In recent years, like many Australian families we’ve been endeavouring to wean ourselves off fossil fuels.
There is no shortage of advice on the web on how to do this. The energy pundits all seem to be saying more or less the same thing: insulate the house; install solar PV; install heat pumps; turn off the gas; buy an EV. When we started out on our road to fossil fuel freedom I envisaged that we would simply follow the recommended route. We have essentially done just that, but with one major exception – we have not used heat pumps.
Our main family car is now an EV; we have double glazed the house; we have installed 8.5kW of solar PV; we have turned off the gas. We are now well on the way to becoming a fossil fuel free family. I have documented our energy transition process and produced a book called Our Household Energy Transition: Becoming a Fossil Fuel Free Family. Heat pumps just did not add up for my family.
Heat pumps are favoured by the pundits because of their remarkable energy efficiency. However, when researching the options for replacing our gas-fired space heating and hot water I became concerned that many of our energy experts appear to be almost mesmerised by heat pumps and show no inclination to consider alternatives. In my view, if there is going to be a widespread community movement away from the use of gas in the home we should be looking to expand, not close down, the number of sustainable options for space heating and generating hot water.
Tackling space heating first. The main reason we did not replace our flued gas central heating system with heat pumps was primarily because we already have a heat pump in one of our rooms at home and my wife is very reluctant to use it. She says that the heat pump doesn’t make her feel warm even though it can very easily heat the air in the room to +20⁰C. In essence, for her, thermal comfort has to involve a fair dose of radiant heat. Against this background, I began a search for an energy efficient space heating option that was primarily based on radiant, not convection, heat.
I eventually came across far infrared (FIR) heating panels. I was not aware of these when I set out on my search but have found them to be quite remarkable (they should not be confused with conventional (convection) panel heaters). Initially I was very sceptical of the claims made about FIR panels, but was intrigued enough to buy a low powered (600W) panel as a trial. On the basis of this trial we have now installed four larger (1,200W) panels on the ceilings in our two main open space living areas. They look very much like whiteboards (other options are available) and do not change colour when they are turned on (see picture). They deliver a lovely pleasant low intensity radiant heat and generate a feeling akin to sitting in weak sunshine on a winter’s day. They are both very efficient and very effective.
Moving on to hot water. In this area the pundits seem to be less dogmatic; heat pumps seem to be the preferred option but solar collector systems are acceptable. I began my research by getting a quote for a heat pump hot water system and would almost certainly have gone down that route except that I would have had to locate the unit very close to my neighbours’ house and I became concerned about potential noise problems. I spent more than 30 years as an environmental bureaucrat and was associated with environmental noise control all that time – I was acutely aware of the nasty circumstances that can arise when noise from fan/compressor units disturbs neighbours.
I thought about installing a solar collector system but since we were already exporting a great deal of electricity that could be used to heat water it made no sense to install a separate solar hot water system. In the end, we simply installed a standard resistive element/storage tank system and fed it with our solar PV electricity. In order to ensure our solar PV was diverted to our hot water system effectively, I installed an energy diversion device (an Immersun unit) – this combination means that we are now getting at least 95 per cent of our hot water from our own solar PV electricity.
In summary, we have not used heat pumps for either space heating or hot water in our energy transition but have been able to achieve excellent energy/carbon outcomes. We have chosen simple, no moving parts, no maintenance solutions.
In heating, we have attained a thermal comfort which is far superior to that provided by heat pumps. With hot water, we have avoided the potential for noise disputes with our neighbours. I provide the detail behind these claims in my book which I mentioned earlier.
The bottom line is simply that just because heat pumps offer the most efficient solution, it is not necessarily the best solution. We need to consider both efficiency and effectiveness. Let’s keep our options open and provide a suite of low carbon measures for households to choose from when they head out on the road to fossil fuel freedom.
Dave Southgate retired from the public service in July 2012 after a 31 year career as an environmental specialist in the Australian Government Transport Department and then as the Australian Government representative on the United Nations International Civil Aviation Organization (ICAO) Committee on Aviation Environmental Protection (CAEP). Since his retirement he has expanded his climate change interests and has become fascinated with renewable energy.