Planning ahead: Three steps to all-electric
Thinking about going all-electric, but unsure what’s involved? Here we present an overview of the steps to going all-electric and where to find more information. In the rest of Renew 140, we answer common queries and present case studies of households who’ve gone all-electric and lived to tell the (happy!) tale.
This article was first published in Issue 140 (July-Sept 2017) of Renew magazine.
In the past, gas was seen as a cheap and clean option for winter heating, hot water and cooking. However, the efficiency of electric appliances has improved dramatically and solar PV has fallen so much in price (and can be used to power those appliances), meaning it can now be cheaper and more environmentally sustainable to go off gas and run an all-electric home.
Renew first looked at this in 2014; updated modelling results from 2018 can be found here. In summary, the results showed that even when paying grid electricity rates (i.e. without solar PV), for many Australian homes it would be cheaper over 10 years to switch from gas to efficient electric appliances, with appliances replaced as they fail or in some cases even before this. Greater savings can be found when disconnecting completely from the gas network as this eliminates the gas supply charge (costing several hundred dollars a year). The report also highlighted that new homes should not be connected to gas, as doing so would lock in higher energy costs than needed.
Savings will depend on the thermal performance of your home, the electricity price negotiated with your retailer, your gas tariffs and the efficiency of your appliances. The Grattan Institute found that a large home in Melbourne can save $1024 per year by disconnecting from the gas grid.
In addition, by using modern electric appliances, your home can be converted to use 100% renewable energy, whether you generate your own electricity with rooftop solar or purchase 100% GreenPower from your electricity retailer.
Three steps to all-electric
There are three main areas where many homes currently use gas: space heating, hot water and cooking (mainly cooktops, but ovens too). To switch to all-electric, there are now efficient options available for these uses. Here we summarise the options and point to where to find more information.
1. Heating (with a cooling side benefit)
Many Australians aren’t aware that a reverse-cycle air conditioner can be more useful in winter, for heating, than in summer for cooling. They are widely used and known as heat pumps in colder regions in North America, Europe, Japan and New Zealand.
Renew modelling for going off gas was based on using separate ‘split’ heat pump units (two or more depending on the house size) to cover the heating loads that would otherwise be provided by a gas ducted system.
For every one unit of electricity purchased to run a modern heat pump, up to five units of ambient heat—a form of solar energy—are collected from the air outside your home. In this way, heat pumps can be up to 500% efficient. Gas heaters are much less efficient (up to 95% for the best currently available), especially for older and poorly maintained underfloor ducted gas systems. Half or more of the energy contained in the gas can be immediately lost as the gas is burned and as heat is distributed through the ducts and around your house.
A side benefit of using a heat pump for heating is that you can also get cooling from the same unit, provided it’s reverse-cycle.
Another option for electric heating is a heat pump hydronic system, but these are a more expensive option as they are generally configured with panels in each room and require a large unit to support this. Hydronic heating of a concrete slab can provide lovely warmth, but has the issue of responsiveness since it takes time to heat the slab to the required temperature—this may be a better option for those at home during the day where the energy/time to heat the slab in the morning isn’t wasted. There is also little experience with heat pump hydronic systems in Australia, but as this becomes a more popular option, prices and availability should improve.
Other options include resistive element heaters (including radiant heaters, convective panel heaters and fan heaters), but these are much less efficient than heat pumps and not very effective for large spaces. They will use large amounts of energy if used for long periods of time, but may be appropriate for small, occasional heating needs, as in a bathroom.
Another option, also a resistive element heater, is the far infrared panel. These provide radiant heat and some people find they provide a high level of comfort at lower levels of energy use than other resistive heaters because they heat objects (including people) directly, rather than the entire room air volume. We covered them briefly in Q&A in Renew 136 and in our new efficient electric heating guide. A strong proponent is Dave Southgate with information online.
People are often worried about comfort from using separate reverse-cycle units compared to ducted. Ducted systems will be less efficient, particularly given losses in the ducting, and more expensive, but may be a good option for those wanting whole-of-house heating without multiple external units. Multi-head split systems are another option, where a single external unit runs multiple internal air conditioners; these are generally more expensive and less efficient than the equivalent single split systems, with higher installation costs. We plan to look at the pros and cons in a later Renew.
- Case studies in Renew 140 demonstrate people’s experiences with switching to reverse-cycle split and ducted systems for heating and cooling; generally positive!
- The Efficient Electric Heating Guide in Renew 144 provides information on efficient electric heating options (or see the buyers guide in Renew 135)
- ‘Winter comfort: not just a heater choice’ by Alan Pears in Renew 127.
2. Water heating
Heat pumps are also an efficient way to use renewable energy to meet your hot water needs. Alternatives include electric-boosted solar thermal hot water and a simple electric resistive element tank run from your solar PV system. Using solar PV with any of these options can help to reduce both bills and greenhouse gas emissions.
By choosing to cook with an electric oven and a modern electric induction cooktop, your kitchen can also be gas-free.
Highly controllable and efficient, induction cooktops use a magnetic field to turn your pot into the cooking element. Induction cooktops look great, are easy to clean and are safer than cooking with gas because there is no open flame. They do require magnetic cookware, so aluminium, ceramic and some non-magnetic stainless steel pots and pans are not suitable.
This article was first published in Issue 140 (July-Sept 2017) of Renew magazine. Issue 140 is our all-electric special, including economic analysis, how-tos and case studies.
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