In ‘Energy efficiency’ Category
Keeping your EV battery healthy
In the first of a series, Bryce Gaton looks at the core part of the EV, its battery pack, and how to give it the longest possible life. In later articles, he will explain the options for testing and monitoring the battery pack in your EV.
WE ARE all familiar with the ways to prolong the life of an internal combustion engine (ICE) vehicle—regular service, monitor the oil, etc—but EVs are a whole new ball game. What do they need to maintain them in tip-top working order? And how can we test them to know if things are going wrong?READ MORE »
While in general EVs need less maintenance than conventional cars, there are some considerations which will help keep the car performing well for longer and reduce maintenance costs. The battery pack is the component that is both the costliest to replace and the most within our control to keep healthy.
For example, for an ICE vehicle converted to battery electric, replacing the battery pack can cost from $110 to $300 per lithium cell with the battery pack size ranging from 30 to 100 cells—at a cost of $3300 to $33,000. For a Nissan Leaf, replacing the 24 kWh battery is around $6500 fitted (AU$ equivalent to US$ replacement cost—Leaf replacement batteries are not necessarily available here).
What is an EV battery pack made of?
All the pure EVs and hybrids on the market now use variations of a lithium ion chemistry. A common one is lithium iron phosphate, commonly written as LiFePO4. Lithium offers many advantages over previous battery technologies. In particular, it allows for much lighter batteries than lead-acid, which is what EV batteries used to be made from.
Lithium batteries can also be more deeply discharged, down to 20% capacity, giving more available energy to take you further; they hold a stable voltage through most of their discharge range (see graph); they can take high charge and discharge rates, allowing for hard acceleration and fast charging; and they are largely maintenance-free.
They should also have a long life, if looked after, with 70% to 80% capacity remaining in the battery after eight to ten years. And even after that, lithium EV battery packs are still usable in less demanding applications, such as home storage
Lithium cells have some features that need to be taken into account in the design of the car and charging systems. If they are overcharged or discharged (below 2.5V or above 4V), they will likely be destroyed (although LiFePO4 are more abuse resistant and may be recoverable). And, in some formulations, they can catch fire. This is particularly a problem for the super light, very energy dense ones in phones and the like: think Samsung Note 7. EV batteries are now made with formulations that are more resistant to starting or maintaining a fire.
To allow for these issues, modern EVs and hybrids include a battery management system (BMS). The BMS is a complex set of electronics that manages the charging of each cell, as well as controlling the current available to drive as the battery discharges.
Read the full article in ReNew 139.
The future of long-distance travel
We regularly look at the future of shorter range personal transport options, but what about long-range and public transport options? Lance Turner takes a look at where long-distance and public travel is headed.
TRAVELLING locally is already becoming more environmentally friendly, with the introduction of electric cars and public transport running from renewables. But what about long-range transport: what’s happening there? There is a global push towards reducing emissions in long-range transport options, be they rail, air transport or shipping, but there are significant challenges. Let’s look at what’s happening around the world, and how we may be getting around in the not too distant future.READ MORE »
According to the European Environment Agency (www.eea.europa.eu), emissions from all passenger rail (with an average of 156 passengers per train) in Europe are around 14 g of CO2 per passenger kilometre. Compare that to a large car (four passengers) of 55 g, a regular bus (12.7 passengers) of 68 g and aircraft (88 passengers) of 285 g. These figures will vary depending on the type of trains, cars and buses, as well as the source of generation for the electricity used (Europe has lots of renewables and nuclear compared to other regions such as the USA and Australia), but the indicators are clear—we need fewer planes and more trains.
HIGH SPEED RAIL
High speed rail (HSR), where trains run at speeds above 200 km/h (for existing lines, or 250 km/h for new lines) between major population centres without stopping, is common in countries such as China (which has some 22,000 km of HSR network) and Japan, and throughout much of Europe. However, Australia has never managed to get a high speed rail network off the ground, despite many concepts and plans being put forward. One problem here has been a lack of political will for such long-term projects. Another problem, specific to Australia, is the huge distances between cities and our smaller population. In short, the cost per taxpayer for a high speed rail network is much higher in Australia than in most other countries, making it a difficult sell (see en.wikipedia.org/wiki/High-speed_rail_in_Australia).
Central to the lower environmental cost in HSR systems is the use of electric trains. Being able to derive power from renewable energy sources rather than on-board diesel engines means that high speed rail becomes an even cleaner transport option as the percentage of renewables in the grid mix increases—just like any EV. Further, the cost of transport is no longer tied to that of fossil fuels so, as renewables become cheaper, the cost per kilometre travelled can fall.
The majority of high speed rail networks still use steel wheels on steel rails, but some of the fastest HSR projects use a more recent technology—maglev, or magnetic levitation, where strong magnets are used to lift the train just above the track, eliminating most sources of friction and allowing for higher speeds. Indeed, the fastest HSR train in regular service is the Shanghai Maglev Train, which runs on a 30.5 km track from Shanghai Pudong International Airport to the outskirts of central Pudong.
Read the full article in ReNew 139.
Hydrogen as a fuel – is it viable?
Is the hydrogen economy ever going to happen and are fuel cell vehicles really a viable alternative? Lance Turner cuts through the hype and takes a realistic look at using hydrogen for transport and energy storage.
ANYONE interested in renewable energy will have come across numerous articles on hydrogen fuel cells, and in particular, their use in cars and other transport as a potentially greener replacement for conventional internal combustion engine (ICE) drivetrains. However, to date there are very few fuel cell vehicles on the roads, apart from a few in demonstrator fleets, all subsidised by either the government or vehicle manufacturers.READ MORE »
So why haven’t we seen the fuel cell revolution as promised? There are a number of reasons, but let’s first look at the basics of fuel cells.
What is a hydrogen fuel cell vehicle?
In its simplest form a hydrogen fuel cell consists of two electrodes (an anode and a cathode) separated by an electrolyte. Hydrogen gas is introduced at the anode and oxygen from the air at the cathode. The two combine to produce electricity, heat and water.
In a fuel cell vehicle, hydrogen is stored in high-pressure tanks and delivered to the fuel cell at a reduced pressure, while air is passed through the fuel cell stack (the common term for a number of fuel cells in a single unit) courtesy of an electrically driven compressor system. By varying the rate of gas flow through the stack, the electrical output of the fuel cell system can be controlled.
The electricity then normally passes through a DC to DC converter to produce a voltage suitable for the vehicle’s drive motor and battery bank (or ultracapacitor bank).
The resulting electricity powers one or more electric motors, which propel the car— exactly like a battery-based electric vehicle.
As mentioned, fuel cell vehicles include a battery or large ultracapacitor for temporary energy storage. This is required as a fuel cell takes a small amount of time to respond to gas flow rate changes. In a vehicle this would be an unacceptable delay—imagine putting your foot down only to have the car do very little for a couple of seconds. The battery and/or ultracapacitor store a relatively small amount of energy but they can deliver it immediately as a large amount of power. They also provide extra power when the total demand exceeds that available from the fuel cell stack (which usually has a lower maximum power output than the motors are rated for) such as when overtaking and hill climbing.
Indeed, the main difference between a purely battery electric vehicle (EV) and a fuel cell vehicle (FCV) is that the FCV has a combination of fuel cell system and small battery rather than a single large traction battery—in most other respects they are quite similar.
To store a usable amount of hydrogen in a small space, such as required for a vehicle drive system, you need to compress it enormously. How much does it have to be compressed? To gain acceptable ranges comparable to a typical petrol car or current long range EV (400 km or more), the level of compression is many hundreds of times atmospheric pressure.
Both Honda with their Clarity FCV and Hyundai with their ix35 vehicle use a maximum tank pressure of 700 Bar, or around 700 times normal atmospheric pressure, 70 megapascals, or over 10,000 psi in the old of pressure per square centimetre of tank surface area. terms. In more common terms, that’s 700 kg
Read the full article in ReNew 139.
Efficient hot water buyers guide
If your old hot water system has seen better days, maybe it’s time for an efficient replacement. We show you how solar and heat pump hot water systems work, what’s available and how to choose one to best suit your needs.
ONE of the biggest energy users in any home is water heating—it can account for around 21% of total energy use (on average, according to YourHome), at a considerable financial cost each year. Water-efficient appliances are one way you can reduce energy use—for example, you could replace an inefficient showerhead (e.g. some use 20 litres per minute) with the most efficient, which uses less than 5 litres per minute, saving water and water heating energy each time you shower. But far greater energy reductions are possible if you replace a conventional water heater with a heat pump, solar thermal or solar electric system.READ MORE »
Such systems have the added advantage of reducing your greenhouse gas emissions. For example, for an average family the reduction can be as much as four tonnes of CO2 per year—the equivalent of taking a car off the road!
What we do and don’t cover
From an efficiency and environmental point of view the future of household energy is electric. The rise of rooftop solar and the availability of GreenPower means that households can use 100% renewable energy to run their appliances, including hot water systems.
This means we don’t cover efficient gas hot water options such as gas instantaneous in this guide, although the solar thermal hot water systems listed do have gas boost options. Gas used to be seen as the cleaner energy choice, at least when compared with burning coal, but there are better non-gas appliances available to households now. And changes in the gas market mean gas prices are on the rise. Replacing a hot water system with a modern solar thermal or electric one is often the first step in disconnecting from the gas grid, and the associated costs and greenhouse gas emissions.
We cover systems designed for household hot water that can run from renewable energy, including electricity, and ambient and solar thermal heat. These include heat pump, solar thermal, electric instantaneous and the newer kids on the block, PV diversion and direct PV water heating systems. Heat pump systems can be designed for other purposes in the home such as pool heating or hydronic heating, but these are out of the scope of this guide.
Read the full article in ReNew 139.
Download the full tables from the guide here.
See an energy use comparison between heat pump water heaters and resistive element water heaters here.
Read a list of questions to ask your hot water system installer before giving them the job here.
Getting into hot water
Five reader stories and five different systems that illustrate there’s more than one way to get into hot water!
A tale of two solar hot water systemsREAD MORE »
Jen Gow has tried out both flat plate and evacuated tube solar hot water systems, and discusses the differences.
Don’t dismiss resistive element hot water
For Dave Southgate, converting to an all-electric house did not involve using a heat pump for hot water. Here’s what he did instead.
How to save money with a hot water heat pump
Jonathan Prendergast shares his quest to reduce his hot water bills by switching to a heat pump.
Troubleshooting issues with solar hot water
Ewan Regazzo’s electrical engineering background was put to good use troubleshooting a faulty solar hot water installation. It’s now working well, but there were several issues along the way.
Resistive versus gas
Linda and Mike Dahm were surprised when the energy costs for their dual occupancy homes, one with solar PV and an electric resistive hot water and one with gas hot water, worked out about the same. Here’s what happened.
Read the full article in ReNew 139.
Knowing that double glazing can be compromised by incorrectly sealed window frames, Jean and Barry Lambert used affordable thermal imaging technology to check and rectify the installation—and find other sources of house heat losses.
LIVING in Canberra’s cold climate you need to think carefully about heat loss. We’ve done work on our house to improve its insulation, glazing and heating system efficiency. But that doesn’t necessarily translate to the best possible thermal performance if there are gaps or weak spots in the insulation—and that’s where we found a thermal imaging camera came in handy.READ MORE »
Some background on our house
Located in an inner suburb of Canberra, our four-bedroom brick house was built in the 1970s. The major axis runs north–south, with the living area to the west (giving views to the Brindabella mountains) and the bedrooms facing east.
Canberra of course has quite a wide temperature range (it’s in climate zone 7). Outside temperatures on winter mornings can fall below zero, while summers are usually dry and warm.
Canberra’s cold winters dictate that insulation is a priority to reduce heat loss. We insulated the walls with R3 rockwool and we topped up the existing ceiling insulation to an R5 rating. We replaced the original oil heating with ducted gas, and added deflectors on the floor vents to direct hot air away from windows. By varying the airflow rate using the outlet dampers in the floor vents, around a 50 °C outlet temperature is maintained, giving a comfortable 18 °C to 20 °C temperature inside the house.
Read the full article in ReNew 139.
Keep your cool: External shading buyers guide
With summers getting hotter in many parts of Australia, keeping the sun off your windows and out of your home is becoming even more important. Anna Cumming looks at the options for external shading, for both new builds and retrofits.
THERE’S been quite a shift from pre-industrial times when glass was an artisan-crafted luxury item, and homeowners were taxed according to the number of panes they had. These days, our houses are getting bigger and so are our windows—often to the point of comprising entire walls. Windows and glazed doors frame views, admit natural light and breezes, and allow a connection with the outdoors. In a well-designed house, they also admit the sun’s warmth in winter to assist passive thermal performance.READ MORE »
However, from a thermal efficiency point of view, windows are the weak link in a home’s building envelope: Your Home notes that up to 40% of a home’s heating energy can be lost and up to 87% of its heat gained through windows. Efficient double-glazed windows with thermally broken frames (preventing heat conduction through the frame) perform considerably better—advanced glazing solutions can exclude up to 60% of heat compared to plain single glazing—but will still allow more heat to enter in summer and escape in winter than the adjacent wall.
Internal thermal blinds or curtains can help a lot in preventing heat loss through windows in winter, but to tackle unwanted radiant heat gain in the hotter months, it’s far more efficient to stop the sun hitting the glass in the first place with appropriate external shading.
Location and orientation
There is a huge variety of options for keeping the sun at bay, from carefully chosen deciduous plantings and simple solutions like a piece of shadecloth on a frame, to awnings, shutters, blinds, and even pergolas with sensor-operated louvre roofs. To choose the best solution, firstly it’s important to consider your location and the orientation of your windows.
In most of Australia, shading is needed on windows on the north, and also the east (to prevent summer sun heating the house from early in the morning) and west (to block hot late afternoon sun). North of the Tropic of Capricorn, thought should also be given to shading windows on the south side of your house, as the sun’s steeply angled path in summer means these windows will also receive direct sun. Helpfully, the Geoscience Australia website (www.ga.gov.au) allows you to find your latitude and calculate the sun angle at any time of the day, on any day of the year.
Find the table of suppliers here.
Read the full article in ReNew 138.
Island of energy: community-owned and renewable
Denmark’s Samso Island went from complete reliance on imported oil and coal to 100% renewable electricity in just a decade. Jayitri Smiles and Nicky Ison explore the community and government partnerships that made it happen.
DURING the global oil crisis in 1973, Denmark began to think creatively about how to supply cheap energy to their population. As they built their first wind turbine, they were unknowingly establishing themselves as future world leaders in renewable energy.READ MORE »
Today, Denmark aims to have renewable energy powering 100% of their country by 2050 and to eliminate coal usage by 2030. These targets build on a track record of success: since the 1990s Denmark has witnessed the quadrupling of renewable energy consumption.
The creation of the world’s first fully renewable energy powered island, Samso, is an exemplar of Denmark’s leadership. Not only has Samso become a carbon-negative region, but it has accomplished this world-first using community investment.
In 1997, Denmark’s Minister for Environment Svend Auken was inspired at the Kyoto climate talks. He returned home with a passion to harness the collective efforts of local Danish communities in a way that promoted self-sufficiency in renewable energy. Auken held a competition, which encouraged Danish islands to consider how their clean energy potential could be achieved with government funding and matching local investment.
The most compelling application came from Samso, a small island west of Copenhagen with a population of 4100. This island of 22 villages, at the time run purely on imported oil and coal, was suddenly thrust into the global spotlight and, through a combination of local tenacity, investment and government funding, transitioned to 100% renewable power in just a decade.
At the heart of this energy revolution sit Samso’s community-owned wind turbines. Onshore turbines with a generation capacity of 11 MW offset 100% of the island’s electricity consumption. Another 23 MW of generation capacity from ten offshore turbines offsets Samso’s transport emissions. Most (75%) of the houses on the island use straw-burning boilers via district heating systems to heat water and homes, and the remainder use heat pumps and solar hot water systems.
The extraordinary result is a carbon-negative island and community. The island now has a carbon footprint of negative 12 tonnes per person per year, a reduction of 140% since the 1990s (compare this to Australia’s footprint of 16.3 tonnes per person in 2013 and Denmark’s overall footprint of 6.8). Not only is the island energy self-sufficient, they now export renewable energy to other regions of Denmark, which provides US $8 million in annual revenue to local investors.
And Samso is not slowing down. Highly motivated, knowledgeable and passionate locals are aiming for the island to be completely fossil-fuel free by 2030. They plan to convert their ferry to biogas and, despite already offsetting their vehicle emissions via renewable energy generation, residents of Samso now own the highest number of electric cars per capita in Denmark.
Read about their transition in ReNew 138.
Straight up: vertical garden design
The last thing you want is to spend a lot of money on a vertical garden system and then have it fail. Jenny and Bevan Bates provide advice and inspiration from their own living walls—five years old and growing strong!
THE inspiration to garden vertically is not new. The Hanging Gardens of Babylon, if they are more than legend, may have been an early precursor, built to bring luscious greenery to the ancient city’s terraced buildings. Your grandma’s hanging pots are a more down-to-earth example, as are vines on a trellis.READ MORE »
More recently, the idea of living walls has become a popular trend, in part in response to higher density living and homes with small gardens. For Jenny and Bevan Bates, their move to a new house with a small courtyard— and a stark black brick wall facing their living area windows—was the reason they started experimenting with gardening on a wall.
“You have to be prepared to experiment,” says Jenny. In fact, their first vertical garden was a failure. “We tried a $100 system, but the pots were too small and it dried out too quickly; it was hard to keep anything alive in it,” she says.
However, they persevered and they now have five vertical gardens providing cooling, colour and herbs, which adds interest to their home. The black brick wall in fact sets off one of the vertical gardens nicely—the colour they didn’t like turned out to be complementary to the planting!
That particular garden was their first success, says Jenny. It’s now five years old and thriving. It’s on a south-facing wall overlooked by the north-facing living area windows—a lovely sight.
They created the garden using Woolly Pockets, a product which at the time they needed to get delivered from the USA (though there are now retailers in Australia).
The pockets are composed of long troughs of recycled polyethylene (PET, from milk bottles for example). That recycled aspect was important to them; “You need to think about the full life cycle; for systems made from virgin plastic, there can be a lot to dispose of at end of life,” says Jenny.
Which plants they use has evolved over time; some plants grew bigger than expected, shaded other plants or didn’t like the position.
Read about their vertical garden in ReNew 138.
Reusing building materials in the garden
There are many uses for old building materials in the garden to create quirky but useful structures, with the added advantage that the materials don’t end up in landfill. Permaculture gardener and teacher Drew Barr shares his tips.
BricksREAD MORE »
Bricks are useful objects. Durable and cheap, their regular shape means they can be stacked or laid in patterns. Almost all bricks have the same dimensions, although older handmade bricks may be slightly smaller. The size and shape are designed for easy one-handed handling by an adult.
Bricks are energy-intensive to manufacture and transport, but will last hundreds of years, and can be used over and over again.
When reusing bricks, you’ll need to clean them to remove the mortar. This is dirty and laborious work and seems very slow to begin with, but once you have mastered the knack you will be surprised how fast you can clean bricks. The best tool for this is a scutch hammer, which has replaceable toothed blades called combs. Chip at the mortar where it meets the brick and it will come off in big chunks. Wear gloves and a face shield though as flying mortar chips really hurt.
Broken concrete slabs
Concrete is also a very energy-intensive material to manufacture, and similarly highly durable and strong, and ideal to reuse.
Concrete slabs, sometimes referred to as ‘urbanite’, can be reused to make crazy paving, or stacked without mortar to form low retaining walls. When sourcing slabs make sure you get only non-reinforced slabs such as from council footpaths or old driveways. Reinforcing steel in the concrete is very difficult to cut, and as it rusts it will swell up and split the slab.
Councils often replace footpaths and must dump the slabs of concrete they remove, and they will usually be happy to dump it at your place for free.
Read more on reusing old concrete slabs, clay pavers, roofing tiles, roofing iron, car panels, bathtubs and more in the full article in ReNew 138.
ATA member profile: Ripples in the community
Long-time ATA member Ali Campbell has no qualms about buying secondhand instead of new and looks at all purchases through a “green lens.” She talks to Jodie Lea Martire about how community is critical to sustainability.
ALI Campbell couldn’t bear to see her old piano go to waste, so it stands in the chook shed as a piece of art. It’s a good demonstration of her creative commitment to sustainability, which has led from high eco-living standards at home to diverse community involvement. As Ali says, being part of an active community “helps sustain you and recharges you for staying in the sustainability field.”READ MORE »
Bushwalking and camping gave Ali a connection with nature, but her real evolution towards environmental action came with her first child. She and husband Bruce had been “unwise, unwary consumers until that point”, but they realised that every other parent had also needed clothes, cots and change tables so they could use “secondhand everything.” From there, the Campbells took a good look at their “consumption and stuff.” They reduced purchases, packaging and waste, considered where their food and goods came from, and boosted their home chook-and-vegie garden.
The garden led to conversations about sustainability with others, and builder Duncan Hall put Ali and Bruce on to the ATA. Soon, the family was experimenting with solar stoves, and now “everything we do has that green lens.”
They have worked to reduce their home’s environmental impact, including greywater systems, water tanks, double-glazed windows, reorienting for better lighting and using Australian-made materials. Ali used ATA-sourced information to explain her decisions to both their builder and plumber during renovations, and emphasises that it’s crucial to hire workers who ‘get it’ and aren’t just greenwashing their work.
Ali says, “The community thing is critical. It goes without saying, but it needs to be said.” She spent six or so years volunteering as an organiser with Melbourne’s Sustainable Living Festival (SLF), and gardened with the Stephanie Alexander Kitchen Gardens in Altona Meadows for a time. She is also active on the Inner West Buy Swap Sell and Freecycle Facebook groups.
Ali participates in Transition Hobsons Bay (THB), and she and Virginia Millard run the Give Take Stand: an unstaffed booth where people share quality, unwanted items (like a free op shop). Ali says the autonomous setup has strengthened community involvement without forcing obligation or onus on anyone. It has been hosted in venues around Hobsons Bay and the council is providing funds to boost the work and establish the stand as a waterproof outdoor shed.
Another project Ali organises through SLF and the transitions group is Bunches of Lunches. Now in its third year, Ali and Transitions Hobsons Bay member Tarius McArthur run three-hour sessions which teach participants to cook five healthy, freezable dishes suitable for school lunches—and promote local food, low packaging and low energy use.
Ali and Bruce have also combined their home and community efforts by signing up their new seven-seater VW Caddy to Car Next Door, allowing locals to rent their vehicle. This let the Campbells balance their need for a second car every now and then, while knowing they’re “not just sitting on this asset.”
Reading ReNew gives Ali great ideas, a sense that she’s not alone in her activism, and—most importantly—hope. The magazine’s coverage of policy developments, news analysis and innovations provides “positivity and support, and that’s what keeps her doing this.”
To end with Ali’s own assessment of her environmental contribution: “I can feel frustrated because I’m not creating seismic change, but I hear frequently, most weeks, ‘You’d love this, Ali!’, so I know I’m having a ripple effect around me and I just hope that keeps rippling on and on.”
This member profile is published in ReNew 138. Buy your copy here.
Tassie off-grid home
Given their distance from the nearest power pole, it made sense financially as well as philosophically for this Sydney couple to go off-grid in their new home in Tasmania. Peter Tuft describes how they went about it.
As we approached retirement my wife Robyn and I knew we did not want to spend the rest of our lives in Sydney. Sydney’s natural environment is glorious but it is also much too busy, too hot and humid in summer, and our house was too cold and hard to heat in winter. We had loved Tasmania since bushwalking there extensively in the 1970s and it has a lovely cool climate, so it was an obvious choice.READ MORE »
We narrowed the selection to somewhere within one hour‘s drive of Hobart, then on a reconnaissance trip narrowed it further to the Channel region to the south. It has lush forests and scattered pasture with the sheltered d’Entrecasteaux Channel on one side and tall hills behind—just beautiful. And we were extraordinarily lucky to quickly find an 80 hectare lot which had all those elements plus extensive views over the Channel and Bruny Island to the Tasman Peninsula. It was a fraction of the cost of a Sydney suburban lot.
The decision to buy was in 2008 but building did not start until 2014 so we had plenty of time to think about what and how to build. We have always been interested in sustainability, and renewable energy in particular, even before they became so obviously necessary: my engineering undergraduate thesis in 1975 was on a solar heater and Robyn worked for many years on wastewater treatment and stream water quality. There was never any doubt that we would make maximum use of renewable energy and alternative waste disposal methods.
From the beginning we knew the house would be of passive solar thermal design. The house sits high on a hill (for the views!) and faces north-east. The main living room is entirely glass-fronted, about 11m long and up to 4m high with wide eaves. That allows huge solar input to the floor of polished concrete. A slight downside is that there is potential for it to be too warm in summer, but we’ve managed that with shade blinds and ventilation and so far it has not been a problem. All walls, floor and roof are well insulated, even the garage door, and all windows are double-glazed. Supplementary heating is via a wood heater set in a massive stone fireplace chosen partly for thermal mass and partly because it just looks awesome. Warm air from above the wood heater convects via ducts to the bathroom immediately behind the chimney, making it very cosy indeed.
Read the full article in ReNew 137.
Still a clever country
Energy efficiency consultant Geoff Andrews admires Australian innovation, but, as has often been noted, finds the next step—commercialisation—is lacking. Collaboration, governments and risk-taking could all improve that, he suggests.
I view innovation as change for good, so change which improves sustainability clearly qualifies. Most readers of ReNew would agree that we have to improve the sustainability of our society, so we must innovate. But, how do we do that, and what lessons can we draw from Australia’s sustainability innovation performance to date?READ MORE »
There is no question that Australia has provided the world with more than its share of innovations, including in sustainability. In renewable energy alone, Australia has led the world in PV efficiency for decades, pioneered many improvements in solar water heaters, and is now developing wave energy. We’ve been first or early implementers of two flow battery technologies (vanadium redox by Maria Skyllas-Kazaco at UNSW in 1980 and zinc bromine by RedFlow). Scottish-born James Harrison built one of the first working refrigerators for making ice in Geelong in 1851 (before that, ice was imported from Canada),and we invented wave-piercing catamarans and the Pritchard steam car. We even had manned (unpowered) flight by heavier-thanair craft a decade before the Wright brothers with Lawrence Hargrave’s box-kite biplane.
Of course, Australian innovations are prevalent in many other sustainability areas including medicine, construction, agriculture and fisheries, but space is limited here. What we could have done a lot better is commercialising those innovations in Australia. Imagine if Australia led the world in the manufacture of solar panels, refrigerators, air conditioners, wi-fi devices and evacuated tube heat exchangers, the way we do with wave-piercing catamarans and bionic ears.
Improving commercialisation would provide funds to improve our budget bottomline and allow us to do even more innovation and more commercialisation. To achieve this, I think we need to do several things.
Read the full article in ReNew 136.
The world’s first baker
Why don’t we know about the oldest grinding stones in the world, found in Australia, or the crops cultivated by Aboriginal Australians? Bruce Pascoe is helping change that.
If you were asked who the world’s first bakers were, what would your answer be? Most would think first of ancient Egypt where it is believed bread was first baked around 17,000 BCE. And yet there is evidence to show that grindstones in Australia were used to turn seeds to flour 30,000 years ago. Archaeologists found the evidence for this at Cuddie Springs in New South Wales in the shape of an ancient grinding stone which had been used to reduce grass seeds to flour. These were the bakers of antiquity. It took Egypt 12,000 years to repeat this baking experiment. Why don’t our hearts fill with wonder and pride?READ MORE »
Australian sovereign nations cultivated domesticated plants, sewed clothes, engineered streams for aquacultural and agricultural purposes, and forged spiritual codes for the use of seed in trade, agricultural enterprises, marriage and ceremony.
This was and is an incredible human response to the difficulties of fostering economic, cultural and social policies. It may be unique in its longevity but also in its ability to flourish without resort to war. Australia’s reluctance to acknowledge what was lost can be witnessed in our ignorance of the birth of baking, the gold standard of economic achievement.
Why is this? Is it a malicious refusal to recognise the economic triumphs of the people from whom the land was taken or a simple culture of forgetting fostered by the bedazzlement of Australian resources and opportunities?
If we could rid ourselves of the myth of low Aboriginal achievement and nomadic habits, we might move toward a greater appreciation of our land. We might begin to wonder about the grains that explorer Thomas Mitchell saw being harvested in the 1830s, and the yam daisy monoculture he saw stretching to the horizon of his ‘Australia Felix’, the early name given to western Victoria. These crops must have been grown without pesticides and chemical fertilisers and in harmony with the climate; surely they are worthy of our investigation.
Read the full article in ReNew 136.
Less noise, no fumes – testing cordless leaf blowers
ReNew reader Colin Dedman puts the latest generation of lithium-ion cordless leaf blowers to the test and is blown away by how far they’ve come, though price and run time can be an issue.
Why would you buy a cordless leaf blower? Why would you buy a leaf blower at all? For the most sustainable living, shouldn’t we rake up all our leaves and debris by hand, and clean out our gutters by crawling around on the roof?READ MORE »
For those of us with rainwater tanks, cleaning the gutters frequently is a necessity rather than a luxury, to ensure that precious rainwater ends up in the tanks rather than spilling out of a blocked gutter. For many years I cleaned up the leaves by hand, while cursing the weekly scream of my neighbour’s two-stroke leaf blower. Then my aging back convinced me that if you can’t beat them, join them, so I purchased my own screaming $88 petrol blower, that does clean the gutters and patio well. But I hate using it on account of the noise, fumes, hard starting and mixing/storing of two-stroke fuel. There must be a better way.
Corded electric leaf blowers are quieter, always start first time and can potentially use renewable electricity, but the inconvenience of a long extension cord rules them out for me. What about the electric cordless blowers then—are they just ‘toys’ as many people think?
Here I blow away the myths, by subjecting a variety of cordless blowers to a series of standard tests so you can judge which blower, if any, is suitable for your needs. I’ve included two mid-range petrol blowers and a corded blower in the tests for comparison.
Measuring blower performance
Some manufacturers would have us believe that the all-important parameter is the air flow rate in cubic metres per hour, while others boast of their impressive discharge velocity in kilometres per hour or metres per second. In reality, both are important.
The most useful single parameter to measure a blower’s effectiveness is the blowing power in watts (W), being the power of the moving airstream, as this relates directly to the ability to shift stubborn debris and move a lot of leaves and debris in a short time. The blowing power is less than the input power, due to inefficiencies in the motor and fan.
Manufacturer published values of air flow and velocity have not been included, because they are sometimes incomplete or inconsistent. In one case the specifications printed on the box were different to in the user manual—both can’t be right! Other issues include quoting the peak rather than average velocity at the discharge nozzle, and quoting the higher flow rate without the nozzle attached. Therefore, to enable meaningful comparison of competing blowers, I’ve measured the air flow rate, velocity and blowing power according to ANSI Standard B175.2, using calibrated equipment, and tabulated this for all the blowers tested, providing a resource for comparison of blower performance.
To read the extended version of this article in its entirety, click here to download it in PDF format.
Heating buyers guide 2016
Heating can be a large proportion of energy use in the home. Lance Turner looks at what efficient options are available, including hydronic and reverse-cycle air conditioners.
OUR previous heating buyers guide looked at heat pumps (commonly called reverse-cycle air conditioners) due to their high efficiency, low cost and simple installation. Later in this guide we take another look at reverse-cycle air conditioners and their advantages, and list the most efficient units currently available.READ MORE »
However, there is another form of heating that not only lets you choose a heat pump as the heat source, but other energy sources as well if they are more appropriate. That system is hydronics.
Hydronic systems consist of a heat source (commonly called the boiler) to heat water, and one or more pipe circuits which have the heated water flowing through them. Each circuit incorporates one or more radiators, which emit warmth into the room.
Most hydronic systems have multiple circuits, so you can heat all or only part of a home, allowing you to leave unused, closed- off rooms unheated to reduce energy use.
Water is circulated through the system using low-pressure pumps, and circuits are turned on/off by electrically operated valves, usually controlled by an electronic controller. The controller enables a system to be programmed to heat certain parts of a home at particular times—for example, heating the living areas during the evening and the bedrooms just before bedtime.
Hydronic systems are recognised to have a number of advantages over other forms of heating. The heat being either underfoot or close to it (through the use of skirting radiators or panel radiators mounted at floor level) means that you get the feeling of warmth with lower ambient room temperatures than with space heating. Also, there is generally very little air movement with hydronic heating, reducing the potential cooling effect of airflows produced by convective heating such as reverse-cycle air conditioners or ducted gas systems.
Read the full article in ReNew 135
Click here to download the full buyers guide tables in PDF format.
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.
A tropical take: smart cooling in the tropics
A Northern Territory program that works with low-income residents to reduce their energy bills and improve their comfort is starting to see results. Robyn Deed talks to one of the energy assessors about his approach and how the project is progressing.
ReNew first reported on COOLmob’s Smart Cooling in the Tropics project in December 2014, when the project was just starting. Since then, 480 households have had initial home visits and many have had upgrades applied to their homes.READ MORE »
Data is also being collected. This is the first large-scale project to identify and measure the best approaches to cooling, comfort and energy efficiency in tropical Australia. The outcomes will be used to inform national energy policy, and to influence building codes and rating systems to make them appropriate for the tropics.
The research findings will consider a range of factors including which treatments produced the biggest energy cost savings, which households achieved improvements in comfort levels, and which participants gained better awareness of energy consumption issues and opportunities.
While the evaluation phase is only just starting some early anecdotal observations are giving a flavour of the evidence to come, says Project Manager Jessica Steinborner: “The two primary issues identified through the home visits are heat gain and air flow.”
- Many homes have no or inadequate shading and a number have dark roofs.
- A high proportion of homes assessed have outside walls of high thermal mass.
By the end of the project, nearly a quarter of participating homes will have had a heat prevention solution such as shading or reflective roof paint.
“Shading has been a really popular treatment. In addition to preventing heat gain, shading creates a protected outdoor living space away from the hot concrete interiors of their homes,” says Jessica.
- Ventilation is often restricted either as a result of the orientation or because of the design, with windows and doors poorly located to capture a prevailing breeze.
- Many homes have fly screens in disrepair and consequently not in use, leading to houses being shut up with the air conditioner on.
Half of the households will have received a treatment addressing air flow including upgrades to their doors and windows to facilitate passive cooling and upgrades to their fans (ceiling, wall and floor).
Other observations and some surprises
- The majority of participants are home during the day and, despite reporting the highest discomfort in the afternoon, they were opting to not use the air conditioner until the evening.
- Average number of air conditioners was three and average temperature setting was 24 °C.
- On average, participants were using 26 kWh/day, the average usage for Darwin.
Until more data is available, it’s great to hear comments like this: “I have lived in Darwin for 15 years and this is the first time I’ve felt cool and comfortable during the wet season,” says Mieme, one of the participants.
Read the interview with one of the energy assessors in ReNew 134.
A focus on thermal efficiency
Energy efficiency is perhaps the most critical aspect of sustainable living, yet it’s oft-ignored and subject to changing government policies. Robyn Deed talks to Lyn Beinat from ecoMaster about the changes she’s seen in the energy efficiency industry and her top tips for householders.
Energy assessment business ecoMaster has seen many government policy introductions and exits over the 11 years they’ve been in business. They’ve had to constantly adapt. “Even changes to solar panel rebates and the RET have affected us, although we don’t deal with solar products,” says ecoMaster CEO Lyn Beinat. Government support is crucial to confidence. Lyn comments, “Perhaps people decide it’s all too hard or likely to be too costly when the government support isn’t there.”READ MORE »
The biggest shift in ecoMaster’s approach has been that they now look at the whole house right from the start. Lyn says, “It’s not that we want people to do everything all at once, but we’ve found that people are often focusing on just one aspect, like secondary glazing, when that may not be the most important thing to look at. The biggest problem is often draughts.”
Another change they didn’t expect at all has been a move into product development. Their research and work on their own home, and with clients, has led them in that direction. Maurice Beinat (Lyn’s husband and ecoMaster’s Chief Technical Officer) has done a lot of energy efficiency assessments (“more than anyone on the planet!” claims Lyn) and through that they identified problems that needed better solutions.
For example, for draughtproofing, Lyn says there are many products available, but it’s hard to find ones that are going to last: “many of the stick-on draught excluders will only last a year or so before they start peeling off, or they’ll cause problems for door closing,” notes Lyn.
Read the full article, including approximate costs for thermal efficiency changes, and Lyn’s top tips in ReNew 134.
On the rebound: countering the sceptics
Does energy efficiency lead to energy use that offsets some of the savings, via a ‘rebound effect’? It’s not that simple, says Alan Pears, and in fact, the opposite can happen.
MANY ‘energy efficiency sceptics’ argue that saving energy simply leads to increased energy use that offsets the savings. Some go as far as suggesting energy efficiency is a waste of time and a sham.READ MORE »
Indeed, there is a large body of literature that documents the existence of a ‘rebound effect’. But there is wide disagreement about how large it is—estimates range from a 10% to 70% reduction in net savings. Studies find that the extent of this rebound varies across sectors and activities.
On the other hand, other studies have shown that estimates of potential savings from energy efficiency policies have often been conservative, and costs have been over-estimated. For example, recent analysis of the effectiveness of Australia’s appliance efficiency programs, using improved field data and analytical methods, increased the estimated benefits by a factor of two (as measured by cost per tonne of avoided carbon).
The International Energy Agency has shown that, if the multiple benefits of business energy efficiency measures are considered, total savings can be up to 2.5 times the value of the actual energy saved. These benefits can include productivity improvement, health benefits, reductions in costs in infrastructure and more.
Like many issues, the rebound effect has an element of truth underpinning it. But, overall, it is not a game changer. Indeed, with the right policy settings and in many situations, investment in saving energy can amplify overall energy savings. This article aims to unravel the story.
What is rebound?
The term ‘rebound effect’ itself reflects a bias against valuing energy efficiency. It implies that some or all of the claimed savings from energy efficiency are inevitably taken back through increased energy use. This can certainly occur, but the opposite, amplification of savings, can also occur. The outcome depends on the policies, the behaviour of decision-makers, and the technical detail.
Broadly, the critical factors influencing the size and direction of the overall change in energy use due to energy efficiency improvement are how big the financial savings are, how they are spent, the overall impact of that spending as it flows through the economy, and technical system effects.
A more balanced term might be ‘flow-on effect’.
Consider an extreme example. If I use the money I save through energy saving actions to buy a block of energy-intensive aluminium, overall energy use may increase, as more energy will have been used to produce the aluminium than I am likely to have saved. But if I invest my savings in more energy saving actions, or to support the growth of an energy saving industry, I will amplify the energy savings.
In practice, the overall outcome is difficult to estimate: if the aluminium I buy is used to reduce the weight of a car, the fuel savings may exceed the lifetime energy ‘cost’ of the aluminium—if I believe the aluminium industry’s research! And, if the aluminium is eventually recycled, up to 90% of the energy ‘invested’ in its production will be recovered, reducing future energy consumption.
Read the full article in ReNew 134.