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Chat about green living, green homes and other eco topics.

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This forum is for discussions on World Environment Day. What are you, or your organisation, doing for World Environment Day? Do you know of any activities happening around the country for World Environment Day? 81 Posts

Latest Forum Posts

Author Post

71 posts
Posted Yesterday, 10:09 PM
styrobec in lower hutt have it.

2 posts
Posted Yesterday, 9:52 AM
I have searched quite a bit but so far haven't been able to find a source for purchasing DIY quantities of PIR board. Can anyone help?

I am in Palmerston North, so a N island supplier would be preferred, if one exists. it's for a DIY solar water heat collector, so polystyrene is not appropriate, it's likely to melt!

74 posts
Posted 18 Oct 14 7:32 PM
Green certification makes sense for corporate companies and businesses who are willing to invest the money into such projects; usually they see it as they’re ‘corporate social responsibility’ and a good way to gain perceived ‘positive marketing’ for the brand, and sometimes they genuinely care for the environment. Yep anyway, back to the real world, with real budgets and real people.

Green certified buildings are also the most expensive buildings to construct. More money equals more resources used for construction, equals more technologies, equals more negative impacts on the environment. Lesser budget buildings are likely to be better for the environment, due to fewer resources being required for construction, compared to high budgets, and highly rated green buildings which require more resources and technologies.

To justify the upfront expenses and direct negative impacts on the environment over a green buildings life time running costs……doesn’t stack up for me.

The more resources used upfront for construction….the worse it is for the environment.

I’m going to go out on a limb here and say, green buildings are quite possibly the worst buildings for the environment due to the high construction costs and high amount of resources required for construction.

The highest level green rated building is likely to cost three times the price as a regular building- this is counterproductive for our environment and makes little sense to me.

Green certifications need to be made more accessible for lesser budget buildings (that are the majority of buildings built), require overall less resources for construction and less money to produce the buildings, with minimised amounts on technologies used, and maximised efficiency from technologies that are used.

When looking at green certifications check lists, they’re geared up for an expensive consumer driven green orgy, and someone forgot to bring the environment along.

5 posts
Posted 15 Oct 14 3:48 PM

A week Friday(24th Oct) we are delivering an Introductory talk on the subject of designing your Eco home. It will take place at the wonderful HIVE Environment center in New Plymouth.

This will be a per-cursor to a weekend workshop that will take place on the 22nd/23rd November.

It would be wonderful to see you there...

See attached poster

1 posts
Posted 13 Oct 14 9:55 PM

Our products offered are as follows:
-Wood Pellets
-Wood Briquettes
-Chacoal (wood, soft wood, barbecue, etc.)
-Timber (Logs and Sawn wood)
contact our email us at

2 posts
Posted 13 Oct 14 4:54 PM
We have also worked with Independent Power in Albany for many years and they are very knowledgable and also very helpful. Start with them ! We live on the west coast of the South island and they just ship what we need.

11 posts
Posted 13 Oct 14 2:46 PM
Polystyrene is recyclable.

4 posts
Posted 13 Oct 14 2:15 PM
Just don't like the environmental credentials of polystyrene - not recyclable, very flammable and also bad fitting can leave holes and slots etc. As I mentioned I was hoping for polyester or wool.
Bosca 360 is a dream. Get's to heat really quickly - can warm our whole house up (200m2) in about an hour. It gets through a cold (Auckland) winter's night with about 6 logs plus kindling.

1 posts
Posted 13 Oct 14 1:21 PM
Howdy. Why your concern with polystyrene under the floor? I'm not sure what kind of insulation to put on my new build, and was looking at a whole house polystyrene wrap.

Also are you happy with the Bosca 360? Looking at one of those, is it pretty economical on the wood? I'm building a 120m2 house in HIllsborough Road, wood on wooden poles as well, so similar to your situation.

342 posts
Posted 13 Oct 14 9:54 AM
Hi Suziebee

Have you spoken with Independent Power in Albany?

I am not off-grid but use an Elcold freezer I bought off them - appliances built for the off-grid market are very different to normal appliances.

For example, the freezer compressor starts and runs different to on-grid freezers: when it is on, it is fully "on" in order to minimise partially loading the inverter. Inverters that are partially loaded are inefficient and chews through your battery power more for every kWh of energy you get out of them. Same as fridges built for off-grid homes do a soft start rather have the massive in-rush currents normal fridge motors draw when they turn on. Again, when these specially designed fridges don't run part load, and don't have little gadgetry that eats power during low inverter loadings which again chews through the battery storage.

2 posts
Posted 11 Oct 14 3:33 PM
After 15 years off the grid I believe the super low energy fridges are a must. Very expensive but unless things have significantly changed recently then ....

13 posts
Posted 11 Oct 14 6:43 AM
Flat plate solar hot water systems might not work very well in the south. But evacuated tube systems are proven to work well in cold conditions. You can also get them with anti-freeze heat transfer fluid instead of just having water pump through them.

4 posts
Posted 9 Oct 14 6:49 PM
I've had an couple emails from a reseller and they seem to think it's find it works okay. These guys say they are the manufacture at: . There is a 48v 1200w model $70USD delivered. During the Skype call they did say only the 1000w is in stock as the 1200w wasn't being requested. Also they have made around 80,000 of these so far.

31 posts
Posted 9 Oct 14 9:55 AM
Hey Markdyer, you're certainly turning up some bits and pieces.
In order of appearance:
Unfortunately, I would not be confident with the DC thermostat. A DC thermostat needs to be purpose designed and this looks more like a light duty general purpose device. The thing with DC is that unless it is switched correctly it damages or destroys the switchgear, with risk of fire etc along the way. Not that it can't be done, it just needs to be done with care using appropriately designed devices.
On the other hand, the AE PV heater is exactly what we are wanting, I would say. The Germans certainly seem to be onto it: this looks similar to another German device someone linked to early in this thread. The only downside was that unit was quite costly (somewhere around $1500???) and I expect this one would be the same. Note this one also mounts direct to the element and I get the impression euro tanks have multiple element ports.

And the DC element with thermostat. This looks a bit meatier. Again, we would need to be confident that the thermostat would last the distance. My reward further enquiries, you think?

4 posts
Posted 8 Oct 14 11:25 PM
For partial heating this looks interesting.

9 INCH DC WATER HEATING ELEMENT USED FOR 48V 1000 WATTS. I like the built-in adjustable thermostat

Seems that would be acceptable to me and well priced.

4 posts
Posted 8 Oct 14 10:37 PM
This is a tidy system that does everything. Not sure how it fits with the regs.

4 posts
Posted 8 Oct 14 10:21 PM
Is this the type of DC thermostat we should be after?

2 posts
Posted 8 Oct 14 4:02 PM
Hi there,
We can sell you INVOLAR microinverters if your panels are suitable. Although they are only 250W - send us your technical datasheets if you are interested. See website for info about our microinverters. You may want a controller as well? But not necessary. All the best!

31 posts
Posted 7 Oct 14 4:28 PM
Oh's not's good............sigh

31 posts
Posted 7 Oct 14 4:27 PM
Hi Uhtrinity, and thanks for your practical input. It's goof to hear some of what can be done (if not in NZ).

NZ and tanks:
The vast majority of houses here are single storey, and of light timber construction. This works well in earthquake country.
Most HW systems used to use a pressure reducing valve before a low pressure cylinder, with simple venting. Unfortunately this valve also reduced flow, and this, combined with a great deal of very stupid plumbing (sorry, plumbing guys, but there it is) resulted in a lot of homes with terrible HW systems.

Enter, then, the mains pressure HW cylinder. The early ones were too thin with the result that the inner coating cracked and they promptly rusted out. They are now more heavily made, and presumably perform better. So mains pressure HW seems to be the current flavour, and of course they are not vented.

Personally I am a fan of header tanks: I grew up in header-tank country, gravity is reliable and predicable, and when the lights go out you still have some water in your tanks and taps.
Flows at taps and shower are more than adequate, even with a single storey building, provided you source the correct low pressure fittings and understand a bit about pipe-losses and such. Just don't ask your plumber.

Maybe I should start a water thread.........

31 posts
Posted 7 Oct 14 10:07 AM
While we're raising some interesting and also invaluable points, we seem to be getting a little off track here again: this strand isn't about raising 300litres of water to temperature on solar only, it's about what may be viable as a supplementary system, with grid power on a timer taking up the slack:
My wetback doesn't heat all the hot water during the shoulder seasons either, but it surely provides a useful supplement.

It looks to me as though we're to a point where we can summarise what can be done within current NZ regs. Nice to know some other readers here are not so constrained, we learn from them too.

Hopefully I will have time in the coming week to put together a summary for general comment.

342 posts
Posted 7 Oct 14 9:58 AM
Uhtrinity posted:
"As far as elements, there are many options....
....parallel 3 panels at 30 volts / 24 amps with a 24v 400 w element or 4 panels at 30 volts / 32 amps with a 24v 600 watt element"

I agree that these are fairly well matched at voltages well within ELV.

And workable if your water requirement is moderate (4 peak sun hours x 400W = 1.6kWh a day, ~30 litres of water heated from cold to hot, give or take 50%)

342 posts
Posted 7 Oct 14 9:21 AM

For an unvented cylinder, your solution is illegal in NZ. The cutout cannot be switched by a relay - the words in the wiring regulations specifically exclude the cutout being operated by a relay.

For vented cylinders, there is no requirement for an over-temperature thermal cutout.

20 posts
Posted 7 Oct 14 8:59 AM
"Your solution for the over temperature thermal cut out is what?"

Thermostat driven HV relay

12v power supply in series with relay coil and stock thermostat


HV side of relay - connects between your panels and the element

But like I said the disadvantage is if your 12v power supply turns off (power outage) so does your solar feed. There are options like UPS, but that adds cost.

2 posts
Posted 7 Oct 14 8:58 AM
Hi, I have read the Consumer report and it compares some models but there are now many more on the market, which I would like to see more about. Thanks for your suggestion.

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