A compact passive house on a postage stamp in Sydney
If you’re not sick of seeing us talk about our house, you can watch another interview that was filmed on the same day as the Renovate or Rebuild interview (see previous post).
This one is for a case study on the YourHome website and we talk in a bit more detail about some of the passive house principles we used.
Our (not even) fifteen minutes of fame.
Gav and I were delighted to meet the team from Renovate or Rebuild when they interviewed for us a segment in the final episode of Season 1. The new TV show works with home owners who need to decide if they should renovate or rebuild. The team bring energy efficiency into the mix of things to consider when planning a new home or when modifiying an exisiting one.
You can find the whole season on 9Life, or check out just our segment below.
Our house is currently looking even better than in the show, as it was filmed in early July before we’d done the landscaping and finalised the exterior painting.
When we purchased our land and the house plans it came with some fancy artists impressions of the final design. We loved them. How did we go with the final outcome?
I’ve posted a lot about the ‘passive’ part of our ‘Passive Not Massive’ moniker, now it’s time to talk about the ‘not massive’ part.
Many of our visitors are surprised, that our house isn’t as small as they expected. In the beginning we joked about it being a tiny house, but then we switched to calling it a compact house. Before the house, when it was just a block of land, we called it ‘the postage stamp’.
So how compact is compact?
We are talking 115sqm of internal floor space.
According to a Domain article from late 2020 the average house size of a new build in 2019-2020 was 235.8sqm. You could fit our house in there twice! That is bigger than our whole block of land.
Then according to a Better Homes and Gardens article the average house size in Australia is at an all time low at 186.3 sqm. This might take into account older stock, whereas the 235.8sqm was referring to new builds.
Another article devoted to tiny houses, explains a tiny house is 37sqm or less, and a small house is anything less than 90sqm. The living/dining area of our Passive Not Massive house is bigger than that. The article goes on to say that anything less than the average house size of 240sqm, will seem small. So yes, our house is…compact.
What have we got in our 115sqm?
Downstairs we have two (small) bedrooms and a main bathroom (sadly, no bath), a linen cupboard and a small storage room which houses the HRV (and choc-a-bloc storage shelves).
Upstairs we have a master bedroom and good sized ensuite, split level open plan kitchen, living/dining and a study nook.
Outside we have a tiny laundry, yes it is outside, but is included in the 115sqm.
I have plans for a deck off the ensuite with an outdoor bath. It’s a just a dream at the moment.
How are we getting away with it?
Freakin’ clever design! Kudos to SDA for maximising the quirky shaped buildable space, and creating a lovely open plan area with high ceiling in the upstairs area.
In addition to the design, we’ve made very considered choices about what comes into the house. It’s been a mix of a ‘less is more’ approach and ruthless decision making. I have been brutal about what is allowed in to the house and committed to not filling it up with stuff just because it was stuff we had. I’ve either given away, or sold loads of stuff online.
Biggest impact of compact
It’s a process
Getting used to living in a compact house is a process. A lot of work that goes into reducing stuff and choosing the right things to bring into the home. Especially when you are trying to dispose of old things ethically and make ethical choices for the new things (that is a whole other post yet to be written).
The clever design certainly helps with compact living. Mainly the fact that the upstairs space is lovely. We wouldn’t be able to enjoy it without a commitment to wanting to live in a compact home, taking a less is more approach, everything needing a home and patience. I’m still working on the last two!
I can’t end this post without a reminder that a compact house means less resources all round. Less building materials. Less furniture, interiors and stuff. Less space to heat and cool (not that we should have much requirement for that). And I can’t forget, less cleaning! Enough said.
We know certification is an essential component of passive house and we fully understand why.
We are passionate about passive house (PH), and what it means for a healthy, comfortable, high performing and energy efficient home; however, sadly, our house won’t achieve passive house certification.
Why aren’t we going to be certified?
A lot of it is to do with budget.
In an ideal world we would have designed for passive house from the beginning; which we could have done, but to be honest, in our particular situation we probably couldn’t have afforded to do so.
We feel so fortunate to have found our postage stamp in the area where our life is based and we’d already paid (within the eye watering land purchase price) for a clever and beautiful house design that we loved with a complying development certificate. It was approved and ready to build; we just needed a builder! Not only would designing from scratch cost more money, it would have cost us more time; and as we all know, time is money.
We recognised from the beginning it was an imperfect process, but we worked hard to find a way to build the approved design with passive house principles.
The first report we received from the Passive House Planning Package (PHPP) looked like it might be feasible, so we went ahead with planning for PH. It looked like we could aim for at least a High Performance Building (according to PH standards). We were happy with this and hoped we could achieve it.
Of the five pillars of PH, it seems that we might be seriously let down by the glazing used in the corner window at the front of our house. It’s a snazzy window and a great architectural feature. However at the time of ordering the windows we weren’t able to get a corner window that met the design criteria with double glazing, so we ended up with single glazed panels making up the apex. We actually didn’t realise this until they were installed. Quotes for windows can be hard to understand when you are not sourcing windows day in-day-out! Had we known, we may have made a different decision.
Possibly the air-tightness of our bi-fold doors would have let us down too? Don’t get me wrong, we know we have good air tightness compared to a house built to code, but we don’t have confirmation if we have the 0.6 required for PH. The initial blower door test measured 1.12 ACH. We ran out of money to do the final blower door test, such is the way the budget went.
We would have been happy to get to the 1.0 required for High Performance Building. On the day of the initial test it seems the bifolds were leaking. The bifolds really make our house feel wonderful. When open they create a great indoor to outdoor flow; so we won’t be giving them up. In my mind the ambiance and amenity they create is also an important feature of a healthy home.
Now that the house is finished and the doors adjusted we may well be at 1.0 ACH, but until we get it tested we don’t know.
There’s more at play
There is more at play in building PH than just the five pillars. In addition to the principles that we’ve tried to incorporate, passive house certification relies on a lot of paperwork and documentation. Although the owner of the building company knew of, and had experience with PH, the onsite team were learning about it on the go.
Maybe having a Passive House Project Manager would have helped? We can’t even afford to pay a painter, so we couldn’t consider that. I would have loved to have done it, but we were flat out working during a pandemic, managing two households, juggling kids, researching things we needed and working every weekend on the house (tips runs, getting and moving timber, PC items etc ).
Shout out to our builder!
On an important side note, we were fortunate to have a young highly skilled builder onsite everyday who has almost single handedly built our house. We hope he is proud of what he has achieved. He should be! Our house looks great!
He is at an early stage in his career and learnt fast on the fly about new materials, processes and passive house. We hope working on our house will inspire him and the other guys onsite to learn more about PH and energy efficient homes. That would be a win for us and the future.
Sacrifices we made to incorporate passive house principles.
I’ve detailed what we did to incorporate the five pillars in previous posts, some of these came various kinds of prices.
Balancing act
Although we won’t be certified, our aim was always to build a high performance energy efficient building and create a healthy home. It’s been a balancing act for us between love of PH and understanding why documentation and certification is important; then the cold hard reality of our time and budget constraints.
We’ve both lived our lives advocating for protection of the natural environment, and trying to walk the talk by changing how we do things to lessen our impact on the plant. I think that our house will still do that, even without certification, and we’ve done what we can with what we had. We’re already thinking of our own ways to measure our house’s performance and have extensive documentation of our own in terms of what we’ve done and learnt along the way. At the end of the day it’s still super energy efficient! And we’re happy in our new home and can’t wait to fully experience it.
Winter is coming. Will we wish we had heating?
We were very lucky to be able to move into our new home 4 weeks before Christmas. The holy grail! It prompted many comments of “oh, you’re in by Christmas!”. Although we’re in, we aren’t ready for Kevin McCloud to swing by just yet. There’s still a few things to be done; some cosmetic, some crucial, some kind of anxiety inducing.
This is a bit of a “worts ‘n’ all” kind of post. It is also slightly belated. Building a house is stressful and it wouldn’t be right to only post about the shiny new excitement of it all. Although, it has also been wonderful!
Building a house has been an amazing process and I feel so lucky to have been able to do this in Sydney; and in 2020!
Cosmetic to do list
I’d like to take some sexy pics of the house, but without the external painting and landscaping even started, we aren’t photo ready yet. We need to do these bits ourselves (mostly for budgetary reasons) and it may well take us all of the weekends in 2021 before we can say ‘done’ to those items.
Somewhere in amongst all that we need to finish the internal painting. We agreed to do the internal painting, and have done most of it. We quickly learnt that ‘painting’ isn’t just painting. Not only is there all the prep that I didn’t know painters do, but painting a quirky shaped architectural home is complicated! We love the angles and shapes, but they make for challenging cortions of the body to reach at times.
As we settle in (i.e. unpack, sort, organise, sell stuff on Facebook Marketplace, rearrange, buy stuff on Facebook Marketplace, cull our stuff, rearrange again, research storage solutions) we notice things still to be done. The Google doc listing them currently has had over 55 items on it. Some big, some small, some complicated, some already ticked off. Yay!
I think this is normal in building a new house, but does mean the work continues despite us having unpacked most of the moving boxes.
Crucial still to be done list.
There’s so much admin to finalise and make a house official. We’ve been working very hard to chase up the things needed and tick all the boxes. Between the end of year close down, Northern Beaches lockdown, and January, it was a slow a slow process. The certifiers folder has been bulging with pics of the safety things we’ve installed and certificates from subcontractors, so we should be good to get our address on Google maps soon. Currently Google maps sends you to a busy side street. That’s not been fun for all my online deliveries!
Stressful things
People keep asking us how it’s going and if we love the house. We do! We love it! There’s no doubt about that, but there has been an issue with mould that has really devastated us. One of the reasons we wanted to build a home with passive house principles is to have a healthy home. Mould doesn’t have a place in any home and especially not a healthy home!
There’s a problem with the slab not drying out, possibly moisture coming up from under the slab or through the sandstone of the hill above us, we’re still playing detective and working out what to do. Our builder and his team are committed to sorting it out. We are getting closer to understanding the problem and getting solutions in place, but until it’s confimed as fixed, there will be some underlying anxiety for us.
I’ve learnt that unexpected issues should be expected when building a new home, once you start digging a hole you never know what you’re going to find. Even so, it is stressful and delaying our pure uninterrupted joy. We are nearly there though!
Done by next Christmas?
I’ve do doubt that we will get there, but ‘in by Christmas’ doesn’t mean done and dusted – maybe next Christmas I’ll kick back on the (complying) deck we built and admire the exterior paint work with the Google doc firmly in the archive bin?
Building a house is expensive, building a passive house possibly even more so (even if it is compact). We’ve made every attempt to reduce costs where possible. One place we’ve attempted to save money is in waste removal, rather than have it included in the building contract we agreed to keep the site tidy and do a weekly tip run.
We might not have much money, but we have time and muscles; and Gav has excellent trailer reversing skills. It’s our sweat equity.
Almost every weekend since construction started we’ve headed to the site and loaded the trailer with the waste that has piled up that week and done a tip run. The kids love it – not.
Rather than have a skip onsite, all the waste is dumped in a pile where a skip would normally be. For us, loading the trailer isn’t just loading the rubbish, we sort it all by hand into various types of recycling or landfill. That’s every bit of wrapping on building supplies, lump of plaster gunk, framing off cut, tile off cut, insulation off cuts, uber eats bag, coffee cup, energy drink bottle, many random piece of metal, cardboard boxes from new fittings, broken buckets etc sorted by hand. Gavin is a fastidious bin chicken when it comes to recycling and patiently pulls things apart to seperate out recyclables e.g. cardboard and plastics in packaging.
Some weeks we make up to eight stops dropping of recycling, and have spent up to 30 mins doing laps of Kimbriki tip weighing on and off. The various stops include:
I know doing this is not for everyone, and I often I wonder why I’m spending hours doing it on the weekend, as it is quite time consuming, dirty and tedious. In the end I’m not sure that we will have saved much money (to date we’ve spent about $2k on tipping fees), but we have diverted some waste from landfill and learnt where our buildings like to buy their coffee. It’s also got me thinking a lot about how to make recycling easier on a building site, a lot of ideas and questions swimming around my head – is it about convenience, incentive or economising it? I wish I had time to devise a new system, but there’s other work to be done.
The passive house pillar that raises the most eyebrows is probably the HRV system, the heat recovery ventilation system. It’s needed due to the house being super airtight (thanks to the membrane and double glazed windows) meaning we need a system to ensure fresh air inside the house.
The HRV will swap fresh air from outside the house with the air inside, but prevent heat being transferred with the air. Not only does it bring fresh air in, but it also filters the air before distributing it throughout the house. Pollen, dust, smoke and smog is filtered out before getting inside. Yay! Of course, those things can still get inside if we open the windows, but that is our choice. The HRV means we can have the windows closed (keeping the house airtight) and still get fresh air.
Each room has a vent connected to a duct that runs back to the HRV unit where the magic happens. Metal plates inside the unit work as heat exchangers picking up and dropping the heat as the air passes through. The unit is connected to the outside world via an inlet and an outlet duct. The inlet side has a filter on it to remove particles as the air comes in, the unit then pushes fresh filtered air into the house via the ducts, entering the bedrooms and living room via vents in the ceiling. The bathrooms and kitchen ducts take air away – think steam, burnt toast and bathroom smells being whisked away to the outside via the unit.
All this air change happens without the heat from outside coming inside during the summer, or the cold during winter coming inside our cosy house. The idea is that without mechanical heating and cooling the house will stay at a stable temperature (22 degrees) all year round and provide excellent indoor air quality. Even better quality indoor air than a home with all the windows open.
Fun fact – we won’t need extraction fans in the bathrooms as the HRV will take care of the steam and anything else.
Some quick HRV Q and A:
I’m really excited about living in a house with fresh indoor air year round and not needing to stick close to the heater in winter or flick the AC everyday in summer.
For further reading see our suppliers website at energyrecovery.com.au
(Image credit for main image: energyrecovery.com.au)
It’s been an exciting two weeks with the window installation making our house feel more like a home. Thermally broken double (or sometimes triple) glazed windows are the third pillar of passive house currently being incorporated into our house.
Window selection and installation in passive house combines consideration of thermal properties and air tightness. The thermal resistance (the R value) of the windows needs to match that of the walls, so that the windows aren’t letting heat or coolth in, or out, of our house without our permission.
Heat and coolth can sneak through the glass directly, or via the frame, hence the need for windows to be ‘thermally broken’. The break in the thermal bridge is created by clever engineering. They are quite a contraption, but they make a difference! Take a look at this diagram from our suppliers website.
Two having two layers of glass means there is an insulating layer of air between them, and that the transfer of the external heat or coolth via the glass is slowed down by air being crap at conduction. Sometimes the air is replaced by a gas like argon, as ours are. Argon has even lower conductive ability. Some climate zones (liker Hobart or Dunedin), will require triple glazing, but we should be able to get away with double glazing here in Sydney, especially as triple glazing is more to do with controlling condensation (a bigger temperature difference between inside and outside).
The next thermal bridge in a window can be the frame, where the amount heat transfer ed via the frame will vary depending on the material. Wood and uPVC are the most thermally efficient. The fancy technical construction method you see in the diagram prevents the heat being conducted via the frame.
Another consideration with a window is air-tightness. Air can leak around the pane of glass and around the frame. Those babies need to be in tight, so that air can’t leak out around them taking precious thermal comfort (and your hard earned dollars in heating and cooling expenses) with it.
The thermal properties of a window are measured by the U-value which is the inverse of the R- value. R-value you want a higher number, U value you want a lower number. When to want a high number and when to want a low number is doing my head in a little.
To select our windows we sent the window schedule to two providers of passive house compliant products, and chose the option that best suited our budget in a colour that suits the style of our house.
The final piece of information in this post is to answer a question we get often when we talk about air-tightness. Can we open our windows? Oh yes we can! And we will! Opening windows just means the house isn’t ‘performing’ as a passive house while the windows are open. Close the windows, run the AC for 5 mins and then let the house (and HRV) do its thing.
The next passive house principle being realised in our house is airtightness. Say whaaaat? Or at least that is the reaction we get when we tell people we need to make the house airtight. People often think it is a given, but it’s not.
When we say airtight, we mean Tupperware-tight! Airtightness is important to avoid swapping heat or coolth (yes, that’s a word) from inside the house with the external environment. Heat and coolth can escape from a house via gaps and cracks that you don’t even know are there; this is why architraves exist. Don’t worry – we can still open the windows; and even with them closed we will plenty of fresh air via a ventilation system – I’ll cover that in another post.
To give you an indication of airtightness in a passive house versus a conventional house built to code; to achieve passive house certification the house must have a maximum of 0.6 air changes per hour (ACH) on a windy day (50 Pa), whereas a house built to code in Australia the average is 15 to 20 ACH! Say whaaaat? That is the total internal volume of air in the house turning over 15 to 20 times every hour! That’s why you need to keep the heater on to keep the house warm – the warm air is literally going out the window! Not through the window, but via the gaps around windows and other unseen or hidden cracks.
A super airtight house provides control over the internal environment and in turn allows greater thermal comfort. Airtightness in a passive house is achieved by wrapping the entire house in an airtight membrane. A test is then conducted to test just how airtight it is.
We’ve decided to use Adhero from Pro-Clima for our membrane. Adhero is a two in one product providing both weather tightness and airtightness in the one wrap. It’s a perfect solution for the compact house, as if we’d used an internal membrane for airtightness (as many passive houses do) we’d lose internal space due to the need to create a service cavity between the membrane and the plasterboard.
Adhero is supplied in rolls. They are like a big rolls of ‘contact’ made out of Gortex that needs to be wrapped around the entire house envelope. Our builders are currently painstakingly attaching the Adhero to the Pavatex. If you’ve ever covered a school book in contact – it’s like that – but on the scale of a house where each roll is 1.25m high. Props to the builders who are wrestling it around our quirky shaped compact house – roof, walls, and everything in between. There are some very squeezy spots! We might need the kids with their slim agile bodies to help, although this will only be possible if we turn off the wifi.
Once the building is completely wrapped and the windows are put in, we test how airtight it is with a blower door test. A blower whaaaat?? Blower door tests simulate a strong wind and take measurements of the ACH to see how air leaky the house envelope is. We’re aiming for 0.6 ACH. Stay tuned!
If you want to nerd out (like we do), check out this video form the Energy Matrix website where they do a blower door test and talk ACH.
This video from Canada is also worth a watch as it explains the two tests required to achieve the final ACH measurement and it’s great to see women doing the building science on this Canadian project. Enjoy!
Passive Not Massive