National Magazine of the Lutheran Church of Australia

Our straw bale castle

May 2016

by Lara Lang

Rather than worrying what the house they have built will do for their social standing or local real estate values, one Adelaide family has placed more importance on the impact it will have on the environment for future generations.

A home is a place to retreat to and recharge from the stresses of the world; a space in which it is safe and comfortable for a family to grow. Darryl Kerrigan, a character from the 1997 hit Australian comedy movie The Castle, was ‘living’ proof of the old saying that ‘A man’s home is his castle’. This past year my family helped design and build our own house, so we could have our own special place to call our ‘castle’.

My husband Benno and I knew we wanted something that encapsulated our values and was an expression of who we are. We wanted a house that was comfortable, light-filled, and sensibly constructed to make careful use of resources. Our Christian belief in being good stewards of the earth’s resources helped inform our choice of building material.

In nature, nutrients are recycled through organisms and waste materials are reused – like food scraps being composted and returned to the soil to grow new plants to feed us. We chose to build our walls out of another compostable waste material: straw bales.

Straw is a waste product from the harvest of grain heads (in the particular example of our house, of wheat). Straw is biodegradable, and if we ever demolish our house, the walls can be returned to the earth by composting them down. Straw is also a readily available and locally sourced material that is easy to work with.

Another consideration for us was having a house that did not require much energy (that is, electricity) to run. We wanted a house that was filled with natural light and could maintain a comfortable temperature year-round, with little additional heating or cooling from air conditioners.

Coincidentally, rendered straw bale walls have very good insulation properties. Straw bale walls have an insulation R value of around 8-10, compared with standard new-build wall insulation, which is R2-3. Houses with high insulation properties should stay cool in summer and warm in winter, making for more comfortable living and reduced heating and cooling costs.

We also selected economical LED lights throughout the house that require little electricity to run; a heat pump hot water system that extracts heat from the air to warm the water; and an electric induction cooktop that directly heats the metal cookware so less heat is lost through radiation. All of these decisions were made to reduce our use of the God-given resources this earth has to offer; to conserve what is available so our children in the future have access to those resources, too.

In addition, we installed a 5.1 kilowatt solar photovoltaic system on our north-facing roof and an 18,000 litre rainwater tank. We feel it is important that we can harvest and use our own rainwater, rather than depleting the resources of the River Murray and our reservoirs, given that we live in the dry state of South Australia.

We enjoy producing our own electricity from our solar panels, as it means we personally require less coal and gas to be burnt in power stations. That, in turn, means less carbon dioxide emissions going into the atmosphere due to our activities, and hopefully our personal impact on global warming is less.