When Stars align: Finding the energy star rating and financial ‘sweet spot’

At one time or other, most of us have lusted after more space in our homes, yet we should instead desire comfort, good health and reduced operational costs. The allure of more space is tantalisingly waved in our face at display homes, in magazines and on TV, when the reality of operating costs is furthest from our mind. Too often we have heard how people have been talked into spending their money on another family room or second bathroom rather than on better insulation and double glazing. We are seeing a double whammy of expensive, almost unaffordable housing plus unintended increasing operating costs.

When we have a look around the world we see a renewed focus on homes that provide a better balance of environmental performance versus cost, without being captured by the singular yearning for space. Super low energy housing is now international best practice. Performance standards such as net zero energy homes or PassivHaus offer occupants superior thermal comfort, reduced living costs and improved health outcomes.

There is a significant gap between the minimum 6 Star NatHERS requirement in Australia and the minimum energy efficiency standards required in most other developed nations1, 2. The gap is even more pronounced when compared against existing Australian homes, which on average fall well below 3 Stars. The question must be asked, is there a sweet spot that satisfies more of our desires affordably? Is there an energy performance level here in Australia that delivers the best ‘bang-for-buck’?
In Australia, there is a growing body of evidence pointing to a sweet spot for energy performance well above the requirement of our building code. And we should remind ourselves that building regulations establish the minimum acceptable standard, rather than a good standard or an economically optimal performance level.

For example, one project modelled 80 single and double storey detached house designs available in Melbourne. The project modelled the cost of these homes at the minimum 6 Star NatHERS standard. Through a series of systematic material upgrades (for example, insulation levels, glazing changes) rather than design changes, the project calculated the impact of energy savings at 7, 8 and 9 Star NatHERS performance. The average upgrade cost from 6 Star was $3,000 to achieve 7 Star performance, $8,100 to achieve 8 Star performance and $25,300 to achieve the 9 Star performance. Across an assumed 40-year life of the dwelling the most affordable option was the 8 Star scenario.

Using data from The Cape project in Gippsland, Victoria, the graph shows the return on investment from improving a 6 Star house to an 8.2 Star standard, plus installing 5kW of solar PV, heat pump hot water, high efficiency heating/cooling and 10,000L of rainwater storage. The blue line represents an all-electric home; the red a dual fuel gas/electric home; and the dotted lines add an electric vehicle to these scenarios. And while the ROI is about 10 years for the house and vehicle option, versus 7 years for the house only, the model shows savings of more than $45,000 over almost 20 years.

Using data from The Cape project in Gippsland, Victoria, the graph shows the return on investment from improving a 6 Star house to an 8.2 Star standard, plus installing 5kW of solar PV, heat pump hot water, high efficiency heating/cooling and 10,000L of rainwater storage. The blue line represents an all-electric home; the red a dual fuel gas/electric home; and the dotted lines add an electric vehicle to these scenarios. And while the ROI is about 10 years for the house and vehicle option, versus 7 years for the house only, the model shows savings of more than $45,000 over almost 20 years.

The evidence from other climates is very similar. Lochiel Park in South Australia is arguably the most environmentally sustainable housing estate in the country3, 4. Its creation was inspired by the Sydney Olympic athlete’s village Newington, which back in 2000 was the first Australian estate to mandate solar PV, solar water heating, and a minimum NatHERS level of 3.5 Stars. Lochiel Park beefed-up the minimum house requirement to 7.5 Stars, required a much larger PV system, better solar water heaters, live energy feedback displays and much more. The result is a ‘performance enhancing’ almost net zero energy estate, full of energy-efficient homes that deliver affordable comfort and healthy living.

Getting back to our question of the sweet spot, are homes built to the Lochiel Park performance level affordable? When we crunch the numbers based on actual costs and real energy and water savings we find that although net zero energy houses cost slightly more to build, mainly because of the extra energy technologies, the owners are much better off financially. In fact, our research shows owner occupiers are nearly $25,000 better off over the life of the home, and that is before we consider the health and wellbeing benefits of better thermal comfort and enjoying almost no utility bills. That’s what we call a win-win-win scenario: the household pays off their loan faster, lives more comfortably and celebrates a real contribution to reducing greenhouse gas emissions. And although the climate varies a lot around Australia which means the solution set will be different, the same principles can be applied and everyone can win.
The homes at Lochiel Park are not perfect, in fact at a minimum of 7.5 Stars we can see many low-cost design improvements which would increase performance by an extra star or more, saving even more money. It is likely that the performance sweet spot at Lochiel Park is nearer 8.5 Stars.

Another excellent example involves a group of local builders and designers at Cape Paterson on Victoria’s Bass Coast. They have clearly demonstrated how good design, efficient appliances and solar energy can liberate Australians from energy bills.

To support the requirement that all homes built at The Cape sustainable housing estate in Victoria meet a minimum 7.5 Star energy rating, project director Brendan Condon commissioned research to assess the economic payoff of ESD investments over time, versus business as usual. The results are in (see graph below): they found an all-solar-electric house rated between about 7.5 and 8.5 Stars would deliver sustained financial benefits over a 20-year period. Image: Ben Mulligan, The Cape

To support the requirement that all homes built at The Cape sustainable housing estate in Victoria meet a minimum 7.5 Star energy rating, project director Brendan Condon commissioned research to assess the economic payoff of ESD investments over time, versus business as usual. The results are in (see graph below): they found an all-solar-electric house rated between about 7.5 and 8.5 Stars would deliver sustained financial benefits over a 20-year period. Image: Ben Mulligan, The Cape

The first home, originally built as a display home, but now to be lived in, is a double storey, 4 bedroom family home of approximately 180 square metres. The building has an 8.2 Star thermal rating, with a build cost-premium of $6,000 above a 6 Star build. The home has also been equipped with 5 kilowatts of solar photovoltaics, LED lighting, efficient electric heating, cooling, hot water and appliances, and good passive solar design. The result is that the home will save around $2,000 a year on the energy bill – a 75 per cent reduction compared to a typical 6 Star Victorian home of the same size5. This leads to a payback time of around 6 years and means the home owner will be over $40,000 better off over 40 years, as compared with if they had invested the money spent on thermal performance, solar and major appliances on their mortgage.

So why not have it all – a home that delivers health and well-being, a home that has impossibly low utility bills, and a home that makes you wealthier. For new housing in Australia, the building performance and financial sweet spot is significantly higher than what our minimum standards require. But why wait for regulation to catch up when the power of change is yours today? And as the cost of energy continues to rise, and the cost of improved building performance and renewable energy technology drops, the sweet spot will move. Once energy storage becomes affordable we might see the sweet spot climb even higher.

Lead image caption: Houses in the Lochiel Park development in South Australia have among the lowest annual energy bills in Australia and, according to the latest research into the ‘sweet spot’ for ESD investment for best returns, they could be made to perform even better. Image: Aldo Trissi

References
1. Horne, R. and C. Hayles (2008). “Towards global benchmarking for sustainable homes: an international comparison of the energy performance of housing.” Journal of Housing and the Built Environment 23(2): 119-130.
2. Moore, T. (2012). Facilitating a transition to zero emission new housing in Australia: Costs, benefits and direction for policy. RMIT University, Melbourne.
3. Berry, S., Davidson, K. (2015). Zero energy homes – Are they economically viable? Energy Policy.
4. Berry, S., Davidson, K. (2016). Value Proposition: Householder Experience. CRC for Low Carbon Living, Sydney, Australia.
5. Szatow, A. (2011). Cape Paterson Ecovillage: Zero carbon study peer review. Melbourne, Prepared for The Cape Paterson Partnership and Sustainability Victoria.

Keep your cool with external shading

There’s been quite a shift from pre-industrial times when glass was an artisan-crafted luxury item, and homeowners were taxed according to the number of panes they had. These days, our houses are getting bigger and so are our windows – often to the point of comprising entire walls. Windows and glazed doors frame views, admit natural light and breezes, and allow a connection with the outdoors.

However, from a thermal efficiency point of view, windows are the weak link in a home’s building envelope. Internal thermal blinds or curtains can help a lot in preventing heat loss through windows in winter (see ‘Not just window dressing’ in Sanctuary 39), but to tackle unwanted radiant heat gain in the hotter months, it’s far more effective to stop the sun hitting the glass in the first place with appropriate external shading.

Location and orientation

There is a huge variety of options for keeping the sun at bay, from carefully chosen deciduous plantings and simple solutions like a piece of shadecloth on a frame, to awnings, shutters, blinds, and even pergolas with sensor-operated louvre roofs. To choose the best solution, firstly it’s important to consider your location and the orientation of your windows. In most of Australia, shading is needed on windows on the north, and also the east (to prevent summer sun heating the house from early in the morning) and west (to block hot late afternoon sun). North of the Tropic of Capricorn, thought should also be given to shading windows on the south side of your house, as the sun’s steeply angled path in summer means these windows will also receive direct sun.

Because of the angle of the sun through the day, one size does not fit all when it comes to shading for all of the windows in your house. For windows within about 25° east and west of solar north, it’s easy to exclude summer and admit winter sun using simple horizontal devices, including eaves and awnings. This also applies to south-facing windows in the tropics. It’s reasonably straightforward to calculate the optimal width and height of eave that will stop the higher-angle summer sun from hitting the window and yet allow welcome lower-angle winter sun to penetrate deeply inside the room; Your Home provides a rule of thumb (see www.yourhome.gov.au/passive-design/shading).

For east and west windows, however, a different approach is needed as the low-angle morning and afternoon summer sun is more difficult to block. Angled or vertical shading is most effective here, and often an adjustable solution is best so it can be deployed only when needed.

Shading options

External shading products and structures fall into two broad categories: fixed and adjustable. Fixed solutions have the advantage of simplicity, and with no moving parts, are usually easier to maintain and last longer. However, they need to be carefully designed to avoid compromising solar access in winter.

Adjustable shading allows the occupants much more control over how much direct sun to admit. Such systems can be manually operated or motorised; fitted with sensors to allow them to respond automatically to sun, rain and wind conditions; and even integrated with comprehensive smart home automation systems.

An energy rating scheme for window coverings, WincovER, has recently been developed by the Blind Manufacturers Association of Australia (BMAA) – see box at the end of this article for more information.

For this holiday house in Shoreham, Victoria, architect Claire Scorpo used fixed horizontal and vertical silvertop ash battens to provide shading from northern and oblique western light. “I wanted to animate the space through the day with the shadows that are cast through the slatting,” she says. The battens lining the breezeway also provide privacy and a sense of enclosure for guests. Photos by Tom Ross.

For this holiday house in Shoreham, Victoria, architect Claire Scorpo used fixed horizontal and vertical silvertop ash battens to provide shading from northern and oblique western light. “I wanted to animate the space through the day with the shadows that are cast through the slatting,” she says. The battens lining the breezeway also provide privacy and a sense of enclosure for guests. Photos by Tom Ross.

Fixed shading

Eaves and overhangs: Don’t miss the opportunity to think about fixed shading at the design stage of your home or extension if you can. Perth-based architect Sid Thoo points out that including appropriately sized eaves or overhangs is a very straightforward, cost-effective solution. “External shading can also form part of the design aesthetic,” he says.

Fixed awnings: Another option for shading north windows (and south windows in the tropics) is a fixed horizontal or angled awning. These can be made from a wide variety of materials including steel, timber, corrugated sheet metal, cement sheet and rigid polycarbonate sheet. They should extend past the sides of the window to keep the sun off the glass for longer.

Fixed louvres/blades on windows: Usually made from metal or timber, louvres or blades are fixed in a frame against the window and can be placed running horizontally or vertically. They are particularly useful where privacy is needed or to comply with overlooking regulations.

Pergolas: Pergolas are an enduringly popular feature in Australian gardens, but striking the balance between having a great shady outdoor living space when it’s hot, and still letting sunlight and warmth into your house when it’s not, can be tricky. Roofing your pergola with fixed blades set at an angle designed to optimise winter sun access is one option; others include translucent but thermally effective polycarbonate sheet roofing, and simply growing a deciduous vine over it.

Shade sails and umbrellas: Made from knitted polyethylene fabric that’s available in a range of different light blockout levels, shade sails can be bought off the shelf or custom designed for specific spaces – or even made at home. If some rain protection is required, sails and umbrellas also come in waterproof coated fabric.

Adjustable shading

Retractable awnings and blinds: Pivot arm, folding arm, horizontal awnings on wires, roller, vertical drop – retractable awnings and blinds come in many styles. They can be closed up when not needed, allowing full winter sun access. With no support poles or attachments when extended, folding arm awnings in particular are quite susceptible to wind damage, but they can be fitted with sensors that close them automatically when bad weather hits.

The design of the Crayon House by Grieve Gillett Andersen incorporates primary-coloured shading - in the form of retractable horizontal awnings and vertical external roller blinds – to regulate the sun and add a playful character to the Adelaide home. Photos by Sam Noonan Photography.

The design of the Crayon House by Grieve Gillett Andersen incorporates primary-coloured shading – in the form of retractable horizontal awnings and vertical external roller blinds – to regulate the sun and add a playful character to the Adelaide home. Photos by Sam Noonan Photography.

Adjustable louvres/blades on windows: They are a pricier option, but metal louvres reflect more heat than fabric shading options, and adjustable versions offer scope for fine-tuning light levels inside the room. This style of shading is also good for privacy without sacrificing too much daylight.

Pergola/solar roof with adjustable blades: Another big ticket item, pergolas with adjustable blade roofs such as those offered by Vergola can be completely rainproof when closed, turning your outdoor living area into an all-weather space.

Shutters and screens: External shutters and screens – hinged, bifold, sliding or roller – are usually made from Thermalite (a high density plastic foam), timber or aluminium, and sometimes steel (although note that metal may heat up and radiate heat inwards, which could be a problem depending on the design). As they are fitted very close to the window, “they stand up to all sorts of weather,” says Joe Turner, president of the BMAA. Depending on the material and style chosen, they can also perform insect screening, security and bushfire ember protection functions.

Built on a tiny five by four metre footprint at the end of a laneway, the 5x4 Hayes Lane Project house by Barley Store Productions is a clever example of environmentally sensitive urban densification in inner-city Melbourne. With such a tight site, effective eaves were out of the question and instead aluminium external venetian blinds provide shading to the large windows that make up the eastern facade of the tall, narrow building. These blinds, from Sonnenschutz, have blades that can be tilted so that the outer edge is up, giving privacy from the ground while still allowing light in – a handy feature in this closely-packed urban situation. Image: Ralph Alphonso

Built on a tiny five by four metre footprint at the end of a laneway, the 5×4 Hayes Lane Project house by Barley Store Productions is a clever example of environmentally sensitive urban densification in inner-city Melbourne. With such a tight site, effective eaves were out of the question and instead aluminium external venetian blinds provide shading to the large windows that make up the eastern facade of the tall, narrow building. These blinds, from Sonnenschutz, have blades that can be tilted so that the outer edge is up, giving privacy from the ground while still allowing light in – a handy feature in this closely-packed urban situation. Image: Ralph Alphonso

Deciduous plants

Don’t overlook the option of using deciduous plants to provide shade to your house. This could be a vine growing on a freestanding frame or pergola, or a tree planted to block western summer sun. Be careful to match plant characteristics (such as foliage density, canopy height and spread) to your shading requirements, and choose local native species with low water requirements where possible. Plants can also be used to shade your walls: see ‘Green facades’ in Sanctuary 37 for more.

Materials

Many different materials can be pressed into service as external shading, depending on the application and desired characteristics. Rigid materials include timber, aluminium, steel, polycarbonate sheet, and even concrete (for formed window surrounds).

For flexible shading, traditional canvas is still available but it’s been joined by more high-tech PVC, polyester and even fibreglass fabrics. “I’d rate these newer sun screen fabrics very highly,” says Joe Turner. “They incorporate small holes that let light in and views, they breathe, and they have a better shading effect than canvas.”

Folding arm awnings provide adjustable shade for windows and patios, with no need for support poles. Image: Portside Shutters & Blinds

Folding arm awnings provide adjustable shade for windows and patios, with no need for support poles. Image: Portside Shutters & Blinds

As always, making an environmentally responsible choice is a matter of considering many factors including renewability of raw materials, the manufacturing process, recyclability, durability and expected lifespan, maintenance requirements and end-of-life disposal. Shaila Divakarla, architect and Standards & Technical Manager at Good Environmental Choice Australia (GECA), sums it up: “Every material has some advantages and disadvantages, so requires careful consideration of your particular needs and location. Think of the life cycle – where is the material coming from? Does it have any toxic components? How much energy does it take to make it? What happens at the end of its life?”

As external shading products are exposed to harsh environmental conditions, natural materials are often not suitable or would have a greatly reduced lifespan. Sid Thoo explains his approach: “Durability can be an issue – I try to avoid things with moving parts or that will require sealing or repainting over time. They might look great when first installed, but if they are then hard to access or maintain, this can become an issue over the life of the building.”

Unfortunately, GECA does not yet have a standard or certification process for shading products, but Shaila says it’s on their wishlist.

Other considerations

Space: The optimal shading solution for a given window just might not fit in the space available, especially if the window is built very close to a boundary. Perhaps consider a combination of a different external shade and an internal (possibly reflective) blind instead.

Visibility and permeability: Older-style canvas blinds and awnings are effective shading, but they also cut off views to the outside, block breezes and dramatically reduce daylight. Louvres, perforated screens and shutters, and blinds and awnings made from more modern high-tech mesh fabrics, allow airflow and diffuse daylight through but still block a significant proportion of direct solar heat gain.

Ease of operation: Consider how your windows open: will your external shading get in the way? Install vertically hung or angled shading far enough away from casement windows to allow them to open. Can manually operated shading be reached easily from inside by opening the window, or will it require a trip outside? If your shading is tricky to operate, it’s likely it won’t be used optimally to regulate solar access, reducing its energy efficiency contribution.

Mechanisation: For shading on hard-to-access windows, particularly those above the ground floor, mechanisation using a switch or remote control – or even, these days, a smartphone app – can make a lot of sense. It does add complexity and cost though, so it’s worth weighing up against the expected energy efficiency gains of better-performing shading.

Double duty: Think about whether your shading solution could fulfil another function at the same time – perhaps wind protection, privacy screening, insect screening or protection from ember attack during a bushfire.

For homes in high BAL bushfire-rated zones, Sonnenschutz’s BAL-FZ (Flame Zone) Shade&Shield shutters are an option; they provide shading and can be retrofitted to existing windows. In lower BAL zones, closely fitted hinged or sliding screens made from perforated steel or steel mesh can provide protection from ember attack and also offer less drastic shading than BAL-FZ shutters. Image: Sonnenschutz

For homes in high BAL bushfire-rated zones, Sonnenschutz’s BAL-FZ (Flame Zone) Shade&Shield shutters are an option; they provide shading and can be retrofitted to existing windows. In lower BAL zones, closely fitted hinged or sliding screens made from perforated steel or steel mesh can provide protection from ember attack and also offer less drastic shading than BAL-FZ shutters. Image: Sonnenschutz

Colour: Your Home notes that lighter coloured shading devices reflect more heat, and those with light coloured undersides make better use of daylight than those with dark coloured undersides. If you’re looking to retain some of your view through your shading, “fabric colour makes a difference,” says Joe Turner. “The darker the colour, the more heat gets in, but the better the view through the blinds; the lighter colours reflect heat better but don’t give quite as clear a view.”

DIY suitability, and ease of removal: If being able to install your shading yourself is important, check that it’s possible for your chosen product. For example, folding arm awnings consist of two tensioned arms that are attached to the wall with very strong fixings to enable them to extend up to four metres from the wall with no support poles; they definitely need to be installed by professionals. Other products like roller blinds are easier to DIY. You might also like to opt for shading that is easy to remove and take with you to your next house, especially if you are a renter. Shadecloth on a freestanding frame or small shade sails are good options here.

At the end of the day

As the climate warms and as cooling becomes a bigger proportion of many home energy loads, the importance of well-chosen external shading to keep the heat out before it hits the glass (or walls or roof) is only going to increase. Shaila Divakarla offers this advice for the most sustainable approach to choosing: “Spend time planning before making the choice; give it some thought with respect to your own particular situation. Don’t be swayed by fashion or what your neighbours are doing. Don’t just go for what’s cheapest or looks nice – think about the long-term cost.”


WincovER energy rating scheme

The Blind Manufacturers Association of Australia has been working on a rating scheme for window coverings and sun control systems. The new WincovER scheme will provide a simple star rating for many different types of internal and external shading products, with each product being rated separately for both heating and cooling performance.

Rated products will be listed in a publicly accessible database so that homeowners can compare products. At present, there are many different types of internal blind types that can be rated, while exterior products are limited to those that sit parallel to the window. It is expected the range will be broadened in the future as simulation technology allows.

Note that the WincovER rating is independent from the WERS (Window Energy Rating Scheme, www.wers.net) rating, which rates the energy impact of the selected window system on the whole house. However, ultimately a WincovER module will be added to WERS which will allow calculation of the effect of adding a shading layer to a window, quantifying the composite performance, whether the shading system is external, internal, or even between two panes of glass.

WincovER is set to be launched by the end of 2017. For updates, keep an eye on the BMAA website.


This article is the second in the Sanctuary series on windows. Anna Cumming’s previous article “Not just window dressing: high-performance curtains, blinds and shutters” is online and in issue 39.

Sustainable House Day success!

Sustainable House Day is over for another year, and the numbers are in: with 206 houses opening their doors around Australia and 29,049 individual visits, it was easily our most successful event yet. Some homeowners chose to collect a small entry fee for charity, and $12,060 was raised for a range of environmental and local community causes.

But of course the true impact of the day is not really measured in numbers, but in inspiring experiences of great sustainable homes and peer-to-peer learning, and for the homeowners, the satisfaction of helping others on their own journeys to comfortable, low-impact, low-bill living. In Sanctuary 40, we profiled nine of the standout houses opening on the day. We checked in with some of them after the dust settled, and asked how things went.

Outside Canberra, Ali and Ann had “an exhausting, but good day”, with 67 people coming to see their new home designed to Passive House principles. “We are now well rehearsed on all the sustainable features of our house!” laughs Ali.

Clare from Clearwind in Glenhope, Victoria, loved showing people her incredible garden. Image: Claudine Collins

Clare from Clearwind in Glenhope, Victoria, loved showing people her incredible garden. Image: Claudine Collins

In Lynton, Adelaide, Margaret and Charles and their architect Bohdan Dorniak conducted tours for 270 people through their urban strawbale home, built with natural materials and all-electric appliances. “The people who came were asking really good questions and many knew lots about the issues. It was really lovely to be informing young couples with babies attached, about how to have a healthy house when they can finally afford to build,” says Margaret.

Over in Fremantle, homeowners Greg and Alice found Sustainable House Day “an empowering and gratifying experience”. They had their architect, their stonemason and eight volunteers on hand to help field questions about their owner-built labour of love, built largely from recycled materials. “We both worked extremely hard on this project and to keep it only for ourselves to enjoy seems selfish, so we get great pleasure out of seeing it ignite other people’s imaginations,” says Greg. They’ve opened their home for Sustainable House Day before, when it was half-completed, and said it was more relaxed this year, despite a whopping 371 people through the doors. “We made up information placards on the house’s features for the first time this year which proved to be a big hit.”

One of the most popular homes that opened was MM house, designed by Luke Middleton from EME Design for his own family.

One of the most popular homes that opened was MM house, designed by Luke Middleton from EME Design for his own family.

For Shelley and Luke, in Canberra, it was “so much fun to fill our house with people who understand and have aspirations to create similar environments for themselves”; although Shelley says it was also slightly adrenaline-inducing! Open for only two hours on the day, they still welcomed 200 people through their house, built by carpenter Luke using as many reclaimed and recycled materials as possible. Another 100 visited the garden, which features an innovative whole-block water harvesting system that stores water in trenches to be wicked up by the plants. “We just had so much absolutely lovely positive feedback about our home,” says Shelley. “It seems people really identified with the simplicity of the actual design of the house and the warm, personal interiors. They liked the fact that it wasn’t too unobtainable, and it struck a balance between extreme passive house theory and liveable functionality and affordability.”

If you missed it this year, Sustainable House Day will be back in September 2018 to offer you the chance to see best-practice sustainable design and material use in action, and to ask questions of the people who are already living in the kind of house you might be dreaming of. And you can read more about all of these houses on the Sustainable House Day website, in Sanctuary 40 and here on the Sanctuary website.


Feature image: Bruce Carrick gives a tour of his beautiful sub-tropical home in Brisbane during this year’s Sustainable House Day. We feature this house in Sanctuary 40 and online here

Sanctuary 41 out now

It’s often joked that ‘doing a reno’ is a national sport in Australia, such is our enthusiasm for hardware stores and real estate. If only our efforts were better directed towards housing quality for in this area we’re far from match-fit. It’s almost 15 years since mandatory national housing efficiency standards were introduced and yet millions of homes perform worse than 2 Stars – woefully poor on any scorecard. On the upside, research into the return on investment for green home improvements shows benefits for health, comfort, emissions and the hip pocket; simple changes shave tens of thousands from energy bills over 20 years (p76). But while there are many good reasons to address the energy performance of all houses, not just new-builds, we lack a cohesive national approach for achieving this. It’s up to proactive households to change the game – but where to start?

This issue of Sanctuary is intended to be your guide. We profile nine extraordinary renovations from across Australia and New Zealand, and identify the key ESD considerations that have set up these old buildings for a low-bill future. From net-zero energy and future proofing, to sustainable materials and thermal upgrades, we show you how a renovation can improve the whole house (p16). Good renovations come in all shapes and styles, and so we visit a tiny refurbished apartment designed for downsizers (p48), a lofty warehouse conversion that’s achieved a 6.1 Star energy rating (p36), and everything in between. Our cover feature is a spectacular Auckland house upgraded to meet strict seismic codes – it’s instructive to see how New Zealand policy is meeting this difficult challenge (p53; design by Dorrington Atcheson Architects, photography by Emma-Jane Hetherington). I hope through these success stories we not only influence your next project but also help lead the housing sector in a new direction, where super efficient is the norm, not the exception.

ALSO IN THIS ISSUE …
As the weather warms up, Anna Cumming presents some cool external shading ideas, Verity Campbell unearths some of the world’s most incredible architectural holiday stays and veterinarian Joanna Griffith explains how cat owners can use design to protect wildlife. And in our summer Design Workshop, architect Rowan Brown weighs up the pros and cons of using shipping containers for a modular mountain retreat.

PS. Don’t miss the 5 to 10 minute Sanctuary readers survey for your chance to shape the magazine’s future direction. With an Orto Rustic wicking bed on offer you could be doubly rewarded.

Sanctuary 41 is on its way to letterboxes and newsagencies near you, full of advice and inspiration for sustainable living and building.

 

And as always we feature a wide range of innovative sustainable products and design tips for your home.

We welcome your feedback. Perhaps there’s something else you would you like to see in Sanctuary? Let us know on FacebookTwitter or by email.

Not just window dressing: High-performance curtains, blinds and shutters

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 per cent of a home’s heating energy can be lost and up to 87 per cent 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 for your home, it’s worth also considering effective window furnishings. Blinds, curtains and shutters can improve a window’s performance, make your home more comfortable and reduce energy costs.

Where to start?

“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.

When choosing a product for a particular window, it’s important to consider the main purpose it will serve. Keep in mind that 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 for more information).

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. And this 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.

Choosing your style

There is a wide range of products available depending on the purpose to be served, your budget, and your design preferences.

Curtains

According to Megan, the humble and currently somewhat unfashionable curtain is set to make a comeback. “Heavy curtains are best for thermal performance and are great to block out light,” she says, “but may not work where floor space is limited or there is no space above the window to mount tracks or at the side to accommodate the open curtains.” There are other considerations to ensure your curtains are effective: they should have an enclosed pelmet at the top or drop straight from the cornice; touch the wall at either side; and just kiss the floor. If not, and as Energy Freedom Home explains, the warm air created by a heater will rise to the top of the window and be drawn down into the space between the window and curtains, driving a current of air that can rapidly cool the warm air in the room and can increase condensation.

Although these curtains don't have a pelmet, they are fitted close enough to the ceiling to have a similar effect: preventing airflow from the room down behind the curtain. They also brush the floor and the wide window sill, further increasing their thermal performance. This energy-efficient Melbourne townhouse is profiled in Sanctuary 35. Image: Ben Wrigley

Although these curtains don’t have a pelmet, they are fitted close enough to the ceiling to have a similar effect: preventing airflow from the room down behind the curtain. They also brush the floor and the wide window sill, further increasing their thermal performance. This energy-efficient Melbourne townhouse is profiled in Sanctuary 35. Image: Ben Wrigley

Pelmets can usually be easily retrofitted to existing curtains and need not be visually intrusive boxes. They can be made from just about any solid material; the most common is timber, but lightweight plastic sheet or even cardboard is an inexpensive alternative, and especially useful for renters. Elizabeth Wheeler, building designer and product specifier for Future Focused, suggests that if you prefer a streamlined look, you can consider integrated bulkheads instead, but notes that usually these must be factored in during the design of your home. One invisible track system that provides this integrated effect is the Ezy-Pelmet from Ezy-Jamb. Another invisible, easy-to-DIY option is a retrofit pelmet cap that sits between the wall and the curtain track and touches the back of the curtain; Ecomaster offers ‘Invisible Pelmets’, an acrylic product sold by the metre.

Considering your window furnishing needs at the design stage of your build or renovation makes it possible to opt for pelmets integrated into the walls or ceilings, giving a streamlined look. These curtains help moderate heat loss through north-facing glazing at the Yarraville Garden House [profiled in Sanctuary 39]. Image: Peter Bennetts

Considering your window furnishing needs at the design stage of your build or renovation makes it possible to opt for pelmets integrated into the walls or ceilings, giving a streamlined look. These curtains help moderate heat loss through north-facing glazing at the Yarraville Garden House [profiled in Sanctuary 39]. Image: Peter Bennetts

Blinds

Effective blinds come in a range of styles including roller, roman and honeycomb, and are a versatile and effective option, as long as due care is taken to fit them snugly (ideally within the window reveal) to minimise air gaps around the edges. (Vertical blinds and standard venetian blinds can help regulate sunlight and privacy but are of limited help with thermal performance.)

The effectiveness of all types of blinds is improved by fitting them snugly within the window reveal. Image: Ink and Spindle and Amorfo Photography.

The effectiveness of all types of blinds is improved by fitting them snugly within the window reveal. Image: Ink and Spindle and Amorfo Photography.

Megan notes that roller blinds are generally cheapest but less thermally effective, and heavy backed roman blinds can be a good option for small and narrow windows where there isn’t room for curtains. However, her favourite type of blind is the honeycomb, a concertina style that’s made from fused layers of fabric that form a series of hexagon-shaped tubes when open, and is very compact and visually unobtrusive when closed.

Roller blinds can be made in an almost unlimited range of fabrics to suit your décor; try to choose a design that won’t date too quickly though. When fully lined, this type of blind can provide thermal benefits, although it can be difficult to ensure a tight fit and prevent light and heat spilling around the edges of the blind. Image: Emma Byrne and Brave New Eco

Roller blinds can be made in an almost unlimited range of fabrics to suit your décor; try to choose a design that won’t date too quickly though. When fully lined, this type of blind can provide thermal benefits, although it can be difficult to ensure a tight fit and prevent light and heat spilling around the edges of the blind. Image: Emma Byrne and Brave New Eco

Dick is a fan too, and summarises the benefits: “They can be blackout, or translucent to insulate while admitting some light; they can be designed to open from the top down and/or from the bottom up, providing versatility for privacy; they are very good insulators if fitted well; and they are clean and contemporary but also work with traditional decor.” Luxaflex Duette blinds by Hunter Douglas were the first to feature this honeycomb design, and they are now available in double and triple honeycomb construction for even greater insulation. Many other manufacturers offer a similar product.

David Baggs, CEO of Global GreenTag International, describes the ‘next tier’ of blinds as those that run in side tracks with an enclosed box at the top, much like a pelmet: “they are great as blockout blinds for bedrooms, as light doesn’t leak around the sides,” he says, “as well as performing well thermally.” Melbourne manufacturer Vertilux’s Fully Enclosed Kassett roller blinds are an example, and are available in varying degrees of light permeability up to complete blockout.

Honeycomb blinds, like these Luxaflex Duette Architella shades, provide a thermal benefit by trapping a layer of air inside their cellular construction. They are compact when closed, and can be configured to open from the bottom up or top down giving extra versatility for shading and privacy. They are also available in double- and even triple-wall construction, and in a range of colours and fabrics from quite translucent to blockout. Images courtesy Luxaflex

Honeycomb blinds, like these Luxaflex Duette Architella shades, provide a thermal benefit by trapping a layer of air inside their cellular construction. They are compact when closed, and can be configured to open from the bottom up or top down giving extra versatility for shading and privacy. They are also available in double- and even triple-wall construction, and in a range of colours and fabrics from quite translucent to blockout. Images courtesy Luxaflex

Shutters

Plantation shutters – usually made from timber or PVC, with adjustable blades – are currently a popular choice for interior window coverings. They provide privacy, but also block a considerable amount of light even when the blades are tilted open. While louvre or blade-style treatments are probably best suited to external shading applications, “they do have some thermal effect when used inside if you can get a good seal; it comes down to good design,” says David.

“And remember that if they are timber it needs to be sustainably certified.” Elizabeth’s recommendation for choosing shutters is to “preferably source a locally made shutter that uses plantation timbers. If you can, buy the shutter unpainted so you can use your own low-VOC finish.”

Purists will install shutters externally, but interior shutters are the next best thing and can make it more convenient to control for light and privacy.

Purists will install shutters externally, but interior shutters are the next best thing and can make it more convenient to control for light and privacy.

Materials

When it comes to materials for your window treatments, the possibilities are just about endless. Curtains, roller and roman blinds can be made in any fabric that takes your fancy, though Megan cautions “pick your fabrics carefully as curtains are a long-term investment. Make sure you don’t pick something that will date in five years, as with good care they will last much longer than that.” David suggests opting for natural fabrics such as cotton, linen or hemp – organic if possible – and if your blinds are mainly for privacy or shading, “you can get a great diversity of rapidly renewable bio-based materials, like rattan, reeds, and bamboo. I have even seen woven products made out of dried hyacinth, [a plant] which is a major waterway pollutant in developing countries.”

Honeycomb blinds and light-admitting roller blinds tend to come in a more limited range of specially designed polyester, acrylic or vinyl fabrics, sometimes with reflective backing. Not so natural, but some brands offer options with recycled content, low-VOC (important for interior air quality) and other sustainable credentials; for example, Vertilux is proud of their Greenvision fabrics which are “PVC-free, low-VOC, Ecospecifier assessed and can also assist in the achievement of points as set by the Green Building Council of Australia.”
David recommends looking for phthalate-free acrylic and vinyl products, as some phthalates can have particularly detrimental health effects when off-gassed; the Global GreenTag certification program will stop certifying products with specific common phthalates after 2019.

Roller blinds with an enclosed pelmet and side tracks, such as these fully enclosed Kassett blinds from Vertilux which have dramatically reduced air and light leakage in this lab. This improves their thermal efficiency and – when a blockout material is chosen – makes them an effective choice for bedrooms. Image courtesy of Vertilux

Roller blinds with an enclosed pelmet and side tracks, such as these fully enclosed Kassett blinds from Vertilux which have dramatically reduced air and light leakage in this lab. This improves their thermal efficiency and – when a blockout material is chosen – makes them an effective choice for bedrooms. Image courtesy of Vertilux

It’s worth looking for fabrics and products that carry an eco certification from an independent body such as Ecospecifier, Global GreenTag or Good Environmental Choice Australia (GECA). You can also look for products that can be recycled at end of life, and for manufacturers who have sustainability policies and material use and waste minimisation plans in place.

Consider durability too. Although interior furnishings are not as exposed to the elements as external window coverings, they will still need to withstand strong sunlight, especially those that are on north and west windows and designed to be used during the day rather than purely for heat retention at night. Choose good quality materials – particularly backing fabric – and ask about expected lifespan and warranties.

In good news for consumers, the Blind Manufacturers’ Association of Australia (BMAA) is developing a rating scheme for internal and external window coverings. The WincovER energy rating scheme due to be launched in the second half of 2017, will provide products with a simple star rating for both heating and cooling performance, allowing easy comparisons between products. BMAA president Joe Turner explains that ultimately, a WincovER module will be added to the existing WERS (Window Energy Rating Scheme), which rates the energy impact of a window system on a house; this will give an understanding of the expected performance of window and window covering together. Keep an eye on the BMAA website for updates.

Other considerations

Ease of use: Make sure the treatment you choose is suitable for the window or door style and use; inward-opening windows will need special consideration, and a pull-down blind might just get in the way of a door opening. Take care also that blinds clear any window and door hardware like latches and winders.

Blinds and curtains will, of course, only deliver benefits if they are actually used. While it’s true that some active ‘driving’ of a house is usually necessary to achieve the best passive thermal performance, “opening and closing lots of blinds every day through summer and winter can be tedious,” says Elizabeth; this is especially true for hard-to-access blinds. “If you think you might be inclined to just give up and leave everything open, firstly consider whether you really need all that glazing. If you do, then consider mechanisation.” There are plenty of options for mechanising blinds these days, some allowing remote control via a smartphone app, and even systems that use a sun sensor to adjust blinds automatically. These systems do add considerable cost and complexity, though.

Budget: Good-quality internal window coverings for a whole house can be a considerable expense: Megan estimates $10,000 to $20,000. “If possible, it’s worth budgeting it into your costings for your home build or renovation, and thinking about it as part of the design stage.” Planning to complete the installation in stages is another option, but “you’ll need to consider how to manage your building’s thermal performance while you stage your fitout, and/or while shade plants grow,” says Elizabeth.

Maintenance: Most parents of young children would think twice about buying a white couch; window furnishings deserve the same consideration! “Think about cleaning: food and dirt from grubby mitts, dust and splashes from spills,” suggests Elizabeth. “Paying attention to cleaning and repairing fixtures is an important yet often-overlooked aspect of a more sustainable home.”

Safety: Remember to pay attention to the safety of blind cords, which present a real strangulation risk for small children. Even if you never have young visitors, the next resident might.

Strata residents: If you live in an apartment, it might be necessary for your internal window coverings to do extra duty for shading and heat reduction, as you may have limited freedom to install external window shading. Exterior walls are generally considered to be common property and alterations require approval from the owners corporation; even installing film on your windows to reduce heat gain can violate strata regulations as it changes the external appearance.

Green Strata’s Christine Byrne has this to say about improving a strata dwelling: “A lot of what you can do is similar to a freestanding house, but you need to consider the extra layers of approval required. Don’t assume it’s not possible or too hard. Understand where the extra layer of approval is relevant, understand what you have to do to get approval, and make your decision from there. If you know the steps along the way, you can make an informed decision about what to do.”

Generally, you’ll have a lot more flexibility to install interior window coverings than external shading (although if you’re a tenant, you’ll probably need your landlord’s permission to drill into walls). But Christine cautions that some buildings even have bylaws about internal window furnishings, for example only permitting curtains if they have a white backing; it pays to check your strata rules before getting started.

If you are relying on internal window furnishings to prevent heat gain in summer, “consider options that still allow some light to penetrate,” recommends Elizabeth. “While they are not as effective as full block-outs, darkened rooms can be really depressing in daytime – especially for days on end.”

The next big thing?

There is certainly scope for further development in design and materials. Joe Turner is excited about the continuing development of mechanisation and automation systems for blinds, to maximise their effectiveness. On Megan Norgate’s wish list is a blackout thermal curtain lining with recycled content, and a wider range of integrated curtain pelmet and track options. Dick Clarke is looking forward to seeing the more widespread availability in Australia of integrated blinds inside double or triple glazing (also known as ‘blinds between glass’), already quite widely used in Europe.

In the meantime, when they are chosen with care and an eye for performance as well as aesthetics, interior window coverings can make a huge difference to the comfort and efficiency of your home, and the range that’s currently available is excellent.


Feature image: Heavy curtains that touch the walls on each side of a window, reach to the floor, and have an enclosed pelmet at the top are very effective at preventing heat transfer between the interior of the room and the window, and thus outside. Good design for curtains includes allowing enough space beside the window to store the open curtain without blocking part of the glazing. Image courtesy Emma Byrnes & Brave New Eco