In ‘Sustainable houses’ Category

20170811_110621

All-electric and hydronic

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

There’s a lot to learn from this highly insulated and well-sealed renovation in Melbourne, not least how a heat pump is providing both hydronic heating and hot water. Cameron Munro explains the house’s modelling-led upgrades and the tweaks made along the way.

WHEN we bought our 1910 weatherboard home in inner suburban Melbourne, we were committed to making it as comfortable and energy efficient as we could. We’d partially renovated a previous home by installing double glazing and injecting foam into the wall cavity, but our new home presented the opportunity to do a far more extensive renovation.

READ MORE »

Our approach was guided by the German Passivhaus movement (also known as Passive House in Australia), which requires extensive insulation and extreme attention to thermal bridging and airtightness. We really liked this approach as it’s guided by building physics and requires extensive modelling and verification.

Moreover, we weren’t comfortable with the usual practice of simply throwing energy into a building to keep it comfortable; whatever additional heat we needed, we wanted to ensure we could keep it within the building envelope for as long as possible.

First things first: going off gas
The previous owner used a conventional gas storage hot water system and gas heaters. Our strategy for heating and hot water was always going to be all-electric using an air-source heat pump and solar PV.

We liked the simplicity of minimising our grid connections and had concerns about the carbon footprint from gas production and use.

One of the first things we did was to have the local gas network utility remove the gas meter and cap the gas main in the street. This was surprisingly easy to do, and cost us nothing.

Read the full article here.

monitoring_guide_phone

Knowledge is power – Energy monitoring guide

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

Need help getting the upper hand on your electricity bills or checking that your solar system is working? You should consider an energy monitoring system, says James Martin from Solar Choice.

DO YOU have a clear picture of what’s drawing electricity in your home right now? If you’re like most Australians, you probably don’t.

READ MORE »

Historically, this hasn’t been an issue because electricity bills weren’t a major concern for most households and, in any case, the number of devices was probably small. But these days electricity prices are high and there are likely to be more electricity-consuming devices plugged into the walls of any given home than the occupants can think of off the top of their heads.

Many Australians have turned to solar panels to help them fight rising prices. Rooftop solar is now affordable and commonplace — the Hills Hoist of the 21st century.

However, comparatively low solar feed-in tariffs in most places mean that solar homes have less incentive to send solar electricity into the grid and more incentive to use it directly. Despite this fact, many (if not most) solar system owners would be at a loss if you asked them how much energy their system produced yesterday, never mind the proportion that they managed to self-consume.

Solar systems have even failed without the homeowner realising until they received their next bill. So monitoring is important!

Types of energy monitoring and management systems
Thankfully, there’s a growing number of products on the market that shed light on household energy consumption and solar generation. These devices take a range of approaches and offer a range of functions, but can generally be classed as either monitoring systems or management systems.

As the name implies, a monitoring system enables the user to ‘see’ what’s happening with their electricity, usually via an app or web-based portal, whereas a management system lets them not only observe but also ‘reach in’ and control which devices switch on at what times.

In reality, the line between the two is becoming increasingly blurred as platforms that once offered only monitoring get upgraded to let them do more.

Monitoring and management systems can be lumped into roughly five categories based on how they are physically installed in the home.

Read the full article in ReNew 141.

1940s cottage with battery

Battery system case studies

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

1940s cottage with battery

IN 2016 Liz and Charlie extended and renovated their 1940s cottage in Ainslie, a suburb of Canberra, applying passive solar design to the extension and retrofitting insulation and sealing to the existing home.

READ MORE »

In early 2017, they also added 4.48 kW of solar, an LG Chem 10 kWh battery and Reposit software, costing around $20,000 as a package, after an ACT government subsidy.

“We chose to get a battery as we wanted to maximise self-sufficiency,” says Liz. They like that the battery allows them to use their generated electricity at night. They chose the LG Chem battery as it didn’t need to be undercover.

Their average usage is around 8 kWh to 9 kWh per day and currently, according to Reposit, they’re achieving 96% to 98% self-consumption, depending on the weather (and therefore their solar generation) and their electrical load for the day.

“Yesterday it was partly cloudy, and we generated 26.8 kWh, used 9.9 kWh ourselves, exported 17.2 kWh and imported just 0.3 kWh,” says Liz. “That’s pretty typical.”

The battery is generally fully charged by 11 am; on a sunny day it can be charged by 9.30 am, and occasionally not until the afternoon if it’s very grey.

The real-time monitoring available via Reposit is fascinating, says Liz. “It gives us useful feedback on our electricity usage patterns and, as a result, we make better choices about electricity consumption.”

For example, they noticed their hot water heat pump was coming on during the night when they’d prefer it to operate during the day from solar, so a timer to prevent that happening is on their to-do list.

Retiring sustainably

WHEN Julie May retired and bought a new home in Canberra, she decided to invest her savings in a sustainable lifestyle to reduce both her environmental footprint and her cost of living in retirement.

The house already had some good energy-efficient features including R3.5 ceiling insulation, R2 wall insulation, north-facing living areas with eaves to exclude sun in summer, high/low windows for cross-ventilation and a Daikin split system for heating and cooling.

Her changes began in July 2015 with the purchase of an Audi A3 e-tron plug-in hybrid electric vehicle, followed by installation of a 4.5 kW solar system (Nov 2015) and a 6.4  kWh Tesla Powerwall with Reposit for energy management (Aug 2016).

Julie also disconnected from gas in 2016, switching from instantaneous gas to electric-boosted solar hot water. Her gas bills previously comprised 80% fixed charge and only 20% for the gas itself, so going all-electric has meant a big saving.

She can now run her home and car mostly off solar and the stored energy in the battery, thus keeping imports low (1 to 2.5kWh/day, down from 10 to 23 kWh/day, counting electricity and gas).

Other notable achievements:

  • Julie has travelled 18,000 km in her Audi over the last two years and averaged just $155/year for petrol.
  • Reposit monitoring has meant she’s been able to better stagger appliance use so that grid energy is seldom required.
  • Julie has been paid Reposit premium GridCredits on several occasions for providing energy from the battery when there was high peak demand, e.g. she was paid $5.24 for four ‘grid credit events’ on 10 Feb 2017.
  • She also runs a cordless battery-powered mower as part of her all-electric home!

Eco additions

GREG and Maria built their passive solar house in Sydney in 1988, with a view to living as sustainably as possible. As technology has improved and become more affordable they have added more sustainable features.

A solar hot water system was the first addition in 1990, followed by 6000 L of rainwater storage in 2009, 2.8 kW of solar PV in 2010 and double glazing in May 2017.

Then, just six weeks ago, in late July 2017, they added a Tesla Powerwall 2 with 14 kWh of battery storage ($9300 installed).

Their motivations included to increase use of their solar and to ensure supply during blackouts, particularly to run tank pumps as they are in a bushfire zone.

The house’s energy consumption averages around 10 kWh per day, and the solar and battery were sized for this.

They expect they’ll use a little from the grid during the winter quarter, but they should be pretty well energy independent the rest of the year.

So far, the system has performed better than expected, with just a few days requiring grid draws of up to 2.5 kWh—usually when they’ve used their fan heater in the evening.

The battery charging and discharging is not timed—“it just works,” says Greg. “My experience is that there’s no need to manage it. So far, our limited experience is that if there’s a sunny day, the battery gets to 100% during the day with a small amount of grid export after that, and then the house runs off the battery all night.”

They can now run multiple appliances without drawing energy from the grid. Greg notes: “Being AC-coupled, the battery and solar add together, so we can supply a load of 7 kW quite easily, which was not possible before the battery.”

 

Read the energy storage guide and more case studies in ReNew 141.

IMG_1790

Towards grid independence

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

What happens when a home with very low electricity use adds a battery? Terry Teoh describes his home’s interesting results.

OUR house is an Edwardian three-bedroom brick home renovated in 2010 along sustainable design lines. With two occupants, our house achieves a very low average electricity consumption of 2.4 kWh/day, though note that gas is (currently) used for space heating, cooking and boosting of solar hot water.

READ MORE »

We installed a 5 kW solar PV system in December 2016. With the array oriented east and west, the seasonal difference in energy production is accentuated compared to a north-facing array: our system produces on average 26 kWh/day in summer and 7 kWh/day in winter.

In April 2017, we added a 4 kWh Sonnen eco8 battery to our system to provide solar load shifting—storing solar energy produced during the day for use at night.

In the first two months of operation (to June 2017), our house has moved from 30% to 70% grid independence—i.e. 70% of our energy is now generated by our solar system.

Interestingly, that 70% is lower than we expected given a substantially oversized solar array and battery. It turns out that our standby energy usage is too low to be served by our inverter!

However, it’s still a good result and the battery has lifted solar self-consumption from 5% to 50% and paved the way for us to disconnect from the gas network and move to an all-electric, renewably powered household.

Motivations
Our motivations for installing a battery system included a desire to maximise solar self-consumption and grid independence. The latter is not out of antipathy for energy companies or the grid. We want to stay connected to the grid.

The grid is good; it will just be used in a different way in the future to support a decentralised energy system where consumers will have more control over how they make, use, store and share energy.

Read the full article in ReNew 141.

Beyond the Stars

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

There’s much more to be gained from an energy rating tool than the number of Stars. Sid Thoo and Alex Raynes-Goldie demonstrate how an energy rating tool can help tweak the building’s orientation, materials, shading and more.

THE Nationwide House Energy Rating Scheme (NatHERS) ranks a home’s potential thermal performance (heating and cooling needs) based on its proposed design and construction. NatHERS is often used to demonstrate that projects meet the mandatory energy efficiency requirements of the National Construction Code.

READ MORE »

In Australia, new residential projects are generally required to meet a minimum 6 Star NatHERS rating.

NatHERS is, however, more than just a certification tool. By estimating a home’s potential heating and cooling needs based on different design and construction options, NatHERS can be a useful tool in identifying the best design strategies for your unique project.

Good design can reduce the amount of energy needed to keep a home comfortable, often with little or no additional cost.

Many ReNew readers will know the fundamentals of designing a more energy-efficient home—NatHERS can help take this one step further, testing how to apply these principles to get the best value for money.

Using an example house design, we will look at some of the fundamentals of energy-efficient design and discuss how NatHERS can be used to inform the design process.

1. Climate
Understanding climate is the first crucial step in designing a more energy-efficient, eco-effective home. It’s for this reason that passive solar design is sometimes more accurately referred to as climate-responsive design.

In Australia, the National Construction Code identifies eight distinct climates around the country, ranging from hot-humid to alpine conditions (see www.yourhome.gov.au/passive-design/design-climate).

NatHERS breaks these down further into 69 climate zones, based on historical climate data which also takes into account solar radiation, wind speed/direction, temperature and humidity.

Because different climates warrant different design responses, a six Star house in Melbourne is very different from a six Star house in Darwin. Melbourne is a heating load dominated climate (i.e. more warmth is needed to achieve thermal comfort), whereas cooling is the main issue in Darwin.

Thus, it’s vitally important to prioritise the most appropriate design strategies for the particular climate.

This means the six Star scale is calibrated differently for each climate zone, depending on whether heating and/or cooling is required to achieve thermally comfortable conditions.

BASIX (a NSW-based rating tool) goes one step further and applies separate targets for heating and cooling, which can help to further fine-tune the thermal performance of a design.

Read the full article in ReNew 141.

Desert Rose render

A net zero energy home

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

A net zero energy home for desert conditions is the mission of the next international Solar Decathlon, but the University of Wollongong’s entry could have applicability far beyond the competition.

The University of Wollongong’s entry in the next international Solar Decathlon is perhaps aptly named. It’s called the Desert Rose, after a plant that can cope with the tough conditions the team will encounter when they build and operate their sustainable house design in the host city, Dubai, in November next year.

READ MORE »

With temperatures of 35+°C every day, less than 2 mm of rain for the month and desert sands that present problems for both greenery and solar panels alike, there are certainly challenges ahead.

Student-led sustainable innovation
What is the Solar Decathlon? Sometimes called the Energy Olympics, the decathlon was started in 2000 by the US Department of Energy to encourage innovation in sustainable, renewably-powered residential buildings.

The contest challenges university student teams to not only design, but also build and operate a home that produces more energy than it consumes—a net zero energy home.

The University of Wollongong (and Australia) first competed in 2013. Amazingly, that entry, the Illawarra Flame (www.illawarraflame.com.au/house.php), won with the “highest score ever recorded,” says a suitably proud Brendan Banfield, building services manager for the 2018 team.

It’s a crash course in construction for the student competitors. The houses they design get built, dismantled and rebuilt, perhaps many times over the course of the competition.

In 2013, the Illawarra Flame was built and dismantled twice before its journey in seven 40-foot containers to that year’s Chinese host city. It took 12 weeks to build the first time (in a warehouse in Wollongong), but then just five days to dismantle and ten to re-assemble on site in China.

It’s an undertaking that gives the student competitors—from diverse fields including engineering, architecture, health, arts, business and communications—incredible hands-on experience in design, construction and problem-solving.

In fact, a US Department of Energy survey (covering four solar decathlons from 2002 to 2009; see www.bit.ly/2jgguaf) found some 76% of past competitors went on to jobs in the sustainable building and clean energy sector, compared to just 16% of non-competing fellow students (and 92% found the competition critical to their job-seeking).

Brendan says, “The technology used or invented is typically five years ahead of the market and 10 years ahead of the building code, giving competitors an ‘edge’ when seeking work or starting a business”—some 16% of those surveyed had started their own sustainability business as a result.

Read the full article in ReNew 141.

Read more about the Desert Rose team and their entry here.

Blower_door_testing

Why test for air leakage?

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

Energy efficiency consultancy SuHo explains the hows and whys of testing for air leakage in your home.

AN INTERESTING subject presently under discussion and development in the home construction industry is air leakage from buildings. You may have heard of terms like air permeability, air infiltration, air change rate and air flow rates. All of these terms relate to building air leakage testing, or ‘blower door’ testing.

READ MORE »

What air leakage is and how it relates to home energy efficiency is commonly misunderstood. Air leakage is the unintentional introduction of outside air into a building and can account for up to 25% of winter heat loss. It occurs via uncontrolled openings such as gaps and cracks. Note that this differs from ventilation, which occurs via controllable openings such as doors and windows.

Testing for air leakage
‘Blower door’ testing is a method of testing how and where a building leaks.

It uses a high-powered fan mounted within an adjustable frame to control pressure levels within a building. The fan is mounted into an external door opening.

All controlled external openings (doors, windows etc) are closed for the test, while all mechanical ventilation outlets (such as exhaust fans) are left unsealed and internal doors are left open.

A blower door test is non-obtrusive and takes a couple of hours.

The rise in pressure elevates air flow through any uncontrolled leakage points such as gaps, cracks and poorly sealed door and window frames, as well as through non-baffled fans. These are photographed using a thermal camera, which differentiates surface temperature from cold (blue) to hot (red).

An added benefit is that the thermal imaging has the ability to identify such idiosyncrasies as missing or disturbed insulation batts, water ingress and electrical faults.

Losing just 5% of the total insulation area of a ceiling effectively halves its performance (based on ceiling insulation calculations from the National Construction Code Volume 2 Section 3.12.1.1 Building Fabric Insulation; see also ReNew 140, p. 84).

The result is generally a building fabric audit report, provided to the homeowner and detailing all results, observations and recommendations, and quantifying potential savings.

Read the full article in ReNew 141.

thermal stratification

Home truths: notes from an energy assessor

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

After conducting home energy assessments for several years, Richard Keech shares some of the all-too-common problems he sees.

Since mid 2015 I’ve worked doing building energy assessments in Victoria, mainly for homes and mainly on behalf of ecoMaster. In that time I’ve visited about 290 clients to inspect their premises. In this article I’ll try to convey insights about homes and energy based on my experiences. Some of this is specific to Victoria’s housing stock and temperate climate and some applies to all homes.

READ MORE »

The assessment process itself
Winter thermal comfort is the biggest motivator in Victoria
I usually begin by asking clients what motivated their interested in an assessment. By far the most common response—probably three-quarters—is thermal comfort. Of that, most is winter thermal comfort. So whatever concerns people may have, it’s thermal discomfort that turns their interest into action. Given the current media discussion about energy costs, it’s interesting that cost is actually far behind thermal comfort in getting people engaged in the process.

People like to talk about their house
There’s an element of therapy about consulting on home efficiency that goes well beyond people simply receiving information about the state of their homes. It’s very much a two-way process. So patiently listening to people talk about how their home does or does not work seems to help people engage in the issue of home energy and comfort.

People don’t value professional advice highly enough
I’m very lucky to work for one of the few companies that consult on home energy efficiency. But even so, many people expect a lot for nothing, especially when it comes to draught proofing and general advice. Understanding a client’s home, sufficient to specify the many things typically needed to draught proof a home, is time-consuming.

The people who most need professional advice are the least likely to get it
A tiny fraction of households seek professional advice about their homes’ efficiency. And I expect that the homes we see are far from being the worst out there.

Tenants are missing out
Only a tiny fraction of our consultations apply to rented premises. Landlords and tenants both obviously lack the motivation to spend the money on a consultation because the cost and benefit incentives are misaligned. As a country we need ways to motivate landlords to improve their properties for the benefit of the tenants. This is worthy of a whole separate discussion; e.g. see www.bit.ly/TCRLOIC and ‘Energy-efficient renters’ in ReNew 134.

Read the full article in ReNew 141.

Orientation matters!

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

With a low average energy use of under 5 kWh/day, Ewan Regazzo shares the lessons he and his family have learnt from building a new energy-efficient home on a budget.

OUT walking the dog one day in my local area—a relatively modern and well-established suburb in Maitland, near Newcastle in NSW—I stumbled across a small, secluded cul-de-sac that contained a huge (1117 m2) vacant block.

READ MORE »

It appeared to be one of the few blocks remaining in the suburb and the faded and forlorn ‘for sale’ sign at the front, barely visible among the overgrowth, indicated it was still available.

Perhaps it wasn’t popular because of the site: the land was south-facing and fairly steep and narrow at the front, with a softer rise to the wider rear section. Further research showed it had a development application in with council for two narrow subdivisions, each with a small three-bedroom house, and I decided to invest with the idea of building two houses on the site, one for myself.

At that time I was living in a rental property which, although fairly modern, was a poor example of house design.

The rental house was unbearably hot in summer; aligned east/west, the lounge room was uninhabitable come afternoon.

In winter it would get down to 3 °C in the master bedroom and the gas heating in the open-plan living area provided little comfort for the financial outlay. In Maitland’s warm temperate climate, with hot summers and mild winters, passive solar design should work well, but it seemed this 15-year-old house had been built prior to the discovery of insulation and decent solar orientation!

Passive solar design was something I had been interested in for some time. I first came across ReNew way back in 1995, and had pored over copies of Owner Builder magazine, and had even investigated what I needed to do to be an owner-builder myself.

Full-time work meant owner-building wasn’t feasible, so I began investigating local builders to see what was available. I visited home display centres, walking through house after house and scrutinising plans for something that would work on my block. I ended up despondent: few designs considered site orientation and few builders were prepared to depart from a rigid formula that allowed for a quick, low-cost build at the cost of long-term efficient energy use.

Read the full article in ReNew 141.

Saltwater_Batteries

Saltwater batteries in use

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

When the old battery bank gave out, it was back to diesel for a time at this significant conservation site in the Mallee. But an innovative off-grid upgrade has changed that and led to a significant improvement over the old system, as Trust for Nature’s Chris Lindorff and Tiffany Inglis explain.

UP IN the Mallee, along the River Murray in far north-west Victoria, lies Neds Corner Station, a former sheep property now being restored as a significant natural habitat by the not-for-profit Trust for Nature.

READ MORE »

With an extreme climate—temperatures soar close to 50 °C in summer and frosts occur in winter—and no grid connection, this 30,000 hectare (300 km2) property presents challenges not only for habitat restoration, but also for the off-grid energy system needed to support the on-site rangers and visitors.

Purchased by conservation organisation Trust for Nature in 2002, the site is now home to two rangers and up to 30 visitors at a time: researchers and students studying the flora and fauna; bird groups conducting site surveys; works crews working on neighbouring public land; volunteers assisting with site restoration tasks such as reducing rabbit numbers, replanting local species and installing fences to keep out foxes; and the occasional corporate days and camping trips.

The site includes a homestead, shearer’s huts (used as accommodation), kitchens and conference/workshop rooms, with associated energy needs for heating/cooling, lighting, water pumping, refrigeration and gas cooking.

Energy system, take 1
When the property was first bought by Trust for Nature, the site ran solely on a diesel generator. Then, in 2012, philanthropic donations enabled the installation of a solar power system with a lead-acid battery bank. The system was designed to cater for an average of 25 kWh/day energy use, with a 25 kVA diesel generator as backup.

Over the following years, however, more people came to Neds Corner and energy demand increased, which led to the generator running more often than not.

Frequent, heavy cycling of the flooded lead-acid battery bank meant it performed poorly and reduced its lifespan. Following the failure of multiple battery cells in 2016, the battery bank was disconnected and the diesel generator again became the sole source of electricity.

Read the full article in ReNew 141.

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

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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.

READ MORE »

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.

mineral wool packing

2017 insulation buyers guide

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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.

READ MORE »

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

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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.

READ MORE »

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

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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.

READ MORE »

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.

IMG_3981 400px

Capital improvements: The path to all-electric

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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.

READ MORE »

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.

window_xavie_v02 copy 400px

Not just window dressing: High-performance curtains and blinds

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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.

READ MORE »

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

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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?

READ MORE »

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.

Capture

Solar sizing: big returns

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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.

READ MORE »

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

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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.

READ MORE »

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

Share : Share on FacebookShare on Google+Pin on PinterestTweet about this on Twitter

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

READ MORE »

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.