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ReNew Editor, Robyn Deed

ReNew 132 Editorial – Not just another brick in the wall

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We’ve gone a little bit Sanctuary (our sister magazine which showcases modern green homes) this issue! Or, at least, our theme of building materials sees us concentrating a bit more on sustainable building materials and systems, and a bit less on technologies such as solar and batteries.


But we haven’t completely forgotten solar, with an article by the ATA’s energy guru Andrew Reddaway on ways to add batteries to an existing grid-interactive system, to create a hybrid system. He suggests that for many in our cities this will be a more cost-effective and sustainable approach than going off-grid, with the recently announced Tesla Powerwall setting a lower-cost and longer-warrantied battery system benchmark that we’re hoping many other providers will follow.

We also look at solar panels as a building material in our article on emerging materials. Building integrated PV promises a way of reducing construction materials, replacing roofing or even windows with solar panels, and we’re pleased to see some roofing companies taking up the challenge.

As part of our building theme, we decided to cast a ReNew eye over the many possible approaches to building walls. The array of choices can be confusing, so we’ve created a quick guide that looks at how each wall construction system works and considers sustainability across a range of criteria.

In terms of building guides, we also feature Mullum Creek, an innovative residential development in Melbourne’s east, which is providing guidelines for purchasers on both sustainable design and building materials. For example, their clay products guide lists local products and suppliers that have lower impacts than typical brick products. Each listing comes with a comment as to why it’s been included, a helpful pointer on the issues to consider in selecting materials.

We also consider longevity and sustainable design. As architect Ande Bunbury asks, shouldn’t we be designing buildings to outlast us? Getting the basics right, flexibility and durability are all important for longevity.

There’s much more besides, including a sustainable farm conversion that’s going from strength to strength, a discussion of the advantages of collaboration in building design, an update on the ever-expanding world of community energy, the results of our cooking challenge, a DIY roof heat capture system and a micro-hydro buyers guide. Alan Pears features several times: with an in-depth look at where/when thermal mass is effective, a book review and his column on the bizarre world of Australian climate policy.

We’d also love to get your views on ReNew in our reader survey, running until 31 July. It really helps us to hear what you’d like to see more (and less) of in ReNew. It only takes 10 minutes and there’s a prize of organic wine or olive oil on offer. Find it at

Robyn Deed
ReNew Editor


ATA CEO’s Report

Our mission at the Alternative Technology Association (ATA) is to enable, represent and inspire people to live sustainably in their homes and communities. We’ve been doing this for 35 years, providing independent advice and sharing stories of practical sustainability from across Australia.

We’re very excited to announce a major step forward in our work, as co-organiser of Sustainable House Day in 2015 with the EnviroShop. The ATA has been a long-time supporter of Sustainable House Day, with many ATA members opening their homes on the day, allowing the general public to see good sustainable design, ask questions and receive unbiased advice.

Sustainable House Day joins a range of events the ATA conducts each year to provide face-to-face advice on practical green living. This year we’ve already held Speed Date a Sustainability Expert events in Sydney, Melbourne and Perth and there are more coming up in Brisbane, Sydney and Melbourne’s western suburbs.

Without the support of our members, with many actively involved in their communities sharing information on sustainable living, none of our work would be possible.

As we come to the end of the financial year you can support the ATA’s work by making a tax-deductible donation. As well as supporting Sustainable House Day, your donation will enable us to continue development of the on-grid battery component of the Sunulator solar system feasibility tool and to advocate for consumer protection and carbon reductions in a changing energy landscape.

You can make a donation online ( or by calling 03 9639 1500. With your support we can continue to enable practical action on climate change free of commercial influence.

Donna Luckman

Three options of hot water plumbing: gas-boosted solar, full gas and solar only.

Farming Renewably: Reaping the benefits

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One person/farm can make a difference: David Hamilton describes how his farm’s sustainable conversion cut carbon, benefited the landscape and turned a profit.


I’ve read many inspiring articles in ReNew from individuals trying to live more sustainably and lessen their impact on the planet. This article takes a slightly different approach–a rural perspective–to demonstrate that it can be commercially viable to run a farming enterprise using systems that are truly renewable, whether that’s for water, electricity, housing, food, livestock, pasture or wildlife.

Our journey to sustainable farming began in 1993, when my wife Roberta and I purchased a 60-acre property in the south-west of WA with the twin objectives of restoring the degraded land and becoming as self-reliant as possible. The land included pasture that was totally lifeless and neglected, along with a dam, two winter streams, old gravel pits and two areas of magnificent remnant native forest. We wanted to be independent for water, electricity and as much of our food as was practical. Withe fewer bills to pay, we could work fewer hours off the farm–which was very appealing.

As a registered nurse with no farming experience, I was on a vertical learnign curve. Luckily, Roberta has a dairy farming background and, with her accounting experience, is a wizard at making a dollar go a long way.

When we began, we were both working full-time. We spent the first two years establishing a gravity-fed water supply, preparing the hosue and shed sites, and fencing the property, including to protect remnant bush from planned livestock. We also planted over a thousand native trees and shrubs, plus a few ‘feral’ trees for their air conditioning and fire-retardant properties.

Read the full article in ReNew 132.



Emerging materials

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The world of building materials is ever-evolving, but which of the new materials will make it to market acceptance? Lance Turner looks at some of the products starting to take off now, and what’s just over the horizon.

Solar panels: the new building material?
Solar panels can take the place of some building materials, known as building integrated photovoltaics (BIPVs). For example, they may be integrated into the roof, replacing roofing sheets or tiles, they may form the roof of a carport or verandah (as on the cover of the last ReNew!) or they can even be part of a wall or balcony rail. Anywhere a surface gets a good amount of sun is an opportunity to use BIPVs.


Although BIPVs sound like a great idea, reducing costs by displacing some building materials while producing a neater, integrated look, they have struggled to gain a foothold in Australia. There are some amazing examples overseas, but the examples here are far more limited. And, unfortunately several manufacturers, such as Schott Solar, have stopped manufacturing them in recent years due to the low cost of standard panels.

However, there are still options available, mostly in the form of roof materials. The original PV Solar Tiles ( have been available for more than a decade, and roofing manufacturers are now getting in on the act, with BIPV systems available from Monier (SOLARtile, see, SolTech (not available in Australia as far as we know, see, Nulok (, Tractile ( and Stratco Solatop (

The roof is not the only place where BIPVs are being used: it’s also possible to install windows that actually generate electricity. This has the added benefit that the windows reduce the incoming energy and so help keep the building cool. The main disadvantage of a PV window is the higher cost should a breakage occur. They’ll also reduce solar gain in winter, thus reducing warmth collected passively.

So what’s currently available in the solar window arena? A few years ago there were several options, but those manufacturers have either stopped manufacturing them or have disappeared. Maybe they were a little too far ahead of the curve or the high manufacturing costs just didn’t add up.

As always though, technology advances and a new breed of lower cost dye-based solar cells are emerging that may change the way we look at windows.

Read the full article in ReNew 132.


Mass effect: The messy realities of mass

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Mass in buildings can help moderate internal temperatures, but it can also be tricky to control its effects. Alan Pears examines when and where mass works well—and when it doesn’t.

The way buildings work is very complicated. That’s why designers increasingly use computer models that simulate hourly performance over a year to try to deliver good performance. Even that has its challenges! Adding mass to a building is no exception; it can bring significant benefits—and some problems.


This article is an attempt to explore the role of mass in buildings and suggest some paths forward for building owners and designers.

First, ‘mass’ is not actually what we want. The beneficial feature of mass is that it increases the heat storage capacity of a building so that, for a given amount of heat input or loss, the change in temperature inside the building is reduced. This outcome can be achieved by using a lot of material (mass), materials with a high heat capacity per unit of mass (e.g. water can store about twice as much heat per cubic metre as concrete for the same temperature rise in the material), or by storing energy as ‘latent heat’ in what are known as phase change materials (PCMs, see more on these later).

High mass buildings tend to sit close to the 24-hour average temperature for the time of year, because it takes a lot of energy to shift the temperature of a heavy building. In much of Australia, especially when 24-hour average temperatures are 18 to 24°C, this means the building tends to be closer to a comfortable temperature more of the time.

Thick, heavy walls slow down the rate of heat transfer into or out of a building, as the ‘wave’ of heat has to work its way through the thick material. This can delay the heat flow until it cools down (or heats up) outside, reducing heating or cooling energy.

But it can have a downside. I once lived in a house with a west-facing uninsulated cavity brick bedroom wall. It would delay the heat flow from the afternoon sun until after bedtime, so I would cook at night unless the outdoor temperature had cooled enough for me to flush out the heat.

Note that mass does not provide better insulation—but under varying temperature conditions it can have a similar impact on energy use to a small amount of insulation. Confused? Let’s look at what this all means in practice.

Read the full article in ReNew 132.


Bricks, blocks and panels: What’s in a wall?

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There are many different approaches used for building the walls of a home, but which one is ideal for your build? Lance Turner takes us on a quick tour of the different systems, materials and their sustainability credentials.

For those embarking on a sustainable building project, there can be almost too much information available, making it hard to quickly compare the possible building approaches. One important decision is the wall-building system to use in your build.


To help in that evaluation process, this article provides a quick guide to the different wall-building systems and materials available. For each system, we consider how the walls are constructed, their thermal performance and sustainability. A table at the end of the article summarises each approach in terms of a range of sustainability criteria. It’s intended as a quick guide; you’ll need more information before you start your build, but we hope to give you a head start on the different systems available.

So, what is in a wall? There are many different methods of wall building, but they all fall into four broad categories—stud frame with cladding, bricks/blocks, cast/poured materials and pre-fabricated panels.

Stud frame with cladding
Probably the most common wall system used in Australia is a structural timber frame with cladding, in either a single or double timber stud system.

Single stud walls have one layer of framing—the internal cladding (such as plasterboard) is attached to the inside of the frame and the external cladding (such as weatherboard, fibre-cement or brick, as used in brick veneer, see later) is attached to the outside. Bulk insulation is fitted into the spaces between the studs of the frame, and foil insulation can be added as an additional layer around the outside of the frame, allowing for R-values up to almost R 4 with the right material combination. For example, according to the TasTimber document R-values for timber framed building elements —walls (, a 90 mm stud wall with R 1.5 batts, reflective foil layer and AAC external cladding can achieve an R-value of 3.9.

To enable even more insulation, a double stud wall can be used. Double stud walls are just like two single stud frames, built one beside the other with a small gap in between. The resulting walls can be 200 mm or more in depth, so a great deal of bulk insulation can be installed. Of course, a double stud wall costs more than a single stud wall, but its advantages may well offset the extra cost if you live in an alpine area or area with low average temperatures, such as north-west Tasmania.

For a truly thermally efficient home, thermal breaks (thin layers of insulation material) between the studs and external wall cladding should be considered, although the extra expense may not be justifiable in moderate climates where low levels of heating and cooling are required.

Read the full article in ReNew 132.


Many hands make light work

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Can a collaborative approach to building design lead to even better sustainability outcomes? Eugenie Stockmann describes a different type of development via The Green Swing.

When setting up The Green Swing in 2010 to develop a plot of land in inner-urban Perth, we wanted to create a distinctly different type of housing development—one that would be sustainable, affordable and with a great community feel. After all, we were planning to live in it ourselves!


The Green Swing is what we called our development company, a partnership of myself, my partner Helmuth and another couple, Alana and Mark Dowley. That first project, Genesis, was completed in 2012 and is now home to the four of us, alongside two other apartment homes. Pleasingly, it went on to win several industry awards.

We learnt a lot along the way; perhaps most importantly, we realised we didn’t want to let all that knowledge and experience just fade away. So it wasn’t long before we commenced our second project, The Siding, due for completion in early 2016.

Oversights and inconveniences
We also learnt that there’s always room for improvement. One area we were particularly keen to improve was the process of collaboration.

You might think that all buildings are designed and constructed via collaboration. After all, it’s very hard for one person to design and build a house completely by themselves. Even the early stages of a project involve a number of people—the client, architect or building designer, draftsperson, engineer, planner and building surveyor, just to name a few.

Yet, the experience of our first project highlighted that effective and meaningful collaboration doesn’t always come easy. With so many people involved, it perhaps comes as no surprise that problems, inconveniences and oversights often occur, resulting in head-scratching exclamations such as, “Why did they do that?” or “If only they’d asked before they did…” and “This could have been easily avoided if…”—you get the picture.

To add to the issues, people’s idea of and commitment to sustainable building design and construction can vary. The Australian Public Service (2007) described sustainability as a complex, ‘wicked’ issue, in that no-one knows what it looks like, nor how to get there. Somewhat ironically, their conclusion was that a collaborative approach is best for dealing with wicked problems!

Read the full article in ReNew 132.


Going hybrid: Adding batteries to grid-connected solar

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Going off-grid may not be for everyone; a better route may be to ‘go hybrid’, by adding batteries to grid-connected solar. Andrew Reddaway explores the options.

The solar battery industry is on the verge of disruptive change. Traditionally, large batteries were only seen in houses at off-grid locations such as Moora Moora (see box on the solar hybrid training course held there, which I attended earlier this year and which provided input to this article).


For off-grid systems, reliability is crucial; failure prompts an emergency call to the solar installer, so such systems have been designed conservatively using proven lead-acid batteries.

Meanwhile, in towns and cities, grid-connected solar systems have gone mainstream. As feed-in tariffs for solar export have dropped far below the rates paid for grid electricity, householders are looking for ways to cut bills by making better use of their excess solar generation. One answer is to add batteries to create a hybrid system: a grid-connected solar system with batteries either for backup or load-shifting.

This article gives an overview of current hybrid technology and the options available for adding batteries to an existing grid-connected solar system.

Different batteries for hybrid
A hybrid solar system is tough on batteries. Unlike an off-grid system that may store enough energy to last multiple days, a hybrid system’s entire usable capacity will be charged and discharged daily. This requires a battery that can handle fast discharge rates at high levels of efficiency. Lithium batteries fit the bill, and have already become dominant in consumer electronics, power tools and electric cars. Compared to lead-acid, they are also smaller, lighter, don’t require monthly maintenance and don’t emit hydrogen gas. The only things holding them back in the solar market are unfamiliarity and price.

The recently announced lithium Powerwall battery from Tesla is priced well below previous products and has a 10-year warranty. Traditional lead-acid batteries cannot compete with this new benchmark, so it’s expected that systems will start to move away from them. Hybrid systems are now expected to become viable on pure economics in a few years or less. Early adopters are already installing lithium hybrid systems, as are some who value maintaining power during a blackout.

Read the full article in ReNew 132.


Local, clean, green: The new generation

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ATA intern Ashleigh McMillan fills us in on the latest community energy projects driving change in Australia’s renewable energy mix.

Several communities around Australia have taken up the challenge of going 100% renewable, and many more are crowdfunding solar on schools, community centres, pubs and more. Community energy is infectious it seems!


One of the driving forces behind that growth is the Coalition for Community Energy (C4CE). Formed in June last year, with the Alternative Technology Association (ATA, ReNew’s publisher) as one of its founding members, C4CE is a coalition of organisations all aiming to assist or develop local community renewable energy projects.

A key stepping stone towards that has just been released by C4CE: the National Community Energy Strategy. This document provides a snapshot of what’s happening now in Australia’s vibrant community energy sector, alongside an examination of future potential. It includes recommendations on community energy models, funding and regulatory reform. An important aim of the national strategy is to create an environment that encourages innovation and new funding models for community energy—something the ATA is deeply supportive of!

For those looking into launching their own community energy project, the strategy includes a detailed appendix (Appendix E) on behind-the-meter solar models—those where the solar energy generation is used on-site rather than being exported to the grid. The appendix provides case studies of successful projects and, more broadly, an analysis of the challenges and costs faced by community energy projects, and how they can be addressed. It also includes an interactive decision guide to assist with working out the model most appropriate for your project (see sample at right).

The Coalition for Community Energy’s Nicky Ison says she hopes the national strategy “will help create a framework for and culture of collaboration between all organisations interested in growing a community energy sector in Australia.”

Read the full article in ReNew 132.


ATA member profile: Shaping the built environment

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Long-time ATA fan and more recent member Natasha Palich discusses her combined passion for architecture and advocacy with Eva Matthews.

“I’m a bit worried about where the planet’s heading.” This understatement belies the level of Natasha’s concern about our impact on the environment, which she has translated into activism of various sorts throughout her adult life. In her early days it was campaigning with The Wilderness Society. Following university and in her professional career as an architect, it has seen her involved in paid and volunteer advocacy roles, as well as bringing sustainability principles to each home she is commissioned to design.


Natasha studied architecture at Melbourne University in the early 90s, “when sustainable design wasn’t a dedicated study stream anywhere really.” Graduating in 1995, she practised her craft in a number of firms over the next few years. However, when a job with the Australian Institute of Architects came up, Natasha was excited to revive her activist tendencies in an advocacy role within her field. She was editor of the BPA Environment Design Guide, developing sustainability information for the industry, and later remained involved on the AIA’s sustainability committees.

Starting to miss the learning acquired through experience, Natasha jumped back into work as a project architect for a medium-sized firm for a few years, trying to incorporate sustainability practices into that forum. In 2004 she took the next step and set up her own practice, while also working part-time in local government advising on and developing sustainability tools and strategies. One decade on, she continues this trend of having her fingers in a few pies that combine her advocacy and architectural practice, currently also working one day a week as coordinator of the Municipal Association of Victoria’s Council Alliance for a Sustainable Built Environment. This is a trend she would like to maintain ongoing, as well as her teaching, training, writing …

In her architectural practice, Natasha says she doesn’t have a signature style—she likes clients to show her things that inspire them, and she uses that for her inspiration. Most important to her is that she designs a home that is comfortable: “Clients need to like it and it needs to make them feel good. You can achieve this with good design and material choices.”

In terms of bringing sustainability principles into the design, sometimes Natasha gets clients who are “super keen” and informed and have clear ideas about what they want to achieve, and she enjoys working with and learning from them. On other projects, she is the one introducing sustainability concepts and encouraging responsible choices.

Working mainly on renovations, Natasha says she enjoys the challenge of dealing with existing conditions and smallish budgets. Add in the factors to consider around what materials or systems to use—embodied energy, whether to consign still-functional items to landfill, for example—and you start to see the line that needs to be negotiated between what a client thinks they want, what they need, what looks good, what will perform well, and what they can afford short- and long-term in order to bring about the best solution.

In terms of building materials, Natasha likes using (recycled) timber internally. Externally she uses metal cladding and cement sheet a lot. She notes, “There are some interesting cement sheet products around that are reducing their carbon footprint. This is one of the most interesting areas coming out.” Despite the many exciting advances being made in building materials, however, Natasha recounts a 2007 RMIT University study that showed that “the single most effective thing to reduce the environmental impact of materials is simply to use less of them—so, make buildings smaller, utilise smart design, ask clients ‘do you really need two bathrooms, do you need floor-to-ceiling tiles…?’”.

She further notes that, on a larger scale, we need to change the way we plan our cities. “We need to challenge people’s expectations of what housing is. The housing we’re providing isn’t broad enough in its typology to meet the needs of communities living in a globally warmer world.”

For more on Natasha’s practice, visit

This member profile is published in ReNew 132. Buy your copy here.

Alan Pears

The Pears Report: The policy bizarre

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Is Australian energy and climate policy beyond rational discussion? Alan Pears reviews recent developments and presents his recipe to improve the effectiveness of appliance Star ratings.

I can’t write this column without discussing the ongoing debacle that is Australian energy and climate policy, although I would much prefer to ignore it.


The Energy White Paper (EWP) has been published ( It was as awful as I predicted. Anyone who relies on it for business planning will likely lose a lot of money. It is completely out of touch with reality: its focus is on growing fossil fuel exports, ongoing privatisation and outdated approaches to reform of electricity and gas supply.

One potentially significant element of the EWP was the proposal to develop an Energy Productivity Plan. In principle this is a very good idea, as it could drive energy efficiency and improve cost-effectiveness of energy utilisation. But don’t hold your breath. There is no timeframe, no clear institutional framework, nor any firm resource allocation. And the kinds of policy measures needed to implement such a plan are anathema to our present Australian government and the powerful interest groups that dominate energy policy.

We have also had a consultation on the National Carbon Offsets Standard. This is not exactly riveting stuff for most people, but it is very important. It sets the rules on how businesses (and their products) and households can be certified as being ‘carbon neutral’. Unfortunately, the consultation paper forgot to discuss GreenPower, while it focused, instead, on the fine print of the fundamentals. It did not confront the issue of how to ensure voluntary abatement action be treated so that it is ‘additional’ to other abatement action.

From a narrow carbon accounting perspective, almost all Australian voluntary abatement action, including installing rooftop PV, energy efficiency improvement and buying GreenPower, does not reduce Australia’s greenhouse gas emissions. It simply makes it easier for the government to meet its weak target and leaves more room under the target for others to emit more. This is, to put it mildly, disempowering!

We’ve also seen the first auction under the Emission Reduction Fund. The average price polluters were paid to offset emissions was $13.95/tonne. However, few of the funded measures will deliver direct abatement through reducing emissions. Most involve storing carbon or not clearing land. And a fair proportion of this won’t occur before 2020. An unknown amount of it is just a continuation of activities that were already being supported under the previous government’s Carbon Farming Initiative. Environment Minister Hunt continued to use creative economic analysis to suggest this was cheaper and more effective than carbon pricing.

Australian energy and climate policy is just so bizarre that it is beyond rational discussion, I’m afraid. If you want my more detailed views on all this, my submissions are available at the relevant government websites. My Energy Green Paper submission is at; the White Paper does not change the relevance of my comments on the Green Paper. My submission on Australia’s 2020 emission targets is at and my submission on the national carbon offsets standard is at

At least there do seem to be some signs that progressive state governments are beginning to move to fill the vacuum created by our truly remarkable national government.

Reframing appliance energy efficiency
To date, Australian appliance energy efficiency policy has focused on new appliances and, within that, on information (via labels) and mandatory minimum performance standards. Despite extremely limited resources, lack of high-level political support and white-anting by anti-regulatory econocrats, this has been a fairly successful approach. As I pointed out last year (, a typical Australian household is saving around $300 on annual energy bills and the overall cost has been minus $119/tonne of CO2e avoided. Not bad value!

But we can do a lot better. Here’s my recipe for success.

First we need to sharpen and broaden our approach to new appliances. We need simplified labels on a wider range of products such as lamps and fans. Instead of the present label, these would carry simplified Star ratings only, but also carry a QR scan code, so a smartphone user can access background information. For products with relatively low energy usage, it can be difficult to justify a ‘proper’ energy label. But a rating that’s simply printed on packaging has minimal cost. This approach could also be applied to many products like digital photo displays: Choice found that the worst of these were serious energy wasters, but no one knows which are the good ones.

We also need to incorporate automated diagnostic monitoring into new appliances, so they tell us if they are not working properly. This is not hard for modern products that include sophisticated monitoring and computing capabilities. One example that does this is the Siddons Bolt-on heat pump hot water service.

We need to sort out the consistency of messaging via labels. A 4 Star fridge is very efficient, while the best TV or air conditioner is 7 Stars. Our 6 Star homes would be illegal in many countries. No wonder people are confused. And lack of effective promotion of what labels mean allows confusion to be misused by salespeople. For example, a home salesperson might tell potential buyers that a house is 6 Stars, so they don’t need to think any more about energy efficiency. Unfortunately that’s not the case.

Our mandatory performance standards are generally weak, as shown by the wide range of Star ratings of products on the market. We could adopt stronger approaches. For example, the Japanese ‘top runner’ program requires all products to be at least as efficient as today’s best performer within a few years. Or we could just say that anything using more than twice as much energy as ‘best on market’ is illegal!

We need to look beyond new products. Many people buy secondhand products, but there is no information on their energy performance. As a basic step, requiring energy labelling consumption data to be included on appliance specification plates seems obvious. At least the secondhand retailer or enthusiastic buyer could gain access to the information. We could go further and require all registered secondhand sales agents to place clear information on energy use on appliances they sell—using the information on the specification plate as a source.

We also need to remove old, inefficient equipment from the stock. Old, often faulty fridges can use up to eight times as much energy as modern equivalent products. Many industrial boilers are up to 50 years old, and appallingly inefficient. Replacing (and recycling the materials from) these items would deliver big environmental and economic benefits, while cutting consumer energy costs. But we need to be able to identify such disasters. This can be done by analysing energy usage data, but it will require some effort by governments and energy companies. At present, energy suppliers have little incentive to do this.

Lastly, we need to be thinking in lifecycle terms. Apple, for example, includes full lifecycle analyses of all their products on their website. For efficient products such as iPads, embodied emissions comprise over half of lifecycle impacts. Operating energy use is only 15%.

More broadly, one Australian study suggested that effective recovery and recycling of waste materials, particularly metals, would cut Australian greenhouse gas emissions by over 5%. And the concentration of valuable rare metals and other materials in wastes can be tens of times higher than in ores we now mine. Failure to capture and use these valuable resources and energy savings is just dumb.

But when neo-classical economic theory and powerful incumbent groups drive policy, it’s not surprising that we end up with dumb policies.

Alan Pears is one of Australia’s best regarded sustainable energy experts. He teaches part-time at RMIT University and is co-director of Sustainable Solutions, a small consultancy.

This article was first published in ReNew 132.


A micro-hydro buyers guide

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A micro-hydro turbine can be one of the cheapest sources of reliable electricity—if you have the right site. Lance Turner looks at what’s available.

Solar panels are the energy generators of choice for most domestic renewable energy systems, but there are other forms of renewable energy generation that can provide supplementary or even primary power generation if you have the right site.


One possibility is a micro-hydro system: the production of energy from water, with domestic-scale systems sized up to 100 kW. If you have a rural property with a suitable water source, then micro-hydro may be a good option, particularly if a high tree canopy precludes the use of solar panels or wind turbines.

The kinetic energy stored in flowing water can be considerable. You just need to look at the deep pools often found below large waterfalls or how the rocks in a creek are worn smooth by the flow of water. To get an idea of the forces involved, try aiming the jet from an ordinary garden hose at your hand. You will feel the force of the water striking your hand and being deflected. This is basically how many hydro turbines work.

Run-of-river versus dammed
Hydro systems fall into two broad designs—run-of-river and dammed systems.

Run-of-river systems simply take water from a high point of the river or creek, pass it through the hydro turbine and return it to the river or creek at a lower point. Only a portion of the water in the water source is diverted through the system.

In a dammed system, the water source is dammed, producing a water reservoir. The height of the water behind the dam produces the required head for the hydro turbine (the head is the term commonly used to describe the vertical height of the water column that is producing the pressure to run the turbine).

Most domestic systems are run-of-river types, as these produce the least environmental impact and are the cheapest to install. They are also the type your council and/or water authority is most likely to approve. After all, damming a water source can cause considerable environmental disruption and should be avoided.

Some run-of-river systems do use a small dam, known as pondage, to ensure an adequate flow into the intake pipe. The amount of pondage can be small or may be increased to provide more reliable energy output from the turbine during times of lower water flows in the water source. It is possible to use pondage that is separated from the water source completely, to prevent any negative effects on the water source.

Read the full article in ReNew 132.


Low cost solar heating: Using free heat from your roof

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After reading an article in ReNew, Alan Cotterill decided to design a closed loop heat exchange system to supplement his home’s heating with free heat from the roof. A couple of iterations later, he describes the resulting effective system.

In early 2014 I commenced efforts to use the heat from our roof cavity to contribute to winter heating. I decided on a closed loop system, which would take in room air, duct it through the roof and return it to the house at a higher temperature. A closed loop system avoids the issue of drawing down insulation fibres and dust from the roof cavity.


Useful attic temperatures
My home combined with our very cold but sunny winter days in Wagga seemed especially suitable for this system to run with reasonable efficiency. The house has a grey Colorbond steel roof and a large roof area relative to the internal floorplan, due to a high pitched roof and the wide verandahs and garage being included under the main roof structure. The east-west orientation of the long axis of the house and the north-facing roof area being covered with solar panels have not prevented useful attic temperatures. Measured 60 cm below the peak of the roof cavity, the average maximum attic temperature was 28 °C for the two weeks starting 16 July 2014 and 37.8 °C for the two weeks from 19 August 2014.

A first attempt
My first prototype forced room air through a system of ducts in the roof using a centrifugal exhaust fan mounted on its side on a shelf in the laundry. The air was distributed to three 12-metre runs of 100 mm flexible aluminium ducting before returning the air to the house. The returned air was reasonably heated but the total volume of returned air was inadequate to contribute significantly to winter heating.

Read the full article in ReNew 132.


SIPs in the tropics: Habitat in the clouds

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With thoughtful design, it is possible to live sustainably and comfortably in the rainforest. Paul Michna describes what his family has dubbed their ‘trapezoidal mountain habitat’, built using SIPs.

There are many challenges, but similarly many rewards, when building a home in the tropics. Humidity and condensation, cyclones, rain, site access, land clearing and cooling in a tropical climate all pose questions to be answered.


Our journey to living in the ‘jungle’ began back in 2002. We purchased this site, surrounded by World Heritage rainforest in far north Queensland, with plans to develop a home. The area was too wet for camping while building (with about 4500 mm of rain a year) so we brought in an on-site caravan for our initial weekend planning visits. In 2005 we constructed our first home, a shipping container retreat (see ReNew 95). Surviving cyclones Larry (2006) and Yasi (2010) taught us valuable lessons for construction and design in a cyclone-prone area (see ReNew 118).

This knowledge fed into the design of our trapezoidal habitat in the clouds, Studio Nimbus.

Built using structural insulated panels (SIPs), the main living area and half-length mezzanine bedroom float three metres off the ground on two rectangular concrete block pods. The pods double as cyclone shelters and usable space, with one a bedroom and the other ‘wet’ spaces: a laundry and bathroom.

The elevated main living area keeps us above the splashback of torrential rain, reduces accidental visits by things that slither, creep, bite or hop and maximises airflow beneath and within the living area. The height also permits the abundant nocturnal wildlife to transit the site undisturbed.

Building with SIPs
We chose to build the living area from a metal frame combined with steel-enclosed SIPs—being durable and termite-proof, metal suits the challenging humid rainforest conditions.

The SIPs (walls by Askin, roof by Ausdeck) comprise two layers of steel enclosing expanded polystyrene (EPS) foam insulation. The Colorbond provides a durable painted exterior and interior surface, minimising maintenance—it may need a repaint in 25 years time! Once a year we spray using a very dilute swimming-pool-type algicide on the exterior walls; the next rain then clears the walls of any potential growth. The SIPs provide insulation and sound-proofing and can span long distances unsupported.

Read the full article in ReNew 132.

Q&A: Point-of-use water heaters

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Q:I’m looking for information on instantaneous electric water heater taps for sinks. I’m considering them to address the water and energy inefficiencies associated with the long pipe runs from my current water heater to kitchen, bathroom and laundry sinks.


I’m aware of instantaneous tap water heaters without storage and with integrated lever taps for this application, and these are what I’m most interested in hearing from people about.
With the shower, similar issues and savings opportunities arise, but the much less frequent use (typically once a day per person) make showers a much smaller opportunity to save water and energy by this means.

However, shower-specific instantaneous water heaters are available (which differ from sink units), so I’m happy to hear any ATA views on those as well.
For example, has there been a ReNew article reviewing any of these in relatively recent times? I remember seeing adverts for these in ReNew at some time in the past.

—Paul Riordan

A:We haven’t reviewed such units, although several have appeared in the Products section of ReNew. These include units from,,,, and

They are all of similar efficiency (i.e. 100%); the main issue is the electrical circuit. The tap-integrated units generally work with a regular 10A power point or standard wiring, whereas the 15A and greater units (shower models seem to be rated around 5000 to 6000 W, or 20 to 25 A) need a dedicated circuit. The larger units are all three-phase and are not usually suitable for domestic installations unless three-phase power is available in the home.

These units can vary enormously in price and some are more repairable than others. Make sure you get one with an easily replaceable element if possible, and ensure spare elements are available.

The other thing to be aware of is the level of heating provided. Most of the single-phase units, especially the tap-integrated units, will only raise the water temperature by 10 to 20 °C for a reasonable flow rate, which might be fine in warmer climates, but if you have colder water temperatures they may not do the job. Check the specifications for each unit at the maximum flow rate required.

—Lance Turner

To read more questions and answers, buy ReNew 132.

Hydrotherm heat pump

Product profile: Low-cost stainless steel heat pump

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Heat pumps are the most efficient form of mains-powered electric water heating, but even after STCs they can be out of reach for many people.


Hydrotherm has a range of lower cost heat pump water heaters using Panasonic rotary compressors to provide a CoP (coefficient of performance) of over 4, so you can reduce your electricity use by over 75% compared to a resistive element hot water system.

There are models available with either 150 or 275 litre tanks. To work out which model you need you can simply use the online system selector by choosing the number of bedrooms and bathrooms your home has and your hot water usage needs.

The systems come with a 2 mm thick 304 grade stainless steel tank with a huge 15-year warranty, with a five-year warranty on the rest of the system. Operating ambient temperature range is -5 °C to 45 °C.

One drawback we can see with these units is that, being a Queensland company, the systems are not available everywhere in Australia. The refrigerant R417a also has a relatively high global warming potential.

The units start at around $995 after STCs are deducted. For more information and to buy, contact Aquatech Solar Technologies Pty Ltd, 94-96 Kortum Drive, Burleigh Heads QLD 4220, ph: 1300 769 904,,

For more product profiles, buy ReNew 132.

Trimetric display

Product profile: Advanced battery monitoring

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If you have a battery-based renewable energy system then adequate battery monitoring is important. Just reading battery voltage isn’t enough to tell you what is happening to the battery through each charge/discharge cycle.


The Trimetric TM-2030-A battery system monitor from Bogart Engineering provides important information on your battery bank condition, including battery capacity remaining, displayed as a percentage (based on amp-hour monitoring, not battery voltage).

Other information displayed includes battery charging or discharging (displayed in amps or watts), battery voltage (the meter can handle voltages from 9 to 75 V and capacities from 10 to 10,000 Ah), the days since the batteries were last fully charged and the days since the batteries were last fully equalised.

Another interesting function is the replaced percentage of charge display, which shows how much energy the battery has received compared to the most recent discharge, so you can ensure the battery bank is receiving appropriate levels of input.

There is also an audible low battery alarm, based on volts and the capacity monitoring, which can be silenced. The unit also logs data for the last five charge/discharge cycles to allow easier diagnosis of system problems.

Available from Australian Solar Industries, PO Box 21, Laidley QLD 4341, ph: (07) 5465 2218, Also see

For more product profiles, buy ReNew 132.