Here are some frequently asked questions we get and some general learnings from this project that we would take into future Passive House designs and builds
1. How much did it cost?
This home cost $470,000 that includes the buildings (house, car port and garage) and structural landscaping (all retaining walls, side fencing replacing and the front brick pillars)
This is at our cost price, naturally we didn't pay a builders margin.
2. How does the cost compare if you were not building a Passive House?
We have calculated that this house cost 12% more than if it were a 'standard 6 star energy rating' home. These are the major elements of the Passive House and their budget impact
1. Heating & Cooling
3. Airtight Wrap & Taping
5. Additional framing materials (walls and service cavities)
For our house and the way it was designed the approximate cost of additional materials needed is $7,500.
Approximately 4 weeks additional labour for 3 qualified carpenters is $15,000
7. Passive House Consulting
3. Can you hear the mechanical ventilation unit running?
The thick walls and floor of insulation plus the triple glazed windows makes the house very quiet in general so yes you can, however this is really only due to the fact that the entire house is quiet from external noise. It is dramatically quieter than a ducted heating/cooling unit in any other home, and another bonus is there is no draft blowing from the vents like you would from a standard heating/cooling ducted unit.
4. How often do you have to use heating/cooling?
In 2019 we plan to more accurately record how many days we turn on either the split system or fireplace, this past year would be a guesstimation of approximately 20 days for the split system (18 days being for cooling and 2 for heating for when we have been away) It's amazing how much general living in the house keeps it warm, for example running the oven, hot water for the shower or bath and just bodies living in the house. If the temperature for the day was forecast to be above about 27-30 degrees we would turn on the split system in the morning on 'night mode' or the lowest fan setting. There were days in the beginning where we wouldn't turn the air conditioner on to see how the house would respond, and when the house reached about 25 degrees it was getting a bit uncomfortable, this would generally be in the mid afternoon.
Another point is that because the air is very slow moving through the MHRV system if the weather cooled down at night we would open doors and windows to 'purge' the house.
5. Would you have a fireplace again?
Honestly, I think the jury is still out on this one. On one hand we definitely did use it over the winter and the fireplace is very efficient in itself. My past experiences of a Coonara is that you could comfortably sit in front of it, but the Euro Fireplace we have can let off some serious heat for such a small chamber! In the beginning I remember one day we had the fire on and a roast in the oven and I actually had to opened a window to cool the house down because it was so warm. So on the other hand now that we have experienced a winter and how much the house retains heat I could understand why you don't need the fireplace.
6. Does it work?
It really does! I think after living in the house for a year you almost take it for granted, but then you will catch yourself either noticing something about another house your in or a hotel you stay at that you don't have to think about in your own home. Just generally coming or going in and out of the house is when you notice how comfortable the temperature is, and then knowing there is no heater or cooler on is pretty amazing.
One of the tell tale signs of it working is seeing the condensation on the windows on the outside. Honestly sometimes waking up it doesn't even look that cold outside but there will be condensation on the windows.
7. What would you do differently?
Sliding Doors instead of French Doors
We would do a lift and slide back door instead of the french doors leading to the deck. Originally we did the French doors because they could be airtight and they fit the traditional style, however they are heavy doors and having little ones around now they are not particularly user friendly.
Single Pane Window in Living Room
In the living room is the biggest window of the house, and it has a openable section which isn't really needed, I would make this one single pane of glass. Knowing what the window manufacturers are capable of in Europe does open up more possibilities of glazing to such a high standard.
Heat Pump Hot Water Unit
We didn't really do much investigating into this at the time and went with a pretty standard Hot Water unit set up, being a evacuated tube storage unit, however now knowing more about the efficienciesof the Heat Pumps would look into these more.
8. Would you do it again?
Without a doubt, couldn't go back.
9. General observations of living in a Passive House
Well close enough, we moved in October 2017, with still lots of bits a pieces to finish off. Some of the light fittings we hadn't decided on, we had no mirrors (due to light fittings), no curtains and don't get me started on the landscaping and the red mud that stains anything in its path but we were in and its all part of the experience of a new home.
From a Passive House perspective there were a couple of final elements to complete. Firstly, the Mechanical Heat Recovery Ventilation (MHRV) needed to be commissioned. Unfortunately I didn't take any photos, but essentially each rooms air flow out of the vent was measured and then restricted if necessary according to the volume of air needed in each room.
Secondly, we had our final blower door test done again by Joseph at Efficiency Matrix. Although quietly confident nothing had gone too severely awry you never know. But the final test came in at .41 ACH so comfortably within the .6 ACH or below needed to be certified.
When we set out on this project the goal was to build a traditional style family home, staying close to standard building practices and by just looking at the home you would never know it was a certified Passive House and last but not least for a modest budget.
Overall we are very happy with the finish, there were lots of challenges and things to learn along the way, and has built confidence and experience in this area of building that is only growing as more people learn about the benefits.