When designing our house, these were our basics requirements:
- House size to be 18-20 'builders' squares (or 162- 180 square meters)
- 3 bedrooms
- Home office
- 2 living areas
- Master bedroom with ensuite
- Family bathroom with seperate toilet
- Detached garage (for Devins work materials and tools)
- Detached car port
As this is Devin's first construction of a Passive House, to make sure we achieve certification, he wanted to keep the exterior wall layout as simple as possible. Therefore the house is a simple rectangular shape, this is to help minimise thermal bridges (but more on that later)
As you can see the main living areas are on the north side of the house, including the home office as we will use this space more than the Master Bedroom. The bathroom, ensuite and laundry are towards the south/west side.
In regards to the size, 18-20 squares for a house is considered on the smaller side in Australia. There were a few reason for this. Firstly, Australia is known to have large homes, 27 squares (243 square meters) which is the average house size. A typical new home these days will boast spare bedrooms for guests or multiple living rooms and formal dining rooms. Personally, Devin and I do not wish to conform to the general mentality that bigger equals better. We don't want to work for the next 30 years to be paying off spare rooms.
The second reason for building a smaller house is because we honestly don't know how much extra it is going to cost to build a certified Passive House. We have heard at seminars and from others in the industry that you can expect to pay anywhere from 10-20% more than what any other new '6 star energy' home would cost. In Europe the cited price difference for a Passive House is only a 5% increase in cost. Since Passive House is so new in Australia, there is no demand on Australian manufacturers for products that will comply with the Passive House standard, therefore naturally the products are going to cost more. So ultimately we wanted to make sure we could afford to build it.
After Anthony our draftsman had completed the initial drawing concepts, it was over to Clare our Passive House consultant to literally run the numbers. This is done in the Passive House Planning Package (PPHP), which I will not attempt to explain as there is no way I could do it justice. Other than to say that every single detail is calculated and used, from Melbournes climate data, the altitude, what materials are to be used internally and externally on the house right down to how many people will be living in the house and much more.
To achieve a certified Passive House there are very strict performance criteria that must be met. At this stage what we are most interested in, is how much the house needs heating and cooling. After all the ultimate goal for a Passive House is to eliminate the need for conventional heating and cooling. Therefore, specifically to be certified as a Passive House, the heating and cooling demand must be equal or less than 15KWh/m2 per year. So what does that mean? The way I like to think about it is that if a Passive House was a person it would need one apple (say 50 calories) a day to run. In comparison a '6 star energy' rating is based off 120KWh/m2, and would consume a burger (around 400 calories) every day.
I have found this little diagram explains more clearly than I can the difference between a Passive House heating/cooling consumption compared to other buildings.
To achieve this heating/cooling demand, Clare's report tells us what level of insulation and glazing requirements are needed. From this information we were able to start speaking to suppliers, primarily of window manufacturers to assess what was both available and financially viable.
These rendered images Anthony made really started to give us a feel for the size of the spaces and what it would look like finished.
Almost as soon as we had signed that dotted line for the land we bought in Emerald, we started talking to designers to begin the drawings.
Devin had met Clare Parry from Grun Consulting, through the Australian Passive House conference. Clare is Chairperson and Treasurer on the Australian Passive House Association, a certified Passive House Designer, an engineer and pretty much the bees knees of the Passive House industry in Australia.
Anthony Burns from Virtual Home Design came highly recommended to us. He has an extensive background in energy rating, competed in the BDAV 10 star sustainable design challenge and although not Passive House trained was very enthusiastic about being involved in designing a Passive House.
We couldn't be happier with the combination of Anthony and Clare, and feel very fortunate to have them on our team. Once the designers were sorted, the next question is which way is North?
If I'm honest, when buying a house or land, orientation is often not on the top of my priority list. Amongst affordability, location, size, distance to shops/schools/work, the slope and possible views, where the sun rises isn't thought of until later when you start designing the house. But don't let this be a deterrent, although there are more preferable orientations for a Passive House, ultimately you can have a Passive House anywhere. This is why countries such as Belgium can make mandatory that all new and renovated buildings from 2015 are to be to the Passive House standard. Amazing to think how advanced they are in their commitment to energy efficient buildings compared to Australia! Therefore, it is important that you keep an open mind about the layout of the house on your land, so that the design can be suited to the unique combinations of your property.
For a Passive House the ideal orientation in Australia is to have your living spaces (living room, kitchen, lounge, study, bedrooms) facing North, to gain the warmth of the sun during the day, and the service rooms (laundry and bathrooms) to the South.
From our site analysis plan above you can see that our land is facing north-east as the house will be designed parallel to the boundary
One of the biggest misconceptions we find when we tell people we are building a Passive House is that it has to look modern, Devin and I have always wanted to build a more traditional weatherboard style house for our family home. In fact, from the from the outside there will be nothing that will indicate that it is a Passive House
Courtesy of Pinterest, here are some the inspiration we used as a starting point for the design of our home.