Stay warm this winter

Keeping it green, as we like to do at Light Home, we’ve investigated some of the options to help you keep warm in bed and happy in the knowledge you’re also doing something positive for the environment and creating an eco home.

Eco-friendly doonas, alpaca doonas – and even green electric blankets. Read on to find out more.

Eco doonas

Gosford-based Bambi, which started as a family business over 30 years ago, specialises in eco bedding and has a great range of eco doona options.

Eco-friendly fibres used in their products include cotton, wool, plantation-grown bamboo, Ingeo™, which comes from corn, and Tencel®, a 100% new age fibre, made of wood pulp cellulose that comes from sustainable forestry plantations.

Bambi’s Ecorenew range of doonas includes several designed for chilly nights, such as the Ecorenew Ingeo™ and the Ecorenew Tencel®.

Be as warm as an alpaca

Alpaca wool is also being used to fill some of the warmest doonas on the market. The wool is light but packed full of some high insulation properties, making it one of the warmest bedding products available.

The Benbellen Country Retreat, on the NSW mid-north coast, produces alpaca doonas, selecting, combing and washing the wool before using it to fill the doonas.

ecorenewquiltTathara Alpacas, in Victoria, also makes alpaca doonas and their standard doona has a thermal rating equivalent to three and a half blankets. But they also produce a ‘His & Hers’ quilted alpaca doona – one side with a thermal rating of three and a half blankets and the other with a thermal rating of five blankets – perfect for couples who can’t agree on how thick their doona needs to be!

Alpaca wool

Should you switch on the electric blanket?
Electric blankets make things super-cosy. But for the eco-conscious, there’s the obvious concern that plugging your blanket in all night is a bad use of electricity.

There are eco electric blankets out there to ease your conscience.

The Econo-Heat E-care low voltage electric blanket uses minimal electricity to keep your bed warm and cosy all night. It also turns itself off automatically if it’s left running for more than 10 hours.

Home Insulation

Insulation is an essential part of a well-designed home and can save 45 – 55% of heating and cooling energy, according to Sustainability Victoria. Not only is it necessary to meet mandatory energy efficiency ratings, it will also improve comfort year-round by ensuring heat stays in during winter and out during the warmer months.
Heat is gained or lost through all parts of a building, with the amounts varying depending on the season. According to Insulation Benefits, a factsheet put out by the Victorian Sustainable Energy Authority, during winter:

25-35 percent of heat is lost through the ceiling,
10-20 percent through windows;
15-25 percent through the walls;
10-20 percent through the floors;
and another 5-15 percent through other air leakages, such as open doors

All up, that’s 90 to 100% of the heat in your home going to the outside!

The reverse happens in the summertime, with 25-35 percent of heat coming through the ceiling, 25-35 percent through windows, 15-25 percent through the walls, and 5-15 percent through other air leakages.

Warmer in winter, cooler in summer.

There are several different types of insulation on the market: bulk insulation (batts) that reduces heat flow by trapping air in tiny pockets, and reflective membrane insulation (sarking) that reflects radiant heat away from the building.

Bulk insulation comes in a variety of R ratings (the value given to their thermal performance) and is inserted inside stud walls and in ceilings. The higher the R value, the greater its insulating effect, but it does need to be installed correctly, explains Anthony Milostic, National Technical Support Manager at James Hardie.

“As a general rule, using a R2.7 batt from a company like Fletchers Insulation into the wall frame, and combining that with the additional R value gained by using lightweight cladding products such as James Hardie’s Scyon™ range will give a rating of R2.8, and satisfy the six star energy efficiency house standard that applies in most Australian climate zones,” he says.

“Reflective sarking also reflects radiant heat away from the home’s interior, however the reflective side needs an airspace of at least 19 mm in front of it for walls,” he says. “If there is something in direct contact with it, such as if the cladding has been squashed on top, it won’t work.”

And while the consequences of under-insulation are fairly obvious, it is also possible to over-insulate.

“It depends on the climate and the building design, but it is possible to create an oven effect that traps hot air inside,” says Milostic.

Well-placed windows that encourage cross-ventilation in the warmer months and appropriate shading will help stop the house turning into an oven.

In response to the reader’s question about insulating a long western wall, Milostic advises building a timber frame with bulk insulation inside the wall frame, and installing a layer of antiglare sarking facing outwards.

“Nineteen-millimetre thick Scyon™ battens should then be fixed to the timber frame then clad with something like Scyon™ Matrix cladding panels. This will give the wall a total R3.4 rating, which will help put the house in the 7-8 star category.”

Lightweight is better.

Architect Ed Ewers faced a similar challenge for a house he built in Melbourne’s Richmond. He has examined a number of wall systems, and agrees that “you don’t want heavy thermal mass [like a brick wall] facing west; it needs to be lightweight”.

However he believes that the best and most efficient solution in terms of time, money and performance is to build two lightweight ‘skins’ with an air gap between them.

“The external wall should consist of a timber frame filled with R2.7 bulk insulation and clad with fibre cement sheeting like the Scyon™ range of products or with Foamboard,” he says, adding that reflective paper (sarking) should be stapled to both sides of the frame.

“A second timber frame that is also filled with R 2.7 bulk insulation can then be lined with plaster. Leaving a gap between the two walls will create an airpocket that provides additional thermal benefits.” Reflective paper should be stapled to the external face of the frame.

While this system will create thicker walls, Ewers says that the double thickness can be used as a feature.

“It is important in a home to have a bit of western aspect because the late afternoon light is quite nice, although you do have to reduce the size of windows,” he says. “[This is made up for] by the deep window reveals created by the thicker walls, which create a feeling of depth in the room.”


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