Looking to build a sustainable home? With climate change and energy bills going up, there’s never been a better time to create an energy-efficient home. Not only is building a sustainable home a fantastic way to help the planet, but it’s also a great investment. Cutting down on our carbon footprint and the bills? Sounds great, right?
Having said all that, what does it actually mean to be sustainable when it comes to building a home? What can a homeowner do to make their new home more eco-friendly? In this article, we’ll take an in-depth look at sustainable living and give you a rundown of what makes a building eco-friendly. To begin with, let’s have a look at energy ratings!
What are Energy Star Ratings and how do they work?
Not sure how to tell if a building is energy efficient? The National House Energy Rating Scheme provides star ratings (out of ten) to buildings, giving a snapshot of how environmentally friendly your home is. Remember, it’s best to use the star rating as a guide more than a definitive answer (more on that soon). A NatHERS rating takes into account:
- The heating and cooling performance of the home.
- The size of the property.
- The construction materials and processes used.
- The size of rooms and the flow of the floorplan.
- The size and specification of windows, doors and archways.
- The orientation of the house and the local climate.
NatHERS focuses on the structure of the home itself, so things like appliances and air conditioning have no influence on the final star rating. Steps are being taken to update the rating to include elements such as lighting, spa, hot water systems, air-conditioning, and even cooking and plug-in appliances. We’ll keep you in the loop with any updates.
It’s required by law that home meet a minimum of 6 stars. Ten stars are incredibly difficult to achieve, and there are only 14 homes in Australia that meet this standard. Below is a measure of the heating and cooling usage for each star rating:
5 stars = 125 MJ/year/m2
6 stars = 96 MJ/year/m2
7 stars = 70 MJ/year/m2
8 stars = 46 MJ/year/m2
9 stars = 22 MJ/year/m2
10 stars = 3 MJ/year/m2
As you can see from the stats above, there is a noticeable drop in energy usage between star ratings!
How do energy assessments work?
You’ll need to get a certified NatHERS assessor to certify your home. There are numerous assessors and NaTHERS assessing companies out there, so you shouldn’t have trouble finding one. Your assessor will use NatHERS Accredited Software to calculate an energy efficiency star rating based on various factors such as expected indoor temperature.
Develop a simulation model
A NatHERS accredited assessor will create a simulation model of the dwelling. Details included in the simulation will include sizes and functions of the rooms, sizes and specifications of openings, building materials/windows/products, type of construction, dwelling orientation and location.
Finding out the temperature of the development
Using the simulation model, the software will calculate the level of heating or cooling temperature occupants need to remain comfortable within the house.
Determining the need for heating and cooling systems
The next step is to determine the need for heating and cooling systems when internal temperatures fall outside of a comfortable range. This calculation takes into account occupants opening and closing windows, blinds or awnings before resorting to using the heating or cooling system.
Calculating a rating out of 10
Once all the above has been done, the total annual estimated levels of energy-efficient heating and cooling are determined by a ranking out of 10 stars.
Flaws of the star rating
Like anything that reduces something to a score, the NatHERS star ratings aren’t perfect and can be taken out of context. As previously mentioned, it’s required by law that new homes meet a minimum of 6 stars. While it’s great there is a minimum requirement, we’ve noticed some builders advertise their six-star rating as if it’s exceptional rather than just meeting an industry standard. The star rating alone also doesn’t provide much detail without the report to provide more depth.
The energy star rating is a good starting point, but if you want to be more eco-friendly, you’ll have to delve deeper and find out about your builder’s practices.
How can builders be more sustainable?
It’s easy for a builder to say they’re sustainable and eco-friendly, but how do you know they walk the walk? Here are a few things builders can do to make their practices sustainable.
Using recycled materials reduces the impact on the environment. Green building materials are either sourced from sustainable forests or produced in eco-friendly ways. They’re also made with manufacturing procedures that create fewer emissions. Eco-friendly materials will also be easier to recycle which means less landfill.
Along with using sustainable materials, builders can practice zero energy construction techniques. This involves a combination of the following steps:
- Using renewable energy sources (such as solar and wind) to power the building.
- Efficient air ventilation systems that eliminate pollutants from the surrounding air.
- Better insulation materials that minimise leaking air and noise pollution.
- Using energy efficient indoor appliances.
Main Factors that influence energy efficiency
The orientation of your home makes a big difference to energy efficiency as it determines how much sunlight enters your home. South-facing windows let in less light, whereas North facing windows take in more. Remember, you need to account for both summer and winter conditions when making these decisions, as what might be perfect for one season could be dreadful for the other. It’s all about finding the right balance.
In Queensland, homes are built with a Northern orientation. The purpose of this is that the home can soak in the sun during the day while remaining cool during the night. Your floor plan needs to take into account the environment and climate you’re working with. Australia has 8 different climate zones, so talk to your builder about what’s best for you.
Structures and Insulation
Insulation is a layer of material in the walls, floors, and ceiling of your home that helps keep heat and coolness in. It’s an essential step to keeping your home at a more comfortable temperature. Though researching this may not sound exciting, if you get your insulation right, it can slash your air-con and heating bills. Insulation can have the added benefits of weatherproofing and soundproofing your home.
Windows and Doors
Up to 40% of cooling and heat can be lost through windows and doors. With the right, energy-efficient windows and doors you can reduce this loss by 80%. Installing double glazing goes a long way to reducing this energy loss, especially if you’re looking to use larger windows. Another tip is to have windows on opposite sides of your property as an easy way to take advantage of any airflow (especially in open-plan houses).
The positioning of your eaves and windows play a crucial role in how much sunlight enters your home. Builders tend to be inflexible with altering eaves and are more likely to change the window size to make your home more eco-friendly.
The darker your roofing, the more heat it will absorb which is bad news during a Queensland summer. Builders are aware of this and should use lighter colours to help keep temperatures down in your home. Colourbond steel roofs are great for reflecting heat energy away from your home. Leeward openings, fly roofs and whirlybirds are other options for keeping heat out of your house. What will work best will depend largely on the shape of your roof and the environment you’re working with.
There are various strategies for ventilating your home:
- natural ventilation (that is, the house openings such as windows and doors)
- mechanical ventilation (for example, fans, heat recovery ventilation systems)
- a combination of natural and mechanical methods.
Open subfloors are a common ventilation technique in Queensland. You’ll need to speak with your builder about whether this is viable with your home design.
Though known as the Sunshine State, Queensland does have its share of chilly nights. Keeping your house warm can use a lot of energy so finding ways to cut down on any heater usage will help in that department. Simply trying a thicker blanket before turning on the heating could save you hundreds of dollars a year. Making good choices in the design stages (including insulation, house orientation, etc) will pay off in the long run when it comes to keeping your home warm.
When people think of eco-friendly homes, solar power is one of the first things that come to mind. By using the sun to create energy, you’ll cut down your electricity bills right down. While initial installation costs can be pricey, in the long run, you’ll save money on energy bills. Nowadays, if you purchase a 6.6kW set of solar panels, you can reduce your power bills by 75%!
There is a range of energy-efficient appliances available to purchase. Here are a few things to consider when you’re buying a new appliance:
- Think of the size and power for your needs. Someone living on their own won’t need the same sized washing machine as a family of five. Along the same lines, do you need a fridge that big, or will it lead to forgotten leftovers hidden at the back?
- the running costs of each model you’re considering.
- the model with the best water and energy efficiency.
It can be tempting to buy second-hand (especially for new-home buyers), but older models are usually less energy efficient, which means higher running costs and a bigger carbon footprint.
Up to 3% of your energy bill can be taken up by machines just being on standby, so consider turning off machines that aren’t being used.
Lighting uses around 10% of your energy bill, but the good news is that there are some easy ways to cut this down. Your choice of lightbulb can also make a gradual but noticeable difference. LED and CLF lights are more energy-efficient than older styles of light bulbs.
Building a home that makes the most of natural light will lessen your need to turn on light which, you guessed it, will cut down on your energy use. You can achieve this through large windowed areas, skylights, and window placement that takes advantage of the sun.
Things to consider when building energy-efficient homes.
- Think long term with your decisions. What might be the most affordable option for the time being may actually turn out to cost you more in energy bills.
- Your location and environment play a huge role in your decisions. For example, a house that gets a six-star rating in Queensland may not get the same rating in Tasmania due to the different climates. If you want an environmentally friendly home, adapting with the environment just makes sense.
- Being eco-friendly is a mixture of good choices and good habits. For example, having LED lighting is great. Turning the lights off when you’re out of the room is the icing on that sustainable cake!
How to get a higher star rating
Want to take your home’s sustainability up a notch? Having that extra star isn’t just a moral victory, but it will also cut down your bills. A 7 star home will cost 20% in energy bills than a six-star home. Taking the above tips will go a long way to reaching your goal. You can have a NatHERS Accredited Assessor inspect your home and provide recommendations to reach a seven or even eight-star rating.
When it comes to living conditions, a 7 star home will be more comfortable to live in without air-con. Due to design choices, the house will stay between 18-26C regardless of the temperature outside.
How to engage a sustainable home builder
It can be challenging to find an eco-friendly builder. Chances are, no builder will just come out and say they aren’t eco-friendly. Here are some questions you can ask to get an idea of a builder’s seriousness when it comes to building sustainable homes.
- How do you minimise waste on-site?
- What sustainable building processes do you use?
- Do you build high-performance or energy-efficient homes?
- Are any of the materials you source locally produced or made from recycled or renewable materials?
- Do you have any environmental affiliations or accreditations?
QLD Home Builders
NatHERS star ratings are given to specific buildings rather than builders overall. However, we can still have a look at what some of Queensland’s biggest builders offer in terms of sustainability.
Solar panels are often a standard inclusion with new homes. While this is a good thing, it can also be compensation for other elements of the home that aren’t eco-friendly. In other words, some builders offer solar panels as a way to bump up their star rating to meet the minimum requirements.
For every house built with the Brisbane North team, they contribute 15 trees to a local reforestation project.
Metricon has built its first Zero Net Carbon display home in Victoria. It is a Delta 29MR design, with a home size 0f 232m2. The annual savings on energy bills would be around $1522. It has a NatHERS star rating of 6.6, above average but still room for improvement.
Brighton Homes offers Solar Power panels as standard. There’s also the option of including a recycled water tank, though this isn’t standard and will cost you extra.
Looking to find out more about local Builders? Click here to see our list of Brisbane Builders we’ve reviewed!
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