Our homes contribute significantly to greenhouse gas emissions. In fact, they account for 11% of Australia’s total carbon emissions. As a result, Infrastructure Victoria wants all homes new homes or renovations to meet a minimum of a 6-star energy rating. Further, they want all homes for sale or rent to disclose their energy rating by 2025. The real estate market has already identified that increasing your home energy rating by one star can increase your market value by 3% on average. This can result in tens of thousands of additional dollars added to the price of your property. With both the government and real estate encouraging an improvement in the energy ratings of your home, you may be wondering what you can do in your home. Energy-efficient homes are more comfortable, cost less, and reduce our impact on the environment. However, most homes are at a far lower energy efficiency rating than they should be, generally due to bad installation by builders.
Today, we’re going to discuss how you can improve the energy rating of your home.
What is a Home Energy Rating?
When people refer to a home’s energy rating, they generally mean the federal government’s Nationwide House Energy Rating Scheme or NatHERS. It assesses the thermal performance of apartments and houses. This involves rating them a star rating from 0 to 10. The more stars, the more energy-efficient a home is.
How is a Home Energy Rating Measured?
When an assessor is evaluating a home’s energy rating they consider a number of factors. These include the “skin” of the building and the materials that make up the dwellings, as well as environmental factors, like the local climate and the orientation of the building. An assessor will assess your home on:
Location – this is the climate zone
Orientation – with respect to the north
Building materials – including the floor type, wall type, and roof type
Windows and glazing – this includes the size, location, framing material, and type of glass
Insulation – including the types of ceiling, roof, wall and floor insulation, the thickness, and the brand
Exterior finish – the roof and wall colours
Ventilation – size and placement
Ceiling fans – size and placement
Lighting – natural or energy consuming
Floor coverings – carpet, tile, timber, etc
Because of these factors, home energy ratings will differ by state. A 6-star rated home in Queensland, for example, might only be a 3-star rated home in Hobart. This is because the airy, cross-ventilation of a Queenslander-style home is incredibly impractical in the colder Tasmanian climate, requiring more heating and, as such, more energy usage.
Windows can also have a huge impact on the star rating of your home as they are often poor insulators. Double-glazing your windows can help control the amount of heat that enters or leaves your home, which improves energy efficiency.
Achieving the minimum 6-star rating isn’t hard. Work with your renovators and builders from the start to keep energy efficiency in mind. Simply selecting the best orientation of your home to take advantage of solar energy will help increase your energy star rating.
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How Does the Average Home Rate?
The energy rating of a home depends on when it was built. Homes built before 1990, on average, have an energy rating of around 1.6 stars. The average energy rating of homes between 1990 and 2005 was 3.1 stars. While the Victorian Government mandated that all new homes, apartments, and major renovations be a minimum of 6-star rated, energy efficiency ratings between 2005 and 2015 only rose by 5%.
While the mandate seemed like it would be a comprehensive victory for energy efficiency in Australia, so far it only indicates a fair thermal performance. The current 6-star minimum falls short of the desired economic and environmental outcomes outlined by NatHERS. And it falls far below the minimum set by many other countries.
How Can I Achieve a 6-Star Energy Rating Home?
As we’ve outlined above, the energy rating of your home reflects how much artificial heating and cooling is needed to keep the inside temperature of your home comfortable. A 6-star energy rating means your home is likely to use 24% less energy through heating and cooling than a 5-star house. At the highest end of the scale, a 10-star home requires no artificial heating or cooling throughout the year. Essentially, the more stars your home has, the more energy-efficient your home is and the less impact it creates on the environment.
38% of home energy use comes from heating and cooling. As a result, there are several ways to increase your home energy savings.
1: Insulation
A well-insulated roof can save you up to 45% on heating and cooling. A further 20% can be saved with wall insulation. Insulation is measured in R-Values. R-Values, in the context of construction, is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat. Roof and ceiling insulation should have an R-Value of 5.1 while wall insulation should have an R-Value of 2.8. Proper insulation can drastically reduce the cost of energy bills.
2: Shade
Shading can block up to 90% of heat gained by direct sunlight. Shade can be achieved with environmental factors, including trees and vegetation. You can also shade your home using man-made awnings and shades that can be pulled down during hot weather and retracted when not needed.
3: Air Leakage
Sealing off draughts can cut up to 25% off your power bill. To do so, consider installing fans and vents that will close automatically when not in use. And, when it comes to doorways, you can simply use a draught stopper at the base of the frame.
What Do I Need to Do to Achieve a 7-Star Energy Rating Home?
Thankfully, achieving a 7-star home is possible through innovative design and doesn’t need expensive construction costs. Upgrading your home to 7-star energy efficiency can reduce your energy costs by 20%, saving you thousands of dollars every year. It also creates a sustainable impact on the environment by conserving natural resources and reducing toxic waste. A 7-star home features the following:
1: Home Orientation for Passive Heating
The foundation of any 7-star energy-efficient home is the orientation of the home. Newly constructed homes should be built facing the north to catch the radiant heat over winter for free warming. It will then keep your home shaded over summer, providing low-cost cooling. When efficiently oriented and complemented with other energy-efficient features, your home can reduce the need for heating and cooling systems.
2: Eliminating Gas as an Energy Source
While it was once viewed as a cleaner alternative to coal-fired electricity or as a stepping stone to sustainable energy, gas is no longer a cheap or environmentally friendly energy source. While switching to a renewable power source may sound daunting but new innovations in the energy sector mean it is easier than ever to eliminate gas as an energy source.
Rooftop solar panels produce no carbon emissions, meaning they’re environmentally sound. Only 16.5% of Australian households have solar panels, meaning most Australian homes a significantly contributing to Australian carbon emissions. Households with solar panels may use as much energy as neighbours without solar panels. However, they draw their energy from the sun rather than from the power grid, meaning they are producing no carbon emissions. By using less energy from outside sources, solar panels are essential to a 7-star rated home.
3: Utilising Passive Cooling Strategies
There are some simple strategies you can put in place so you can enjoy passive cooling in your home. When designing your home, placing windows on opposite sides of the property is a simple and effective way to encourage natural ventilation. And when it comes to construction, adding the appropriate insulation to your roofing can save up to 40% on your cooling bills.
Adding effective shading can also reduce cooling costs, blocking up to 90% of summer heat. By keeping direct sunlight out of your home, you significantly reduce the need to use air conditioning in your home. Effective shading you can add to your home includes:
Awnings
Eaves
External blinds
Pergolas
Trees
Natural vegetation
A mistake most homeowners makes is assuming blinds or curtains can keep out heat. Heat from the sun can easily pass through your windows and curtains or blinds, entering your home. This is where it becomes trapped and heats up your home, requiring you to use your air conditioning on a higher setting. This means more energy is being used and, in turn, more carbon emissions are being produced. This is why effective shading is important. Making small changes like these can have a huge overall impact on your home and energy rating.
What Makes Up a 10-Star Energy Efficient Home
Across Australia, there are now 14 accredited 10-star energy-efficient homes. This is due to the fact that creating a 10-star home is a challenge. A 10-star energy-rated home does not require any heating or cooling. In order to achieve this in Australia’s harsh climate, architects and builders must carefully design homes. This means taking everything from window volume to thermal mass to material choices to orientation into account. Aiming for a 10-star home informs every decision you make about your home design.
All habitable rooms must include north-facing windows, making building a 10-star home on a small lock of land in an urban environment challenging. While it is challenging, and everything from insulation to ventilation to thermal mass must be taken into consideration, there are success stories proving this is possible.
Example: The Cape Paterson House
This four-bedroom home’s sustainability credentials were set from day one. Designers and builders aimed for zero waste from construction through to completion. In fact, just three bags of rubbish were generated during the build process. This is thanks to the use of recycled and repurposed materials, as well as little or no packaging on the materials delivered to the construction site.
The home makes use of cross ventilation and passive solar design. Its key features include:
Solar panels
5KW photovoltaic solar panel on the roof
Thermal mass concrete floors
Highly efficient LED lighting throughout
Heavy-duty insulation with under-slab insulation
Bio-Phase Change Material (BioPCM) in the walls and ceilings
Double-glazed windows
Night-time power shut down switch
Due to its clever design, the home requires no heating or cooling, with the internal temperature sitting at 18-26°C all year round. And by shutting the power off at night (except for the fridge), appliances like TVs and computers aren’t left on standby. This significantly reduces unnecessary energy waste. Natural sealants and paints were used on the floors, walls, and ceilings, as well as environmentally-friendly furniture and décor to reduce environmental impact.
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The Challenges of Achieving a 10-Star Energy Efficient Home
Builders, architects, and homeowners are trying to work out the best way to build 10-star energy-rated homes. Most elements of a 10-star home require different construction techniques, including bespoke roof design and triple glazing. Treading new ground like this does require some enthusiasm from homeowners, builders, and architects.
Does Improving Energy Efficiency Cost More?
There are costs involved when it comes to improving the energy efficiency rating. Renew, the national not-for-profit sustainability advocate estimates the cost to build an 8-star energy-efficient home is $6,000 more than a 6-star energy home. But the power bill savings will compensate for the extra expenses in just 6 years.
Further, Sustainability Vitoria estimates that improving your home’s energy efficiency by one star will reduce household heating and cooling by 30%. As a result, an 8-star home will require half as much energy for heating and cooling as a 6-star home, while a 9-star home will use 80% less energy. But, at the end of the day, your home is more than a payback machine. Energy efficiency and good design are about your and your family’s comfort. At the end of the day, it makes it a nicer place to live.
Who Regulates Home Energy Star Ratings?
All new homes must meet energy-efficiency requirements that are mandated through the NCC or the National Construction Code. From there, it is up to state and territory bodes to implement the code and regulate the building industry.
NatHERS
The Nationwide House Energy Rating Scheme or NatHers, as we mentioned before, is one method of demonstrating compliance with the minimum energy-efficiency standards for new homes. These assessments are carried out before construction by using the software. NatHERS rates the energy efficiency of a home’s design and gives it a rating out of 10.
In order to do this, the NatHERS tools assess building mass, insulation, roof types, window size, and a number of other factors in order to rate the heating and cooling loads of the home.
NABERS
NABERS or The National Built Environmental Rating System is a simple online calculator for assessing the energy and water use of an existing, occupied home against that of an average household. It provides information from 12 months of energy and water bills and then looks at all appliance usage. The calculator then gives a rating out of 6 stars, with 6 stars indicating leading energy performance, 3 being median performance, and 2 being below average.
NABERS complements other rating systems that only assess the design of a building, not the construction, maintenance, appliances, and how the occupants use the home.
Green Star
This national rating system is for new buildings and fit-outs, including units and townhouses. It is awarded after the construction of the home. Green Star rated homes provide a much higher standard of sustainability, energy efficiency, and comfort than buildings which simply comply with the national building code.
Green Star award 3 rating levels – 4-star is “Best Practice”, 5-star is “Australian Excellence”, and a 6-star rating represents “World Leadership”. In order to come to these ratings, Green Star assesses the design and delivery of the buildings and fit-outs against benchmarks in energy, water, waste, and indoor environment quality and ecology.
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