Reverse-cycle Air Conditioners: Australian Renewable Energy Giants

And maybe the cheapest way to heat your home this winter!

Date of this version: 22 Dec 2015

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Why is this presentation needed?

1). Save money! Many Victorians are unaware that when they installed a reverse-cycle air conditioner to keep their home cool during a few days in summer, they also installed a space-heater than can heat their home more cheaply than gas for months-on-end in winter.

2). Heat with renewable energy! Many Victorians don’t realise that the heat coming out of a reverse-cycle air conditioner (known elsewhere in the world as a heat pump) can be from 50% to 100% renewable energy.

Where will this presentation reside? On any website where people want to post it. Please share it around.

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Who created this presentation? Tim Forcey - Energy Advisor and author of many publications on this topic. See the last slide for links to further reading, such as this top article from The Age:http://www.theage.com.au/victoria/heat-pump-tech-could-save-victorian-homes-up-to-658-a-year-on-gas-report-20150825-gj7gzt.html

Acknowledgements Tim recognises the following individuals and people at the following organisations who have added to his knowledge of heat pumps and home heating:

The University of Melbourne Energy Institute (MEI)

The Alternative Technology Association (ATA)

Positive Charge

Matthew Wright (Pure Electric and Univ. of Melbourne)

Alan Pears (RMIT and ATA)

Richard Keech of Beyond Zero Emissions (BZE)

Danielle King at Green Moves

Everyone at https://www.facebook.com/groups/996387660405677/

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What you will find described in this presentation 1). Reverse-cycle air cons (heat pumps) are significant renewable energy generators. 2). Heat pumps are all around us! 3). How Victorians can save ~ $250 million per year by using their reverse-cycle air cons in winter. 4). Case studies: How your neighbours are using their air cons to save on heating bills. This presentation focuses on Victoria in southern Australia.

The Big 4 in Australian renewable energy:

Hydroelectricity

Wind

Rooftop Solar Air Conditioners

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Air conditioners? What the … !

I thought air conditioners were bad!

Costly to run.

A drain on the electricity grid.

Environmentally unfriendly.

Please explain!

And how can an air conditioner generate renewable energy anyway?

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True! When used excessively in summer, air conditioners can do all of those bad things…. …but when used in winter on reverse-cycle heating mode, air conditioners might be the cheape$t and most environmentally friendly way to heat your home.

Here’s how and why… 7

To minimise summer air con running costs, pay attention to

insulation, draught-proofing, shading, the efficiency of heat

producing appliances (lights, TV, fridge, etc.), your thermostat

setting, and lastly upgrade to a modern efficient air con if needed.

USA: “Affordable heating is an emergency issue for low income earners, and heat pumps are one of the most efficient means to produce energy for heating”.

UK: “The Renewable Heat Incentive pays more than 22,000 home owners a combined £125m for running green heating systems such as heat pumps.”

NZ: “The Mayfield School principal said about $129,000 would be spent on the "long overdue" refurbishment of a toilet block and replacing the coal boiler heating system with heat pumps.”

Tasmania: “Gas appliances have an average efficiency rate of 80% compared to some electrical appliances (such as heat pumps) that can have an efficiency rate of 300%.” (Aurora Energy)

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Overseas, reverse-cycle air conditioners are called heat pumps.

So why are we talking about

heat pumps,

when we are meant to be talking about

reverse-cycle air conditioners?

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“Heat pump” is a term used in Canada, the USA, the UK, New Zealand, and Tasmania - instead of “reverse-cycle air conditioner”.

A heat pump does not aim to create heat. It uses the refrigerant cycle to move heat from a cold place to a hot place - in the direction opposite to natural heat flow.

Technically, fridges are also heat pumps.

Heat pumps are all around us!

See the following examples…

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Heat Pump Example 1: Your Fridge

A fridge moves heat from a cold place (inside your fridge) to a hot place (your kitchen).

Heat pumped from food => to kitchen. Uses the 4 refrigerant-cycle components: compressor, evaporator, expansion valve, condenser.

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Example 2: Summer Air Conditioning

Moves heat from a cold place (your lounge room) to a hot place (outside your house).

Heat pumped from inside of your house => to outside. 12

Example 3: Winter Space-Heating

Reverse-cycle air con mode moves heat from a cold place (outside your house) to a hot place (your lounge).

Heat pumped from the air surrounding your house => to inside.

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Example 4: Hot Water Heat Pump

Moves heat from a cold place (outside your house) to a hot place (inside your hot water storage tank).

Heat pumped from the air outside the house into the water stored in your tank.

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Example 5: Industrial-Scale Heat Pump

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Heat pumps are used by industry too!

And now, for the part about renewable energy…

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Heat pump water heater: 1 part of electricity produces

4.5 parts of hot water.

How? 3.5 parts of renewable heat go in here.

In Australia, heat pump water heaters receive

renewable energy certificates, just like solar PV.

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Reverse-cycle air conditioner in heating mode producing temperatures of up to 50 °C

1 part of electricity produces up to 6 parts of space heating.

5 parts of renewable heat go in here.

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In Australia, more renewable energy is produced by reverse-cycle air conditioners,

than by roof-top solar PV panels. Who knew!

http://www.energy.unimelb.edu.au/switching-gas-–-examination-declining-gas-demand-eastern-australia

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Note: Not all electric space-heaters are the same!

Because these simple resistance-element type electric heaters can’t recover renewable energy, these can cost up to 5 times more to run...

…than one of these.

Heat pumps have been widely used in the USA, Europe, and Japan since the 1970’s, with 58 million sold globally in 2013. The efficiency of heat pumps continues to increase, as does the number of comfort and convenience features.

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Humidity addition

But will my heat pump still work when it gets really cold outside?

Globally, modern reverse-cycle air cons operate at temperatures colder than minus 10 °C.

Your reverse-cycle air con may briefly engage its defrost cycle at around 0 °C.

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Canada

OK, now I understand that heat pumps can recover up to 5 parts of renewable ambient heat.

But what about that “1 part of electricity”? Won’t that come from burning brown coal?

To make sure you heat pump is 100% green, you can buy accredited GreenPower. Costs 6¢ per kWh extra. See www.greenpower.gov.au

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And now for the part about saving money…

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I always thought using gas was the cheapest way to heat my home. Well, no longer! In a large home, you can save up to $658/year by heating with your air con.

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Historically in Victoria, gas was viewed as a cheap fuel and the economic choice for home heating. What has changed?

1. People started buying modern reverse-cycle air conditioners (heat pumps) that are very efficient, especially in Australia’s relatively-mild climate zones.

2. Meanwhile, the price of gas has increased because, starting in 2014, eastern Australian gas is now exported to Asia.

3. Cheap electricity deals can be found, even for those without solar PV.

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So how big is the prize in Victoria?

Around 500,000 Victorian homes are equipped with reverse-cycle air conditioners that are not (yet) used for heating.

Every year, more home-owners are installing reverse-cycle air conditioners.

As more Victorians learn that reverse-cycle air conditioners are the cheapest way to heat their homes, collectively, Victorians can save around $250 million each year.

I have a reverse-cycle air conditioner that I have never used for heating. How much can I save?

Well, it depends… on 4 things…

a). What do you pay for a MJ of gas?

b). What do you pay for a kWh of electricity?

c). How efficient is your reverse-cycle air conditioner?

d). How efficient is your gas heating system?

With those 4 pieces of information, the HEATULATOR (see Slide 40) or an energy professional can help assess your potential savings. See also case studies of homes that may be similar to yours (Slides 35 to 39).

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a). What do I pay for a megajoule (MJ) of gas in Victoria?

Current prices* range from:

0.013 $ per MJ for cheapest “block” (incl 11% discount)

to

0.022 $ per MJ for dearest “block” (no discount)

Get the maximum discounts from your gas retailer! * As at December 2015. Cost of energy-used only. Excludes fixed supply charges. Includes GST. “Declining-block” tariffs mean the more gas is used, the cheaper it gets.

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b). What do I pay for a kilowatt-hour (kWh) of electricity in Victoria?

Prices* range from: 5 ¢ per kWh recent solar feed-in tariff 10 ¢ per kWh for off-peak, w/ 30% discount 16 ¢ per kWh for average all day, w/ 30% discount 26 ¢ per kWh for peak, w/ discount 38 ¢ per kWh for peak, no discounts

Get the maximum discounts from your electricity retailer!

* As at December 2015. Cost of energy used only, excluding fixed supply charges. Includes GST. Add 6 ¢ per kWh for GreenPower.

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c). How effective is your reverse-cycle aircon?

Australian Gov website www.energyrating.gov.au shows government-regulated air conditioner ratings.

Best: 7 stars 580 % efficiency* Mid: 3 stars ~ 400 % efficiency* Worst: No stars ~ 200 % efficiency*

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* Split-system air cons with no air ducts. Duct heat losses reduce efficiency.

To get an idea of the efficiency of your reverse-cycle air con, divide HEATING CAPACITY by INPUT and multiply by 100.

For the example below 4.0 / 0.995 * 100 = 402 %.

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d). How efficient is your gas heating system?

The star-rating system used for gas appliances is industry-led and not government regulated.

The highest overall heat-delivery efficiency for a ducted-gas heating system can be as high as 70 %.

The worst efficiency for an old and poorly-maintained ducted-gas system can be less than 40 %.

Thermal and visual Images of damaged, leaking under-floor heating ducts.

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Making “cents” of it all

The ATA found that a large Melbourne home with an older

ducted-gas heating system and a gas-heating bill of $1,050/year

per year, could reduce their heating costs to only $390/year (a

savings of $658 per year, or 63%) by heating instead with a

middle-efficiency-range 3 star air conditioner.

Please refer to the following case studies

that might be similar to the specific situation

in your home…

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Case Study 1 – “Gas-less” Gayle Gayle lives with her son in a single-story, 3-bedroom, semi-detached brick-veneer home in Mentone, Victoria.

Gayle has a 2-star Brivis-brand gas burner connected to under-floor ducts. The efficiency of this set-up may be ~ 60% overall. Gayle also has a 16-year-old 1-star ducted (through the ceiling) reverse-cycle air con manufactured by a Thailand-based company that has gone out of business. The efficiency of this system is estimated to be 250%. Since Gayle was already using electricity for cooking and water heating, before winter 2016, she decided to switch off her gas heater. With the onset of winter she proceeded to heat her home with the old air-con instead. We estimate that Gayle saved about $200 by heating with her air con, reducing her heating costs from about $500 to $300. When Gayle someday upgrades her 16-year old 1-star air con, she will be able to cut her heating costs down by a further $150/winter. Gayle saved an additional $200/year by eliminating her connection to the gas network.

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Case Study 2 - Chloe Chloe lives alone (generally) in a one-story, 2- bedroom, 14 year-old masonry-sided home in Sandringham, Victoria.

Chloe has a 3.5-star Stadt-brand gas burner connected to under-floor ducts. Two years ago, part of the ductwork was flooded due to a bathroom incident, and now no heat emanates from one of the registers. Unfortunately accessing the ducts is difficult and the possibility of high repair costs means that this fault has not been addressed.

Chloe has a single reverse-cycle air con (split system), situated in her main living area. It is a large unit (6.3 kW heating) made by LG and has a rated efficiency of ~ 400% (or ~ 3 star). Chloe has never used this as a heater. Chloe purchases electrical energy at a price of 18 ¢/kWh (includes 30% discount and 10% GST, but excludes fixed supply charges).

Chloe spent about $500 heating her house with gas last winter (includes discounts and GST but excludes fixed supply charges). We estimate that Chloe can introduce heat to her house with her air con at a cost about half that of using gas. Chloe intends to give this a go next autumn and see if the single air con can satisfactorily heat most or all of her house.

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Case Study 3 - Jillian

Jillian lives alone in a one-story brick-veneer Home in Glen Waverley, Victoria.

Jillian has a new “5-star” gas burner connected to under-floor ducts that appear to be in good repair. The overall effectiveness of this system is estimated at 70%.

In her bedroom and main living room, Jillian has individual Mitsubishi split-system reverse-cycle air conditioners with a rated efficiency of ~ 400% (around 3 star). She rarely has used these for heating

We estimate that it will cost Jillian half as much to introduce heat to her home if she uses the air cons instead of the ducted-gas system. However, given the positioning of the two air cons, there may be times when Jillian feels it is necessary to use the gas system in order to heat the entire house.

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Case Study 4 - Rick

Rick and his wife live in a single-story double-brick home in St Kilda, Victoria.

In the central lounge area of their home, they have a Rinnai non-decorative gas heater that has been retrofitted into an old fireplace. They suspect the heater needs maintenance. The overall effectiveness of this heater at delivering heat is estimated to be 70%.

In the kitchen/eating area at one end of their home, Rick has a Mitsubishi reverse-cycle air conditioner with a rated efficiency of 370% (which is a bit less than 3 star). He is thinking about buying a top-quality reverse-cycle air con for the main bedroom at the other end of the house.

We estimate that it would cost Rick about half as much to heat with his air cons instead of using the gas heater. Savings could be about $400/year.

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Case Study 5 – Tim Forcey, Melbourne, Victoria “Home science experiment” detailed in Renew Magazine, October 2015. Top-of-the-line 7 star air conditioners easily beat 20-year-old whole-house ducted gas, especially when only part of the house needs to be heated. Heating costs across the entire winter reduced to ~ 1/3rd of previous winters. Savings in this well-insulated home = $300 to $400/year. http://renew.org.au/current-issue/comfortably-ahead-a-tale-of-two-heaters

The HEATULATOR: a simple-spreadsheet heating- comparison calculator for all homes.

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HEATULATOR

CaseName Frankston

5starBrivisBX520vsMitsubishi

OutputCostofheatingwithgas/dividedbythecostofheatingwithelectricity 1.46 >1isgoodformakingtheswitchfromgastoelectric.

InputsElectricalEnergyCost(noGST) $/kWh 0.175 Energycostonly.Nofixedcharges.Assumes30%discountachieved.

GasEnergyCost(noGST) $/MJ 0.0124 Energycostonly.Thisisthecheapestblockonthebill.

RCACStarRating RCACHeatingCoefficientofPerformance 4.00 MitsubishiElectricMUZGA25VA

RCACEffectiveness % 100 Airdistributionlosses.

GasHeaterEfficiency+Effectiveness % 70 Combinescombustion&airdistributionlosses.

Inputs: Electricity price, gas price, and efficiencies/effectiveness of gas and electric heating systems. Output: The ratio of heating-with-gas divided by heating-with-electricity. A result > 1 means using electric heat pump(s) are cheaper than using gas.

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HEATULATOR Nomogram

For energy professionals!

This nomogram can be used where, in lieu of a spreadsheet, a quick illustration of the relative unit costs of gas vs electric space or water heating systems is needed. To use, draw straight lines between the energy price and system efficiency scales on the right and left. The drawn line that intersects the green centre line at the lowest position illustrates which heating system is cheaper to operate. The greater the difference between those intersections with the centre line, the greater the savings that will result from using the cheaper heating system. In the example shown, a reverse-cycle air conditioner with 400% efficiency and accessing 15 ¢/kWh electricity is 1/3rd the cost to operate vs a ducted-gas heating system operating at 50% efficiency.

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With any heating system, it pays to minimise winter-heating costs by attending to: • insulation • draught-proofing • window treatments • your thermostat setting.

See the ATA’s “Green Home Heating” ebook, BZE’s “Energy Freedom Home”, and other references.

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But what will happen to the electricity grid if we all start using more electricity in winter? At present, demands on the Victorian electricity grid peak in summer, and are much less in winter. “Economic fuel-switching” is happening as people switch off petrol and gas – moving to electric cars, heat pumps, and induction cook tops. Fuel-switching to modern electric appliances increases the productive use of electricity grid assets all year round and allows gas distribution infrastructure costs to be wound down. Managing summer-peak demand will continue to be an area of focus for electricity network companies and regulators. This can be addressed with demand-management, energy efficiency, energy storage, and other means.

How to make your home gas-free If you are happy heating your home with your reverse-cycle air con(s), you can also think about switching…

…from gas water-heating to electric heat-pump hot water

…from gas cooking to electric induction

Making your home gas free means you can stop paying monthly gas connection charges. These add up to hundreds of dollars per year.

See last slide for further reading.

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Final item: Why evaporative cooling systems may not be the best way to cool your home in Victoria. Evaporative cooling systems (also known as swamp coolers) have been popular in Victoria over the last few decades. However if you are looking to buy a new cooling system, a modern reverse-cycle air con (or two or three) is probably the better choice these days. Drawbacks of evaporative cooling when compared with reverse-cycle air con:

• cannot be used to heat your house in winter • don’t work well when it is humid in summer • can spread noise throughout the neighbourhood because of the equipment

mounted high up on the roof • though cheap to run in summer, can lose winter heat up through their

ceiling ducts • in bushfire prone areas, can catch burning embers and result in homes

being lost to the bushfire (see photo) • can use up to 25 litres of water per hour.

So perhaps you will never look at an air conditioner the same way again!

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THE END

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Further reading http://www.businessspectator.com.au/article/2011/10/5/smart-energy/why-i-have-six-air-conditioners https://bze.org.au/buildings http://energyfreedom.com.au http://www.ata.org.au/news/are-we-still-cooking-with-gas https://theconversation.com/get-more-out-of-your-solar-power-system-by-using-water-as-a-battery-37807 https://theconversation.com/its-cold-in-my-house-and-the-price-of-gas-is-going-up-what-can-i-do-44824 http://www.energy.unimelb.edu.au/switching-gas-–-examination-declining-gas-demand-eastern-australia http://www.theage.com.au/victoria/heat-pump-tech-could-save-victorian-homes-up-to-658-a-year-on-gas-report-20150825-gj7gzt.html

https://theconversation.com/the-cheapest-way-to-heat-your-home-with-renewable-energy-just-flick-a-switch-47087 http://pure-electric.com.au http://www.positivecharge.com.au/news/article/Top-Summer-Tips