Mar 21, 2015: Latest Results and Reader Feedback

One Month To Go!

With just one month left to go of our first year in the Greeny Flat we continue to log very positive results. If you care to examine the table on our Results Page you’ll see that we are on track to finish the year way beyond energy positive. In fact, over the last month we have exported six times as much electricity to the grid and we have imported from it and for the whole year we have exported almost for times as much as we have imported. We’ve had a very dry month but we’ve still managed to use almost three times more tank water than town water for this month and overall we’ve used 50% more tank water for the year. We’re finding the Greeny Flat to be very easy to clean and maintain and we’re staying perfectly comfortable through a nice, mild autumn. In short, the Greeny Flat is meeting or exceeding all of our original Goals and expectations.

Don’t forget that we’ll be hosting The Greeny Flat’s First Earth-Day Party on April 22nd from 3-7pm at 16A Queen St, Mittagong, NSW and everyone is welcome to come and help us celebrate a highly successful year.

Does Thermal Mass Really Work?

On the subject of comfortable indoor temperatures, last week Glenn from Bundanoon sent me an excellent Report from the Australian Solar Council about the effectiveness of Thermal Mass at keeping the interior of a building comfortable. The report summarises a study recently completed in Tasmania where they computer modelled the annual temperature profiles for three almost identical homes in Tasmania. The only difference between the three homes was the amount of Thermal Mass on the interior (i.e they modelled a building with low-mass, one with mid-mass, and one with high-mass). Not surprisingly the study shows that ‘Buildings with high thermal mass experience lower temperature swings within a 24 hour cycle compared to low mass buildings, resulting in lower maximum day time temperatures (preventing overheating) and higher minimum temperatures at night (keeping the building warmer).’

The ‘high-mass’ home in the study has a concrete floor, masonry interior walls and reverse brick-veneer on all the exterior walls. The Greeny Flat would qualify as a ‘mid-mass’ home having timber framed walls and a concrete slab. What I find fascinating is that the actual results from Greeny Flat almost exactly match the predicted results for a mid-mass building. The study predicts a summer temperature range of 19.5C to 27.5C and the Greeny Flat recorded 18.8C to 27.9C in January (see Results Table). The study also predicts a winter temperature range of 13.8C to 23.3C and the Greeny Flat recorded 12.7C to 23.3C in August. Obviously there are many, many variables including location, size and shape of the buildings and insulation levels but still, it surprises me that we came so close to the predicted results.

Glenn’s comment in his email to me was this:

‘Really good info simply showing the role of thermal mass in a cool temperate climate, Shows that with a good floor plan there is not much difference (performance wise) between just a masonry floor and the addition of masonry internal walling. Floor plan of sample house is the best I have seen for a family home, sun in every room and all plumbing on internal walling so it lends itself to SIP exterior walls.’

Glenn makes a very good point that the high-mass home in the study doesn’t perform THAT much better than a mid-mass building (like the Greeny Flat or his own energy positive home in Bundanoon). The big difference is that a high-mass home with masonry interior walls and reverse-brick-veneer exterior walls is MUCH more expensive to build. So, given the affordability goals of both Glenn’s house and the Greeny Flat, it’s encouraging to see this study which confirms that you don’t really need to spend all that extra money to get good performance.

Now, before you shout at me that 12.7 degrees is NOT COMFORTABLE, please bear in mind that that was the temperature inside the Greeny Flat in the middle of winter with NO ADDITIONAL HEAT applied other than the Passive Solar Design. In terms of energy efficiency this means that, in order to maintain a ‘comfortable’ temperature of, say, 18C you only have to heat the interior by 5.3 degrees which takes MUCH less energy than heating it by 9 degrees as would be the case with the low-mass home in the study.

This report makes a very important point that the ‘Thermal mass should be located within the well insulated building envelope.’ Thermal Mass is of absolutely no use when it is on the outside of a building, so brick-veneer walls and tile roofs are worse than useless from the point of view of maintaining a comfortable interior. Personally I think that building ‘brick and tile’ homes should be illegal in Australia and yet it remains the predominant building type (at least in our area). So please remember that Thermal Mass will only help to keep you comfortable inside a home if it has a good Thermal Boundary (insulation and air-sealing layer) around the outside of it.

Regarding Glenn’s other point about the floor plan of the home. I made the following response:

‘I also agree that the floor plan is an excellent layout for a three bedroom house. It just has too many exterior corners. It only needs four and it has twelve. One thing I learned from testing many, many buildings in Montana is that the corners are where it’s hardest to effectively insulate and air-seal the thermal boundary so the simpler the shape the better.’

This is the floor plan of the homes modelled in the Australian Solar Council study on Thermal Mass.

This is the floor plan of the homes modelled in the Australian Solar Council study on Thermal Mass.

One thing I really didn’t understand from the study was that they claim to have modelled the homes with R5 insulation in the walls and R8 in the ceiling. What they don’t show is how they intended to achieve such high levels of insulation. The Greeny Flat has R2.3 in the walls and R3.7 in the ceiling and seems to be performing perfectly well. So, from the point of view of affordability, it seems that the homes they are modelling would be pretty expensive to build. I plan to contact Dr Detlev Geard to ask him about this.

Nevertheless the study has a lot of good information about why we need to include Thermal Mass in our Passive Solar Buildings and, very importantly, HOW MUCH Thermal Mass to use in relation the amount of North Facing glazing. It’s well worth a read for anyone interested in energy efficient design for a cool climate.

Click here to read the full report.

ACF Names and Shames Australia’s 10 Worst Polluters

The Australian Conservation Foundation, led by President Geoff Cousins, has released a damning report which names the 10 companies that are Australia’s worst polluters. Hopefully this will help to steer investors and divesters away from supporting these companies and perhaps help to persuade our various governments to stop providing subsidies to the big energy companies which make up seven of the top ten.

Click here to read the ACF report.

All You Need to Know About Solar Power

I also came across this very clear and concise Article from which outlines all of the fundamental information you should know if you’re considering installing or upgrading a solar power system. There’s a particularly interesting segment on the potential pitfalls of upgrading to a larger system if you are currently receiving a 60c Feed-in Tariff. If this applies to you then you’ll want to click here and read this segment.

Click here to read the full article from

More About 3D Printing

In our Feb 2nd Newsletter we provided links to a couple of fascinating articles about 3D printed buildings. Last week I came across another absorbing piece about Growing 3D Objects From a Vat of Liquid Polymer. Apparently this new technique (which was inspired by a scene from one of the Terminator movies) is much quicker and can create much smoother and stronger objects than ‘traditional’ 3D printing. (Don’t you love that they use the term ‘traditional 3D printing’ when, as far as I know, I haven’t even seen an actual 3D printed object yet).

Click here to read the Article from Gizmag.

A Beautiful, Floating Eco-Nest

I very seldom have any time for groovy architectural statements such as Frank Gehry’s buildings. Typically they simply glorify the architect, cost a fortune, and provide no benefit whatsoever to the owner, the occupants, the wider community or the planet. Take Gehry’s new $180M building for the UTS in Sydney as a good case in point. $180 million dollars for a building that looks like a ‘crumpled paper bag’… the man’s a genius!

But I do feel compelled to share with you the gorgeous WaterNest 100 by Giancarlo Zema. Yes, it’s made mostly from reclaimed materials and powered by solar panels, but primarily this thing just looks absolutely delightful to be in as well as fitting beautifully into the land/waterscape.

Giancarlo Zema's lovely WaterNest 100

Giancarlo Zema’s lovely WaterNest 100

Stutchbury Wins Architecture Gold Medal While Living In a Tent

Since I’m talking about architects, it’s also worth noting that Peter Stutchbury this week won the Australian Institute of Architects Gold Medal while he himself lives in a tent. The tent is apparently Stutchbury’s way of making a point about sustainability and the need for us to reduce our use of resources.

Click here to read a recent Domain article about Stutchbury’s Award

2 comments to Mar 21, 2015: Latest Results and Reader Feedback

  • ray

    Happy party! Sorry I missed it. Tks for posting on the building 🙂

    Glenn says ‘best floor plan I have seen for a family home’

    Which floor plan is he talking about ?

    Later he says he doesn’t like the unnecessary corners (makes sense)
    Is he talking about the floor plan above, in both instances ?

    I am confused (it’s not hard to do!)
    Kind rgds

    • admin

      Ray, thanks for you comments. We had a great party in spite of the foul weather. About 50 people came through which was all we could manage inside our small house (it was too wet and cold to be outside). Sorry you couldn’t make it and I’d be happy to give you a tour any time which goes for anyone reading this too.

      To answer your questions, yes, it is the floor plan shown above that Glenn is referring to in both instances. Andy

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