Mar 8, 2015: Reader Feedback

Over the last few weeks I’ve received some helpful and interesting feedback from various readers of this Newsletter which I thought was worth sharing.

Alternative Transportation Options

In response to Last Week’s Newsletter I received the following from my friend Glenn Robinson who has built a wonderful, energy positive, affordable house in Bundanoon:

Note your interest is personal transport alternatives. Had a visitor on the weekend with a Nissan LEAF , very happy with performance and she advised Nissan has a batch of older model units they are discounting to move before the new model arrives. Been reading the LEAF forum and users up to 80k kilometers report operating cost similar to petrol vehicle when battery replacement at recommended interval is done, most users going beyond advised replacement mileage.
Folding bikes, check out “Strida“. Had a folding bike club at the hostel last week, they travel the world using an American model the “Bike Friday” , For a serious cargo folder check out the “Cargo Joe
Finding my electric cargo bikes replaces most car trips, can sit on 40kph on the flat with a little pedal input, have carried a large wheelbarrow flipped on the back and easily transported an extension ladder. Uses a Bafang 240w crank drive unit and a 10ah lithium ion battery.

Glenn Robinson expounds on the virtues of his electric bike with cargo carrier

Glenn Robinson expounds on the virtues of his electric bike with cargo carrier

Hot Water Issues

In our Feb 8th Newsletter titled ‘In All Sorts of Hot Water’ I described the difficulties we have had with getting our very expensive solar hot water system to function correctly. I came to the conclusion that we would have been better off to  simply use our excess solar power during the day to heat water in a simple electric tank water heater with a standard element. In response to this Glenn wrote:

The detailed report of your water heating tribulations may benefit from addition of the info that electrically boosted solar water heaters if adopted widely risk shock loading the grid in extended overcast weather just like air conditioners do in summer leading to a  greater infrastructure cost. i.e causing the need to construct a bigger grid to cope with otherwise avoidable peak loads. Beyond Zero Emissions 1014 report on domestic water heating  advises the broad scale adoption of heat pumps timed to match pv availability as the preferred community wide option.

While I completely agree with Glenn that there is a risk of shock loading the grid if there was a widespread move to electric element water heaters that were timed to come on during peak solar power production times (e.g. between 10am and 2pm every day). However I have a hard time recommending that people install a significantly more expensive, complicated and noisy heat pump water heater right now given that very few people are currently heating their water with their own solar power. Perhaps a satisfactory compromise might be to install an electric element type tank water heater now but plan it so that you can easily add something like the Siddons Bolt-on Heat Pump in the future if the shock loading issue becomes a serious problem

More About Phase Change Materials

In our Feb 15th Newsletter I mentioned the use of Phase Change Materials for heat storage in buildings that have inadequate Thermal Mass to which Mary Bowe, an Environmental Designer with Coolfield Pty Ltd, sent the following feedback.

You may have already seen this, but if not I thought it was an interesting article on Architecture & Design – The state of Phase Change Materials in Australian building design, 3 March, 2015  by Warren McLaren

Keeping Our Cool

Finally, in response to our Newsletter on Feb 15th which detailed some case studies I received the following questions and suggestions from Lorraine in Northern Queensland.
Just wondering, due to the fact that underfloor heating ( using water)  is available – why can’t we have underfloor cooling for the “hot house” you referred to. Also spray paint the dark tiles a lighter colour , I believe there is a special paint to do this job – not sure of its success rate but have heard some people here in the tropics have done this.
  As for the green shade cloth, I made 3meter drop blinds for my front verandah , using yacht rigging pulleys for easy roll up – in the tropics on sunny summer mornings the sun is blistering before 9 am, dropping my blinds stops the heat hitting the verandah pavers & protecting the many glass doors & windows  that this house has , it works.
To which I replied:
Thanks Lorraine,
Underfloor cooling is a possibility that can be installed in new houses but it’s impossible to retrofit into an existing house with a concrete slab. There are also potential issues with water supply, water pumping, and condensation that have to be considered. In the tropics, radiant cooling won’t help with reducing humidity which air-condition does but in hot, dry climates I think it can be an effective option if you have the water supply. In a cooler climate like ours it’s better just to insulate properly and use night cooling.
I’ve also considered the roof paint option but, unless the roof was leaking or in bad repair I would be reluctant to paint a tile roof because then you’re creating a maintenance issue for the rest of the life of the building. With the house in question I thought we’d try the other options first and only consider painting the roof if it was still too hot.
My family used to have a house with a big verandah and we would do the same thing with a drop-down shade cloth which was very effective and also kept the flies and mosquitoes out.

Thanks to everyone who has sent in feedback and please feel free to send me your thoughts, questions and suggestions via our Contact Form

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