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  • Writer's picturePengfei Yang

Let's continue the North saga - orientation and energy assessment

Maybe you have read about the benefit of a better orientation - 'Go North and Face the Sun' in our blog (It's ok if you missed it. Click the LINK if you are interested). To further explore the 'warmer' side of the building positioning, we use a typical Tasmanian home as an experiment subject to find the impact of four orientations on energy efficiency.

With the 7-star energy rating requirement mandate in 2025 for Tasmanian homes, it's time to prepare for the change. We've covered it in the latest experiment. Also, the new weather data is utilised for calculations to fit the new energy efficiency requirement in NCC 2023. Let's see what it can reveal!

To begin with, the house for the energy modelling is a typical brick veneer and slab-on-ground construction. This is the most common building method in Tasmania in the last 12 months, according to CSIRO's Australian Housing Data portal, which has over 3000 NatHERS energy assessments and their associated energy certificates.

For the consistency of the experiment, the model has the same level of thermal properties, including R2.5 insulation in external walls, R5.0 ceiling insulation, and no added under-slab insulation (e.g. XPS).

All windows are typical standard aluminium-framed, double-glazed units without argon fills. Their performance values are sliding door - U-Value = 4.0, SHGC=0.61 (+/- 5%); awning windows - U-Value = 4.3, SHGC=0.55 (+/- 5%); fixed windows - U-Value = 3.9, SHGC = 0.63 (+/- 5%). In addition, the ceiling height of the model is 2400mm, and the roof and window frame colours are in the dark range.

The result is here. The north-facing model was the only one meeting the 7-star energy rating requirement with the newest weather data. Other orientations, including East, West, and South, failed, although they looked ok as they were over 6-star. However, in 2025 it will be non-compliance.

Apart from ticking the box, a better orientation means reducing unnecessary costs. In the short term, building owners can save on building costs. The calculation shows if the house is facing north, it can avoid two major spendings: under-slab insulation and higher-performance window systems. That is because the house can receive the energy certificate with ease. In the long term, the occupant can reduce up to 9% and 8.3% of energy demand for the whole house in Hobart and Launceston compared to south-facing ones. If only counting on the living room, the energy reduction can go up to 28.2% and 35.1% in the two cities for this particular house we modelled.

As we've mentioned in our latest blog post, orientation is only one part of the pie. Sometimes the building site or an existing home doesn't have an ideal orientation. To taste the benefit of a higher energy efficient home, other building elements, including window systems, insulation materials, cladding materials and colours, ventilations, energy-efficient appliances, and so on, also need to be considered. These elements will be discussed in our future posts, too.

To wrap it up, we think a correct position should be one of the most crucial and foremost steps toward the best energy efficiency. It costs lower than materials and can help save on building elements and future energy usage. To help you decide how we have some tips for you to consider:

  • Ask a designer, such as a building designer or an architect, for help with the design of your project for the best outcome.

  • Engage an energy efficiency consultant in the early stage of your project. They can work with your designer and help your project meet the requirement with practical options.

  • Always prioritise the biggest and most used space of your home, such as the living area. Their orientation will significantly impact your energy consumption and meet the requirement.

That is it. We hope this can provide you with some directions for your project. We also encourage discussions around energy efficiency topics and their relationship to energy assessment. So, please feel free to share your thoughts with us through the comments below or direct messages. Let's work together to bring more quality homes to Tasmanian families!

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