Previous Updates - The Greeny Flat Experience

Apr 12, 2015: Sand Wars, Floating Solar Farms and other Fun Stuff.

Sand Wars… (not the happy, summer, beach kind).

For those of us who are concerned about the impacts our building choices have on people and the planet, there are so many things that we just don’t think about or hear about. Here’s a new one… a friend from the states just sent me this article about the Deadly Wars Over Sand that are going on around the world. The article claims that after water and air, the thing that humans consume most is sand… who’d have thought it?

I suppose it makes sense when you think about all the ways we use sand: for concrete, bricks and mortar; as the basic ingredient of glass, silicon chips and solar panels; and in a thousand other products… As it turns out, in many places in the world, the right kind of sand is in very short supply and people are getting desperate to the point of killing for control of sand resources.

For me this is yet another reason to find alternatives to standard concrete in building construction. I have read studies that claim that concrete production consumes up to 10% of the world’s resources annually. Cement manufacture is incredibly energy intensive; mining for limestone, aggregate and sand consumes thousands of hectares of land and vast amounts of energy worldwide; and transporting both the heavy raw materials and the ready-mixed concrete to where it is needed also requires an enormous amount of energy and resources.

Alternatives to Concrete

The LEED Platinum Missoula Federal Credit Union, Russell St Branch in MIssoula, MT.

All of the concrete in the building is made from 100% recycled glass and flyash.

Back in 2008-9, when I lived in Missoula, Montana, I was greatly privileged to be part of the team that designed and built the Missoula Federal Credit Union’s Russell Street Branch building. At the time it was only the second building in Montana to achieve LEED Platinum certification. This meant that the building had exemplary environmental and sustainability goals which you can read about at the link above. The most impressive thing about the building for me was that (as far as we know) it was the first modern commercial building in the world to be built with no portland cement. In fact, all of the ‘concrete’ in the building (including the precast exterior wall panels, interior posts and beams, and the cast-in-place polished ‘concrete’ floor and foundations) were made with a mixture of recycled glass and flyash. Flyash is a waste product from coal-fired power plants that is piling up in huge quantities around the world and no-one knows what to do with it. As it turns out, it can be used (sometimes after secondary treatment) as a binder to replace portland cement in concrete. In the MFCU building we also replaced all of the aggregate in the ‘concrete’ with a mixture of coarse (to replace the gravel) and fine (to replace the sand) crushed recycled glass. So there is NO concrete or portland cement in this entire building (although there was a bit used in the landscaping around it) and all the material used instead was recycled.

The coolest thing about this building for me is the way it sparkles as the sun reflects off the glass in the wall panels and the polished floor in the main lobby. Every time I rode my bike past it I would feel a surge of pride and hope knowing that we CAN find radically different ways of doing things that greatly reduce our impact on the planet, work well, look great and tell a fascinating and hopeful story.

Floating Solar Farms

On another hopeful note, I read this week about a proposed 350MW solar farm in Brazi that will float on the surface of a hydro-electric dam. What a simple, obvious and brilliant idea! Hydro electric sites already have transmission lines running to their power plants so the solar farm can tie directly into the same grid connection. The land that is now underwater has already been lost so why not use the surface of the water to make solar power rather than building solar farms on unspoiled land somewhere else. AND, as the article above points out, the solar panels shade the water (which helps to reduce evaporation rates and algae growth). PLUS the constant temperature of the water helps to cool the solar panels (which makes them work more efficiently). It’s a win, win, win, win situation.

One not-so-hopeful thing I read in this article is that ‘In addition to the loss of habitat that occurred with its construction, it’s claimed that methane released from the massive reservoir, which covers 2,360 square kilometres, means the facility emits more greenhouse gases than most coal plants.’ It’s pretty scary to think that the decomposition of organic matter beneath the surface of the world’s dams could be producing far more greenhouse gas than is saved by the hydro power they produce. This is all the more reason to put floating solar farms on the surface of the existing dams to make more renewable energy and hopefully, help reduce the greenhouse gas problem.

As it turns out, Australia’s first floating solar farm is also about to be built at a waste-water treatment facility near Jamestown in South Australia. This will not only produce more than enough electricity to run the treatment plant but will also shade that water, reduce algae growth in the treatment pond and reduce evaporation by an estimated 90%.

Artist’s impression of Australia’s first floating solar farm (source abc.net.au).

Solar Power for Small Businesses

Here’s an excellent article from Solar Quotes which asks the question; why do we not see more solar power systems on small to medium sized businesses when the return on investment is so good? Most businesses use the majority of their power during the day when the sun is shining. This makes solar power an even more attractive option for commercial buildings than for residential where most of the power is used at times when there isn’t much sunshine. Averaged over twenty years, solar electricity typically costs less than 10c/kWh and commercial electricity rates can be as high as 50c/kWh. Because of the low cost of solar power systems many businesses are able to invest in solar power and see an immediate reduction in costs (the repayments on the solar system are less than the savings in electricity) along with a return on investment of between 10 and 35%. One of the main reasons we don’t see more PV panels on the roofs of businesses (and dwellings for that matter) is because many of these buildings are rented. Landlords typically don’t see the benefit of investing in solar power systems because they don’t pay the electricity bills. This is starting to change though as renters become willing to pay more for premises (and homes) that have solar power installed. It will be interesting to see how people solve this puzzle in a way that encourages landlords to install solar power on rental properties. Once that happens we’ll likely see a massive increase in the uptake of renewable energy systems on rental properties both commercial and residential.

De-politicising urban infrastructure planning to promote deliberative decision-making…

Don’t you love academic language? Despite the jargon this is a very interesting article from ABC’s The Drum about how Portland and Vancouver have been much more successful than Sydney or Melbourne at planning for population growth without increasing urban sprawl and all it’s associated problems. One thing the article advocates is to take the responsibility for planning the future of our cities away from our state governments. It points out that Melbourne is now in its fifth 30-40 year plan in five decades and that each successive state government undoes all the work of the previous one and starts again (sounds like our federal government doesn’t it?).

‘Both (Portland and Vancouver) have been able to maintain an urban consolidation boundary for more than 30 years, in part due to a governance structure that is based on local governments working together on a common vision, rather than having it imposed by their state government.

This has the additional benefit of de-politicising metropolitan infrastructure planning. Rather than priorities being completely revised after each state election, metropolitan planning outlasts both state and local government election cycles.

Both cities also have political cultures that promote deliberative decision-making between the private sector, governments and civil society. For instance, both have taskforces to end street homelessness, bringing together all levels of government with philanthropic and private sector contributions towards a shared goal.

Both cities have a goal of “complete communities”, with all residents having easy walking access to public transport, schools and health care (which are all sources of local employment). Both cities map access to this infrastructure, and then prioritise infrastructure spending in poorly served areas, along with prioritising affordable housing provision in well-served areas….

…almost half of the residents of central Vancouver walk to work, which cuts down considerably on living costs and improves residents’ physical and mental health.’

Which all sounds pretty sensible to me and a whole lot better than the sprawling traffic nightmare that our planners have made for us in Sydney and Melbourne.

Fossil-Fuel-Free Investments Showing Good Returns

This article from The Sydney Morning Herald talks about the excellent returns that the financial markets are seeing from investments that don’t support the fossil fuel industry (which is good news for the Divestment Campaign). Of course it is helped greatly by the fact that the Arabs are flooding the market with oil and driving fossil fuel prices down to very low levels.

‘This study proves that fossil fuel divestment is not just morally right, it’s financially prudent, too,’ 350.org Australia campaigns director Charlie Wood said. ‘It shows fossil fuel stock are actually performing worse as we move forward. We’re listening to Bernstein, Goldman Sachs and HSBC, who are all saying coal has entered a structural decline, we’re not going to see it pick back up.’

If you haven’t already considered getting out of fossil fuel investments (which I’m proud to say my entire family has done) now might be time to think about it.

Reader Feedback

Glenn from Bundanoon likes to get right into the details of things. So if you’re like Glenn, below are some specific questions about the Greeny Flat with my answers in CAPS.

‘Have been pondering the greeny flat design for a while, I know the site limited the east west length so the north south depth had to increase reducing solar penetration(had the same compromise with our studio). Wondered

why,with such a small footprint you gave up so much floor space to internal walling and corridors? THAT WAS MUM’S CHOICE. I INITIALLY PREFERRED A DIFFERENT DESIGN BUT THIS IS THE ONE SHE WANTED. AS IT IS THOUGH, I FIND THAT THIS DESIGN WORKS ALMOST PERFECTLY FOR CINTIA AND I.
why have such a large internal air volume relative to the area of floor available for solar heating? would be nice and warm if you sat on a swing up near the roof apex. ONCE AGAIN, MUM’S CHOICE. I ADVOCATED FOR A TRUSSED ROOF AND FLAT CEILING FOR THAT VERY REASON BUT SHE WANTED THE HIGHER CEILING. INTERESTINGLY, I’VE TESTED THE TEMPERATURE AT THE APEX AND AT FLOOR LEVEL AND THERE WAS NO DIFFERENCE. I CAN’T EXPLAIN WHY BUT THE TEMP AT THE TOP WAS THE SAME AS THE TEMP DOWN LOW IN WINTER.
why run an exhaust fan constantly when moisture is not being generated constantly? pulling more cold outside air in than really needed for a healthy atmosphere. GOOD POINT. I SUPPOSE A BETTER OPTION WOULD BE TO CONTROL THE EXHAUST WITH A HUMIDISTAT. AS IS, I MONITOR THE HUMIDITY MYSELF AND ADJUST THE SPEED OF THE CONTINUOUS FAN ACCORDINGLY.
why such a big PV system for such a small efficient house? not cost effective. HAVING NOT BUILT AN ENERGY POSITIVE HOUSE BEFORE I JUST TOOK A GUESS AT THE SIZE OF SYSTEM WE MIGHT NEED. COMPLETELY OVERSHOT IT, I ADMIT. BUT MY INTENTION FROM THE START WAS THAT IF WE HAD MORE POWER THAN WE NEEDED WE WOULD LOOK AT GETTING AN ELECTRIC CAR. I’D LOVE TO BE ABLE TO SAY THAT WE WERE ENERGY POSITIVE – HOUSE AND CAR! PLUS THE 3KW SYSTEM ONLY COST $4500. I JUST WISH WE HADN’T SPENT $6250 ON THE SOLAR HOT WATER SYSTEM.
does your sarking provide an effective thermal break outside the R 0.5 studs? most soft foams lose effectiveness when clamped under cladding. REMEMBER THAT THE INSULATED SARKING IS ONLY SQUEEZED AT THE VALLEYS OF THE CORRUGATED SHEETING SO PROBABLY 70-80% IS FULL DEPTH. BUT NO, 8MM OF SOFT FOAM DOES NOT GIVE AN EFFECTIVE THERMAL BREAK. BUT I WOULD ALSO ARGUE THAT THE INSULATING STRIPS YOU USED DON’T EITHER BECAUSE THEY STOP AT THE EDGE OF THE STUDS SO HEAT AND COLD CAN STILL GET TO THE WOOD. I’M NOT SURE WHAT THE MOST COST EFFECTIVE ANSWER IS FOR THIS.
What purpose does the external reflective surface on the sarking serve without an air gap to reflect heat into and vent away? SIMILAR TO ABOVE ANSWER, THERE IS AN AIR SPACE BEHIND MOST OF THE CORRUGATED CLADDING. WITHOUT BUILDING WALL SECTIONS AND TESTING THEM IT’S HARD TO SAY EXACTLY WHAT’S WORKING AND WHAT ISN’T. I’VE ACTUALLY CONSIDERED BUILDING AN R-VALUE TESTING BOX IN ORDER TO TEST SOME DIFFERENT WALL OPTIONS.
The metal roof is good for about 50 years, what happens when the outer skin needs replacing but the foam and inner skin are still good? Do you just roof over the existing materials? I SUPPOSE YOU COULD EITHER DO THAT OR TRY A ROOF PAINT. HADN’T REALLY COME UP WITH A GOOD ANSWER FOR THAT BUT MUM WANTED THE CATHEDRAL CEILING AND THIS SEEMED LIKE THE BEST WAY TO BUILD IT. HAVING TESTED MANY HOMES IN MONTANA WITH CATHEDRAL CEILING I NEVER FOUND ONE THAT WAS WELL INSULATED AND AIR-SEALED EXCEPT THE SIPS PANEL ROOFS.
In trying to be elder friendly the bathroom ended up not incorporating the usual accessibility clearances and features that let people age in place. Council LEP recommends provision for these features be made but the design did not address this, why did you elect to not incorporate these features as this, along with level egress are the main reason for buildings not serving occupants for their full lifespan? WE WEREN’T SHOOTING FOR WHEELCHAIR ACCESSIBILITY AND THERE IS PLENTY OF ROOM IN THAT BATHROOM FOR SOMEONE IN, SAY, A WALKING FRAME. WE PUT BLOCKING IN THE WALLS AND CEILING TO ACCOMMODATE GRAB RAILS IF AND WHEN NEEDED AND THERE’S ROOM IN THE SHOWER FOR A SEAT OR EVEN A CARER. AS FOR LEVEL EGRESS, WE INSTALLED THE ABSOLUTE MINIMUM NUMBER OF STEPS GIVEN THAT WE HAD TO EXPOSE THE EDGE OF THE SLAB FOR TERMITE PROTECTION PURPOSES. I ASSUME THAT THE TERMITE BARRIER SYSTEM THAT YOU USED WOULD HAVE ALLOWED US TO ALMOST COMPLETELY ELIMINATE STEPS AT THE EXTERNAL DOORS.

If you have questions of your own feel free to send them via our contact form.

Apr 5, 2015: Invitation to a Party

As the Greeny Flat glides smoothly towards the hugely successful completion of its first year, we are planning a celebration and you, dear reader, are hereby invited to join us for our first

Earth Day Party, April 22nd, 3-7pm

The address is:

16A Queen St, Mittagong, NSW

Drinks and snacks will be provided.

Everyone is welcome so please feel free to forward this to anyone who might be interested.

Thanks and hope to see you there.

Andy and Cintia.

Apr 4, 2015: UK’s First Carbon Neutral Town

While Australia bumbles along under the mismanagement of our various governments, falling further and further behind the rest of the world in taking action to create a better future, there are exciting things happening on the other side of the globe. As I mentioned in our Newsletter on Dec 14, 2014, the conservative government in the UK under David Cameron has already mandated that all new homes are to be built ‘carbon neutral’ starting next year. Exactly how this will be measured, regulated and achieved will be interesting to follow. Meanwhile, we here in NSW are still suffering under the useless BASIX system which adds layers of red tape, complexity and expense to our planning and approval process without doing anything worthwhile to improve the performance of our buildings.

You only have to look at any new subdivision with its rows and rows of brick and tile McMansions that are too big and totally inappropriate for our climate (or any climate for that matter) to see that our building codes and regulations are failing to adequately protect us, let alone move us towards a positive and sustainable future.

And you only have to look at the rush-hour traffic jams in our cities or the constant stream of cars and trucks on our highways to see that our broad-scale town and transport planning is also completely failing to cope with our wasteful and consumptive lifestyles. So it’s with great relief and a sense of hope that I read about projects like North West Bicester in the UK.

An artists impression of eco-town living in North West Bicester

A Carbon Neutral Community

The first phase of the North West Bicester (NWB) development is currently underway. Called ‘Exemplar’ this will provide the first 400 of a planned total 3500 new homes in a development with very ambitious Triple-Bottom-Line goals which aim to improve the environmental, social and financial outcomes of any venture.

‘At North West Bicester, we’re creating a new kind of development, one that’s designed to be good for the environment, the economy, and most important of all – is a great place to live.

We’re doing that by creating vibrant and sustainable neighbourhoods where:

Families can afford to live
Jobs are created for local people
Children can play outdoors safely
Wildlife can thrive
And there’s a strong community spirit’

Doesn’t that sound like something we could use in Australia right now?

I won’t go into too much detail but here is a quick list of just some of NWB’s goals (and you can click on this link to learn more):

A zero carbon community
Jobs, businesses, shops and services located close to people’s homes
Super energy efficient homes
PV on all homes so whole town becomes a solar power plant
Real-time information system in all homes for managing energy, tracking public transport, etc
40% green space with integrated food growing areas
Combined heat and power plant
30% affordable homes
Walking and bicycling prioritised, then public transport, then electric cars
School within 800m of all homes
Bus stop within 400m of all homes
Reduce embodied carbon by 30%
Zero waste to landfill during construction
Commitment to use local trades and suppliers

‘It is also one of a handful of One Planet communities around the world. The One Planet scheme was set up by sustainability charity BioRegional. It aims to find ways for people and societies to reduce their level of consumption to an extent that is sustainable based on the amount of resources that one planet can provide.’ Source http://www.gizmag.com/north-west-bicester-eco-town/36764/

The NWB development has a lot in common with an idea that I presented in our Dec 16 Newsletter for an Eco-home Display Village. What is most exciting about North West Bicester is that it is already being built, with the first residents slated to move in later this year. It gives me hope because we can use it as an example to help persuade our own developers and regulators that this sort of thing is not only necessary but also achievable. Let’s face it, if they can build a carbon neutral town in England’s gloomy climate, it should be very easy for us to do it here in the sunshine.

‘Examplar’ the first phase of North West Bicester

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.

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 Solarquotes.com.au 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 solarquotes.com.au

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

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

Mar 16, 2015: Our Double-glazed Windows

Last week I wrote in more depth about why we chose to use Galvanised Iron and Plywood on our walls. The bottom line of that discussion was that these were personal choices that had very little to do with the energy performance of the Greeny Flat. There were many other sound and practical reasons why we chose those materials but we could have built an energy positive and affordable house with a very different look and equivalent performance if we had chosen different cladding materials. By contrast I would argue that, at least in the Southern Highlands of NSW, our use of double-glazed windows was not a choice but a necessity.

Double-glazing Essential in Most Parts of Australia

Perhaps, if you live on the coast between Sydney and Brisbane where the climate is VERY mild and is moderated by the relatively constant temperature of the ocean and by cooling sea breezes in the summer time, you might be okay with single-glazed windows. In fact you could live in a tent and be pretty comfortable for most of the year. But almost all of the rest of Australia is either too hot in the summer or too cool in the winter (or both) for single glazing to be appropriate if you want an energy efficient building.

If you want your building to be energy efficient you can start by following the principles of Passive Solar Design, one of which is that you need good insulation and air-sealing around the ‘Thermal Boundary’ of the building. The ‘Thermal Boundary’ is the barrier between ‘Conditioned Space’ (heated or cooled areas of the building) and any ‘Unconditioned Space’ (including the outside, the earth and any parts of the building that are not heated or cooled such as a garage). To put it more simply: in order to minimise the amount of energy required to maintain comfortable conditions inside the building you have to have good insulation and air sealing between the inside and outside.

Windows are always the worst part of Thermal Boundary

In every building that I have designed, built and in most of the buildings that I have tested or seen, the windows and exterior doors are the most poorly insulated and the leakiest part of the Thermal Boundary.

I spent twenty years designing and building in Montana where the summers can get up to 40degC and the winters down to -40degC. In that climate we would often install triple and sometimes even quadruple-glazed windows. Even then the very best windows might have an insulation value of R2.0 (R11 in US numbers) and we would be installing them into walls with an insulation value of R6.0 (US R30). So even the best and most expensive windows we could get only had a third of the insulation value of the walls.

Here in Australia it is common to install single-glazed windows with an insulation value of about R0.13 (US R0.7) into walls that might have R1.5 (US R8). Even with that meagre amount of wall insulation, the windows only have 1/12th as much insulation as the walls.

But even the coldest parts of Australia are nothing like Montana so how much insulation is enough. For the Greeny Flat experiment we chose to try 90mm stud walls with R2.0 insulation PLUS we wrapped the whole exterior of the building with an 8mm reflective foam-and-foil product so our total insulation value is about R2.3 (US R13) and this is proving to be adequate. Of course it would always be nice to have more insulation but then you get into serious cost increases and it’s pointless if the windows aren’t dramatically improved as well.

For the windows we chose to try simple double-glazed windows with standard aluminium frames from a company called Stegbar. The powder-coated aluminium frames are nice because they require no maintenance and will not rot or burn. The trouble with aluminium frames is that they readily conduct heat between the indoors and the outdoors. This can be overcome by using ‘Thermally Broken’ aluminium frames. Basically these have a plastic piece in the middle that stops heat from conducting directly through the frames of the windows. Unfortunately buying ‘thermally-broken’ aluminium frames here in Australia would have doubled the cost of our windows. In order to meet our various goals of being energy positive, low-maintenance and affordable we decided that the standard aluminium frames were the way to go.

These windows have an average insulation value of about R0.25 (US R1.4) which is improved on some of our windows by the addition of a ‘Low-E coating’ on the glass. This is twice as good as a standard single-glazed window but is still only a tenth of the insulation value of our walls.

For future projects I will seriously consider using Stegbar’s Siteline range of wood-framed windows with an aluminium cladding on the exterior of the wood. These have the combined advantages of having better thermal performance (about R0.4 vs our R0.25), low-maintenance exterior, and fire resistance but the disadvantages of requiring maintenance on the interior and about 25% higher cost.

An example of an aluminium clad wood window.

Solar Heat Gain

The insulation value gives a pretty good indication of how good a windows is at KEEPING HEAT IN a building but another vital consideration with windows is how good they are at LETTING HEAT IN OR KEEPING HEAT OUT. This is where the ‘Solar Heat Gain Coefficient’ (SHGC) comes in. SHGC is a measure of how much radiant heat can pass through the glass in a window. The higher the number, the more heat it will let through. Windows with Low-E coatings have significantly lower SHGC numbers than windows with ordinary clear glass so they are much better at stopping heat from radiating in through the windows in summer time. They are also slightly better at keeping heat from radiating out through the windows in winter. The trouble is that they are also much worse at letting heat in from the sun in winter. So for a passive solar design like the Greeny Flat that relies on winter sun entering the building to keep it warm we have to be very careful where we use Low-E coatings. For us the answer was very simple, we used clear glass on the north-facing windows to allow in more of the heat from the winter sun and we used Low-E coatings on all the other windows in order to limit the amount of heat gain in the summer and heat loss in the winter. On all the windows we added insulating blinds to assist with keeping us warm in winter and cool in summer. And for the north facing windows we rely on the correctly sized eave overhangs to keep the summer sun off the windows and out of the house.

Ventilation and Condensation

One of the reasons for using double-glazed windows instead of single-glazed is that you are likely to have much less condensation on the inside of the windows in the winter time. This is due to the fact that double-glazed windows will have a much higher interior surface temperature than single-glazed ones so they are less prone to condensation forming on the cool surface of the glass. Nonetheless, in a fairly tightly air-sealed house like the Greeny Flat it is very important to pay attention to ventilation in the winter time in order to reduce humidity levels and therefor the likelihood of condensation on the windows (or other cold surfaces).

Serious condensation can form on the interior surface of the windows in winter if adequate ventilation is not provided.

Conclusion

Overall we feel that the Stegbar aluminium-framed, double-glazed windows we chose to use in the Greeny Flat are a good compromise between cost, quality, energy-efficiency, low-maintenance, and fire-resistance. In future projects we might consider using their Siteline range of wood-framed windows with aluminium cladding on the outside. These would provide the beauty of wood on the interior along with better energy-efficiency while maintaining the low-maintenance and fire-resistance on the exterior. But this would be offset by the higher cost and the need for maintenance on the interior wood surfaces.

P.s. Another hidden benefit of double-glazing is that it adds significantly to the weight of the exterior doors which gives them a real feeling of quality that you would not get with a single-glazed aluminium-framed door.

Mar 8, 2015: Form Follows Function

As we continue to glide comfortably towards a hugely successful completion of one full year of living in and monitoring the performance of the Greeny Flat we are working on plans for a little celebration to mark the occasion on Earth Day (April 22nd, 3-7pm). Meanwhile, we’ve been receiving a lot of interest and positive feedback on the progress of the experiment. One issue that comes up regularly relates to the look of the Greeny Flat which I thought was worth addressing in depth.

The ‘Galvanised Iron and Plywood Look’

At a Southern Highlands Green Drinks event this week I was chatting with Ian Scandrett, one of our local councillors, about the need for compact, energy efficient, accessible and affordable housing. We both agree that there is a huge opportunity in this area where house prices are being pushed up dramatically by the Sydney market and the options for single people, young families, pensioners, in fact anyone on a moderate income, are severely limited. Clr Scandrett is a huge proponent of ‘compact housing’ and, when we were discussing the benefits of the Greeny Flat, he made a comment something to the effect that, ‘it’s great if you like the galvanised iron and plywood look’. I pointed out to Clr Scandrett that our use of galvanised iron cladding on the exterior and plywood lining on the interior were personal choices that have very little to do with the energy performance of the Greeny Flat.

One of the great things about writing a website versus writing a book is that, using a free tool called Google Analytics, I can see how many people have viewed our site and which pages they have visited the most. I find it interesting to note that the Gallery Page is by far the most visited after the Home Page. This tells me that a lot more people are interested in what the Greeny Flat looks like than in how it functions. While this is not surprising, since something like 6 out of 7 people are guided by their emotions (i.e. how something looks or feels) rather than by their intellect (i.e. how something works or functions), it does make me realise that I need to explain a bit more about why we chose the materials that we did.

Why Galvanised Iron?

As you have probably already noticed from the photo above, one of the most eye-catching things about the Greeny Flat is the galvanised iron cladding on the exterior walls. This was chosen because it helps us to meet a number of our Goals.

Low Maintenance – one of the things the client for the Greeny Flat (my mother) was adamant about was that there should be no paint on the outside of the building. Over the years my parents have owned a number of houses that had paint on all of the exterior walls, windows, and trim so they are well aware of the tedious work and high cost involved with scraping, sanding, and repainting the exterior of a house. So Mum chose to solve that problem by having no paint on the exterior at all. This immediately limited our choice of exterior cladding materials to either masonry or metal.
Energy Efficiency – obviously, with our goal of being Energy Positive, we were very keen to make the Greeny Flat as energy efficient as possible. While I love the look of mud brick and rammed earth, they offer very poor insulation for our cool winter climate. Standard brick veneer is an insane way to build houses for our hot summer climate because the bricks absorb and hold heat on the exterior and prevent a building from cooling down at night. So masonry was out for us leaving metal as our choice for the exterior which has the advantage of rapidly releasing heat after the sun goes down. We researched various types of metal cladding (some that look like weatherboards) but decided that we really like the durability, low-maintenance and clean look of corrugated metal cladding.
Comfort – metal cladding has the advantage of being light weight which means that it does not hold heat. So the corrugated cladding helps to keep the Greeny Flat cool during the summer. Originally we chose to use a light coloured Colourbond because it would absorb less heat during the day than galvanised or zincalume. In the end our local council requested that we use galvanised because we are in a Heritage Conservation Area. It was tempting for us to argue that our proposed Greeny Flat was anything but a ‘heritage’ design but you have to choose your battles so we agreed to use galvanised cladding. In the end we’re glad we did because we love the overall look and feel of the Greeny Flat and the galvanised steel is a big part of that. More importantly we love the fact that we will never have to paint (or repaint) the outside of the building.
Affordability – galvanised iron (actually steel) is a common and affordable material that has the advantage of going up in large sheets which makes the process of cladding the exterior quite quick, easy and inexpensive. There are some tricky details about windows and doors that have to be carefully considered and executed to prevent leaks but, in general it is an easy material to work with and once it’s up it’s done, no painting or pointing or bagging or other processes need to be completed.
Recyclability – if the Greeny Flat ever has to be taken down it has been built in such a way that almost the whole thing can be taken apart with a screw driver. Metal cladding has the advantage of being very easy to unscrew and take down if that ever proves to be necessary.

Why Plywood?

Oct 29, 2014: Living room looking north-west

Plywood lining on the interior walls give a real feeling of warmth and comfort to the Greeny Flat.

As with the galvanised iron cladding on the outside, we chose to use plywood lining on the inside because it helps us to meet the following Goals:

Recyclability – one of Mum’s design criteria was that she wanted the Greeny Flat to be able to be taken apart at the end of its useful life (hopefully centuries from now) so that all of the materials can be reused or repurposed into something else. It can be argued that gyprock can be recycled by tearing it off, grinding it up, and remaking it into another product, however it cannot be simply taken down and reused somewhere else. So we chose plywood for the interior wall lining because it can be unscrewed from the walls and reused in a thousand possible ways.
Sustainability – the particular plywood we chose to use is called Ecoply (made by Carter Holt Harvey). Ecoply is made in Australia/NZ (as opposed to a lot of plywood sold here that is imported all the way from Chile) from sustainably harvested plantation forests. Using wood products has the advantages of not promoting mining as well as sequestering carbon which is locked away in the fibres of the wood.
Health – Ecoply also uses no urea formaldehyde glue so have very low levels of formaldehyde emissions and a very durable structure. We finished the interior walls with a clear coat product called ‘Polyclear’ (made by EcoColour in Byron Bay) which has zero VOC emissions and is certified Carbon Neutral. It is the same product that we used to seal the concrete floor which was handy because, when we sealed the walls, we didn’t have to worry about covering the floor, we simply wiped off any drips which became part of the floor seal.
Low-maintenance – our plywood walls won’t have to be repainted (although we might choose to apply further coats of clear sealer if necessary in the future) and they are very durable which means that it is easy to attach things to the walls, and any screw holes, etc, can easily be filled with a little putty.
Comfort – having lived in the Greeny Flat for almost a year now I can tell you that I have come to love the feeling of warmth and comfort that the plywood walls impart to the interior. There’s a softness and friendliness to the plywood which is very appealing and, especially in winter time when the sun comes pouring in, the warmth of the plywood makes us feel cozy and protected. In short, we love it and I could spend hours gazing at the grain patterns which remind me of aboriginal paintings and sometimes look like people, sometimes like landscapes, and always interesting.

I could go on about the reasons behind the selection of each and every material used in the Greeny Flat (e.g. click here to read about why we chose to use a light Coloubond steel roof) but suffice to say that nothing was chosen simply for how it looks. There were, for us, many more important reasons relating to the energy performance, affordability, maintenance requirements, health, comfort and sustainability of each of the products we have chosen to use. As it turns out, we love both the function and the look of the finished product which we think is a fine advertisement for the concept of Form Follows Function but please remember that, if galvanised iron and plywood are not for you, you can still apply the principles that make the Greeny Flat work to a house that looks very different. An excellent example of this is Glenn and Lee Robinson’s house in Bundanoon which was designed to not only be net-zero energy and affordable, but also to look and feel as much like an ‘ordinary’ house as possible.

Glenn Robinson’s Granny Flat nearing completion with his house in the background

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

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

link:

http://www.architectureanddesign.com.au/comment/a-state-of-change?mid=f4db31a652&utm_source=Cirrus+Media+Newsletters&utm_campaign=5afcd31880-Architecture+and+Design+Newsletter+-+201&utm_medium=email&utm_term=0_fe913f1856-5afcd31880-60065157

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

Mar 1, 2015: Some Fun Stuff

With everything here progressing smoothly towards an overwhelmingly successful completion to our first year of living and monitoring the performance of the Greeny Flat (see last week’s post for news on our latest results) I thought I might share a few fun things that I’ve come across in the last week or so.

World’s Smallest Folding Bike

The Helix Bike – folded and unfolded

Apart from being on the lookout for an electric car, bike or scooter that we could charge during the day from our solar panels, I’m also in the market for a really good folding bike that I could easily take on public transport for use at my destination. The Helix folding bike looks like the best prospect I’ve seen so far. It’s still in development and will be running a Kickstarter campaign soon to raise money to go into production. I’m seriously considering parting with the US$1200 to help get it off the ground and get myself one of their bikes. Click here to read an article about the bike and see a video of how it works.

The amazing world of Elon Musk

Most people have heard of the Tesla electric car developed by billionaire Elon Musk and perhaps most people already know about some of the other astounding things that he is involved with. I am really just starting to learn more about him and his innovations. All I knew until recently was that he was into space exploration and high-priced electric sports cars so I, incorrectly, assumed that he wasn’t interested in the social or environmental consequences of his profit-making ventures. What first caught my attention was when ‘Musk announced in a press release, conference call and blog post^[59] on June 12, 2014 that the company (Tesla Motors) will allow its technology patents for use by anyone in good faith in a bid to entice automobile manufacturers to speed up development of electric cars.’ In other words he’s giving the technology to anyone who wants to use it which I find immensely admirable. Since then I’ve become more interested in what he’s doing including:

Plans for an astonishing 1000km/h rapid-transit system called the Hyperloop. A prototype Hyperloop system is planned to be built in California with the goal of building a complete system to get passengers from LA to San Francisco in 35 minutes. Whether or not that actually happens will be interesting to watch meanwhile, if you’re interested in how things work, the technology involved in the Hyperloop is fascinating. Click here to read about how the Hyperloop works.

Elon Musk’s Hyperloop approaching reality

Musk is also the chairman of SolarCity, the No.2 installer of solar power systems in the US. ‘Among SolarCity’s more well-known financing partnerships was a $280 million fund created with Google to finance residential solar installations in June 2011. The Google Fund was the largest fund of its kind in the U.S., and Google’s largest investment in clean energy.^[36]‘

It seems I was very wrong in my assumptions about Elon Musk’s motivations. ‘In April 2012, Musk joined The Giving Pledge, committing to donate the bulk of his fortune to philanthropic causes.^[79]‘ and I recently read that ‘The underlying motivation for funding both SolarCity and Tesla is to help combat global warming.^[63]‘

‘Musk is chairman of the Musk Foundation, which focuses its philanthropic efforts on science education, paediatric health, and clean energy. In 2010, the foundation created a program focused on donating solar-power systems for critical needs in disaster areas.’

Meanwhile, Tesla Motors is in the process of building a network of solar-powered, fast-charging stations across the US for their electric vehicles and preparing to go into production of a reasonably priced electric family car. ”The Supercharger is a proprietary direct current (DC) fast-charging station that provides up to 135 kW of power, depending upon location, giving the 85 kWh Model S an additional 150 miles (240 km) of range in about 20 minutes, or 200 miles (320 km) of range in about 30 minutes. The electricity used by the Supercharger in the West Coast corridor comes from a solar carport system provided by SolarCity. Eventually, all Supercharger stations are to be supplied by solar power. The network is exclusive to compatible Model S sedans. Supercharging hardware is standard on Model S vehicles equipped with an 85 kWh battery and optional (with a one-time payment of $2,000) on Model S vehicles equipped with a 60 kWh battery. The Roadster is not equipped to charge from the Superchargers, but according to the automaker, all future Tesla models will be.^[208]^[209]^[210]According to Musk, “…we expect all of the United States to be covered by the end of next year [2013]”. He also said that Tesla owners’ use of the network would be free forever.^[211‘Free charging forever! Now that would be an incentive to buy one of their cars!

‘In 2012, Musk announced that SolarCity and Tesla Motors are collaborating to use electric vehicle batteries to smooth the impact of rooftop solar on the power grid, with the program going live in 2013.^[64]‘

In short, Elon Musk sounds like an incredible individual who is doing some great things. It will be fascinating to watch where he goes from here.

Josh Byre’s House

Since we don’t have a television I was not aware of Josh Byrne. Apparently he’s a regular presenter on the ABC’s Gardening Australia show. More interesting for me is the fact that he has a project going called Josh’s House with the aim of ‘showcasing the benefits of Sustainable Housing to the community through demonstration and inspiration’. As part of the project Josh has designed and built two 10-star homes in Fremantle for his family.

‘Tired of hearing that sustainable construction has to cost more, Josh and his colleagues set out to prove that resource efficient homes can be built at a comparable cost and timeframe to regular houses. The homes are thermally comfortable year round, without the need for air conditioning or additional heating. They generate more electricity than they use, and will harvest and recycle water.’ Sounds a lot like the Greeny Flat to me except that he, no doubt, has a lot more people paying attention to what he’s doing. Click here to visit the Josh’s House website joshshouse.com.au or Click here to see a video about the project.

Greens Launch Plan for 100% Renewable NSW

I tend to avoid politics like the plague but it’s worth noting that the Green Party has finally come up with a bold and ambitious proposal to actually do something significant about climate change. It’s not quite what it claims to be (but then what is when it comes from politicians) as it is not actually a plan to move NSW to 100% renewable energy but rather a plan to make the electricity sector in NSW 100% renewable. So all the energy that is consumed in the form of gas and petrol would still be fossil fuelled. Nevertheless, as a counter-point to the Abbott Government’s policies which seem intended to make climate change significantly worse, this proposal has the potential to make a very positive difference. It’s a relief to see something worthwhile and purposeful from the Greens and it will, hopefully, prove to be a smart political move for them as more and more people become disgusted with Abbott’s distain for the environment and for the potential economic, social and environmental benefits of moving to a renewable future. Click here to learn more about the 100% Renewable NSW plan.

And Australia has a new Renewable Energy Party

Still on my least favourite topic, politics, I read recently that Peter Breen (former member of the NSW parliament) has recently launched a new national political party called the Renewable Energy Party ‘committed to an Australia powered by 100% renewable energy by 2050 and to scrutinising the fossil fuel industry’s gravy train of subsidies.’ Click here for more information about the party…. sounds like a good idea to me.

Meanwhile we’re planning a party of our own so don’t forget to mark your calendar for the

Greeny Flat Earth Day Party, April 22, 3-7pm

All welcome, snacks and drinks will be provided.

Feb 22, 2015: Proof Positive

Today marks the end of our 10th month of monitoring the performance of the Greeny Flat. At this point we can confidently predict that we will complete our first year of testing with a large energy surplus. In fact, at this point, we have exported well over three times as much energy to the grid and we have imported from it.

Photo taken this morning of our electricity meters showing that we have put into the grid more than three times as much energy as we have taken out.

Photo taken this morning of our electricity meters showing that we have put more than three times as much energy into the grid as we have taken out… Proof Positive!

When people come to see the Greeny Flat for themselves and to learn about how it works I particularly enjoy showing them our electricity meter box. The electricity meter is not something you would usually think about in most homes, let alone proudly show off to your visitors. I find that I can talk about the concept of being energy positive until I’m blue in the face and a lot of people smile and say, “that’s a nice idea”. But when they see the meters and are faced with concrete and irrefutable proof that we actually do make much more power than we use, their reaction is very different. I can tell that they immediately “get it” and understand the point of this whole experiment.

Now that we are sure the experiment is going to prove to be an overwhelming success we’re thinking about ways to spread the word that building an energy positive house is easy and affordable.

Earth Day Party to mark end of first year

April 22, 2015 will not only mark the 45th Anniversary of Earth Day, it will also mark the end of our first full year of living in, and monitoring the performance of, the Greeny Flat. So we’re going to throw a little party to celebrate the success of the experiment. Snacks and drinks will be provided. Everyone will be welcome so please help us spread the word and mark your calendars for:

Wednesday, April 22 between 3pm and 7pm.

I’ll post more details soon. Meanwhile, if you’re interested you can check out the latest set of results from the experiment on our Results Page.

Feb 15, 2015: Case Studies – Heat Doesn’t Rise

It is a commonly held misconception that heat rises. In fact heat travels equally well in all directions. While it’s true that hot air and hot water will rise due to convection currents, this is only one of the ways that heat moves. The truth is that heat moves in three main ways; conduction, convection and radiation and, particularly with conduction and radiation, heat will travel just as easily downwards as upwards or sideways.

So why the science lesson? Over the last week or so I’ve been involved in consulting to a couple of clients who have problems (or potential problems) with heat going downwards. These are common issues in houses so I thought it worth sharing some information about them.

Case 1: The Unventilated Black-tile Roof

The north wall of a house in teh Southern Highlands of NSW. Note the black tile roof with no eave overhang and no ventilation.

The north wall of a house in the Southern Highlands of NSW. Note the black tile roof with no eave overhang and no ventilation.

One of my regular readers has recently bought a house near the Greeny Flat in the Southern Highlands of NSW. Although this has been a very cool summer, she is finding it hard to keep the building cool on hot days. She has tried doing what I recommend for the Greeny Flat, which is to close all the windows and blinds during the day and open everything up at night, but it isn’t working for her. She thought it was because there was too much sun coming in through the north and west facing windows so she asked me to come and have a look and make some recommendations on how best to shade these windows.

While this is generally a cool climate by Australian standards, it can get pretty hot in the summer time. There is an unfortunate tendency these days to build houses like this one with brick-veneer walls, dark tile roofs and no eave overhang. In my opinion this should be illegal in Australia. Thermally massive materials are only helpful to the energy performance of a building if they are placed inside the thermal boundary (the insulation and air-sealing layer). Brick veneer puts the thermal mass on the wrong side of the insulation. So does a tile roof. These will not help to keep the building warm in winter and will only serve to keep the place hot well into the night in summer. So when I arrived at this house the first thing I noticed was the black color of the tiles and the lack of any eave overhang on the hipped roof. I don’t know why anyone would build a house with no eaves but I suppose it’s a combination of a current trend and a cheaper way of building. Nevertheless, eaves do several important things: they help to keep rain off the walls, windows, and doors; they help to shade the walls, windows and doors in the summer; and, particularly in a house like this one that has a hipped roof, they provide a way ventilate the attic. With other roof forms like gable roofs it is possible to ventilate the attic by providing louvre vents in the gable end walls. But with hipped roofs there are no gable end walls and the only places you can put ventilation are in the eave overhangs or directly through the roof (using something like a Whirlybird). This house has neither of these.

After hearing what her problems are and having a look around the house, I climbed up into the attic to have a look. It was a cool and overcast day outside but the attic was probably 50degC. As I suspected, there was very little ventilation in the attic, just a few cracks around the edge of the roof. So, in spite of the fact that there was a reflective foil sarking installed directly under the roof tiles, there was a great deal of heat radiating down from the black roof tiles above and accumulating in the attic space. On a really hot day I would not be surprised if that attic got up to 70degC or hotter.

As I also suspected, there was only a thin layer of insulation batts on the ceiling (probably about R1.5) and not very well installed. This means that the heat from the attic can readily radiate DOWN into the house below (hence the science lesson above). So, in effect, her entire ceiling becomes a radiator during the day and well into the night (due to the tendency for massive materials like tile to hold heat). This is why it wasn’t working for her to close the house up during the day. That technique only works if the ceiling is well insulated, the attic well ventilated, and the walls and windows well shaded. Her’s aren’t.

My first recommendation to her was to get quotes for a) installing some sort of ventilation through the roof (either the Whirlybird type of some sort solar powered fan) and b) to add another, thicker layer of insulation to her ceiling (at least R2.0 over the top and laid in the opposite direction to the batts that are already there).

I also suggested that, as a temporary measure she attach some shade cloth to the gutters on the north and west sides of the house and angle it out away from the building to some tent pegs in the lawn. This will serve to shade the north and west facing walls, windows and doors which will further help to reduce the heat gain to the interior during hot days. This is cheap and easy to do and, if it works well, we can look at ways of doing the same job in a more permanent way such as awnings, porches or trellises.

‘Draftstoppa” ceiling fan cap

One further recommendation was that she look at installing something like the ‘Draftstoppa’ pictured onto the bathroom exhaust fans that currently vent directly into her attic. In a poorly ventilated attic like hers this can create serious condensation problems in the attic in winter time. For this reason, ideally, all bathroom and kitchen exhaust fans should be vented directly to the outdoors and NOT into attics or under houses. The Draftstoppa doesn’t correct that problem but adding ventilation to the attic will help to alleviate it. What the Draftstoppa’s will do is to help prevent cold air from the attic dropping down into the house in the winter time. And the extra insulation that she adds for summer cooling will also help to keep the warm air in the house where it belongs in winter.

Case 2: The Steel Framed Floor

Mittagong granny flat with walls and roof of steel-clad foam-core SIPS panels. Note the steel framed, off-the-ground floor structure.

Another project that I’ve been helping with lately is a little granny flat that a friend of mine is building in the back yard of his Mittagong home. The owner is on a very tight budget and doesn’t have a lot of building experience so he has chosen to use a SIPS panel building system which promises to be quick and easy to erect while still providing exemplary thermal performance. Right now, as you can see from the photo above, it looks a bit like he’s building a big esky because the windows and doors will mostly be cut out of the panels after the roof is on. I’ll be very interested to see what it looks like when it’s all finished. Meanwhile he’s finding it relatively simple to cut and fit the panels into place.

These 200mm thich steel-clad SIPS panels make up the granny flat's walls and roof.

These 200mm-thick steel-clad SIPS panels make up the granny flat’s walls and roof.

As you can see from the photo above, there is a LOT of foam in those walls and the roof will be at least as thick. He also will be using double-glazed windows. So five sides of his simple six-sided structure will be very well insulated. The tricky part for him is going to be the steel-framed floor.

As discussed above, heat can travel by radiation and conduction equally well in all directions and steel is a VERY good conductor of heat. So it’s going to be very interesting to see if we can come up with a system that effectively reduces the amount of heat loss through his floor in the winter time. It will also need to be relatively inexpensive, easy to install, and durable. I’m glad he took my advice to raise the floor far enough off the ground to make it fairly easy to move around under the house because all the work of insulating the floor is going to have to be done from underneath. If anyone has any brilliant ideas for how to easily, durably and effectively insulate this floor please let me know.

The other problem with this type of construction is that it doesn’t incorporate any sort of thermal mass inside the thermal boundary of the building. This means that he’s going to have trouble maintaining a relatively constant temperature unless we can figure out a way to store heat inside the house. One possibility that I’ve been exploring for some time now is the use of Phase Change Materials for heat storage. More on that soon.