In ‘Sustainable houses’ Category

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.

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.

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Solar sizing: big returns

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Why it’s now advisable to ‘go big’ when installing a solar system, even if you don’t use much electricity: Andrew Reddaway presents the latest ATA modelling.

Many people ask us what size grid-connected solar system they should get. Traditionally, the ATA (ReNew’s publisher), has advised people to consider this carefully. If you primarily want to help the environment and cost is of little concern, it has always made sense to install as many panels as possible, as all their generation displaces electricity from dirty, centralised power plants. But most people have budgetary constraints, so their solar system needs to make economic sense as well as help the environment. To achieve this, we’ve previously recommended that people size a solar system based on their electricity consumption and maximise their other opportunities, such as energy efficiency. However, things have changed.

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Two big changes

1. Solar system prices

The last five years have seen significant price reductions, especially for larger solar systems. Prices vary with component quality and location, but on average a 5 kW solar system now costs around $6200 according to Solar Choice’s residential price benchmark data.

Let’s compare a 5 kW system to its smaller 2 kW cousin. To compare two different system sizes, the cost is presented in dollars per watt. Figure 1 reveals that since August 2012, the larger systems have halved in price, while the smaller ones have dropped by only a quarter.

Larger systems have always enjoyed economies of scale compared to smaller systems, because while the installer is on the roof it’s relatively easy for them to add more panels. One difference now is that the price of solar panels has fallen faster than other components. The industry has also become more familiar with larger systems, as they are now more frequently installed than small ones.

2. Feed-in tariffs

The Victorian government recently announced that solar feed-in tariffs will rise to 11.3 c/kWh from 1 July 2017, roughly double their previous level, and IPART has recently recommended a similar change in NSW. These changes are primarily due to wholesale electricity prices in the eastern states roughly doubling over the past year to around 10 c/kWh. We expect other states to follow suit, as feed-in tariffs below the wholesale electricity price are clearly unfair to people with solar. (In WA, a similar rise in wholesale rates hasn’t occurred, but prices might still rise due to the state government winding back its subsidy of electricity prices.)

What this means for solar system sizing

Given these changes, if you’re planning a solar system, is it worth it to upsize from, say, 2 kW to 5 kW?

The extra panels will be relatively cheap but more of their generation will be exported, which doesn’t help the economics.For example, depending on household consumption, a solar system rated at 5 kW might export 80% of its generation. Electricity exported to the grid only earns the feed-in tariff, ranging from 5 c to 14 c per kWh, depending on your location and electricity plan. Solar electricity used on-site, rather than exported, saves you paying the grid tariff, typically around 20 c to 35 c per kWh.

Surprisingly, our modelling of the economics found that a 5 kW system now has a shorter or equivalent payback time to the 2 kW system. We studied the economics by simulating a large number of scenarios in half-hour intervals for a whole year using Sunulator, ATA’s free solar feasibility calculator.

Our primary economic measure is payback time, the number of years until bill savings recoup the installation cost—the fewer years the better. Payback times shorter than 10 years are generally considered attractive to solar customers, as the system is likely to pay for itself before any significant expenses, such as replacing the inverter. The panels should last at least 20 years, so cumulative bill savings are large, especially for a larger system.

To do the modelling, we assumed a feed-in tariff of 11.3 c/kWh in Victoria and in other states a doubling of feed-in tariffs from current levels, phased in over the next five years. We considered common grid tariffs in each capital city, for a variety of household consumption profiles, along with likely tariff increases (we used AEMO’s retail tariff forecasts, but since they were based on Hazelwood closing in 2020, which happened this year, we pulled them forward by three years; this allows for annual tariff rises between 1.5% for Queensland and 3.4% for Tasmania). Panels are assumed to be north-facing with a 20-degree tilt. Our analysis also includes panel degradation over time.

Read the full article in ReNew 140The full report on solar sizing, including references, is available at www.ata.org.au/news/bigger-solar-is-better-ata-report

 

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.

Bringing nature back

Sub-tropical build – Bringing nature back

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Richard Proudfoot and his partner have brought nature in to their suburban block, at the same time as reducing energy and water use. He describes their house and garden build, and the satisfying birdsong-filled results.

IN 2008 we sold our small cottage in inner-city Balmain, in Sydney, and moved to Bribie Island, just off the Queensland coast between Brisbane and the Sunshine Coast.

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Why a life on Bribie Island? My partner Fiona was born and raised near Royal National Park, just south of Sydney. I was born and raised in the Australian outback. We both appreciate the bush and as we neared retirement, we looked for a simple, sustainable life in a leafy setting. While we loved the inner Sydney vibe, it could never be called simple, and true sustainability was always going to be difficult to achieve.

Bribie also has arguably Australia’s best climate. In summer, the temperature rarely exceeds 29 °C, while in winter the temperature range is 15 °C to 25 °C, and annual rainfall is 1.2 metres. It is a great environment to use passive solar design techniques to build a sustainable, more self-sufficient house.

We bought an ordinary suburban (650 m2) block (of sand!), 200 metres from the beach, bordered by neighbours on three sides. Much of the time, a cool sea breeze from the Coral Sea blows across our block. The block runs east-west and has many mature trees on the back boundary.

 

So what kind of house to build?

Working closely with the builder, we came up with a design based on their classic Queenslander kit home. The house is elevated to catch the sea breeze and there is always cool air flow under the floor. It has verandahs on all four sides. It has high ceilings with a fan in every room, essential for sub-tropical days and nights. Most of the windows are north facing. There is very little glazing on the south and west sides, to provide maximum protection from the many storms which come in from the south-west. Every room opens onto a verandah, including the bathroom.

We wondered about building on sand, but our builder allayed our concerns. He used about one metre (depth) of concrete per footing. He couldn’t go much deeper because the water table starts about two metres below the surface. To date we have not observed any cracks in the walls, so our initial concerns appear to have been unwarranted.

Read the full article in ReNew 139.

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What’s in a timber finish?

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Choose right, prepare well and work with the timber’s properties: Peter Smyth delves into the issues to consider when selecting and using timber finishes.

What are we talking about when we say we are finishing timber rather than painting it? Perhaps the most fundamental and obvious difference is that we care what the underlying timber looks like. We have gone from regarding the timber purely as a functional substrate to using it for its aesthetic properties.

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This has a number of consequences. The first is that how we prepare the timber for the finish is of much greater importance; this includes obvious points such as not filling holes with an undesirable colour, to more subtle concerns such as how we sand the timber. Second, we are often using the finish not just to preserve the timber but also to enhance its look, so the timber and finish must work in a kind of symbiosis. This relationship is at the heart of what we are trying to do when we finish timber and there are a multitude of ways it has been approached over the years.

Timber selection

Not all timber is created equal and through all of what follows it is worth bearing in mind the importance of appropriate timber selection. This is particularly important in outdoor applications, with some species being more susceptible than others to weathering, termites and other forms of ageing and decay. A wealth of information exists in this area; see links at end.

Read the full article in ReNew 138.

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A roof over your head

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There are many different roofing materials to choose from, but what are the advantages and disadvantages of each, and how sustainable are they? Lance Turner surveys the market.

IN ReNew 132 we looked at options available for walls when building a home or extension. But of course there’s more to a home than just the walls—roofing is equally important as it not only protects the rest of the building, but also has to withstand the most intense levels of solar radiation of any part of the home, as well as considerable forces from wind, rain and hail.

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The roof must also be able to support added structures such as solar panels and solar hot water systems, satellite dishes, ventilation and air conditioning systems, as well as the weight of people walking on it while installing and maintaining such systems. Plus it’s used to collect rainwater for your home and garden.

There are many different roofing materials available, including corrugated iron and Colorbond steel, concrete, ceramic, metal and composite tiles, slate, shingles and even load-bearing panels such as SIPs (structural insulated panels). Each option has its advantages and disadvantages, each has its own particular look, and each comes in a range of options for that particular material.

Which roofing you go for will depend in part on the materials and the general look of the rest of the home, as well as your personal preference, which may be determined by a number of factors including appearance, the eco-credentials of the material, the range of colours and styles available, the building method (some roofing materials need more structural support than others), the level of maintenance you are willing to give to the roof, the fire resistance level required, and, of course, the location and hence surrounding environment of the home, including heritage or aesthetic requirements of your local council.

The article looks at each material in turn and also considers roof pitch, insulation and keeping your roof cool.

Read the full article in ReNew 138.

vertical-garden

Straight up: vertical garden design

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The last thing you want is to spend a lot of money on a vertical garden system and then have it fail. Jenny and Bevan Bates provide advice and inspiration from their own living walls—five years old and growing strong!

THE inspiration to garden vertically is not new. The Hanging Gardens of Babylon, if they are more than legend, may have been an early precursor, built to bring luscious greenery to the ancient city’s terraced buildings. Your grandma’s hanging pots are a more down-to-earth example, as are vines on a trellis.

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More recently, the idea of living walls has become a popular trend, in part in response to higher density living and homes with small gardens. For Jenny and Bevan Bates, their move to a new house with a small courtyard— and a stark black brick wall facing their living area windows—was the reason they started experimenting with gardening on a wall.

“You have to be prepared to experiment,” says Jenny. In fact, their first vertical garden was a failure. “We tried a $100 system, but the pots were too small and it dried out too quickly; it was hard to keep anything alive in it,” she says.

However, they persevered and they now have five vertical gardens providing cooling, colour and herbs, which adds interest to their home. The black brick wall in fact sets off one of the vertical gardens nicely—the colour they didn’t like turned out to be complementary to the planting!

That particular garden was their first success, says Jenny. It’s now five years old and thriving. It’s on a south-facing wall overlooked by the north-facing living area windows—a lovely sight.

They created the garden using Woolly Pockets, a product which at the time they needed to get delivered from the USA (though there are now retailers in Australia).

The pockets are composed of long troughs of recycled polyethylene (PET, from milk bottles for example). That recycled aspect was important to them; “You need to think about the full life cycle; for systems made from virgin plastic, there can be a lot to dispose of at end of life,” says Jenny.

Which plants they use has evolved over time; some plants grew bigger than expected, shaded other plants or didn’t like the position.

Read about their vertical garden in ReNew 138.

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Reusing building materials in the garden

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There are many uses for old building materials in the garden to create quirky but useful structures, with the added advantage that the materials don’t end up in landfill. Permaculture gardener and teacher Drew Barr shares his tips.

Bricks

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Bricks are useful objects. Durable and cheap, their regular shape means they can be stacked or laid in patterns. Almost all bricks have the same dimensions, although older handmade bricks may be slightly smaller. The size and shape are designed for easy one-handed handling by an adult.

Bricks are energy-intensive to manufacture and transport, but will last hundreds of years, and can be used over and over again.

When reusing bricks, you’ll need to clean them to remove the mortar. This is dirty and laborious work and seems very slow to begin with, but once you have mastered the knack you will be surprised how fast you can clean bricks. The best tool for this is a scutch hammer, which has replaceable toothed blades called combs. Chip at the mortar where it meets the brick and it will come off in big chunks. Wear gloves and a face shield though as flying mortar chips really hurt.

Broken concrete slabs
Concrete is also a very energy-intensive material to manufacture, and similarly highly durable and strong, and ideal to reuse.

Concrete slabs, sometimes referred to as ‘urbanite’, can be reused to make crazy paving, or stacked without mortar to form low retaining walls. When sourcing slabs make sure you get only non-reinforced slabs such as from council footpaths or old driveways. Reinforcing steel in the concrete is very difficult to cut, and as it rusts it will swell up and split the slab.
Councils often replace footpaths and must dump the slabs of concrete they remove, and they will usually be happy to dump it at your place for free.

Read more on reusing old concrete slabs, clay pavers, roofing tiles, roofing iron, car panels, bathtubs and more in the full article in ReNew 138.

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DIY earth bricks

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Creating pressed earth bricks isn’t hard when you have a machine and willing helpers. John Hermans describes the process and advantages of this low embodied energy approach to construction.

THIS article aims to inspire owner-builders to minimise the carbon footprint of their new sustainable dwellings by using pressed earth bricks. By explaining the many virtues of this building material, I hope to spark interest in my offer to share the amazing machine that I use to make them.

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I started making and using pressed earth bricks in 1988, shortly after commencing excavation for our house site. I had seen a hydraulic brick press working very effectively around this time and, with the intent of making a copy, I took several photographs of it in operation. I then found four aspiring owner-builder friends who were willing to become ‘shareholders’ and finance the brick press fabrication; my input was to build it.

The machine I built back then is still going strong today. To date, this press has made in excess of 70,000 bricks and has been responsible for some very creative, cost-efficient and low embodied energy housing.

A pressed earth brick is simply a brick made by compacting soil that has a high percentage of clay. The machine compacts the soil by 50% using the power of a hydraulic press. The result is an attractive and easy-to-use brick that needs no firing and can often be made from subsoil excavated from the house site— and thus has much lower embodied energy than the average house brick.

My machine makes bricks that are 300 mm long by 220 mm wide by approximately 130 mm high, so quite a bit larger than the average house brick (dimensions 230 x 110 x 76 mm). The height of the brick depends on the amount of clay mix put into the press, but averages around 130 mm. At that size, the brick ends up weighing around 15 kg.

It is important to seal the bricks to prevent surface erosion. There are many earth brick sealing products available now (e.g. Your Home suggests linseed oil and turpentine; or you can use one of the Bondall products).

Quality bricks are achieved by using a clay-based subsoil that will bind well and dry hard. This is often an excavation waste product, with little commercial value. Using a press to make several test bricks is a sensible idea.

An addition of 5% to 10% cement will form a brick that will handle days of total water submergence, although this is a condition rarely encountered! No cement is needed in the mix if the bricks are used indoors. If used in exterior walls that are likely to be impacted by rain, then the use of cement is recommended.

Read the full details in ReNew 138.

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ATA member profile: Ripples in the community

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Long-time ATA member Ali Campbell has no qualms about buying secondhand instead of new and looks at all purchases through a “green lens.” She talks to Jodie Lea Martire about how community is critical to sustainability.

ALI Campbell couldn’t bear to see her old piano go to waste, so it stands in the chook shed as a piece of art. It’s a good demonstration of her creative commitment to sustainability, which has led from high eco-living standards at home to diverse community involvement. As Ali says, being part of an active community “helps sustain you and recharges you for staying in the sustainability field.”

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Bushwalking and camping gave Ali a connection with nature, but her real evolution towards environmental action came with her first child. She and husband Bruce had been “unwise, unwary consumers until that point”, but they realised that every other parent had also needed clothes, cots and change tables so they could use “secondhand everything.” From there, the Campbells took a good look at their “consumption and stuff.” They reduced purchases, packaging and waste, considered where their food and goods came from, and boosted their home chook-and-vegie garden.

The garden led to conversations about sustainability with others, and builder Duncan Hall put Ali and Bruce on to the ATA. Soon, the family was experimenting with solar stoves, and now “everything we do has that green lens.”

They have worked to reduce their home’s environmental impact, including greywater systems, water tanks, double-glazed windows, reorienting for better lighting and using Australian-made materials. Ali used ATA-sourced information to explain her decisions to both their builder and plumber during renovations, and emphasises that it’s crucial to hire workers who ‘get it’ and aren’t just greenwashing their work.

Ali says, “The community thing is critical. It goes without saying, but it needs to be said.” She spent six or so years volunteering as an organiser with Melbourne’s Sustainable Living Festival (SLF), and gardened with the Stephanie Alexander Kitchen Gardens in Altona Meadows for a time. She is also active on the Inner West Buy Swap Sell and Freecycle Facebook groups.

Ali participates in Transition Hobsons Bay (THB), and she and Virginia Millard run the Give Take Stand: an unstaffed booth where people share quality, unwanted items (like a free op shop). Ali says the autonomous setup has strengthened community involvement without forcing obligation or onus on anyone. It has been hosted in venues around Hobsons Bay and the council is providing funds to boost the work and establish the stand as a waterproof outdoor shed.

Another project Ali organises through SLF and the transitions group is Bunches of Lunches. Now in its third year, Ali and Transitions Hobsons Bay member Tarius McArthur run three-hour sessions which teach participants to cook five healthy, freezable dishes suitable for school lunches—and promote local food, low packaging and low energy use.

Ali and Bruce have also combined their home and community efforts by signing up their new seven-seater VW Caddy to Car Next Door, allowing locals to rent their vehicle. This let the Campbells balance their need for a second car every now and then, while knowing they’re “not just sitting on this asset.”

Reading ReNew gives Ali great ideas, a sense that she’s not alone in her activism, and—most importantly—hope. The magazine’s coverage of policy developments, news analysis and innovations provides “positivity and support, and that’s what keeps her doing this.”

To end with Ali’s own assessment of her environmental contribution: “I can feel frustrated because I’m not creating seismic change, but I hear frequently, most weeks, ‘You’d love this, Ali!’, so I know I’m having a ripple effect around me and I just hope that keeps rippling on and on.”

This member profile is published in ReNew 138. Buy your copy here.

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Tassie off-grid home

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Given their distance from the nearest power pole, it made sense financially as well as philosophically for this Sydney couple to go off-grid in their new home in Tasmania. Peter Tuft describes how they went about it.

As we approached retirement my wife Robyn and I knew we did not want to spend the rest of our lives in Sydney. Sydney’s natural environment is glorious but it is also much too busy, too hot and humid in summer, and our house was too cold and hard to heat in winter. We had loved Tasmania since bushwalking there extensively in the 1970s and it has a lovely cool climate, so it was an obvious choice.

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We narrowed the selection to somewhere within one hour‘s drive of Hobart, then on a reconnaissance trip narrowed it further to the Channel region to the south. It has lush forests and scattered pasture with the sheltered d’Entrecasteaux Channel on one side and tall hills behind—just beautiful. And we were extraordinarily lucky to quickly find an 80 hectare lot which had all those elements plus extensive views over the Channel and Bruny Island to the Tasman Peninsula. It was a fraction of the cost of a Sydney suburban lot.

The decision to buy was in 2008 but building did not start until 2014 so we had plenty of time to think about what and how to build. We have always been interested in sustainability, and renewable energy in particular, even before they became so obviously necessary: my engineering undergraduate thesis in 1975 was on a solar heater and Robyn worked for many years on wastewater treatment and stream water quality. There was never any doubt that we would make maximum use of renewable energy and alternative waste disposal methods.

From the beginning we knew the house would be of passive solar thermal design. The house sits high on a hill (for the views!) and faces north-east. The main living room is entirely glass-fronted, about 11m long and up to 4m high with wide eaves. That allows huge solar input to the floor of polished concrete. A slight downside is that there is potential for it to be too warm in summer, but we’ve managed that with shade blinds and ventilation and so far it has not been a problem. All walls, floor and roof are well insulated, even the garage door, and all windows are double-glazed. Supplementary heating is via a wood heater set in a massive stone fireplace chosen partly for thermal mass and partly because it just looks awesome. Warm air from above the wood heater convects via ducts to the bathroom immediately behind the chimney, making it very cosy indeed.

Read the full article in ReNew 137.

powerwall

Australia’s first Powerwall home

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Nick Pfitzner and family are the proud owners of the first Tesla Powerwall home in Australia. Nick Pfiztner describes their configuration and the lessons they’ve learnt so far.

Our household had the privilege of the first Tesla Powerwall installation in Australia (maybe the world, they say). It has been a very interesting experience so far, and we’ve learnt a lot about what makes the house tick from an electricity point of view.  I’ve also had the opportunity to discuss the energy generation landscape with several organisations developing similar energy storage technologies.

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As a self-described Elon Musk fanboy, I became seriously interested in energy storage for our house after the Tesla Powerwall launch in 2015. I knew about other home storage systems, but mostly associated them with lead-acid systems and off-grid enthusiasts. We had previously got a quote for an off-grid AGM lead-acid system at one point, but we didn’t have the finance or space to make the BSB (big steel box) happen at that time.

However, by late last year with our finances more in order, we decided to take the plunge with the Powerwall. We chose Natural Solar as the installer. They had advertised themselves as the first certified installer of Powerwall in Australia and helped guide us through the options available.

We opted for 5 kW of Phono solar panels with a SolarEdge inverter and, of course, the Powerwall, for a total cost of $15,990 installed.

And add Reposit grid credits

Natural Solar also informed us about Reposit Power, a software package designed to maximise the benefits of home storage for the consumer. In a nutshell, Reposit is a software-based controller for the entire system. It learns the household usage patterns, gathers weather forecast data and interfaces with the inverter to make decisions about import or export of energy based on two important concepts:

Tariff arbitrage. This is the practice of switching to a time-of-use grid tariff and charging the battery at times advantageous to electricity pricing. This may occur when solar PV generation predictions for the next day are poor or where energy storage has been used up overnight. In either case, off-peak power can be imported for use the next morning.

GridCredits. This is an ARENA-supported project to investigate the use of intelligent storage and distribution of power via consumer-level battery systems, with the aim of reducing network infrastructure costs in future. Consumers are rewarded not through feed-in tariffs based on intermittent solar generation, but rather guaranteed power delivery from the battery. When the wholesale market for electricity is especially high, the electricity retailer discharges electricity from the battery into the grid, paying the consumer $1 per kWh.

These two factors could assist with the financial equation, so we figured it was worth the add-on cost of installing Reposit—an extra $800 at the time.

Read the full article in ReNew 137.

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A house built of straw

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You’re unlikely to go from building newbie to strawbale expert after a four-day workshop, but you should come out with basic skills, a better understanding of the process and the ‘right’ questions to ask. Enga Lokey explains.

THERE are many good reasons to choose to build with strawbales—better thermal performance, non-toxic material, agricultural waste product, low embodied energy, very high levels of insulation, beautiful curved walls, etc. But once you have made this decision, it may be difficult to find an architect, engineer and builder to provide the assistance you require in working with this unique medium.

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One of the best ways to give yourself the knowledge and skills necessary for a successful build is to do a strawbale workshop. If you have no prior architectural or building experience, a workshop won’t prepare you to undertake your own project from start to finish unassisted; however, you will be able to gain enough understanding to ask the right questions of the professionals you choose to employ and also gain basic strawbale building skills yourself.

What should you look for and what should you expect from a workshop? At the most basic level, participation in a workshop should provide you with enough of an understanding of what you are getting yourself into to confirm your convictions or prompt a reconsideration of your building plans. Additionally, most workshops will give you hands-on experience with some of the unique aspects of building with bales, such as alternative framing techniques, bale tying, stacking walls and corners, prepping for render and rendering.

There is a huge variety in the offerings available. Before signing up for a workshop, ask yourself what you are looking to achieve and what level of participation you plan on having in your own project. The more you expect to do yourself on your own house, the more detailed and precise your level of understanding needs to be. Are you just interested in understanding the process so you can decide if this is the type of house you want to build? Are you interested in the theory and principles of good strawbale design? Do you want to participate in every aspect of the building process or just help with the bale walls and rendering? Asking yourself these questions will make it easier to pick the correct one. Some of the major differences between courses are discussed below, followed by a chart that tries to summarise the various options on offer.

Read the full article in ReNew 136.