What Is the Best Energy Efficiency Upgrade?
Maybe you've got limited resources to pay for upgrades that will reduce your bills and improve home comfort, or you're time poor and need to get straight to the most impactful upgrades. This article will walk through the different factors affecting home energy use and direct you to the one to prioritise.
Key Factors Influencing Home Energy Use
To start, let's cover the different levers that you can pull to improve energy efficiency.
Building Shell Efficiency
The building shell includes walls, roof, and windows – the barrier between your indoor space and the outside environment. Its efficiency is determined by the construction materials, how well it's sealed against drafts, the type of insulation, and window features like glazing or shades. A less efficient shell means more heating or cooling is needed to maintain comfort inside. This is the most impactful and cost-effective in the long run (depending on the upgrades you choose).
Energy Efficiency of Appliances
Appliances vary significantly in how much energy they use for the same tasks. For instance, two different water heaters might consume different amounts of energy to heat the same amount of water. Opting for energy-efficient appliances can lead to reduced energy consumption and lower utility bills, but can carry significant up-front costs, depending on the appliance.
User Behaviour
The way occupants use energy in the home also impacts overall consumption. Practices such as shortening shower times and setting the heating thermostat to a moderate level can contribute to energy savings. This option costs nothing, but requires discipline and navigating the tricky business of changing habits!
Improving energy efficiency in a home involves considering all three of these factors, as they interact and influence each other. Balancing these aspects is key to achieving optimal energy efficiency.
However, if you don't want to slog through behavioural change and want to get a healthy return on investment for up-front expenditure, there's a clear winner.
Ceiling Insulation
According to Environment Victoria, ceiling insulation gives you the most benefit for cost of all possible building upgrades. This is due in a large part to the reduction in use of heating and cooling appliances because comfort levels in the home are higher, which reduces energy bills.
Homes can lose up to 55% of their heat through the ceiling (1) – so making sure ceiling insulation is adequate should be the top priority.
Insulation is rating using a system of R-Value. R-Value is a measure of insulation's ability to resist heat flow. The higher the R-Value, the better the insulation's effectiveness. It's like a thermal barrier rating: the higher the number, the better the material is at keeping heat in during winter and out during summer. For example, current ceiling insulation regulations in Melbourne call for a minimum of R4.4 for new builds.
Bulk Insulation
Bulk insulation stands out as the top choice for insulating your home. Its effectiveness comes from trapping countless tiny pockets of still air within its structure. These air pockets are key to resisting heat flow, making the insulation work. However, it's crucial not to compress bulk insulation, as this squeezes out the air pockets, diminishing its insulating power. Available in various forms like batts, blankets, boards, and loose fill, bulk insulation caters to different needs and spaces.
Types of Bulk Insulation
Batts or Blanket Insulation
Ideal for flat ceilings under pitched metal or tile roofs, batts or blankets come in materials like polyester, natural wool, glass wool, and rockwool. They're easy to handle and install, making them a popular choice.
Board Insulation
For cathedral ceilings with limited space between the ceiling and the roof, board insulation is a great fit. It's typically made from extruded polystyrene, which may also include a foil layer for extra thermal resistance.
Loose-Fill Insulation
Often used for retrofitted wall insulation, loose-fill insulation can be applied in areas that are hard to reach. Available in cellulose fibre, polyester, natural wool, and granulated rockwool, it's pumped or blown into place. However, keep in mind that it can settle over time, potentially reducing its effectiveness.
Comparing Bulk Insulation Materials
Each insulation material has its own set of benefits. Here's a quick comparison:
Insulation Material | Low Toxicity | Environmentally Friendly | Soundproofing |
Polyester | ✅ ✅ | ✅ ✅ | ✅ |
Natural Wool | ✅ ✅ ✅ | ✅ ✅ ✅ | ✅ |
Glass Wool | ✅ | ✅ | ✅ ✅ |
Rockwool | ✅ | ✅ | ✅ ✅ |
Cellulose Fibre | ✅ ✅ | ✅ ✅ | ✅ |
Extruded Polystyrene | ✅ | ✅ | ✅ ✅ |
Source Home Insulation Materials guide by Sustainability Victoria
Polyester is a good option for people with allergies as it does not shed small particles. It is the same material found in doonas and pillows. Polyester will not corrode or deteriorate over time and can be recycled at the end of its use.
Insulation considerations
If you're seeing the value of insulating, there's a couple of things to consider.
More Is Not Always Better
If you are upgrading insulation in an existing home, the ‘diminishing value of return’ (see chart below) should be considered when deciding whether adding more insulation is worthwhile. The best return is when you are upgrading from very poor insulation, and the return decreases when you are starting with reasonable insulation – such as if you are considering upgrading from R3 to R5.
Good Coverage
It is really important to get full coverage when you upgrade your insulation; one study concluded that a 16 mm gap in insulation represents a 35% decrease in R-value (2). In other words, a tiny space can make a big dent in the effectiveness of your insulation.
Downlights: A Tricky Challenge
Downlights, particularly halogen ones, are not just energy hogs; they also create insulation complications. Non-sealed downlights can lead to unwanted air movement between your indoor spaces and the roofspace, disrupting temperature control.
Safety regulations also mandate gaps around each downlight for insulation, which could be anywhere between 50 to 200mm (3). When you have multiple downlights, these gaps can add up, greatly reducing insulation effectiveness.
The solution? Opt for sealed, IC4-rated LED units. These are draught-proof and allow insulation to cover them completely.
Roof Ventilation: Balancing Summer Heat
Proper roof ventilation can significantly reduce heat accumulation in your ceiling space during summer. The ideal solution is to use motorized ventilators, either electric or solar-powered, as passive units aren't as effective. The ideal setup includes a temperature-sensitive, powered ventilator to regulate the roof space temperature, ensuring activation only when necessary.
Tiled roofs usually provide sufficient ventilation without extra help.
For effective ventilation, air intake at a lower roof point is essential. This allows air to circulate and cycle through the roof space, replacing hot air with cooler air.
Safety First
Working in roof cavities is not for the faint-hearted. It poses electrical and dust hazards and ideally is done by professionals or those experienced and well-equipped.
If you do want to save money and have the time, you can always opt for a DIY installation, but always turn off the mains electricity before starting any work.
Beyond the Ceiling: Walls and Floors
Once you've tackled draught proofing, ceiling insulation, and windows, consider underfloor and wall insulation. For new builds in Melbourne, R2.5 wall insulation is the standard. Retrofitting wall insulation involves pumping insulation into the wall cavity, either through the roof or small wall openings.
Underfloor insulation is particularly beneficial for homes with open underfloor areas and non-carpeted floors. The right product choice and quality installation is vital to avoid issues like sagging.
In Summary
Insulation is the quiet hero of energy efficiency; who knew? If you have a home with a roofspace and you're looking for the best way to spend money that reduces your bills, ceiling insulation is a winner. Depending on the construction of your home, you can also add wall and underfloor insulation to enhance your home's comfort and energy efficiency.
As mentioned in the introduction, the building shell is just one area where you can improve your home. Find out your other options in our article, "What do I need to do to get an Energy Freedom Home?"
If you've got your own roof space but there's no solar panels on it, you're missing another good opportunity. Find out more about solar in our article, "How To Pick The Best Solar Power System"
Want to fast-track home electrification? Join an Energy Freedom Homes Masterclass and learn to identify your needs, gain expert installation advice, and meet trustworthy tradespeople. Check your Masterclass readiness now!