Sanctuary: Modern green homes

Building to Passive House standard

This is an excerpt from an article in Sanctuary magazine issue 17.

Developed in Europe as “passivhaus”, the Passive House Standard is gaining popularity worldwide. New Zealand building designer and Passive House Consultant Glenn Murdoch explains how it can help produce energy efficient, healthy houses.

Words Glenn Murdoch

Everybody deserves to live in a healthy society. A society cannot be healthy unless its people are, and a fundamental requirement for this is that the buildings in which people live, work, play and learn are healthy.

A healthy building has many aspects; the one with the greatest impact on human health is indoor environmental quality. On average Australians spend about 90 per cent of their time indoors, so it is essential that it’s spent in a healthy environment. Even if you are outdoors most days, you still need to sleep in a healthy environment.

By applying the Passive House Standard to the buildings we design and build, we can guarantee that they will be perpetually comfortable, healthy, energy efficient, with excellent indoor air quality, extremely low running costs and a durable structure, as well as free from mould and damp.

The Passive House Standard is an international building energy performance code developed as “passivhaus” in Germany in the late 1980s. At the time the minimum building code standards in Germany were higher than those in Australia and New Zealand but were still considered inadequate. The Passive House Standard came out of a large research project and has subsequently been tested and verified to the point that it works in all climate zones.

If you’d like to read the rest of this article you can buy this issue here.

Turning an inside-out world right way around again

This is an excerpt from an article in Sanctuary magazine issue 17.

When it comes to thermal efficiency, reversing traditional brick veneer construction and putting the brick on the inside makes so much more sense. Dick Clarke explains why.

Words Dick Clarke

Reverse brick veneer (RBV) which, although self-explanatory when we think about it, has often caused people to do a double take: “Yes, that’s right, the bricks are on the inside of the wall… No, the plasterboard doesn’t get wet – it’s clad with… (whatever).”

In an RBV building, the brick layer is located within a protective external insulated skin. That skin can be made of pretty much anything that takes your fancy – but it must be well insulated to allow the thermal mass of the brick to do its job of regulating internal temperatures. (The brick layer can also be blocks, mud brick, rammed earth, or recycled concrete – so RBV is actually more correctly called Insulated Masonry Construction, but that name is nowhere near so well recognised or so much fun!)

We have to use the “reverse” in RBV because in the late 1950s somebody had the not-very-bright idea of replacing weatherboards and fibro on timber framed houses with a veneer of bricks (BV). “Brick veneerial disease” has since become the dominant building method in southern Australia, with people in the tropics generally avoiding its contagion. Many among us have come to assume that BV is normal brick, such that double-brick construction has come to be called “full brick”. This implies that brick veneer is “half brick”, perhaps “half as good”. This isn’t far off the money. It may save a coat of paint every 15 years or so, but costs a whole lot more than that.

If you’d like to read the rest of this article you can buy this issue here.

SIPs for structure and insulation

This is an excerpt from an article in Sanctuary magazine issue 18.

Structural Insulated Panels (SIPs) are an established building envelope technology gaining new ground. Dick Clarke explains why well- designed SIPs can be a sustainable solution in contemporary homes.

Words Dick Clarke

Looking to the future of house construction, one feature that keeps popping up is the increased use of prefabrication systems in place of building on site brick by brick, stick by stick. Traditionally the domain of the cheap and nasty, prefab’s image is changing. Some of Australia’s most sustainable buildings are now prefab and, thanks to UK television show Grand Designs, most people have seen some superlative European prefab systems.

One component we will see more of in projects of all sizes and budgets is Structural Insulated Panels (SIPs, often loosely called foam sandwich panels) for floors, walls and roofs. These large panels replace the conventional framing, cladding, insulation and lining we usually see houses built from. They are load bearing and provide the necessary bracing as well. They can be prefinished, so little site work is required once they are stood and connected together.

The SIP concept is far from new. In fact, US First Lady Eleanor Roosevelt opened an experimental house built with SIPs in 1937, which saw active service until 1998, only demolished to make way for a much larger university building.

If you’d like to read the rest of this article you can buy this issue here.

Condensation? Let your building breathe

This is an excerpt from an article in Sanctuary magazine issue 18.

Tighter building standards have given rise to condensation issues, but there are ways to minimise moisture build-up in your home: ventilation is key.

Words Michael Green

As we improve the air- tightness of our homes and fatten our insulation, we need less energy for heating and cooling. But there’s another side effect to consider: condensation. Condensation occurs where humid air hits a cooler surface, like the way droplets appear on the outside of a chilled glass of beer. In a house, it tends to form when warm internal air meets the building envelope that’s been cooled by exposure to the outside air.

Steve King from the Built Environment faculty at the University of New South Wales says Australian homes have always been draughty – until recently. “Traditionally, while there may have been condensation in homes, it dried out very easily because of the ventilation, so there weren’t any cumulative effects.”

In recent years, however, he says New Zealand, Canada and the UK have witnessed widespread condensation troubles after tightening their building standards.

The Australian industry is beginning to take notice of the issue too. Earlier this year, the Australian Building Codes Board released a guide on condensation for designers and builders.

Andy Russell from Proctor Group Australia was one of the contributors to the handbook. He says that where condensation forms regularly and doesn’t dry out, it not only causes mould, but can also decay the framing and lining of the house. In some cases, residents will experience the symptoms of “sick building syndrome”, including asthma, itchy eyes and nasal allergies.

If you’d like to read the rest of this article you can buy the issue here.

Straw bale: an enduring building technique

This is an excerpt from an article in Sanctuary magazine issue 18.

Whether you’re planning a sleek or rustic-looking house, straw bales are a low cost and sustainable building material with flexibility, writes Paul Downton.

Words Paul Downton

What has an accredited fire resistance of two hours, is more resistant to vermin and rot than most timber, and provides insulation values that comfortably exceed the most stringent demands of the building code? The answer is rendered straw bale – and as a sustainability bonus, when the building’s life is over, most of its walls can be turned into mulch.

The rise of straw bales
Straw bale building has been around for over a century. The oldest surviving buildings date back to the early twentieth century, when pioneering farmers in the Nebraska Sandhills facing a dearth of trees found the local soil made poor building material. The most famous historical example of a straw bale building is a church, built in 1928, listed in the US National Register of Historic Places – it is still in use today.

The modern straw bale movement dates from the early 1980s, when the rediscovery of bale building was fuelled by renewed interest in ecological building. In the early 1990s a book called The Straw Bale House by Athena Steen, Bill Steen and David Bainbridge became a manifesto for the growing movement towards healthy, affordable, environmentally responsible building.

If you’d like to read the rest of this article you can buy this issue here.

Thermal Bridges and Breaks

This is an excerpt from an article in Sanctuary magazine issue 16.

Heat conducted into or out of your home by frames, fixings and building materials can have a dramatic effect on its energy efficiency. The good news is that this thermal bridging can be avoided by careful design.

Words Paul Downton

Thermal bridging is what happens when fixings, frames or materials conduct heat through the skin of a building where it should be insulated. A thermal break is a construction element designed to prevent thermal bridging. Thermal bridges and breaks have long been recognised as critical to energy efficient design, but Australian domestic construction has only recently begun to pay them proper attention.

Many houses still lack the sort of detailing that takes “bridges and breaks” into consideration. If your home was built before insulation was required by the building code, it may not have sufficient insulation and thermal bridges are very likely.

If you’d like to read the rest of this article you can buy this issue here.

Insulation

This is an excerpt from an article in Sanctuary magazine issue 15.

Paul Downton takes a look at insulation, how it works and why you need it.

Words Paul Downton

Readers of Marie Wallin’s article in Sanctuary 13 may understand “thermal mass”, but even some design professionals remain confused about the difference between thermal mass and insulation.

Thermal mass absorbs, stores and slowly releases heat energy. Insulation is about stopping the flow of thermal energy. Thermal mass holds on to thermal energy, insulation rejects it.

Our clothes are like a “second skin”, augmenting the ability of our naked bodies to deal with heat, cold and extremes of weather. Buildings, according to “building biologists”, are our “third skin”. Insulated walls and roofs create a kind of all-over doona, keeping a building’s occupants snug. Insulation under a slab or floor creates a more complete insulated enclosure for a stronger “doona effect”.

If you’d like to read the rest of this article you can buy this issue here.

Earth Coupling

This is an excerpt from an article in Sanctuary magazine issue 15.

Is it better to connect your home to the ground below, or insulate your slab from it? Dick Clarke explores the pros and cons.

Words Dick Clarke

There have long been two approaches to residential design: lightweight structures that “touch the earth lightly” and high mass ones that are dug into the site and connect completely with the earth. Unless cleverly designed, however, lightweight buildings can actually hit the earth pretty hard with their higher requirements for active heating and cooling. In Australia’s population centres, most new houses take the high mass approach for their floors, with concrete slabs sitting firmly in touch with the ground. However, in recent years controversy has erupted over whether concrete slabs should be insulated from the ground, or fully connected with it (known as earth coupling). Separation, usually achieved using rigid foam insulation, allows the thermal mass of the slab to be controlled by the interior of the building, preferably through good passive solar design. Coupling the slab directly to the mass of the earth below by not insulating it effectively boosts the thermal mass of the slab and allows it to behave as if it was three metres below ground (see diagram on the facing page), meaning that its winter minimum and summer maximum temperatures are similar to those of the ground at that depth.

Depending upon where in Australia a house is located, earth coupling seems to be an attractive option. For instance, according to David, Joan and Sydney Baggs’ respected book Australian Earth-covered and Green Roof Building, in Sydney the soil temperature at a depth of three metres ranges from about 16 degrees Celsius in September to about 19 degrees Celsius in late February. Passive solar design theory says that with adequate direct solar gain from correctly oriented glazing, and with efficient insulation to control other heat flows, this winter minimum will receive a top-up of four to five degrees Celsius at the surface, resulting in a slab temperature of about 21 degrees Celsius: a perfect start for a zero energy house. In summer, a little heat is unavoidably added to the ground temperature of around 19 degrees Celsius by imperfect insulation, opening of windows and doors, and general occupation, allowing the slab temperature to creep up toward the mid-20s. This is also a good start for a zero-energy house, considering the human body’s seasonal acclimatization ability.

However, in colder alpine and tropical climates, these temperature patterns are shifted too far one way or the other and classic theory has always suggested that the floor should be separated from the ground. For instance, in Darwin soil temperatures at a depth of two to three metres can be as high as 29 degrees Celsius, providing little useful temperature control. There are other reasons for earth coupling in the tropics, such as cyclones, and it should be noted that ground coupling in “low set” houses still allows passive design to work.

If you’d like to read the rest of this article you can buy this issue here.

Building your sustainable dream home

From Sanctuary issue 10. More articles like this

By Alan Strickland with Judy Celmins

Excerpt: Wanting to live sustainably is not a fringe occupation. Millions of Australians want to make a difference to their homes and lives. But as a member of the Alternative Technology Association and an organiser of Sustainable House Day the question I am constantly asked is: “Where do I start?”

Many people come away from Sustainable House Day fired with enthusiasm. They see homes that are warm in winter and cool in summer, without the need for large heaters or airconditioning. They see water-wise homes that gather rainfall and greywater and use these to produce wonderful, food-producing gardens. They want that for their own home. The problem is that visitors only see the finished house. Time doesn’t usually allow visitors to ask the owners about how they went through the whole saga of planning and creating a sustainable home. The wondering, the indecision, the frustration and dead ends, and the many stages of learning they had to go through.

This article aims to help fill that gap. The more you learn before you start, the easier the process will be and the less the likelihood of repeating the mistakes that others have made before you.

Further information

This article is the combination of two online posts at shmeco.com: “I’d like a sustainable home but where do I start?” by Alan Strickland and “Building the self-sufficient dream” by Judy Celmins. Alan Strickland is the Alternative Technology Association’s South Australia Branch Treasurer. Judy Celmins is a director and co-founder of shmeco.com. shmeco.com invites people to exchange their ideas, stories and experience on sustainable living choices. shmeco are managers of Sustainable House Day.

www.ata.org.au
www.shmeco.com
www.sustainablehouseday.com
www.yourhome.gov.au
www.sanctuarymagazine.org.au

A naturally warm home

This is an excerpt from an article in Sanctuary magazine issue 3.

By making a few changes to your home you can considerably reduce your heating bills and stay comfortable in the process.

Design for warmth

The cheapest way to heat your home is to use the warmth of the sun. If you are building or renovating, include passive design principles in your plans to let the winter sun in and keep the summer sun out. Position the daytime living areas so that they face north, with windows strategically placed to let in the winter sun and shaded by eaves, sails or external blinds during summer.

In cooler climates, thermal mass can help regulate the temperature inside the house, especially when there is a big difference between day and night outdoor temperatures. Use building materials that have high thermal mass such as concrete, bricks and tiles to absorb heat during the day and radiate the warmth back into the home during the night.

Changes around the home

Even if you are not building there are some measures that you can take to stop heat escaping from the house. Good insulation is a must. Insulation is like a barrier, preventing heat passing in and out of the house and can be placed in the ceiling, walls and floor. When looking for insulation check its R-value; the higher the value the greater the level of insulation.

Do a walk around your home with a candle, using the flame to show if there are any drafts. Place draught excluders, such as under-door strips, and foam door and window seals around doors and windows. They are low cost, very effective and are one of the simplest ways to reduce energy use. Replace or seal off open air vents and exhaust fans that allow warm air to escape into the roof cavity or the outside air. Don’t forget gaps between walls and skirting boards, and even the gaps between floorboards—these gaps may be small, but put together they can make for a great deal of cold air entering the house, especially when it is windy outside.