This week we present Episode 4 in our ongoing series of short videos on the Energy Retrofit of the old cottage next to the Greeny Flat. In last week’s video we were dealing with the ventilation of the under-floor area. This week we focus on relining the eaves and ventilating the attic. Ironically, in a well-sealed and energy efficient house, ventilation is extremely important. The adage that we used to work with in Montana was, ‘Build Tight, Vent Right’ and it’s just as true here. Properly venting an attic is essential for helping to keep the building cool in summer but more importantly, ensuring that there is no condensation issues in the attic in winter.
But just before we get to this week’s video, I wanted to share a delightful news story that appeared on page 2 of our local paper last week. The headline read….
‘Unprecedented Crime Rate’
…and the story was about the fact that there was absolutely no crime to report at all. The reporter stated that, ‘In all my time reviewing crime intelligence I’ve never witnessed such results’. I have to say that I am endlessly grateful to live in a place where this can make headline news. We are so incredibly blessed to be safe, comfortable, well-fed, and have ready access to fresh air, clean water, good food and such a delightful place to live as the Greeny Flat. I also greatly appreciate all of you who read this Newsletter. Thank you very much for your interest and support. Now on to this week’s little video…
Home Energy Retrofit – Episode 4 – Eave Linings and Attic Ventilation
Once again, if you live in the Southern Highlands and are interested in solar power systems and battery storage you will probably want to come to one of the two upcoming (free) information sessions. The first will be at the Mittagong RSL Club on Wednesday, October 26th at 6pm and the second at Moss Vale Services Club on Tuesday, November 15th at 6pm. If you’re planning to come, Suncrowd would appreciate if you can RSVP on their website so that they know how many people to plan for. CLICK HERE TO GO TO THE RSVP PAGE. But don’t worry, if you don’t want to sign up on the website you can just come to one of the events and I guarantee they won’t turn you away. Just remember to bring your most recent electricity bill and a couple of photos, one of the inside of your meter box and a close-up of the meter itself. This is so they’ll be able to help you figure out whether you need to have your meter replaced. Already over 200 people have registered for the information sessions which promise to be both fun and informative evenings. I hope to see you there.
In our Newsletter on Sept 23rd you may recall that I had some reservations and listed a number of questions about the Catchpower system. I had sent those questions to the developer of Catchpower but had not received the answers by the time the Newsletter went out. Well, Scott from Catchpower was kind enough to answer my questions and I have been slow in passing on his answers due to being preoccupied with house renovations. So, my apologies to Scott and, for anyone interested in the Catchpower system, please see Scott’s answers to my questions below…
ANDY: As I understand it, the CatchPower system costs $1,700 and does one simple thing… it diverts some of the excess power from a home’s rooftop solar system either to an electric water heater (resistance element, not heat pump) or to an electric in-floor heating system. Assuming this is correct, I have the following questions about the system:
1. Most people who still have the old-style electric resistance water heaters are running them on off-peak at night and paying around 7cents/kWh for the electricity. If they have a solar system, after the end of this year they will get paid about 7c/kWh for any excess solar power that they produce. So where is the economic benefit for them in shifting their water heating to the middle of the day? Without Catchpower they simply export their excess energy to the grid and get paid the same price that they pay at night on off-peak. So how can they ever recoup the $1,700 cost of buying the Catchpower system?
SCOTT: You are quite correct; the closer the price of off-peak power is to the rate of export the less value there is for CATCH. This isn’t the case everywhere though. In regional NSW the typical cost of off-peak power is $0.12/kWHr. This means we are effectively doubling the value of that surplus energy.
Also, people don’t always make decisions based solely on return on investment. Some people don’t like the idea of giving away their power to the electricity retailers, they would prefer to store it and use it themselves.
Also, some people are attracted to the information that the CATCH login offers, in particular the system monitoring feature, which as you saw this morning, is quite sophisticated. I’d be happy to show you what the monitoring looks like and how in-depth you can go next time I’m in the Highlands if you like.
2. For about the same amount of money the same customer could buy a heat pump water heater from an Australian company named Hydrotherm. These systems come with a built-in timer that the customer can easily set so that the heat pump only operates between 10am and 3pm (the time of peak solar output and warmest air temperature). This system is three to five times more efficient than their old electric resistance water heater and would end up costing the customer about a quarter as much to run as the Catchpower system. Wouldn’t that use less energy and make more sense?
This is true too. It just comes down to personal preference and circumstances. Not everyone likes the sound of a motor whirring away outside their window. Heat pumps lose their effectiveness in colder climates and many of my customers, who are solar installers, generally don’t recommend them due to cost and failures. This is the direct feedback I’ve got from them which may differ to your experience, but it’s what I am hearing from within the market.
If the customer already has solar installed, then CATCH means a genuine reduction of the total load of that house. If you use that money to buy a heat pump then you are adding the load of the heat pump to the household load. While it’s far less than an electric hot water service, it’s still a load. CATCH removes this load as much as it can, using the available infrastructure (solar array and hot water service).
3. Some local friends of mine have an electric resistance in-floor heating system that operates on off-peak at night and uses about 60kWh/day to heat their house. In order to make enough solar power to run that heater using Catchpower they would need to spend about $30,000 on a 20kW solar power system (plus $1,700 for the Catchpower system). Alternatively they could install a high-efficiency reverse-cycle air conditioning system for about $10,000 and run that on a timer during the day. That system would be 3-5 times more energy efficient than the in-floor electric resistance heating they currently have so it would only require a solar system a third the size with a cost of about $10,000. So they could save approximately $11,700 compared to using their current system with Catchpower plus the running cost would be about a quarter as much. So why would they choose to install Catchpower?
We’re not telling people how to heat their homes. It’s true that underfloor heating isn’t a particularly energy efficient source of heating, however, some people love their floor heating and will opt for this over all other methods of heating. If they want to use CATCH with solar panels they can, and regardless of the size of the array it would help in reducing the amount of power taken from the mains. CATCH and solar isn’t a replacement power source, it is supplementary. ie. it works in conjunction with off-peak. Prior to CATCH there was no way of utilising both the power from solar AND continue to have off-peak.
4. As far as I know, you can’t build a new house in NSW with either an electric resistance water heater or electric in-floor heat because they are outdated and inefficient technologies that won’t meet the BASIX requirements. So, just to confirm, Catchpower only works with those outmoded technologies, is that correct?
There is a points system used in the construction of new homes. If you manage to reach the required points from, say solar and some other energy efficient methods, then you can install an electric hot water system and underfloor heating. It just happens that solar and solar hot water are the most accessible to most people/builders.
5. I’m looking into a system called Reposit Power that promises to be a complete home energy management system that can do much more than Catchpower and costs less than half as much to install. So why should I choose Catchpower over the Reposit Power system?
I’m not totally familiar with Reposit however my understanding is that it takes available stored energy and sells it on the open market when energy costs are high. This makes great use of stored energy. I don’t know if it is used to control loads in the house however. Carolyn made me aware that Reposit works better on flat tariffs than it does Time Of Use, due to on-selling surplus energy at a time that is most profitable to Reposit and not necessarily the customer.
6. The two technologies that CatchPower work with, i.e. electric resistance water heaters and electric resistance in-floor heat, are very old technologies that are rapidly being phased out because they are such inefficient ways of using power. So how does CatchPower help people to use less energy?
The reality is that electric hot water is by far the most common means used for heating water in NSW (65% +). It’s also the cheapest way of replacing a hot water system that has failed (hot water systems are cheap!), so they’ll continue to be a part of our landscape for the foreseeable future.
Whatever the technologies that are deployed, heating water (or floors) is a high energy process. CATCH just makes use of the available solar to help do that job. We don’t have a strong view of how that’s done, we are just being practical and offering a product that works with what is predominantly out there.
7. The only real benefit I can see in the Catchpower system is its ability to incrementally adjust the amount of excess power it diverts from a solar system to a resistance heating element (which is, of course, is the reason why it can only work with resistance devices). So, while I don’t see any cost advantage to the customer in this (see items 1 and 3 above) I do acknowledge that it does allow a home to use more of its own renewable energy and less fossil fuel generated power. So there is a bit of an environmental benefit there. However, isn’t there a bigger environmental benefit plus a potential economic benefit to the customer from installing energy efficient heat pump water heating or reverse-cycle air-conditioning and simply running it on a timer to coincide with the period of maximum solar production?
It all comes down to what the customer has and what they want. If they have an existing solar system and they have electric hot water CATCH is a very good fit. The more hot water they use and they dearer the power is to heat that water the better the story is for CATCH. These circumstances vary right across the country. If it isn’t a compelling argument for your customer then that’s what it is, however there are many, many cases where CATCH will make a huge difference to the amount of energy a household uses and the cost in using that power.
Also, some people really like the online information that CATCH offers. On a central page you can see the total amount of solar generated, the hot water used, plus the total loads in the house. You also have the ability to see how much power is being exported and so making an informed decision about whether batteries are a viable alternative for the home. In addition, there is the system monitoring aspect of the system. Being informed that your solar is no longer functioning as expected or ailed completely is useful information. We have sold units purely on this basis alone.
And on top of all this the owner of CATCH has the ability to control the use of hot water if they need or want to, including disconnecting from the use of mains altogether!
Using a timer for either function (hot water or floor heating) will almost invariably lead to an increase in the electricity bill for most people. There are a number of reasons why and I am happy to detail these for you if you would like, but be reassured that timers are definitely NOT the answer to making use of available solar power.
So there you have it. If Scott’s answers have convinced you that Catchpower is the right thing for you then you can contact Catchpower via their website at catchpower.com.au or by calling 1 300 131 995.