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Guide to Energy Rating in Australia

Energy Effiecient House

Sustainable architecture is one of the thrusts towards an energy-efficient and environmentally sustainable future. In Australia, the concept is well-accepted and encouraged by the government. During the 1980s, a Five Star Design Rating (FSDR) came into play. It is an award given by the Glass, Mass, and Insulation Council of Australia together with the Commonwealth Scientific and Industrial Research Organization (CSIDRO) Division of Building Research to builders who have shown exemplary performance in construction and design – sustainability included.

Energy Efficiency Standard in Australian Buildings

On the other hand, the FSDR system was not widely accepted. In order to transform the campaign into a nationwide thrust, the Australia Building Code introduced ‘energy efficiency’ into the Building Code of Australia (BCA). The Building Code of Australia is included in the National Construction series containing technical provisions for the design and construction of buildings all throughout Australian states. This paramount move has initiated the rise of the House Energy Rating, a standardized measurement of thermal performance. This also led to the upsurge of the Nationwide House Energy Rating Scheme (NatHERS) in 1993. This mandates that all structures – inclusive of residential and commercial buildings – should have a standard rating of 6 stars and above.

Reinforcing the demand for more thermally comfortable homes.

The star rating determines the thermal makeup of a particular household. A household can be rated from zero to ten stars – with zero as the lowest and ten as the highest. A low star rating would mean that the structure is not thermally conducive for occupancy. An under-performing household, in order to be thermally ambient, would need to increase its demand for artificial cooling or heating – this, on the other hand, increases energy consumption. Meanwhile, a thermally compliant household requires little to no artificial cooling or heating system – thus saving more energy.

Ventilation with high heat recovery

To prevent the construction of thermally under-performing buildings, the National Construction Code (NCC) requires minimum energy efficiency performance requirements. It also provides a number of options to demonstrate compliance with energy efficiency performance requirements. In general, the thermal performance assessment will evaluate the following: 1.) construction materials used, 2.) window glazing specification and orientation, 3.) insulation details, and 4.) orientation of the building. The evaluation may also take the following into consideration: heating and cooling loads, insulation of heating and cooling ductwork, artificial lighting, and swimming pool heating.

The above may be demonstrated in various ways including an alternative verification solution known as Deemed-to-Satisfy (DTS). Moreover, a NatHERS accredited software is used to make the assessment when conducting a NatHERS-DTS way. To date, there are three software programs accredited by NatHERS and these are the following: Accurate, BERS Professional, and FirstRate. Compliance to the NCC is frugal to be granted permission to construct a particular structure. Thus, compliance is necessary.

How NatHERS stars are calculated.

NatHERS star ratings are calculated based on the data encoded into the system and this includes the following: size and function of rooms, size, and specification of openings, building materials, type of construction, dwelling orientation, and location. The software will then simulate the amount of cooling and heating needed to make occupants comfortable in a typical year. Prior determining the temperature based on the varying seasons, it first simulates how the local climate heats and cools the house every hour of every day of the year.

Nationwide House Energy Rating Scheme

Once temperature falls out of comfortable range, the software calculates the need for cooling and heating provided that measures such as opening or closing the window has been done. The total estimated annual heating and cooling requirements are then converted into star ratings. In order for the software to be at par, the software packages use the same climate zones, weather files, occupancy setting for a standard family, internal heat loads, and star rating scale for the home’s location. In terms of climate zones, Australia is divided into 69 zones. This allows the software to accurately calculate based on the given climate zone. Weather files, meanwhile, are based on the compiled records from the Bureau of Meteorology for each climate zone including additional information such as air temperature, humidity, solar radiation, wind speed, and direction.

Crafting a thermally ambient household begins in the design stage.

Sustainable architecture is one of the pivotal factors in creating a thermally effective structure. One of the cheapest methods to incorporate is the concept of passive solar building design. Passive Solar Building design, like this solar roof vents, harness the sun’s energy without using any form of active solar mechanism. It also utilizes a set of strategies aimed at reducing the need for mechanical heating or cooling. Moreover, it may also be used in line with the following concepts: thermal mass, thermal insulation, and shading or glazing.

Passive Solar Building

Building materials that are high in thermal mass can retain heat in a specific place. It also works hand in hand with thermal insulation to keep heat and prevent it from escaping. It is very beneficial during the cold season as heat is retained in the household without the use of artificial heating. Shades, meanwhile, prevent the sun from entering the threshold during warm summer days. Windows are also important to maintain thermal equilibrium.

There are so many concepts that can be incorporated into a house design to make it thermally convenient and energy efficient – and this is where energy rating consulting can help. We, at Ideas for Good, believes that energy rating provides specific structural strategies as well as carry out simulations to provide a detailed analysis of the thermal makeup of a specific structure even in the design stage. A Thermal Performance Assessor Consultancy accredited with the Building Designers Association of Victoria (BDAV), Bayside Energy Consulting provides a roster of services including Thermal Performance Assessments, External Window Assessments, Energy Compliance Assessments, Basix Energy Assessments for NSW, Deemed-to-Satisfy Assessments, and Artificial Assessments. The firm provides fast, reliable, and accurate NatHERS Energy Reports using FirstRate5 software and Energy Compliance Assessments using Deemed-to-Satisfy provisions of the National Construction Code.

For more information regarding NatHERS rating, check this video out:

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