Whether you’re building a new home or buying a ready-built one, the following is a quick guide for making the right environmental choices in designing your home based on our LCA knowledge. Note that these recommendations are based on the Australian grid and therefore may not be relevant for those who are on ‘cleaner’ grids.
Due to the carbon intensity of the coal powered Australian grid, operational energy use of a building can take up more than half of the total global warming impacts of the whole building. Therefore, electricity use is a large hot spot and focusing on this area is key to reduce environmental impacts for buildings.
Energy Monitoring: Behaviour change is key for sustained low-energy use throughout the life span of a building. However feedback loops are important to help to maintain those behaviours. Energy monitors are a great way to provide visual feedback for occupants to see how much difference they are making. Studies show that energy monitoring can provide between a 5% and 30% savings in electricity. The savings are largely dependent on the sophistication of the interface and level of customer support available. For higher savings throughout the life-cycle of the dwelling, use building integrated systems with comparative feedback. Watch this TEDTalk by Alex Laskey for more information on how to cause behaviour change.
Heating/Cooling: High efficiency air-source heat pumps are great energy-wise especially for small spaces like an apartment. More electricity use reductions can be made by also installing ceiling fans so that you reduce air-conditioning dependancy. You can further reduce the global warming impact of your air-conditioner by choosing a system that uses low-carbon refrigerants like CO2 or R32 or swap it out of an existing system. You can find out more about the energy rating scheme or check the energy ratings for the most commonly available models here. If you can afford it and there are no practical/legal restrictions for it, the best system is to use ceiling fans for all your cooling needs and a wood pellet heater/slow combustion wood stove for the lowest carbon heating & cooling system.
Hot Water Systems: Solar thermal systems with gas boost is the best choice in terms of carbon impacts and practical application followed by gas instantaneous or heat-pump systems. Pair it up with low-flow showerheads and taps for further savings on hot water use plus water savings. If the option is available to you, a wood-pellet heater/slow-combustion wood stove with a wetback to heat your water is the best option in terms of environmental impacts.
Cooking: Although gas is a fossil fuel, using a gas stove for cooking still has much better environmental impacts over an electric stove untill the grid decarbonises. Read this article for more information on why. However if gas is not a viable option, induction tops are your next best choice. If you have a wood-pellet/stove heater with built in cooktop that would be the best option in terms of low carbon cooking.
Refrigeration: Fridges run non-stop 24/7 on electricity. Therefore an unneccessarily large fridge is a waste of electricity. Larger fridges also make it harder to manage food consumption rates as often people fill it up with food (because there’s the space) and then forget or can’t consume it fast enough before they spoil. Food can have 10 times more embodied energy than the electricity used by the fridge, therefore preventing food waste is just as important as reducing the energy use of your fridge. If you find that your fridge is often mostly empty or if you’re often throwing out food, you should probably look into downsizing your fridge. Limiting your fridge size to a maximum width of 750mm will have an estimated 10.3% energy saving for that refrigerator. You can also improve the efficiency of your fridge up to 25% by ensuring that it is well-ventilated. Use this guide to find out how big your fridge needs to be based on your household size.
High Efficiency Appliances (Washing Machines/Dishwashers/Microwaves/TVs/etc): High efficiency appliances help to reduce electricity consumption without compromising on your usual modern conveniences. Nonetheless, do look out for zero electricity options such as an indoor/sheltered clothes line instead of a dryer. Installing an internal clothesline could reduce reliance on a dryer by a predicted 25% provided the drying space can take a full load of washing (approximately 10m of line). You can find out the specs and compare the energy ratings on various appliances through the energy rating website.
Appliances with Extended Warranty: For an additional 25-30% to the cost, many suppliers now offer extended the warranties for their appliances. Most extended warranties include regular servicing, maintenance and replacement which is an added convenience for the elderly and those living in apartments. Extending the lifespan of your appliance reduces the frequency of replacing the whole applicance and the environmental impacts of doing so.
Lighting: LED lights are the most energy efficient. Do pay attention to ensure that the lumens per watt of LED lights are sufficient to provide the required illumination. If the option is viable, also consider increasing the amount of natural light in your space through skylights or light tubes. There are also other passive ways of increasing natural lighting such specifying lighter matte colours to surfaces such as the balcony, ceiling and walls, light shelves or adjustable louvres in windows to bounce light deeper into the dwelling. Translucent partitions and clerestory windows between rooms also allow light to be drawn into deeper rooms. Note that a daylighting simulation may be required in order to prove the value of these initiatives to ensure expense is not incurred without benefit.
Renewable Energy: Renewable energy is one of the best ways to reduce the environmental impacts of your operational energy use. On top of that, the falling cost of installing solar panels has made moving to renewable energy easier and more economical than ever. Depending on the size of the photovoltaic system installed, it can easily cut the total global warming impact of your home by half. For those who don’t have the option of installing solar, you can still make the better choice by buying green power from the grid which most utilities offer as an option. Find out which utilities offer green power here.
If you are in the position to influence the type of materials used for the building fabric, the following are some typical recommendations to reduce your impacts:
Reduce Concrete Use: Concrete has very high embodied impacts due to its energy intensive manfacturing process. Nonetheless it is a very popular material choice due to its cost and thermal mass properties which provide passive thermal performance benefits. Replacing concrete with low-impact options such as timber, concrete replacement options like fly-ash blends or alternative construction methods that require less concrete like bubble-deck will help reduce the embodied impacts of the building. Rammed earth is another a low-impact option that doesn’t lose out on the passive thermal performance benefits that concrete provides.
Use More Timber: Timber is unique as a building material because its very fabrication requires the capture and conversion of CO2 as opposed to most other building materials like concrete and brick. Technologies such as cross laminated timber (CLT) are now used in Europe for more than a decade and parts of Australia to construct high rise buildings that have previously been dominated by steel and concrete. Some architects or builders even adopt a hybrid timber building system that combine the cost advantages of traditional timber framing with the strength and speedy construction of pre-fabricated timber panels or CLT. The other benefits of building with timber includes: light-weight which makes it faster to build and requires less foundation, cheaper and its insulative properties. Other typical areas in your home where you can use timber is in flooring and window frames which additionally provide better thermal properties and lower embodied impacts than standard aluminium frames.
Reduce Surface Finishes: surface finishes like carpets, tiles, paint, plasterboard and renders often have high recurring impacts due to their high embodied energy, short life spans and the need to replace them frequently throughout the life of the building. Timber flooring or grind & polished concrete (on the actual floor slab) are great low-impact, low maintenance finishes. If you must have carpet, ensure that they have an Environmental Product Declaration (EPD) such as those from Interface Carpets which have over 50% lower impacts than industry average carpets. Hemp, jute or sisal carpets are other low-impact options. Note that wool carpets have much higher environmental impacts compared to synthetic materials due to the methane from sheep which has 34 times more global warming impact than CO2! Therefore replacing your nylon carpet with wool ones will greatly increase your environmental impacts. Unrendered brickwork walls have also gained massive popularity with the added benefit of being low in recurring impacts over rendered or plasterboard lined finishes.
Build Smaller: Australia is leading the world in terms of new dwelling size at an average of over 200m2. If the rest of the world can survive with dwellings nearly half that size, we must be doing something wrong. Smaller homes lead to many benefits such as:
- less building material
- less embodied & environmental impacts
- faster construction times
- lower building costs
- less heating/cooling and lighting energy use
- less time and money spent on maintenance
- less time spent cleaning
- more time and money to spend on other important things in life
With all these benefits, there is not much reason why we need to continue with the MacMansion trend.
With this guide, any one in Australia or similar grids should be able to make environmentally better choices with regards to their home. You will still need to take into consideration the specific factors (such as financial or legislation reasons) of your particular situation that may affect the practicality of implementing these options and weigh the benefits of one strategy over the other.