The housing area in Australia is getting bigger and bigger, but it is usually not sustainable. In our recent research, we studied the energy use of Australian houses, including the energy needed to build, maintain and power houses. Perhaps unsurprisingly, we found that more energy enters larger houses. This is not only bad for the environment, but also bad news for our wallets. However, these considerations are not always built into sustainability ratings.

So, whether you are building, buying or curious, what is the most important thing? How big does the size of the house affect the total energy consumption?

The house is getting bigger

In the past 65 years, the area of ​​Australian houses has more than doubled, from an average of about 100 square meters in 1950 to about 240 square meters today. This makes them the largest animals in the world, surpassing Canada and the United States. At the same time, the average number of people living in each household is declining. This means that the average building area per person has soared from 30 square meters to about 87 square meters. We know that larger houses require more heating and cooling, leading to higher energy costs. They also need more materials to build and maintain, and more energy to manufacture and replace these materials.

But how much is there? This is what we are trying to find out. In order to systematically evaluate the relationship between house size and resource use, we analyzed a typical six-star new brick house in the Melbourne climate.

Then, we used 90 different size configurations to modify the house size from 100 square meters to 392 square meters (only four are shown in the image below). For each size, we measured the energy contained in building materials and the energy required to replace these materials for more than 50 years. We also calculated the operational energy consumption of two, three, four, and five occupants over 50 years. Finally, we considered the energy loss in the entire energy supply chain. The results show that larger houses consume more energy, and as the size increases, the energy used to build and maintain the house will grow more than the energy used to operate the house.

For example, the energy embodied in only a 392 square meter house is greater than the energy and operating energy embodied in a 100 square meter house with three passengers in 50 years. Logically speaking, with the sharing of resources, more occupants means less energy per person.

Benefits of smaller, better designed houses

Smaller houses slide less on the earth and your pocket. According to Rawlinsons data, for every additional square meter of brick houses in Victoria, an average of A$1,245 will be spent on construction. Together with the resulting heating, cooling and lighting energy bills for more than 50 years, the total cost per square meter exceeds A$1,988. Therefore, removing a 12-square-meter bedroom from your next house can save about AUD 24,000 and avoid using a lot of resources. You might think that smaller housing means lower quality housing. But in fact, it’s not.

Examples of well-designed small houses can be seen everywhere. They can be designed for durability and low energy consumption, such as filling in dense urban environments, conducive to natural lighting and ventilation, symbiosis with nature or as smart city apartments. For developers and architects, it is important to provide low-cost, high-comfort and comfortable houses.

The benefits of smaller houses are not limited to the family itself, but also have an impact within the city. Small houses-possibly a mix of small houses in small houses, plus some larger apartment buildings-can save valuable space available for public infrastructure. Considering walkability, use of amenities and other factors, this must be done, but from an infrastructure and transportation perspective, this may result in a more efficient community. So what needs to happen?

How do the rules need to be changed?

Current energy efficiency regulations do not consider the energy contained in building materials, so they cannot fully reflect the size of the house. Most energy efficiency regulations also only measure energy usage per square meter. Using this indicator, larger houses seem to be more efficient because energy consumption grows more slowly than the size of the house. When considering heating and cooling, Australia’s 6-star standard does include housing area, but other certifications do not. With other conditions unchanged, according to these other certifications, larger houses will be easier to certify.

The irony is that the larger houses use a lot of resources in both construction and operation. If we are to reduce the total energy and broader resource requirements associated with buildings, we need to revise current energy efficiency regulations to include reflected energy and other energy measures.