time, certain there was a very expensive towing bill in our near future. But Bluey was amazing, and our life’s treasures were planted carefully in front of the shed to wait out the winter while we gallivanted off to a life-changing northern summer.
A full season later, we returned to commence our new life as farmers. Our design for the interior of the container was inspired by the RockVan (a 1977 GMC motorhome) we’d used on our holiday in the USA. The RockVan has terrarium-like windows that made us feel constantly connected to the outside world. I wanted my bed’s placement to replicate the RockVan pleasure of waking to the gentle visage of trees and sky.
I had imagined cranes and costs and the stress of working with contractors to move the container into position as our new bedroom/office with ensuite, but my partner Stuart had better ideas. All we had to buy were some pine fence posts, which we needed anyway for, well, fencing, and borrow Stuart’s folks’ 4WD.
Stuart dragged the container into place, using eight round fence posts as rollers. In total, he had to move it about 50 metres, and 90 degrees. He then jacked it up and put pad footings with brick piers under each corner.
The building commenced in earnest then, with the roof we pulled off the house’s superfluous, low carport becoming a feature on the container—and reducing the heat load on its roof.
Stuart bought double-glazed, aluminium-framed windows and doors direct from China, for both this and a second guest container. The windows in fact arrived in the soon-to-be guest container! The total cost was around $5500, including delivery, of which about $3500 was for the container.
Dealing directly with Chinese suppliers meant the windows were much cheaper, but it can be tricky, as quality can vary and the logistics require a lot of knowledge and time. However, Stuart already had 10 years experience dealing directly with Chinese companies, so for us this went smoothly.
Read the full article in ReNew 133.
Downlight transformers: The good, the bad, and the very inefficient
Not all halogen downlight transformers are created equal when using them with retrofit LED globes. Alfred Howell explains how the wrong transformers can be costing you money.
With the retrofitting of LED downlight bulbs to MR16 halogen fittings, households have seen great efficiency gains and cost savings.
However, if you change your bulbs to low-power LEDs but don’t check the transformers, you may be wasting energy. Many of the older downlight fittings use ferromagnetic (iron core) transformers. While simple, they are inefficient compared to modern electronic replacements. To determine the extent of losses in these transformers I performed some simple testing.
Testing and results
I tested a typical ferromagnetic transformer alongside an Osram Redback electronic transformer. Both transformers were tested, with and without a Brightgreen DR700 retrofit LED globe. A Power-Mate Lite energy meter was used to measure power draw.
||Type||No globe, or globe blown||10.5W globe fitted|
Table 1. Energy consumption of electronic versus ferromagnetic transformers,
with and without a load (globe) fitted.
As can be seen in Table 1, the electronic transformer performs well with or without the globe. While it seems a bit pointless to test a transformer without a globe fitted, it’s actually a good indicator of the efficiency, or otherwise, of each transformer. Compare the electronic transformer’s 0.38 W draw without a globe with the ferromagnetic transformer’s draw of an extra five watts. Indeed, the ferromagnetic transformer uses an extra five watts more than the electronic transformer with or without the globe’s load.
While that doesn’t sound like much, it’s not uncommon to find 20 or more downlights in a home. With all 20 lights on, that would be an extra 100 watts burning a hole in your wallet—or 0.5 kWh if they’re on five hours a day.
Solutions and options
To reduce this energy use, the cheapest option is to swap the ferromagnetic transformers for electronic ones when you retrofit. They are low cost, usually under $15, and available from electrical wholesalers and lighting stores. Alternatively, you could upgrade the halogen fittings to dedicated LED downlight fittings with an incorporated driver.
An even better option is to remove the downlights altogether in places where suitable. Downlights compromise ceiling insulation as they must be uninsulated to prevent the fitting from overheating. Also, many downlights, even LED ones, have a fairly narrow beam angle and so tend to produce pools of light. To get high ambient lighting levels requires a greater total wattage from downlights or a light fitting with a wider dispersion, such as an oyster fitting.
It’s clear that changing the globe as part of an energy saving makeover is only part of the solution. For maximum efficiency and results, the whole lighting system, and how the system is used, needs to be evaluated. This includes behavioural changes such as turning lights off when not in use. With a bit of effort, you will be amazed at the savings that can be realised.
Alfred Howell has years of experience managing complex machines, which he reckons puts him in a terrific position to understand how we can work as part of this complex machine we call Earth.
For more great articles like this buy ReNew 133.
Cooking Challenge: ReNew enters the kitchen
For our recent cooking challenge, we asked ReNew readers how they’re reducing their energy use in the kitchen. In true ReNew fashion, we got entries addressing the problem from a range of DIY angles.
As Alan Pears highlighted in ReNew 130, while the kitchen is a small part of energy use in the full food system, it can be a significant part of household energy use, particularly for low-energy-use households. From improving our understanding of the energy efficiency of appliances and cooking techniques to improving the insulation in saucepans, Alan presented a range of things to think about when you get into the kitchen.READ MORE »
The entries in our competition reflected that. Several tackled the topic by looking at equipment, with pressure cookers, solar ovens and haybox cooking featuring. Several looked at techniques, such as not cooking with a half-empty oven, defrosting food in the fridge (or on the bench) and even cooking multiple things in a stack of pots, to use the escaping heat.
And the winner is…
The ATA crew particularly like Jan Heskes’s entry, making that our winner: it’s a practical, simple approach to reducing energy use. We’ve included the winning entry in full, along with parts of several other entries that reflect the range of responses. Jan wins a GoalZero portable solar USB charger kindly donated by Laughing Mind and valued at $169.
Never cook with a half-empty oven
Much as we would like to, we cannot always afford to have the latest energy-efficient appliances in our home. However, by using what we do have more thoughtfully, we are still able to significantly reduce our energy consumption.
Our kitchen contains a standard-sized stove with a fan-forced electric oven and gas cooktop. The stove is a few years old and would have been energy efficient for its time. Before turning on the oven I plan and prepare as many dishes as possible to bake while the oven is heated. Surplus food produced is stored in the freezer for future meals. The freezer is also used efficiently by avoiding operating partially empty. With ongoing planning, food is defrosted passively and reheated either quickly in the microwave or, if possible, in conjunction with accompanying dishes. As a result the oven is generally only used about once a week in our house even though nearly all of the food we consume is homemade.
Read the full article in ReNew 132.
Low cost solar heating: Using free heat from your roof
After reading an article in ReNew, Alan Cotterill decided to design a closed loop heat exchange system to supplement his home’s heating with free heat from the roof. A couple of iterations later, he describes the resulting effective system.
In early 2014 I commenced efforts to use the heat from our roof cavity to contribute to winter heating. I decided on a closed loop system, which would take in room air, duct it through the roof and return it to the house at a higher temperature. A closed loop system avoids the issue of drawing down insulation fibres and dust from the roof cavity.READ MORE »
Useful attic temperatures
My home combined with our very cold but sunny winter days in Wagga seemed especially suitable for this system to run with reasonable efficiency. The house has a grey Colorbond steel roof and a large roof area relative to the internal floorplan, due to a high pitched roof and the wide verandahs and garage being included under the main roof structure. The east-west orientation of the long axis of the house and the north-facing roof area being covered with solar panels have not prevented useful attic temperatures. Measured 60 cm below the peak of the roof cavity, the average maximum attic temperature was 28 °C for the two weeks starting 16 July 2014 and 37.8 °C for the two weeks from 19 August 2014.
A first attempt
My first prototype forced room air through a system of ducts in the roof using a centrifugal exhaust fan mounted on its side on a shelf in the laundry. The air was distributed to three 12-metre runs of 100 mm flexible aluminium ducting before returning the air to the house. The returned air was reasonably heated but the total volume of returned air was inadequate to contribute significantly to winter heating.
Read the full article in ReNew 132.
Building a solar reticulation system
Martin Chape explains how he replaced a power-hungry bore pump with a low-cost solar unit and automated his watering system at the same time.
For some time I’d wanted to get rid of my power-hungry three-phase mains-operated bore pump, used to water my garden from the aquifer beneath my house. This forms part of a bigger plan to move all my 240 volt appliances off-grid. The large power drain of the three-phase bore pump would almost double the size of the inverter I’d need to go off-grid, even though it only gets used in summer, and then for just 15 minutes, three times a week.READ MORE »
So, I decided to replace it with a 24 volt DC bore pump run from solar PV. This pump fills a rainwater tank from the bore, using a float switch to turn the pump off when the tank is full. The resulting system can be completely automated and independent of utility-supplied water and electricity.
The pumps and tank
I ordered a 24 volt DC multistage submersible bore pump (a Kerry M243T-20) from a dealer on AliExpress, for US $178. This pump is class IP68 (fully dust and water tight; see en.wikipedia.org/wiki/IP_Code), has a 25 mm outlet pipe, can pump to a head of 20 metres at 3000 litres per hour and draws 384 watts (at 24 volts that’s about 16 amps).
While waiting for the solar pump to arrive I removed the existing bore pump and sold it for $500. Using that as my starting capital, I hunted down a 2500 litre poly rainwater tank through Gumtree and, with the help of my neighbour, installed it on a brick and concrete foundation. I had first considered building an elevated tank stand, to provide water pressure from the height, but decided against this after reading a story of a home-built stand collapsing on someone. I also would have needed local government approval.
So the tank ended up on the ground and I purchased a second pump to move the water out of the tank to the garden. It’s a 24 volt DC submersible pump (US$35 from another AliExpress seller) with a single impeller (the spinning rotor that pushes the water), a 25 mm outlet pipe, 12 metre head capacity and it draws 120 watts. Oddly, it claims a flow rate of 8000 litres per hour compared to the 3000 litres of the bore pump.
[Ed note: Cheap devices bought directly from China can vary in quality; checking the seller’s feedback score and comments can assist, but as Martin’s experiences show, there can still be issues.]
When this pump arrived from China it had been damaged in transit so I ordered a second one and then contacted the supplier. The supplier was very good and supplied parts which I used to repair the first pump, which is now in my shed as a spare.
The solar bore pump then arrived and with the help of a friend I soon had it installed in the bore. It seemed to work initially, but then stopped after just 10 minutes.
I contacted the supplier in China but they claimed their pumps don’t fail. After many tests and emails, I removed the pump from the bore and made a video of it running in a container of water. The video clearly showed that it didn’t pump water but rather blew out smoke. Only then did the manufacturer agree to replace the pump—if I paid the shipping from China for the new one.
When the replacement bore pump arrived, I installed it in the bore and wired it through the float switch (a boat bilge switch) mounted upside down in the top of the rainwater tank. This switch turns the pump off when the tank is full.
Read the full article in ReNew 131.
Going off-grid slowly: a DIY project
Stan Baker dreams of ditching his energy company and going off-grid. He explains how he aims to achieve this, one step at a time.
The well-documented ‘gold plating’ of the poles and wires networks has meant rising service fees for consumers despite falling demand for delivered energy. My own electricity bills reflected this and caused me to seriously consider leaving the grid altogether. A further consideration was the increasingly disruptive weather being experienced around the country resulting in power outages caused by high winds and electrical storms. When attempting to be energy independent, however, the problem is the high cost of the batteries and other equipment necessary to generate and deliver electricity.READ MORE »
Being something of a DIY type, I considered what bits I had sitting around in my garage and what expertise I might have that could be relevant. A passion over the years for converting hybrid cars to plug-in hybrids meant I had a reasonable understanding of lithium batteries, including the management electronics needed to ensure their longevity. I also had a 1.5 kW, 12 VDC Latronics inverter acquired years earlier for some long-forgotten project. Naturally, I had the usual nerdy stuff such as miscellaneous electronic parts as well as some understanding of microcontrollers.
In effect, I had much of what was needed to deliver 240 VAC off-grid, but with one question unanswered: where was the input energy to come from?
My house has a flexible pricing plan from Origin that provides cheaper electricity between 11 pm and 7am. This meant I had a lower cost source of electricity for charging the batteries, at least for initial trialling. So, about six months ago I put together a simple system using lithium iron phosphate (LiFePO4) batteries from an electric vehicle conversion that were down to around 50% of their original capacity and therefore unsuited for vehicular use.
The battery charger was a simple linear unit that used toroidal transformers. I had my fuse box modified so that the lights in the house could be powered either from the inverter or directly from the mains.
The original system was not particularly efficient and I estimated I was losing around 50% of the incoming energy, mainly due to the battery charger. However, it did keep my lights going during most nights and encouraged me to consider a more sophisticated battery storage system.
Read the full article in ReNew 131.
Efficiency on a budget: Easy, low-cost retrofitting
Alan Cotterill takes us on his journey retrofitting a standard brick-veneer home for energy savings.
Eleven years ago we bought a near-new four-bedroom brick-veneer house in Wagga Wagga, an inland town in NSW, in an area that experiences hot summers and cold winters.READ MORE »
It’s a fairly standard house for the area, set on a concrete slab, with a verandah running the length of the eastern side. The house is long and narrow, on a north–south axis, with only the double garage facing north. Excluding the double garage and verandah, the house size is 183 m2 and the window area is 19% of the floor area.
R3.3 batts were already installed in the ceiling, along with reflective foil in the walls and under the colorbond roof. We found that an evaporative cooler provided effective summer cooling on most days and later-fitted gas central heating provided winter heating, albeit at a cost.
There were several areas, however, where we found we could significantly increase comfort and decrease bills, through simple retrofits. Some of these are detailed below, including information on any issues we encountered and how we overcame them. Hopefully this will be of assistance to others planning similar retrofits.
The house’s original lights were 12 V, 20 W halogen downlights. A 30 cm clearance without insulation batts is required around each downlight to guard against overheating and fire. There were 18 halogen downlights, meaning 18 gaps in the insulation. Thus, there was about 6 m2 of ceiling without insulation.
So, four years ago I did a simple changeover from 20 W halogen globes to 3 W LEDs ($15 each at the time), using the existing fittings and transformers. I later covered each downlight with a downlight mitt ($18 each) and, ensuring that all transformers were held above any insulation to prevent overheating, I filled in the insulation gaps up to the mitts.
Each mitt comes with a wire support to secure it to the plasterboard and a wire tower to secure each transformer above the mitt and batts. Installation of the mitts was easily done from below, standing on a ladder. Because they are soft, you can simply collapse them, insert them through the hole for the light fitting, and open them up inside the roof cavity and position them over the hole. Then you just push the light fitting back in place, as they are held in the ceiling with spring clips.
The main energy saving wasn’t from the significantly lower wattage for lighting, but from the improved ceiling insulation, which reduced energy costs, especially from winter heating.
There were some problems, however. The original transformers were designed to run with a higher wattage than the 3 W LED globes I used, resulting in some flickering and some transformers failing. With what is available today, I would, instead, plug in an entire new 12V LED downlight unit, which includes a matched transformer ($28 from a specialist electrical trade/retail outlet).
Also, the 3W LED bulbs were bright enough for general socialising, but a little dim for reading. We’ve since added newer 8 W LED bulbs selectively, such as over a chair used for reading or over a work area in the kitchen. Not only is there now plenty of light, but the beam angle of 95 degrees (rather than a narrow 33 degrees) gives wider and more even illumination.
The choice of downlight mitt also needs to be considered carefully. Mitts need to be matched to the type of light fitting and may need a ventilation hole. Mitts without ventilation holes can be used with fittings of the gimble type, where the light can be tilted in its fitting. This tilting action requires a small circular air gap, flush with the ceiling, and this allows some ventilation around the bulb. But, where fixed fittings are used, mitts with ventilation holes are required. We used mitts with ventilation holes to avoid any risk in the future; for example, a new homeowner could unwittingly replace a gimble fitting with a fixed fitting.
Read the full article in ReNew 130.
Winter Energy Challenge
We asked ReNew readers how they are reducing their winter energy use. We received some interesting and novel ideas—here is the winner!
We had many great entries from ReNew readers for our Winter Energy Challenge, from the simple to the complex, from a single lifestyle change to an entire lifestyle choice (see Karen Cheah’s excellent presentation at www. bit.ly/YZ0dYe).READ MORE »
The ATA crew particularly like the Trombe wall that replaces conventional heating in the home, making John S our Winter Energy Challenge winner. Read all about his trombe wall below.
John will receive a portable ‘Sydney Tube’ solar BBQ from Run on Sun worth $550.
WINNER—John’s Trombe wall
I had this idea for a solar heater many years ago, and thought if I ever built a house it would be a main part of the energy efficient design. Well, I had been beaten to the idea by a guy named Trombe—so it won’t be named John’s wall!
Trombe made it using glass, but mine uses black painted corrugated steel. The principle is based on getting the sun to heat a cavity, with the warmed air thermosyphoning into the building. I had the advantage of computer fans to make the extraction of the warm air more efficient. The air enters the house through five vents.
The black corrugated steel wall is 2.4 m high and about 12 m along a 20 m north-facing wall. Windows break up the sections. The wall is 15° west of north facing. A veranda shades the wall to varying degrees, but completely from November to April.
The best winter days are clear, calm and cool. As soon as the sun hits the black wall it starts to warm, and by 11 am the air coming from the vent will be 28° C and as high as 49.7° C at 3 pm. I have saved running the reverse cycle air conditioner and still keep warm; saving money and the planet.
We’ll share more great entries with you over the coming weeks, or read the full article in ReNew 129.
Fridges for caravans
Collyn Rivers looks at simple ways to improve the performance of fridges in caravans—particularly important when they’re running off batteries.
The energy use and cooling performance of fridges installed in caravans and motor homes is related more to installation than technical differences between the fridges. Few are fitted as makers advise, leading to increased energy draw and hence cost; this also applies to domestic fridges, many of which are enclosed on three sides and inadequately ventilated.READ MORE »
Fridges are simply boxes from which heat is removed from inside the cabinet and dumped outside. It is vital this dumped heat is removed effectively. Owners, many builders, carpenters and even some electricians perceive fridges as ‘back to front’ ovens that generate cold. This approach often leads to ventilation being ignored, resulting in poor installation—the bane of fridge makers.
All fridges require adequate ventilation spaces at their rear. However, that alone is not enough. Cool air must be routed to flow unhindered over the cooling coils (also called fins) and the heated rising air must be routed to where it cannot heat the fridge again. With caravans, this is outside the van, and for homes, it is also preferably outside. This is often poorly done in RVs, and all but ignored for self-installed domestic fridges.
Most caravan/motor-home fridges have rear-coil cooling. For this to work, cool air at the fridge base must be directed to flow over the coils. This is assisted by baffles (flat plates inserted into the airflow to change its direction and make it more effective); even baffles made from cardboard will work well. A high exit for the warmed air provides enough suction to draw in cool air.
With such fridges, adding more insulation on their sides, top and (if feasible) to the door also helps hugely. Even 100 mm is not overkill.
Some caravan and domestic fridges dissipate heat from their outer skin; these fridges have an enclosed back without cooling coils. These need a 50 mm side gap and ideally the top area should be vented to the outside. Cool air needs to be directed to the base of their sides, and back if it is used for heat dissipation (you can tell which sides are used for heat dissipation as they will get warm when running). Obviously, you must not insulate the sides and/or back of this type of fridge!
Chest fridges need provision for cool air entry, and ideally nothing located above them to roof or domestic ceiling height. Some have a fan that draws cool air in via vents in their sides and over the compressor’s associated cooling fins.
Chest fridges with coil cooling are aided by adding insulation. However, a few (such as the Indel and Ozefridge) dissipate heat from their side walls and so need a minimum 50 mm gap around the walls.
Collyn Rivers has published several books on solar electrical systems and caravanning. Visit Caravan and Motorhome Books.
Read the full article in ReNew 129.
No wires and too much power!
Kevin White describes his off-grid home in Queensland as a renewable energy ‘power station’, with more energy than they can use!
It all began with eighty-three acres in southeast Queensland, an almost clean slate, up for sale by a good friend who’d fallen in love and was emigrating. Suddenly we had acquired a property with a bit of everything— dairy pastures running out to steeply treed hills, peaking at a ridge before descending into remnant rainforest; a 300-foot hill rising from the flats completes the picture.READ MORE »
Buying the property was the easy bit; deciding what to do with it was more evolution than plan. The flats had been used for grazing so we decided to continue that. In went cattle yards and a reasonably large shed—your shed can never be big enough! We decided to build a studio within the shed as temporary accommodation while we planned our build.
As ex-yachties who’d swallowed the anchor for the country life, we knew we wanted to maintain our independence. The ‘reasonably large shed’ had plenty of roof area to supply a water tank and there was plenty of fallen timber nearby for heating.
We wired the studio for both 12 and 240 volt power. We had no idea where on the property we wanted to build so we didn’t consider getting a quote for grid power at the time. However, we did get a telephone connection put into the shed.
At that time (just a few years ago!), solar panels were a rather costly item, so for our interim system we decided to mount four 80 W panels on a frame and have them track the sun for peak efficiency, along with using an MPPT charge controller and 400 Ah of Trojan T105 batteries.
Being an ex-electronics tech I built the tracking system—from an old C-band satellite dish mount, coupled to a homemade trackin controller. ‘Noddy’ did his duty, day in and day out. We were always delighted when guests asked, “Did your solar panels just move?”
With 12 volt LED lighting, a modest 12 volt fridge/freezer, 12 volt entertainment devices, a laptop and a pot belly stove (with a year’s worth of cut timber), my tolerant wife Gudrun spent over a year living in our temporary home while I went to work in Antarctica for a year.
Read the full article in ReNew 128
A DIY no-care worm farm
Discarded plaster or paint cans get put to good use in Valerie Yule’s simple and cheap worm farm.
This simple design for a homemade worm farm is rat-proof and fits a small shady space. It suits a family of four, as the worms eat the kitchen scraps so fast!READ MORE »
All you need are two empty plaster or paint buckets or cans, often thrown out from building sites, and two cheap plastic garden sieves. Builders and plasterers at a building site will usually be happy to give you the used cans rather than throw them into a rubbish skip.
Place one can in a depression in a shady space on damp ground. Put a sieve on top. Cut the bottom from the second can. Place the can on the sieve. Top it with the second sieve (if there are very clever rats around, weight this sieve with half a brick, so vermin can’t lift it).
The sieves stop rats, mice and blowflies getting in, but allow worms perfect freedom to come and go.
Start off the worm farm by putting some damp earth with a few worms into the top can. They will multiply quickly, so there is no need to buy worms.
Read the full article in ReNew 128
Low-power, low-cost computing
If you need to be energy frugal, you can still have a real computer for real tasks that won’t cost the earth. Lance Turner shows you how.
OVER the years we have looked at many low-power computers in ReNew, and there are new models out on a regular basis. Many of these have considerable computing power for their size, but most cost in the realm of several hundred dollars and many are simply not available in Australia.READ MORE »
The needs of computer users vary widely—some need higher processing power whereas others, who do everything in a web browser, need far less. The same applies to energy consumption. If you live with a small renewable energy system, your main priority may be to minimise energy consumption.
So just what options are there for really low-energy computing? Let’s take a look at the options, and then look a bit more closely at a low-cost option with surprising power.
Phones, tablets and phablets
Mobile phones, tablets and phablets (basically big-screen phones) are everywhere, and they may be all many people ever need to get connected. They have considerable processing power, are portable and are, by design, energy sippers. But they also have numerous drawbacks that make them unsuitable for many computer users.
Trying to type anything more than a few words on a tablet’s on-screen keyboard is a real pain, at least to anyone used to using a ‘real’ keyboard. Most tablets can take some basic peripherals, such as Bluetooth keyboards, or come with optional keyboard docks that also extend battery life. These can make a tablet more like a tiny PC and can push them into the realms of usability for users who may otherwise have overlooked them as an option.
Read the full article in ReNew 127.
Low-cost solar heating
Solar hydronic systems don’t have to be complex and expensive. Chris Hooley describes his simple and low-cost solar hydronic heater.
WINTERS in Melbourne used to be predictable: four months of sog from May to September. However, whether due to climate change, El Niño or simple drought, the winter of 2010 had a particular impact on me in that I kept coming home in the late afternoon to a very cold house, lit by shafts of brilliant winter sunshine. “Wouldn’t it be good,” I thought to myself, “if I could catch some of that energy and keep the house warm?”READ MORE »
I had a rough idea of what was available to make water hot using sunlight. Being a devoted handyman and incurable tinkerer, the seed of an idea took root and grew. My basic parameters were simple: I wanted a completely off-grid, stand-alone system that would ‘catch’ some energy in cooler months and put it to good use, without having to be plugged in or modified seasonally. Since the house already had gas central heating, the system would not need to meet all heating requirements but would rather take the edge off the cold on days when the sun happened to shine.
With this in mind I prowled eBay and mentally drew up plans until I could stand it no more and started buying parts. The key elements consisted of an evacuated-tube array piped to a fan-forced radiator. The collector heats the water and a pump transfers the hot water to the radiator in the house. A fan forces air through the radiator and into the room, heating it.
The system would be controlled by a thermo-switch and powered by a pair of 20 W PV panels. To avoid it freezing solid overnight or boiling away in summer and to eliminate the need for seasonal draining and refilling, I resolved to fill the whole system with car radiator coolant.
Read the full article in ReNew 127.
Warm sun, cool house
Martin Chape describes how he put an old evaporative cooler to good use, automating the system in the process.
Last year I promised myself that I was going to try and use the excess heat that my solar hot water system generates to cool my home.It was my intention to do this by extracting the heat from the hot water tank, either directly or with a heat exchanger replacing the redundant electric heating element, and use either an absorption or adsorption cooling process.READ MORE »
However, after one or two unsuccessful experiments, I put this idea aside for a while and instead decided on a much easier build: an evaporative cooler using solar PV to power it directly.
My plan was to source a discarded evaporative cooler rooftop box and replace the AC-powered fan and pump with 24 volt DC versions to be powered by a solar PV/battery system. I would also add a control system for monitoring and controlling the system remotely. Evaporative coolers are simple devices that draw air through wet absorbent pads. This cools the air through evaporation, and has the advantage of using a lot less energy than a refrigerated air conditioner. The main issue with using a second-hand unit is the cost of replacement pads, as they degrade over time and may become mouldy if unused for a while.
Step 1: sourcing the cooler rooftop box
I figured there ought to be plenty of those evaporative cooler rooftop boxes discarded after they wear out, break down or folks switch to other forms of air conditioning. I put the word out and within days my nephews had dropped off the parts for a Bonaire Brivis they’d found on the side of the road!
However, I ended up deciding to use a Bonaire Celair instead, which I bought for $50, as the Celair has thicker pads than the Brivis and the cost of pad replacement is lower.
Step 2: replacing the fan
I decided to source a fan used in the automotive industry, an 18 inch (457 mm) 24 volt DC fan, commonly used to cool the radiators of the big haul pack mining trucks.
The Celair’s removable fan mount made modifying it easy. However, the original fan was larger (19 inches), so I got a plastics company to make me a spacer to close the gap at the outer edge of the blades.
Read the full article in ReNew 126
Monitoring a rooftop solar hot water system
David Gobbett is using a Netduino microcontroller to monitor the temperature fluctuations in his rooftop solar hot water system.
For decades, the first or only solar appliance installed by many Australian households was a rooftop solar hot water system. My parents installed one on our family home in Adelaide in the mid 1970s. In my current home we installed a conventional 300-litre rooftop system in 2006. Superficially at least, the design seemed to have changed little over the intervening years. In both cases an electric booster was connected to off-peak power, which is switched on automatically by the power meter from midnight to 7 am each day.READ MORE »
To reduce our energy consumption over summer, we turn off the electric booster at the main switch during late November to late March, and we still have adequate hot water most of the time. However, occasionally we unexpectedly get caught short of hot water, and at those times it’s been frustrating having no way of knowing how hot the water in the tank actually is.
Another concern with switching off the booster is that there are potential health issues when hot water system temperatures are allowed to drop below 60 °C. Lévesque et al. (2004) indicate that Legionella bacteria can grow in water temperatures up to 45 °C, but that growth stops above 55 °C, and over 60 °C the bacteria are killed. Even in hot water systems with the thermostat set to 60 °C, the lower part of the tank can remain at temperatures that are optimal for Legionella growth. It would be nice to avoid this—but that would entail having a way to sense the temperatures in the tank, which is high up on the house roof.
A project idea was sparked when a friend showed me that he was using a small microprocessor board to log solar PV power outputs. He had also connected a sensor on his water meter so he could log household water consumption. This inspired me to start on my own project to get a better understanding of what the temperatures in my solar hot water system were doing.
My interests in this project were to:
• minimise unnecessary power usage
• know when we’re running low on solar hot water, so the booster can be turned on
• minimise any risk associated with Legionella.
Setting up the temperature logging
Although I have experience as a computer programmer, I had never programmed microprocessors or worked with such things as temperature sensors. After some internet research I decided to use 1-wire devices (1-wire is a technology by which sensors and other devices can communicate). I took the plunge and purchased:
• 1-wire temperature sensors (DS18S20; 10 of these cost $18). These sensors operate over a temperature range of -55 °C to +125 °C. Several of these sensors can be connected to a single cable to form a mini network where each sensor has its own unique identification.
• a USB to 1-wire adaptor, to allow me to connect the sensors to my PC for testing (DS9490R; $28)
• a Netduino Plus microcontroller (US$70) which included a network socket and micro SD memory card slot. (See side box ‘Arduino style microcontroller boards’).
I proceeded to build the system in small steps. First I soldered three of the 1-wire sensors to a length of old telephone extension cable and then used the 1-wire to USB adaptor to connect them to my PC. Using free software (from www.maximintegrated.com) I was reassured that I had wired them correctly (phew!). Then with some extra lengths of phone extension leads, I inserted the sensors under the insulation at one end of my hot water tank and immediately saw big differences between the top, middle and bottom of the tank, as well as temperature changes in response to hot water use in the house. This was encouraging since it showed that I could get useful temperature readings from the outside of the tank.
Read the full article in ReNew 125
An introduction to making biochar
John Hermans explains what biochar is, its environmental benefits and the process he uses to make it.
It was not until I read The Biochar Revolution by Paul Taylor that I began to think about biochar’s agricultural and environmental value, and decided to make the effort to make biochar at home. This article won’t attempt to summarise the book but rather focus on how I’ve used its approach to benefit our household.READ MORE »
What is biochar?
In a word, biochar is charcoal. Crushed into small particles, the charcoal can be used to improve the nutrient- and water-holding capacity of soil, and so improve plant growth and productivity.
Biochar is a relatively new word, but biochar’s use has been documented as far back as the Amazonian Indians, who created tera preta or ‘black earth’. These nutrient-enriched soils retain much of their higher fertility, and their char, thousands of years after they were created.
Biochar can also permanently lock up carbon to help neutralise our carbon footprint. In this world where governments are largely failing to mitigate a climate catastrophe, this is another path for a ‘bottom-up’ global effort.
Why make biochar?
Biochar is now commercially available as a soil conditioner, at around $10/kg, but if you are not confined by allotment size, it is quite easy and cheap to make instead. You can also then control what goes into it.
In my case, I have been using the sticks and leaves that I would otherwise have burnt to reduce summer bushfire risk.
Making it has also given our household another option for becoming truly carbon neutral, other than planting trees. Biochar means we can now lock up atmospheric carbon in the soil, potentially for thousands of years, rather than have it re-enter the atmosphere when the ground litter rots or is burnt. Once it is added to the soil, it remains mostly inert to oxidation and hence does not re-enter the carbon cycle. At the same time, it increases the soil fertility in our extensive food garden.
When organic matter is burnt in the open air, it nearly all burns to ash, with only very small amounts of unburnt black char. It is possible to make char in a controlled open-air fire by extinguishing it early with water, but smoke, heat, flames and gas emissions will result.
In biochar manufacture it is preferable to use enclosed steel drums to control oxygen delivery and to burn most, if not all, of the carbon monoxide, hydrogen and methane which otherwise are given off in smoke. If unburnt, most of these gases have a far higher greenhouse gas effect than CO2. When the fuel is burnt in controlled conditions, they are converted to CO2. An added advantage is that it is a fairly smoke-free production process—far more neighbour-friendly than open-air fuel reduction burning.
Read the full article in ReNew 124