July 21, 2016: Fibro Cottage Energy Retrofit

The existing fibro cottage at 16 Queen St, Mittagong with The Greeny Flat in the background.

The existing fibro cottage at 16 Queen St, Mittagong with The Greeny Flat in the background.

Now that we have been in the Greeny Flat for over two years and it has proven itself to be so very successful we are turning our attention to upgrading the original house on the same property. As you can see from the photo above, it is a typical fibro cottage built somewhere around 1940-1950. As is common in houses from that era it has a dark tile roof, no insulation in the walls or floor, single-glazed, wood-framed, double-hung windows, open fire-places and lots of vents through the walls. These date back to the days when homes were lit by gas lanterns. If you didn’t have lots of air coming in, the lanterns would use up all the oxygen in the home and potentially poison the occupants with carbon monoxide. Now that we have electric lighting these are no longer necessary however this particular house has had some problems with condensation and mould in the past so we have kept the vents open in order to try to keep the humidity under control. But, as many readers will know, the Southern Highlands is a fairly cold climate by Australian standards so having open vents through the wall makes it very difficult to keep the interior comfortable in the winter time. Thankfully the ceiling has been reasonably well insulated and the tile roof doesn’t have sarking (this means that the attic gets lots of ventilation via the gaps between the tiles) so the house stays nice and cool in the summer time. But the time has come to fix the old girl up… so what are we going to do?

Renovating for Health, Safety, Comfort, Durability and Energy Efficiency

3D Model of our proposed energy retrofit.

3D Model of our proposed energy retrofit looking from the NE.

Step 1: Remove the Asbestos

As most of you will know, old fibro contains asbestos which is a nasty carcinogen. It is not considered harmful when it is encased in a sheeting material like fibro and coated with paint however the moment you disturb the fibro (by breaking, cutting or drilling it) you release asbestos fibres which are potentially very dangerous. Many people who renovate old fibro houses simply cover over the fibro with a new wall cladding material like weatherboard. This is an okay approach because it leaves the asbestos (mostly) undisturbed however it makes it much more difficult to ever remove the asbestos in the future. For this reason, plus the fact that we want to insulate the exterior walls without disturbing the interior of the house unnecessarily, we have decided to get rid of the asbestos entirely. To that end we got quotes from a few licensed asbestos removal companies and we will be hiring one of them to come and do the job.

Step 2: Replace the Windows and Add More North-facing Glazing

In the image above, the right hand side of the house is the north-facing wall (and yes, the solar panels are facing east and there is another set of solar panels facing west which I will explain in a minute). In our original application to council we had proposed to put a LOT more glazing on the north wall in accordance with the principles of Passive Solar Design particularly relating to the placement of windows. However, due to the fact that we are in a Heritage Conservation Area, the council requested that we keep the size and proportions of the new windows within a range that is compatible with the age of the house. So we have added a couple more windows and made a couple more a bit bigger but we still won’t have as much north-facing glass as we would like. To solve that problem I have devised a way to turn the whole of the north wall into a winter solar air heating panel. In summer this wall will be shaded by the roof overhang (as per Passive Solar Design – Eave Overhang) but in winter it will be in full sun. When we reclad this wall we will create an air-space behind the cladding. At the bottom of this air-space we will make a screened opening to let cool air in but keep insects out. The sun shining on the wall will warm the air in the space behind the cladding. At the top of the wall we will have a box from which we will collect the warm air and duct it through the attic to the south side of the house. In effect we will be creating a large version of the experimental solar air heater that is currently attached to the north wall of the Greeny Flat. This has proven to be very successful at pre-heating fresh air, reducing humidity and helping to warm the Greeny Flat through the winter. So we will be using the entire north wall to provide the same benefits to the original house. I’m excited about this innovation and convinced that it has the potential to greatly improve the comfort and energy efficiency of buildings, like this one, that have a limited amount of north-facing glazing. I will be documenting the entire renovation project via this Newsletter as we proceed over the coming months and I will provide plenty of details as to exactly how we do each of the steps.

Apart from adding more north glass we will also be replacing all of the old wood-framed, double-hung, single-glazed windows with new aluminium-framed, double-glazed windows. The new windows will either be fixed or casement sashes because these seal against air leakage much more effectively than sliding or double-hung windows.

Step 3: Insulate the Walls

Once the fibro is off we will have ready access to framework of the exterior walls. We will make some minor changes to the framing (such as the windows described above) and take the opportunity to close off the old wall vents, run some new wiring and add some more powerpoints to the house. Then we will insulate the exterior walls from the outside using R2 Earthwool batts.

Step 3: Air-seal the Structure

In order to prevent air leakage we will wrap the whole house with a vapour-permeable sarking. This will create an air-barrier while allowing any moisture that might find its way into the walls to escape (this is important to avoid mould or rot inside the wall cavities). At this point we will also work our way around the attic and seal up any places where air might be leaking between the interior of the house and the attic.

Step 4: Reclad the Walls

For reasons I will go into in more detail as the project proceeds, we plan to reclad the house with galvanised corrugated steel to match the Greeny Flat. This provides a light-weight, easy to install, cost-effective, low-maintenance, durable and attractive finish. In order to improve the insulating qualities of the exterior walls we intend to use foam strips to create an air space between the sarking and the steel cladding. These will also help to give a thermal break to the framework and I will cover this in detail when we get to that stage.

Proposed renovation looking from the NW showing the new porch on the west side and the Greeny Flat to the right.

Proposed renovation looking from the NW showing the new porch on the west side of the old house and the Greeny Flat to the right.

Step 5: Add West-facing Awning Roof

In order to provide a covered outdoor eating area and to shade the west wall of the house from the hot afternoon sun we will be adding an awning roof along the west side and extending it over a new patio. This roof will also provide covered access to the laundry room in the south west corner of the old house.

Step 6: Add a High-efficiency Reverse Cycle A/C

The house currently has no heating or cooling system. It stays pretty cool in both summer and winter. The open fire in the living room is used to ‘heat’ the house but open fires actually make houses colder by sucking all the warm air out and sending it up the chimney. So we will be looking to install a high-efficiency reverse-cycle, split air-conditioner to the living room area to supplement the heat we will collecting from the north-facing wall.

Later Stages

The above steps are probably as far as we will get in this round of renovations. In the future we will also:

  • Remove the dark tile roof and replace it with a light-coloured Colorbond roof to match the Greeny Flat (this will help to keep the attic and thus the house cooler in the summer).
  • Remove the existing open fireplaces and chimneys (which suck warm air out of the house in winter).
  • Add solar panels to the east and west facing roofs (this provides more electricity in the morning and evening which are the times that most homes use more electricity).
  • Install a new kitchen and make some other minor changes to the interior of the house including adding another toilet.
  • Add rainwater tanks.
  • Insulate under the floor.


As mentioned above, I will be documenting the entire energy retrofit process as the project proceeds and providing a lot more detail on each step as it happens. Feel free to contact me with any questions or suggestions for things you want me to write about. I would also like to make a series of YouTube videos to demonstrate the process so if you have the skills, equipment, time and energy to help with that (or know someone who does) please let me know.

A Win for AI?

Regular readers will know that over the last couple of months I have been verbally struggling with the pros and cons of robots and artificial intelligence (AI). This week I learned about a project that seems like a pretty good win for AI. As reported in this Guardian article, Google has used an AI program called ‘DeepMind’ to help reduce the energy consumption of its enormous data centres.

‘Google does not disclose exactly how much energy its data centres use, but says as a company it’s responsible for 0.01% of global electricity use, and much of that is data centres. Their energy use for cooling was cut 40% by DeepMind, and total energy use by 15%.’

‘The trial using machine learning to further cut those data centres’ energy – and carbon emissions – began two years ago, and was tested on “more than 1%” of its servers, Suleyman said. It is now being used across a “double-digit percentage” of all Google’s data centres globally and will be applied across all of them by the end of the year.’

This seems like very good news, at least in terms of reduction in carbon emissions but, I have to say, it makes me pretty nervous to think that an artificial intelligence is going to be turned loose across ALL OF GOOGLE’S SERVERS. Does this remind anyone else of the ‘Terminator’ movies and an artificial intelligence called ‘Skynet’?

As described in this Wikipedia post… ‘Skynet gained self-awareness after it had spread into millions of computer servers all across the world; realizing the extent of its abilities, its creators tried to deactivate it. In the interest of self-preservation, Skynet concluded that all of humanity would attempt to destroy it and impede its capability in safeguarding the world. Its operations are almost exclusively performed by servers, mobile devices, drones, military satellites, war-machines, androids and cyborgs (usually a Terminator), and other computer systems. As a programming directive, Skynet’s manifestation is that of an overarching, global, artificial intelligence hierarchy (AI takeover), which seeks to exterminate the human race in order to fulfill the mandates of its original coding.’ 

Hmmm… I’m not sure I like where this is going… but I believe in accentuating the positive so I will try not to get too bogged down in scary stuff in the future.

Rest In Peace Chris, Chris and Pam

Having said the above, I do feel the need to acknowledge that last week was a sad one for quite a few of our readers, friends and family. We attended the funerals of two very dear friends and received news that another one (a keen reader of our Newsletter) passed away in Canada just a few days ago. Our thoughts go out to their families and loved ones as we remember Chris, Chris and Pam… three wonderful people who will be greatly missed.

2 comments to July 21, 2016: Fibro Cottage Energy Retrofit

  • Mark Hetherington

    Looking forward to seeing your progress! Cost effective retrofits are probably the biggest game changer in terms of our housing stocks energy efficiency. It’s also of particular interest to us as we move into an existing house with the idea of lowering running costs in mind!

    • admin

      Thanks Mark. While I agree that retrofitting our existing housing stock is of vital importance the problem is that it is extremely difficult to make it cost effective. I have done a lot of retrofit work and, not only is it extremely difficult to do well and generally very unpleasant work, I would estimate that it typically costs about three times as much to go back and try to fix bad buildings than it would have cost to just build them right in the first place. So yes, obviously we will have to bring all of the old homes up to a decent standard but I think it’s even more important that we start building new homes to a high standard right now otherwise we’ll have to go back and retrofit all of them too. The current standard of energy performance of new homes in Australia is woeful. What passes for ‘Standard Practice’ in the building industry is truly shocking and we are churning out these huge, energy-sucking McMansions as fast as we possibly can. They’re all going to have to be fixed eventually and it is going to be horrendously difficult and expensive.

      Our retrofit is not going to be cheap but we believe it will be worth it and, after 70 years, the old girl is due for a facelift.

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