10 things to consider when planning an energy-efficient home

10 things to consider when planning an energy-efficient home


If you want a more comfortable, energy-efficient home, the path lies in good planning and sustainable design

A well-designed and sturdily built home is often said to have “good bones”, meaning its underlying structure is well planned and sound. These days, however, a bit more is required of architects and builders. With climate change pressing ever more firmly on our rooftops, future-proofing your home is becoming imperative. This process of anticipating future developments to minimise negative consequences is crucial as cities become overcrowded and housing is pushed to the limit.

Melbourne-based Zen Architects specialises in ecologically sustainable design (ESD), architecture that does its best to protect biodiversity and the future of environmental resources. ESD consultant Erika Bartak says, “I like to think of sustainable design as good design and not necessarily about bolt-on technology. Being comfortable and healthier, not wasting lots of money on heating and cooling bills, is not revolutionary — it’s just part of good design.”

Current trends

Perhaps the mass market is following a less-virtuous trend. Part of the problem stems from the current fixation for eaveless housing and renovations that pay minimal respect to climate.

“The eaveless house is a disaster waiting to happen,” says Margaret Dengate, urban designer and managing director of Trading Places. “You’ve got to work the eaves of your house so the sun penetrates the windows in winter when the sun is low in the sky, and doesn’t penetrate them in summer when the sun is high.” This explains why the vernacular (or indigenous) house in Australia showed incredible foresight with its large verandahs, intended to screen out the harsh summer sun.

There are many other factors to take into account. Sustainable development consultant Margaret Slattery from Energy Architecture says, “For most people, it’s crucial to consult with an architect or design consultant who really understands how all the elements work together and how a design solution can make a huge difference. It’s such a worthwhile investment. It’s onerous for people generally to try to gather all the information themselves, let alone understand it.” Erika agrees.

“There’s a constant bombardment of new products coming out,” she says.

Margaret believes things should be done right the first time and that doesn’t have to involve large expenses. “You can make a lot of financial stress for yourself if you don’t do it right in the beginning,” she says.

Orientation and siting

“Orientation is number one; it’s free and all you have to do is organise yourself to take advantage of it,” explains Margaret.

“In summer, you don’t want sun to come in and in winter, you want the opposite. You need to orient your house so it’s north-facing to control the sun. Siting can have a major impact on creating a healthy and economic building.” This forms the basis of passive solar design and is integral to reducing heating and cooling requirements.

Thermal mass

Thermal mass or heat capacity is the ability of an object to store heat. Environmentally conscious designers are drawn towards materials such as straw bale, rammed earth and mud brick, which capitalise on thermal properties.

New Zealand architect firm Melling Morse is highly experienced in working with straw bale. Sustainable in terms of being a byproduct of a locally grown crop, straw bale is renowned for its thermal qualities. “The temperature control is superb for living in because straw bale offers such great insulation,” says the firm’s Allan Morse. “As the width of the walls is almost a metre deep, the walls have increased strength. You can treat it like a free-standing wall with glass between the walls,” he explains. Council regulations require straw bale builds to have 2m eaves, which naturally create large, shady courtyards. Power bills tend to be minimal because the need for heating and cooling systems is reduced by the straw’s thermal capacity.

Rammed-earth or adobe houses have a very high thermal mass and natural thermoregulation. Rammed-earth homes date back more than 600 years and parts of the Great Wall of China were built using an early type of rammed earth technology. Soil is often sourced locally then stringently stress-tested for suitability. Rammed earth does not creak in strong winds or storms, is engineered to withstand earthquakes, is a healthy non-allergenic substrate and does not contribute to deforestation and pollution.

Good insulation

The insulation grading system is a useful guide; the higher the R-value, the better insulated your home will be. Natural insulation is superior and healthier than alternatives. Natural fibres have breathability and low toxicity, do not attract pests and are less highly flammable than their synthetic counterparts. Wool is readily available either in off-cuts, which can be blown into the ceiling, or layered blanket style. Cotton is popular in Europe, as is clay-coated straw. Nut shells, corncobs, hemp, flax and recycled tissue and clothing are also diverse examples of effective insulators.

Heating and cooling

In terms of minor upgrades, consider stack ventilation. This consists of ceiling and roof vents in all rooms to assist with the extraction of warm air during the night. It is very inexpensive and easy to do. Margaret also suggests sealing all doors and windows properly, double-glazing your windows and installing a solar hot water system and photovoltaic panels. Capturing sunlight to generate electricity and heat water is an efficient use of a free natural resource.

Landscaped spaces

Landscaping plays a huge part in aiding passive heating and cooling. “Deciduous plants are useful for trellising as the light gets through in the winter, then is blocked in the summer,” says Margaret. Native planting can provide excellent screening and is easy to maintain. Why not grow a garden on your roof? Green roofing not only softens the appearance of an urban environment and sound-insulates, it can also reduce ultraviolet radiation. A green roof will protect and prolong the life of your home by supporting the framework.

Sustainable materials

With the burgeoning range of sustainable materials in the current market, designers have plenty of options. “We use the term ‘environmentally preferable materials’ rather than ‘sustainable’,” says Erika. “We set a range of criteria for materials selection that look at issues to do with energy in transport and production, whether it uses much water or affects water in its production, indoor environment quality and human health impacts, and renewable or recyclable products.”

Forest Stewardship Council timber guarantees responsible forest management, restoration and sustainable buying practices, although home-grown may not always be best. For example, green-conscious customers can include materials such as Onduline roofing. Made from recycled corrugated cardboard soaked in bitumen, Onduline is harmless to health and the environment but manufactured in France. “Sometimes you have to strike a balance between competing issues; for example, between a local product and a product that’s more sustainable in other ways but it has to be shipped from overseas,” explains Erika.

A matter of size

A growing corner of the architectural market is pre-fabricated and modular housing, because size does matter for many people. “Downsizing is important. It’s pretty scary when you see the scale of houses in the project home market which are not very efficient but so cheap. People can get a whole lot more space for very little additional cost,” says Erika.

Zen Architects has used pre-fabricated principles to design its own modular house. “Some people might see it as a squashing of grander design, but it’s creativity within constraints. You have to refine your brief and refine your design. I don’t think you need to lose out on aesthetics. Buildings can be more cost-effective without necessarily being uglier,” she adds.

Informed choices

Considering the plethora of guidelines and resources, people are still cautious about certain factors governing a more sustainable build or renovation. “A couple of obvious barriers would be cost and a lack of information, or even information overload,” says Erika. “Everything is now marketed as greener but there are some good databases out there to help people make informed decisions.” These include Ecospecifier and independent certification schemes such as Good Environmental Choice Australia.

On an international level, sustainability standards are high in Europe due to an earlier implementation of building regulations. “Regulation brings the worst performers up to a minimum standard and helps to raise community awareness as we now get a broader spectrum of clients concerned about sustainability,” says Erika.

Is Australia lagging behind? “It depends on how you look at it. There are plenty of people quietly going about their business and making buildings more sustainable,” she adds.

Thermal performance

“Thermal performance essentially refers to the shell of the home. The better insulated it is from the external conditions, the more comfortable it will be to live in,” says Ian Fry of Frys Energywise. “By improving thermal performance, that is, reducing the amount of heat that gets into the home during summer and taking advantage of the winter sun, you will be able to save thousands of dollars in additional energy costs.

“Some of the key areas that help the thermal performance include orientation, the type of building products used, the quantity and quality of the glazing and the correct use of shading,” he continues. “The most important factor is orientation. A poor design with poor orientation will cost substantially more in energy costs than a well-designed home that takes full advantage of the winter sun and protects the home from the summer sun.

“When selecting materials, consider the climate you are in and keep in mind that darker colours will absorb heat, while light colours will reflect heat. When it comes to windows and glass doors, remember that improved glazing makes a huge difference to how much additional energy will be required to heat and cool a home. Adding quality insulation to walls, floors and ceilings during construction will also add to the comfort of a home and reduce energy costs.”

Written by Meryl Hancock

Originally in BuildHome Magazine Volume 24 Issue 3