May 24, 2015: The Heat Goes On

29 Degrees of Free Heat

In last week’s Newsletter I described our efforts to build a solar air preheater to assist with ventilating the Greeny Flat during winter. For various reasons, we haven’t been home much over the last week so I haven’t had a chance to fully test the prototype. I did get a chance to play with a bit though and the early results are very promising. Yesterday was a nice, cool, sunny day so I gave the system a bit of a run. As you can see from the photos below, it was 12.7 degC outside and, with the fan running full bore, we were getting 41.8 degC air coming into the house from the heater panel. This means it was producing a temperature rise of 29 degC. 

Temperature at inlet from solar preheater and temperature outside (circled)

Temperature at inlet from solar preheater and temperature outside (circled)

This is pretty amazing! Especially because the fan was running full speed which means that the air was moving through the solar collector rapidly giving it less time to heat up. I have no way of measuring air flow but the fan is rated at 220 m3/hr. Someone who knows about thermodynamics could probably calculate how many watts of heat we were getting out of 200 m3/hr of air raised by 29 degC (if you’re reading this and can tell me the answer I would appreciate the information).

This was a very quick trial and at other times during the day I noticed that the inlet temp was in the 25 to 35 degree range. It would be very interesting to set up monitoring equipment to log the temperatures and air flows over a long period of time to figure out exactly how much heat and fresh air we could expect to gain from this inexpensive DIY project. But for now I’m content to play with it and think about ways to make it quieter and to control the fan using thermostats (as discussed in last week’s Newsletter).

Quite a few people who read last week’s article contacted me with questions about how they could heat their house with one of these. The answer is that it’s not a heating device, it’s a ventilation device.  It’s purpose is to provide pre-heated fresh air to a well-sealed, energy efficient house that is kept closed during the winter to keep the heat in. Without the solar collector we could simply use a fan to blow fresh air into the building but we would lose our energy efficiency in the winter time. By using the solar collector to pre-heat the air we can maintain good indoor air quality and keep the interior humidity level under control (which reduces the chance of condensation and mould) without sacrificing our overall comfort and energy performance.

We still have more work to do to make the system quieter and more controllable but it’s going very well so far and I’ll keep you posted.

The Experiment Continues

Last month’s Earth Day Party marked the end of our first year of living in and monitoring the Greeny Flat experiment. It has been a resounding success so far and I can see no reason to stop here. It has been very instructive for me to compile the results and present them on our Results Page each month so I plan to continue doing that for anyone who is interested.

I have also added a row to show the averages per month for each of the columns. It shows that, on average we have: exported 317 kWh and imported 96 kWh of electricity per month; used 2337 L of town water and 4233 L of tank water per month; maintained a comfortable indoor air temperature between 16 degC and 26 degC while the outdoor temps have swung between 3 degC and 30 degC. In short the Greeny Flat continues to do exactly what it was designed to do.

I have also added a table that shows our running costs for the first year ($312 for an entire year!) and an explanation of those costs on the Results Page.

Pushing the Greeny Flat into the Mainstream

One of the many questions I continue to ask myself is, ‘Why don’t more people build affordable energy positive houses?’ As the Greeny Flat shows, it is relatively easy and inexpensive to build a house that is comfortable, healthy, cheap to run and much more sustainable than most Australian homes. So why do we continue to build huge, energy sucking McMansions at such an alarming rate? Part of the answer lies in inertia and the power of the status quo and part in education and exposure. I am quietly chipping away at both ends of that stick.

Energy Positive Project Home Concept

I am currently having discussions with a number of different project home building companies to see if there’s a way to apply the principles that make the Greeny Flat work so well to a mass-produced product that could be appealing to a much wider customer base and built at a very reasonable cost. It’s early days yet but I’m starting to see some signs of interest.

Sustainable Home TV Show

I’ve also put out feelers to see if there is any potential for doing a TV show aimed at showcasing the best examples of affordable, sustainable buildings and at educating the public about what is truly more sustainable (versus just Green-washing) and what is currently possible.

Renewable Energy Investment

I’ve discovered that there are very few opportunities for small investors to find a secure and decent return by investing in the renewable energy revolution that is currently occurring at home and around the world. So I’m involved in discussions with financial advisors and renewable energy experts to try to develop mechanisms to offer stable and profitable renewable energy investments to small investors. We are working on ideas for how to fund solar farms and how to encourage landlords to install solar on rental properties by utilising small investors that could profit from the promising returns available from renewable energy systems. We have nothing to offer yet but I will keep you posted as things develop.

Good Times for Solar for Small Businesses

There has never been a better time for small businesses to invest in solar power. The advantage is that businesses tend to use electricity during the day when their solar system is producing power. This means that the return on investment (ROI) for solar for businesses can be MUCH better than for homes. In fact I recently heard about a business in the Southern Highlands that is expecting a 25% ROI (i.e. a four year payback) for the system they have just installed.

Meanwhile Abbott and Hockey (isn’t it a shame that Peter Costello isn’t the treasurer at the moment so that we could all enjoy having Abbott and Costello running the country… mind you the current combination is almost as amusing) have, probably unwittingly, given a further incentive to small businesses to install solar power. The new budget includes a provision to allow small business to deduct the entire cost of expenses up to $20,000 in one hit.

So now a small businesses can install a solar power system costing up to $20,000 with an ROI of up to 25% and deduct the entire cost up front. IT’S A NO-BRAINER and I think we’re going to see a HUGE increase in the uptake of solar for SME’s (Small to Medium Enterprises) over the next couple of years. Wouldn’t it be deliciously ironic if we saw renewable energy lead an economic recovery in spite of all Abbott’s efforts to destroy it.

If you live in the Highlands and want to learn more, there will be a seminar put on by our local council entitled Solar Benefits Business on Thursday, June 4th at 5:30pm at the Mittagong RSL Club. Click here for more information and to register. You won’t want to miss it if you own a small business and if you don’t live in the Highlands you might consider forwarding the information to your own local council and requesting that they put on a similar event.

That’s all for this week.

Thanks for reading, you’re interest is greatly appreciated.

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