Nathers Energy Rating Assessor

NatHERS Accredited Assessor in Australia: The Nationwide House Energy Rating Scheme (NatHERS) is a star rating system, ranging from 0 to 10, that evaluates the energy efficiency of residential homes based on their design. By providing a standardized method for estimating a home’s potential heating and cooling energy use, NatHERS helps to make Australian homes more comfortable while enabling residents to save on energy bills through smarter design choices. Good design can significantly reduce the energy required to maintain comfort, often without increasing construction costs.

To calculate a NatHERS star rating, accredited software models expected indoor temperatures using data specific to each dwelling. This data includes design and construction details, climate, and typical household usage patterns, excluding the impact of electrical appliances except for ceiling fans.

A NatHERS Accredited Assessor inputs various data into the software, including room size and function, openings, building materials, construction type, dwelling orientation, and location. The software then simulates the home’s interaction with the local climate, predicting the heating and cooling needs throughout the year. It calculates how often the internal temperatures would fall outside a comfortable range and the subsequent need for heating and cooling. These total annual energy requirements are converted into a star rating.

To ensure consistency across homes, the software uses standardized climate zones, weather files, occupancy settings, internal heat loads, and a star rating scale based on the home’s location. NatHERS divides Australia into 69 climate zones, considering the country’s diverse climates when modeling a home’s energy requirements. Weather files for each zone are compiled from Bureau of Meteorology records, incorporating data on air temperature, humidity, solar radiation, and wind. These files, known as Reference Meteorological Years (RMY), represent over 25 years of climate data to assess the weather’s impact on a building’s internal temperature, calculated hourly over a full year.