NatHERS, (or Nationalwide House Energy Rating Scheme), provides a rating system to determine the thermal comfort of Australian homes through software simulations. This system rates from zero to ten stars. The more stars a home gets the more comfortable the occupants will feel when living in the house/unit without additional cooling or heating systems. A building is unlikely to need any artificial heating or cooling system if it gets a 10 star rating.
A high star rating also means that a home has excellent performance in terms of saving energy and being environmentally friendly.
The rating is usually accessed by the layout of the home, the construction components such as roofs, walls and windows, windows orientation, and how well the building design fits its local climate.
Listed below are the six ways that homeowner and architects alike can achieve a higher star energy rating:
- Use high rating appliances
The appliances installed in a building, such as the hot water system, shower head, cooling and heating system and lighting will affect energy and water consumption of the building. This is why it is so important that appliances with a high star rating are chosen. A high star rating device can avoid wasting energy/water, and has a better efficiency to supply water, cool or heat an area or supply illumination.
- Consider the home’s location and its orientation
The design of a building should consider its neighbouring buildings. For example, if a home is surrounded by some buildings the architectural design should be adjusted to achieve maximum solar exposure, otherwise it would use up too much energy due to the potential overshading from neighbours. It is also advised that non-habitable rooms (laundries, bathrooms etc.) should be placed to the east and west, bedrooms to the south and living areas (dinning) to the north.
- Proper design of windows
A home builder should use double glaze if possible, as it has better thermal performance than single glazing. Also, an architect should try to maximise on north-facing windows in an attempt to keep the internal environment warm and reduce heating load. However, if the windows to the east and west of the building are too big, it will make the building over-heat during the morning with the rising sun or lose all heat in the evening when the sun sets. Moreover, window shading should also be considered in the case that the building needs a lower cooling load.
- Insulation of building materials
The better the insulation of building materials provides the better the thermal performance. In such cases, the insulation of the ceiling can be increased to R6 and external walls can be around R2.
- Be careful about the size of the home
It will be more difficult to get a good star rating for a bigger home. This is because when the home is designed bigger, it will take more cooling and heating appliances to provide comfort for the larger internal spaces.
- Seal doors, windows, vents and exhaust fans
This can increase the total R value of the building and provide a better thermal performance, as heated or cooled air will not escape from the gaps between the celling vents (or fans) as well as the gaps in the windows.
A higher staring rating of NatHERS not only provides more economic benefits to the owners and occupants in the long term, but also helps more people achieve the goal of sustainable development. It reduces energy consumption of heating and cooling, and reduces the carbon footprint of the building. Thus, it is important for architects and consultants to improve sustainable performance and NatHERS star rating of every building.
NatHERS n.d., Nationwide House Energy Rating Scheme (NatHERS), viewed 10 April 2018. <http://www.nathers.gov.au/about>
Wills, R. 2011, ‘Your 6-Star Guide to building on energy efficient home’, Sustainable Energy Association of Australia, Northbridge, viewed 10 April 2018. <https://greengurus.com.au/wp-content/uploads/2015/09/sea-6-star-booklet-240511.pdf>