2 February 2017

How Australian Designers Focus on Passive Design to achieve Sustainable Homes

In an ideal world, you’re going to select a block and your designer will then design a structure that suits both the site and the local climate. This is passive design. It is all about sustainable homes.

Passive design is a sustainable building standard which responds to the local climate and site conditions, thus maintaining a comfortable temperature for the occupants. It makes use of the sun and cooling breezes to provide natural heating, lighting, cooling, and ventilation ­­­at home. Through passive design, you can reduce the energy consumption, temperature control, and greenhouse gas emissions of your home or business.

“Matching a structure with the environment doesn’t cost anything. It’s our responsibility to make sure that your home fits your location and your lifestyle,” says Laura Robinson, the resident Thermal Performance Assessor of Superdraft Pty. Ltd. She’s now leading the energy efficiency and sustainable design department within the company.

“Homeowners may choose to upgrade their windows, insulation, and other newly discovered building materials, and we see these as critical investments in the design process,” she added.

With that in mind, building new homes and other structures based on the environment requires experienced designers who are familiar with passive design strategies for your location. A Thermal Performance Assessor with access to simulation tools like Laura can also help measure the impact of multiple, interrelated sustainable design decisions early in your design process.

It is not just new homes that benefit from the inclusion of passive design, Laura says that upgrades and renovations on existing buildings are also highly beneficial.

“When you use a renovation to not only improve on the design of the home but include some additional insulation to the existing structure you can really feel the difference it can make”, she said.

How Australian building designers use Passive Design

Passive design is the most important tool of a building designer. It enabled the industry to create climate-responsive homes and buildings, the ones the construction industry tagged as future-friendly structures.

“It’s about having flexible strategies in dealing with changing weather conditions,” she added.

To achieve proper passive design, our designers follow these principles:

Design by Location

Australia has eight major climate zones and each one requires a specific structural design that responds to the weather. The first thing that you need to do is to identify your climate zone.

“Understanding your local climate can guide you in making the best design decisions,” Laura says.

The critical part of this process is on constructing the building envelope. It’s about choosing the right material for the floors, walls, roof, and doors. A well-designed building envelope minimises unwanted heat gain and loss, which is the key to achieving thermal comfort.

sustainable home design
Sustainable kitchen design we implemented in our Peak Avenue Project.

Orient the Structure properly

Building designers should position a structure in a way that it takes advantage of the sun and cooling breezes.

“Across the majority of Australia should open up to the north, or close to north,” says Laura.

Having a large window on the northern part of the house invites natural light in during winter. But you have to properly shade this window during summer to protect you from the sun’s strong rays.

Choose the best form of shading

There are wide varieties of shading done in the country: eaves, window awnings, shutters, pergolas, and plants or trees can block up to 90% of unwanted heat from the sun (if positioned properly). Having trees in your backyard is a great way to achieve natural shading and wind protection.

Consider the building material’s thermal mass

Thermal mass is the ability of a material to absorb and store heat energy. Knowing the thermal mass of the building materials, you can stabilise indoor temperature. Concrete, brick, and tiles have high thermal mass, hence it requires higher heat energy to change the temperature inside the structure. Timber, on the other hand, has a lower thermal mass.

For example, if you have a tiled or concrete floor inside your home that is exposed to direct sun through a window in winter, but shaded from the sun in summer, it will absorb the heat of the winter sun and keep it in the house. In summer, when the sun is kept off the floor, the thermal mass keeps the house cool.

However, proper thermal mass is not an excuse to put insulation aside. Thermal mass is about storing and releasing heat while insulation is preventing heat from flowing in and out of the building.

Use the right kind of Insulation

As said earlier, insulation acts as a barrier which stabilises indoor temperature. The amount and type of insulation your home requires will depend on the climate and your design.

Make use of natural ventilation

Passive design allows cooling breezes in the building to cool the interiors and to improve indoor air quality. The approach and design of natural ventilation systems always vary depending on the type of structure, the location of the building, and all associated climate conditions. The floor plan of the home should provide cross breezes and avoid corners of the home that don’t provide for natural air movement.

sustainable home design
We renovated this Hampton-styled home in Wavell Heights so it gets proper ventilation.

Smart window material and design

Windows are great sources of natural light, fresh air, and entertaining views. However, windows are also responsible for unwanted heat gain and loss. About 40% of the heating energy you generate using auxiliary heaters during winter escapes through your windows. Windows can also make your home up to 87% warmer during summer if not designed well. Hence, improper window design means more energy consumption and greenhouse gas emission due to appliances.

Australians want more livable homes

Aussies are willing to pay for sustainable homes with energy-efficient features.

This was the result of the recent study conducted by researchers at the Curtin University Sustainability Policy Institute (CUSP). They found out that 46% of home buyers surveyed for the study will purchase an energy-efficient structure and sustainability was a major factor in their decision making. Sustainability is the fourth biggest driver in home choice, aside from affordability, location, and size.

The study also found out that dwellers in Perth are willing to pay more for sustainable homes.

“Aside from decreasing their electrical bills, I believe more people are investing in sustainable design because they’re becoming environmentally, socially, and economically concerned,” Laura says.

“The cost of owning sustainable homes is not just about initial costs but also operational costs. With increasing energy prices and changing weather conditions, sustainable homes are the best choice for us,” she added.

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