In ‘Energy efficiency’ Category

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ReNew 140 editorial: It’s electrifying – the benefits of changing fuels

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AS ONE of our case studies says, many living in the colder parts of Australia have long assumed that winter equals high energy bills (often gas) for heating. But what if that association could be changed, with benefits for both the hip pocket and the environment?

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Over the last few years, the ATA, ReNew’s not-for-profit publisher, has been promoting a shift to efficient electric appliances for the three major energy users in the home— heating/cooling, hot water and cooking—with the important message that in many cases this shift will be both cheaper for the householder and better for the environment. It’s a message that is resonating with many committed to making sustainable changes at home.

Another of our case studies makes the point that part of the reason for the shift is the tremendously improved effectiveness of new state-of-the-art efficient electric options; how much better is a heat pump for heating over an old electric bar heater, or the responsiveness of an induction cooktop over the old electric coil cooktops (I still remember the excitement at the covered coils on my parents’ new stove in the 1980s!).

Apart from case studies, the ATA revisits its modelling of the economics of going all-electric, including how having solar panels helps in the financial equation. We also answer some commonly asked questions: how do you disconnect from the gas network; when do you need to start thinking about three-phase or a higher amperage power connection; and can a keen cook be wooed away from cooking with gas, even if they are ‘wokstars’ (short answer: yes)?

There’s much more in the issue besides. Staying warm is not just a heater choice— house design, draughts and insulation all need to be addressed. Our buyers guide looks at insulation—what’s available and where it’s needed—along with installation case studies and the warming results. Plus we look at window coverings, including the beauty of high-performing honeycomb blinds adopted in many of our case studies.

Designing with structural insulated panels (SIPs) also gets highlighted this issue, with two houses using this prefab construction approach to produce well-sealed, high-performing homes. These projects suggest a shift towards thinking about air tightness, with several houses also using blower door tests to find out just how sealed they are.

We also cover one of the most inspiring outcomes of the Community Energy Congress, held in March this year. With many representatives from Australian and other First Nations communities, out of the congress came the formation of an alliance of First Nations peoples seeking a renewables pathway to energy justice for their often remote and poorly served communities.

Stop Press! The ATA has just won not one, but two awards from the United Nations Association of Australia, one for climate change leadership and one for Sustainable House Day’s role in education and engagement. Great stuff

Robyn Deed
ReNew Editor

ATA CEO’s Report

THOUGH very disappointing, it came as no surprise to many that Donald Trump followed through on his election promise and pulled the United States out of the Paris agreement on climate change. The USA joins Syria and Nicaragua as the only UN member countries not to sign the agreement.

Donald Trump’s move seems to have only strengthened the commitment of others to take the lead on action on climate change. The momentum for a low-emissions future grows apace with the price of renewable energy continuing to fall—it is now cheaper to develop solar and wind energy than new coal-fired power stations in most countries.

The stories in this issue of ReNew show the transition is happening already, and communities and the market are leading the way. Now we need government on board to ensure it is fair and equitable and that everyone is brought along on the journey.

At the ATA we continue to provide independent advice to help renters, apartment dwellers and disadvantaged communities. Working with our partners in the social sector we advocate for reform of the energy market to ensure it is of benefit to consumers as well as the planet. Delivering on-the-ground projects in East Timor and to community groups across Australia, we put knowledge into action for a fair and just renewable future.

The ATA cannot solve climate change—no one organisation can—but we can and do empower people like you to take responsible and effective action to reduce Australia’s, and the world’s, carbon footprint.

If you would like to support the work of the ATA, make a tax-deductible donation by the end of the financial year on 30 June. Go to shop.ata.org.au or call 03 9639 1500.

Donna Luckman
CEO, ATA

You can purchase ReNew 140 from the ATA webshop.

An all-electric home can reduce your bills and ‘green’ your energy use, particularly if you run your house from the sun. And, as the grid gets greener, so too does your house. The roof of this Hawthorn, Melbourne extension was designed specifically to house the 4.5kW solar array that powers the house. Design by Habitech; read the full profile in Sanctuary 37.

Three steps to all-electric

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Thinking about going all-electric, but unsure what’s involved? Here we present an overview of the steps to going all-electric and where to find more information.

IN THE past, gas was seen as a cheap and clean option for winter heating, hot water and cooking. However, the efficiency of electric appliances has improved dramatically and solar PV has fallen so much in price (and can be used to power those appliances), meaning it can now be cheaper and more environmentally sustainable to go off gas and run an all-electric home.

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The ATA first looked at this in 2014 and the modelling results can be found at www.bit.ly/ATA-GVE. In summary, the results showed that even when paying grid electricity rates (i.e. without solar PV), for many Australian homes it would be cheaper over 10 years to switch from gas to efficient electric appliances, with appliances replaced as they fail or in some cases even before this. Greater savings can be found when disconnecting completely from the gas network as this eliminates the gas supply charge (costing several hundred dollars a year). The report also highlighted that new homes should not be connected to gas, as doing so would lock in higher energy costs than needed.

Savings will depend on the thermal performance of your home, the electricity price negotiated with your retailer, your gas tariffs and the efficiency of your appliances. The Grattan Institute found that a large home in Melbourne can save $1024 per year by disconnecting from the gas grid: www.bit.ly/GATCAHC

In addition, by using modern electric appliances, your home can be converted to use 100% renewable energy, whether you generate your own electricity with rooftop solar or purchase 100% GreenPower from your electricity retailer. The ATA’s latest modelling compares gas running costs to electric with solar; see p. 44 for preliminary results.

Three steps to all-electric

There are three main areas where many homes currently use gas: space heating, hot water and cooking (mainly cooktops, but ovens too). To switch to all-electric, there are now efficient options available for these uses. This article summarises the options and points to where to find more information.

Read the full article in ReNew 140.

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2017 insulation buyers guide

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Is your home hot in summer and freezing in winter? It probably has little or no insulation. Lance Turner takes a look at how insulation can help.

Download the full buyers guide tables here.

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Insulation, like orientation, is often overlooked by householders, perhaps because it’s not on display, hidden as it is in the ceiling, walls or underfloor. You may not be able to see it, but, in most homes, you can feel its presence, or absence. Insulation is key to providing a liveable home when the weather cools down or heats up, without breaking the bank on energy costs.

Insulation works by resisting the flow of heat, slowing down heat loss in winter and heat gains in summer. In a well-insulated home, once the home has been heated to a comfortable level in winter, it will stay warm with far less energy input than an uninsulated or poorly insulated home would require.

The same applies in summer: a properly insulated home will take longer to heat up and, if an air conditioner is used, it will use less energy than one cooling an uninsulated house. One summer-time caveat: any windows that receive direct sunlight need to be shaded, particularly west windows, as insulation can slow the ability of the house to cool down if there are large heat gains from windows.

Heat transfer and insulation
There are three ways that heat is transferred to or from a building: conduction, convection and radiation (and through gaps, of course, but draughtproofing is outside the scope of this guide).
Conduction is the transfer of heat through a substance, in this case the walls, floor and ceiling of a house. The type of insulation used to reduce conductive heat transfer is known as ‘bulk’ insulation.

This is the most common home insulation and may be in the form of fluffy ‘batts’ or ‘blankets’ made of materials such as polyester, glass or mineral wool or sheep’s wool. Bulk insulation may also use a loose-fill material, which is pumped into the roof or wall cavities and sealed with a spray-on cap. All these materials are poor conductors of heat and so reduce the rate of heat flow, provided they are installed correctly.

Convection heat transfer—heat transferred through the circulation of air—is the undoing of many insulation jobs. Circulating air can pass between poorly installed insulation materials and thus transfer heat into or out of the house, vastly reducing the effectiveness of the insulation.

Radiation is a different type of heat transfer. All warm objects radiate heat in the form of infrared radiation. This heat can be reflected back to where it has come from using reflective foil insulation, so that heat loss or gain through radiation is greatly reduced.

Reflective surfaces such as foil don’t just reflect, they also have low emissivity—the ability to emit radiation, or heat in this case. This means heat that has entered the material from the non-reflective side is not emitted from the reflective side easily. Thus, foils work to reduce heat flows in both directions, even if only one side of the material is reflective.

Download the full buyers guide tables here.

Read the full article in ReNew 140.

Thermal image post wall insulation

Wall insulation retrofits on trial

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A recent series of trials by Sustainability Victoria has investigated the viability and cost-effectiveness of energy efficiency retrofits. Eva Matthews summarises the overall study and the results from one trial, retrofitting wall insulation.

WHILE residential development (new housing and renovations) continues apace throughout urban Australia and mandatory building standards have been introduced over the last couple of decades to improve energy efficiency and reduce greenhouse gas emissions, there remains a huge pool of older existing housing stock that hasn’t benefitted from these improvements. There have also been few studies to determine the extent of inefficiency in this existing housing, how it might be practically upgraded and how cost-effective it would be to do so. Step in Sustainability Victoria (SV), who commenced a study in 2009 to investigate these information gaps.

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Their On-Ground Assessment (OGA) compiled data, based on modelling, from a “reasonably representative” sample of 60 pre-2005 homes in Victoria, with the results published in December 2015 (The Energy Efficiency Upgrade Potential of Existing Victorian Houses; www.bit.ly/2cTP6eJ). The second phase of the study was to implement energy efficiency upgrades in a selection of houses and to assess costs and savings, householder perceptions and any implementation issues. The results of these trials are also at the above link.

Here we outline the results of the OGA as it relates to wall insulation, focusing on the Cavity Wall Insulation Retrofit Trial, conducted with 15 homes in 2012 and 2013, with results published by SV in January 2016.

Why the focus on wall insulation? Simply, because it is a significant factor in the energy performance of buildings, and millions of older homes don’t have it. Those that do, benefit from a home that is warmer in winter and cooler in summer with reduced need for supplementary heating/cooling due to greater retention of the heat and coolth, fewer draughts, less noise pollution and less condensation on internal walls in winter—the latter inhibiting mould growth which can be a significant health hazard.

Why consider pumped-in wall insulation as the most feasible retrofit option? Unless you’re undertaking a renovation that includes the removal of internal wall linings or one in which weatherboards are to be removed to allow access to the wall cavities from the outside, pumping in wall insulation is the only practical option for existing housing stock.

The OGA found that 95% of the 60 homes in the study had no wall insulation. With 15% to 25% of heat gain/loss being attributed to uninsulated walls, this helps clarify why the average house energy rating of these pre-2005 houses was just 1.81 Stars (significantly lower than the requirement of 5 Stars for post-2005 and 6 Stars for post-2011 homes).

Read the full article in ReNew 140.

SIPs house in Toowoomba

SIPs house in Toowoomba

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Bill and Margaret Curnow’s house in Toowoomba is built using structural insulated panels and is being monitored for heating and cooling energy use by QUT. Dr Wendy Miller reports on the research.

MOST Australian homes are built using timber or steel frames, over which internal and external wall linings and a roof are then added, along with insulation between these ‘skins’. Structural insulated panels (SIPs) present a whole new construction technique: these panels provide the linings, insulation and structural framework all in one unit.

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My research team at Queensland University of Technology (QUT) has been examining how houses using SIPs are actually performing, in terms of comfort and energy use (i.e. heating and cooling impacts), as well as how the homeowners and their designers and builders have managed this new construction method. This research is part of an Australian Research Council project looking at how innovation and high energy performance can be implemented in Australia’s housing industry. Bill Curnow’s house in Toowoomba is one of four SIPs homes in our research. The other homes are located in South Australia, Victoria and Western Australia. Our project also examines performance of homes that have implemented other innovations.

Temperature performance

Toowoomba is in a warm temperature climate zone that tends to require more heating than cooling in houses. There are six months of the year where the mean minimum temperature is less than 13 °C and only two months where the mean maximum temperature is higher than 27 °C. Despite this, temperature extremes as high as 40 °C and as low as -3 °C (or -16.5 °C with wind chill factor!) can occur. Houses should be able to provide some level of occupant comfort under ‘normal’ as well as extreme weather conditions.

We compared the outdoor temperatures for Toowoomba with temperatures in Bill’s living room. In January 2016, Toowoomba’s outdoor temperatures ranged from 19 °C to 34.2 °C, with a mean of 28 °C. In July, the outdoor temperature ranged from 10.8 °C to 24.5 °C, with a mean of 17.5 °C (interestingly, almost 1 °C hotter than the long-term mean for this month).

Compare this with the much more comfortable range of temperatures in Bill’s living room, as shown in Table 1, with January temperatures largely in the range 20 °C to 26 °C and July temperatures in the range 15 °C to 21 °C. This performance with no additional space heating or cooling suggests that the living room is performing equivalent to an 8.5 to 9 Star rating.

Read the full article in ReNew 140.

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Capital improvements: The path to all-electric

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Switching to electric appliances wasn’t really thought of as economically or environmentally beneficial 10 years ago when Ben Elliston’s household started their efficiency improvements, so theirs has been a gradual path to all-electric. By Robyn Deed.

You could call Ben Elliston’s household a ‘poster child’ for getting off gas, but that’s not how it began. Rather, when they started the process to improve the efficiency of their Canberra home 10 years ago, the family’s mindset was aligned with the message at that time that gas was a cheaper and relatively clean fuel, compared to grid electricity. Ten years on and several ‘face-palm-why-did-we do-that’ moments later, they are now enthusiastically all-electric, with their energy use, operating costs and greenhouse gas emissions all pleasingly reduced—and with some added advantages of their new electric appliances that they didn’t expect.

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Looking back, Ben says one of the biggest shifts has been in what a state-of-the-art electric appliance looks like. From the simple electric element appliances of the 80s (the coil cooktop, electric blow heaters and electric element tanks), many of the newer appliances offer not only lower running costs—over both gas and older electric units—but also safety and other benefits. Ben says, “There were lots of advantages we hadn’t anticipated when we shifted to electric appliances. For example, our induction cooktop has smarts to switch off if it senses that a pot is too hot and has run dry; our heat pump air conditioner is also much quieter than our old gas wall heater.”

The other major factor for Ben’s family is environmental. With the ACT now well on the way to 100% renewable electricity by 2020, Ben says, “In 2020, our household will be net zero emissions, which would not be possible if we were still using any gas appliances.”

Read the full article in ReNew 140This article is based on a talk given by Ben Elliston at the ATA’s Canberra branch meeting in April 2017 and an interview with Ben. Click here for slides from the talk.

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Not just window dressing: High-performance curtains and blinds

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Internal window coverings can protect privacy and dramatically improve the thermal function of a house, and if you choose with care, they can help keep you comfortable for years, writes Anna Cumming.

Windows are a complex and interesting part of the building fabric of a house. They admit light, warmth and fresh air; they connect the occupants visually with the outside world; sometimes they frame spectacular views. But from an energy efficiency point of view they are usually the weak link in the building structure. Through windows up to 40% of a home’s heating energy can be lost and up to 87% of its heat gained, according to Your Home. High-performance, double or even triple glazing helps this equation, as does careful consideration of window size, location and orientation. But to ensure the best thermal performance of your home, you’ll need effective window furnishings. Blinds, curtains and shutters can improve a window’s performance, make your home more comfortable and reduce energy costs.

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What’s the purpose?

“Internal window furnishings serve a variety of purposes, including light control, privacy, reducing glare, heat reduction and heat retention,” says interior designer Megan Norgate of Brave New Eco. Soft window furnishings can also buffer sound. If you’re building or renovating, consider window treatments as part of the design process, because taking into account the associated requirements and thermal contributions may mean you make different decisions about the extent and location of your glazing.

It’s important to consider the main purpose when choosing window coverings. If minimising heat gain in summer is the main aim, it’s best to keep the sun off the glass in the first place with an external shading device such as an eave or awning (see our article on external shading options in ReNew 138). Semi-transparent blinds or curtains are a good option if privacy or glare reduction is the primary aim; they can be combined with heavier curtains for night-time heat retention.

Thermal performance is where great window coverings really come into their own: “They can act like de-facto double glazing if they are multi-layered and tight fitting to the window,” says designer Dick Clarke of Envirotecture. Snugly fitted and insulative blinds and curtains trap a layer of still air next to the window, reducing transfer of heat from the room to the window and thus outside. They also provide a feeling of cosiness: “If you are sitting in a warm room at night between an uncovered window and your heating source it is likely you will feel a chill, partly because of the draught created by the interior heat making a beeline for the cool exterior. Properly fitted and lined curtains and window treatments are the best way to avoid this effect,” explains Megan.

Read the full article in ReNew 140.

Induction cooktop and control area

Convert to induction

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Keen cook Sophie Liu loved cooking on gas until induction came along. She describes why it won her over.

IT’S BEEN two years since I researched and purchased an induction cooktop, and wrote a product profile for ReNew’s sister magazine, Sanctuary (see issue 30). Since then I’ve been using this new technology on a daily basis and it’s official—I’m an induction convert!

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I am a keen cook and for the longest time I loved cooking on gas. But the advantages of induction for the environment and usability won me over. Like any new appliance, it took a while to get used to, and there are a few tips and issues worth pointing out and a few downsides to avoid. I’ve also outlined my good experiences and the many advantages of induction cooking below.

Renewably sourced electricity—one, Gas—nil

While cooking makes up a small part of a household’s energy use, it is still important to a home’s environmental footprint and running costs, particularly when other higher energy use areas have been addressed (see ‘Energy-efficient cooking’ and ‘Are we still cooking with gas?’ in ReNew 130). In terms of energy efficiency, ATA’s analysts have found induction comes out on top, just ahead of ceramic electric resistive cooktops, and with both these electric options ahead of gas hobs (input: induction 600 MJ/year, ceramic electric 667 MJ/year, gas 1200 MJ/year, all for the same energy output of 480 MJ/year).

ATA energy analysts estimate that energy use for an average household with a gas cooktop and oven is 2000 MJ/year—less than 4% of the average household’s energy use. By contrast, an induction cooktop and electric oven come out at 1000 MJ/year, 50% less. I also prefer electric induction to gas as I can run it on renewable electricity rather than using a fossil fuel.

With great power comes great responsibility

My experience of cooking with induction is that it’s the fastest, most responsive and most powerful method of cooking out there.

It took some time to get used to the faster, more powerful cooking. At the start, I certainly burnt or overcooked a lot of things—I even spectacularly ruined rice one night, which, with my Chinese heritage, is embarrassing to admit!

However, as with any new appliance, you gradually learn how to use it successfully. Now I know the power levels to start rice or pasta on, then what to turn them down to. We can slow cook things, too, and not have to worry about the gas going out, which often happened on low with our old hob.

Read the full article in ReNew 140.

SIPs house

Sealed with a SIP

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Last year the energy costs for this four-person household came to just $560, due to an airtight house design, a PV system well-matched to usage and a switch to all-electric. Kyle O’Farrell describes how they got there.

IN DECEMBER 2012 we were living in a small double-brick ex-Housing Commission home in the northern suburbs of Melbourne. With two growing kids sharing a bedroom and a very non-user-friendly layout, we knew it wasn’t going to work in the longer term. However, we liked where we were living and didn’t want to move. The house was built in 1953 and, aside from some minor wall cracking, it was basically sound and could probably be used as a base for a renovation. So what to do?

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We asked architect Mark Sanders at Third Ecology to create three concept house designs for us: two incorporating the existing house and one a completely new build. To our surprise, the estimated cost for the new build was only around 10% more than the renovations. And, with the existing house set well back on the block, the most logical renovation design would mean building in our north-facing backyard with a significant loss of garden space, not something we were keen to do.

Thus we decided on a new build, given the benefits in orientation, block placement, reduction in project time and cost risk (renovations often throw up costly issues along the way), design layout and improved thermal performance.

The previous house was connected to the gas network, but we disconnected it during demolition and we wanted it to stay that way: for environmental, health and financial reasons, not least of which is that gas is a fossil fuel which contributes to climate change. We were also planning to install solar PV and wanted to maximise on-site usage of electricity, rather than pay the expense of a gas connection, gas plumbing and increasing gas prices. Finally, we were planning to build a very well-sealed house, so we felt that piping an asphyxiating and explosive gas into it was worth avoiding if possible. We also didn’t want the combustion products (mainly CO2 and water vapour, but also nitrogen oxides and carbon monoxide) in the house.

Around the same time, Beyond Zero Emissions released its Buildings Plan, which strongly supported going gas-free and outlined how to do it. Nice report.

Design for thermal performance

When it came to the house design, we liked the features of the Passive House approach to house construction, but knew there was a higher cost associated with the additional design, construction and certification requirements. Looking around for construction methods that could achieve similar insulation and air sealing, without additional building costs, we found structural insulated panels (SIPs). These are wall panels with a foam core and rigid panels glued to each side. The panels are weight bearing, so timber framework for the external walls is not required.

Read the full article in ReNew 140.

gas bill

Disconnecting from gas: what’s involved

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Just how do you disconnect from the gas network, and what will it cost? Consultant Kate Leslie investigates.

CONGRATULATIONS, your last gas appliance has been replaced and you are ready to disconnect. How to go about it and what should it cost?

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Like all good answers, the answer to this one is “it depends”. It depends mostly on the state you live in and the distributor, a little on your retailer—and there could be an ‘X factor’ of how you approach it.

Generally, retailers are set up to compete for your switching business. Distributors are set up to connect new customers. The experience of dealing with a customer who wishes to disconnect, while not unheard of, is uncommon.

Many people who have disconnected from the gas grid simply organised with their retailer to close their account. The retailer expects you are moving house (and the next occupant will reconnect) or, in states with retail competition for energy, they might think you are taking your business elsewhere. The retailer will notify the distributor and the special meter reading for the final bill and disconnection of supply may or may not be a line item on the bill. Retailers vary.

Alternatively to disconnect, you might contact the distributor that owns the pipes and meters. They also have a set of in-built expectations. You might be demolishing your house (to rebuild it). Or, in infill developments, it is usual to remove the meter of a single dwelling, with the distributor coming back in a number of months or years to install multiple meters for the townhouses or apartments that now stand on the block. Or perhaps for some reason the property will be vacant for a while.

Distributors have options for disconnecting supply, other than physical removal of the meter. Some distributors use plugs and locks (usually where a customer is not paying their gas bill). One distributor in WA removes the pressure regulator. Some distributors say they will ask for enough information from the customer so they can determine the appropriate disconnection method.

Read the full article in ReNew 140.

Induction cooking

Money-saving results in Melbourne

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This family of four saved around $250 last winter by heating their home with a reverse-cycle unit instead of their older gas ducted system. They went on to swap out the remaining gas appliances, disconnect gas from their property and save even more. Stephen Zuluaga explains.

IN 2012, our family moved to a three-bedroom brick veneer townhouse in the south-eastern suburbs of Melbourne. The house was constructed in 2001 and it’s likely that’s when its original gas ducted heating, water heater and stove were installed.

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We’d always been interested in keeping our energy costs down, but, like many people, we just assumed that high gas bills in winter were a part of life. We found that our two-month gas bill spiked significantly in winter due to heating, rising from around $80 in summer up to around $400 in winter.

Then in September 2015 I came across an article on The Conversation which proved to be a turning point. Tim Forcey’s article1 described research undertaken at the Melbourne Energy Institute which suggested that efficient electric appliances—heat pumps—could heat your home more cheaply than gas.

Intrigued, I got in contact with Tim to learn more. He introduced me to the My Efficient Electric Home Facebook group and, through contacts made there, I spoke to many efficiency experts and interested householders like myself about ways to reduce costs and increase efficiency.

In hindsight I can see that I was heading down the path of all-electric, but I wasn’t really looking at it like that at the time: it was just about replacing inefficient appliances with efficient ones.

There are many motives for wanting to improve efficiency and for us the primary driver was financial. Over the course of converting our house to all-electric, I spoke to others who had a combination of environmental, efficiency, financial and technological motives. I really like the fact that no matter what your motive is, you can get an outcome that both lowers costs and reduces environmental impact.

Read the full article in ReNew 140, or on the website of our partners Positive Charge.

pumping in wall insulation

Insulation upgrades

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Reader stories on how they improved the thermal performance of their homes, while reducing energy bills. By Eva Matthews.

Dennis Kavanagh has been incrementally improving his home in Blackburn, in Melbourne’s east, over the last few years. As well as deciding to go all-electric and installing a 9.8 kW solar PV system on his roof around 11 months ago, Dennis turned his attention to improving the home’s thermal performance through insulation and draughtproofing.

Little existing insulation

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After attending a free EnviroGroup presentation run by ecoMaster on these topics, Dennis ordered a premium assessment for his home, which resulted in a number of recommendations and quotations to address them. They identified his ceiling insulation, which had been installed about 40 years ago, as being in reasonable condition but only rated R1.0. There was no insulation in the walls or underfloor. With Dennis unable to “crawl up or into awkward spots” himself, ecoMaster installed the insulation in the roof and underfloor in August 2015, both in the same day. Access to the roof was via the manhole; underfloor access was limited under the bathroom, laundry and some of the third bedroom, so they achieved around 70% coverage there.

For the walls, being brick veneer, Dennis’s best option was to have the insulation pumped in. As this type of application can cause a fire hazard, and the installers ecoMaster recommend require an electrical safety certificate, Dennis organised an inspection prior to the installation, using electricians from EnviroGroup. After checking behind power points and testing at the meterbox, and with Dennis having upgraded his wiring recently, they determined that all was good to go.

In January 2017, one man with a truck of granulated Rockwool (mineral wool) pumped in the insulation in less than a day. Most of the walls were accessible by shifting some tiles on the roof, through which the insulation was pumped in down a flexible hose. Solar panels were in the way in some spots, so not all the walls could be accessed from above; in this case Dennis thinks the insulation may have been pumped across from a neighbouring entry point. Holes were then drilled under the windows to pump into those lower spaces, and a mortar mix used to patch them. Although Dennis was somewhat concerned about whether it would match the existing mortar, he says it worked out well: “Unless you look closely, you don’t even notice it.” Also, batts were put in to fill gaps between the top of the timber wall framing and roof.

Read the full article, with two other case studies, in ReNew 140.

Nissan Leaf battery

Keeping your EV battery healthy

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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?

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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.

Shanghai maglev train

The future of long-distance travel

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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.

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Trains

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 fuel cell powered train

Hydrogen as a fuel – is it viable?

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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.

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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.

Hot water savings

Efficient hot water buyers guide

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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.

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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.

Water heating ways

Getting into hot water

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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 systems

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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.

Thermal imaging camera

Energy detectives

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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.

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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.

meg-warren-north-aspect-2

Keep your cool: External shading buyers guide

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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.

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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.

credits-onshore-wind-turbine-franseska-mortensen-and-samso-energy-academy

Island of energy: community-owned and renewable

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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.

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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.