A year of living in a Passive House
- Tracy
- Jun 30, 2022
- 5 min read
I am sitting in my bedroom, isolating from the rest of the house as I have finally tested positive to Covid 19. More than 2 years after the virus arrived in Australia, 6 months after the Delta strain and the decision to give up on elimination, and my RAT surprisingly came back positive. I thought I had a mild cold. I am, therefore, isolating in my room to prevent the family from catching it and so I have time to write!!!
An unplanned bonus of living in a passive house is that if someone needs to isolate, the Heat Recovery Ventilation (HRV) system makes it extra safe. I was able to isolate in the main bedroom/ensuite area and know that, not only was I still receiving fresh, filtered and tempered air, but also, that the stale air from my area in the house was extracted and discharged out of the house, keeping my germs separate from the rest of the house… (Editor's note: It must have helped as no-one else caught it).
Some reflections on how Passive House has behaved across the seasons:
Winter
I am sitting in a T-shirt and light pants, gazing out of our triple glazed North facing bedroom, enjoying some relaxing music and watching the birds on the lake. It is 12 degrees outside and we have no heating on. It was partly sunny today. We do need some heating when there’s a run of cloudy days. On those days we run one of the small split systems/heat pump (one is 2.5, the other is 3.5 kW) for a bit in the morning. It is probably around 22 degrees inside… it doesn’t really change much. We are used to it now but still need to check the temperature and rug up before going outside as we can be fooled on a sunny day. The house is so well insulated against cold and wind noise, it’s easy to miss the cues. It is harder in Spring and Autumn, you just expect it to be as pleasant as inside and I have often come back twice to add extra layers.
We thought we would want a flame effect heater, even though we wouldn’t need or want it for heating, just to feel the psychologically soothing effect of a heater after coming in from outside… but we just don’t need one at all! I can even walk around in bare feet and my PJs in the morning in the middle of winter comfortably (which is amazing since I have Raynaurd’s – poor circulation). I recently visited Melbourne and stayed in a typical house and it reminded me how wonderful it is to live in a passive house… I put one bare foot on the bathroom floor and recoiled in shock at the freezing floor (and it was on the second story). We also recently stayed in a holiday rental in Albury and had to choose between some warm air and not hearing the TV, or freezing so we could avoid so much background noise. I also love the fact that we don't need to go around closing doors all of the time so that we only have to heat the main living area.
The near constant temperature did require quite an adjustment at first…. Evenings felt a bit too warm, so we got rid of our doona and just use an empty cover.
Inside temperature while looking outside at frost on the ground
Spring
In spring we did not yet have insect screens on the windows so didn’t open them to avoid getting bugs inside. There was really no need since the HRV delivers filtered, fresh air to all the living and bedroom spaces, but on sunny days it did get a bit warm. The family members with hay fever no longer woke us with their morning sneezes as the filter did it’s job. There were still sneezes, but it was hard to know if they were from going outside, but they were definitely a lot less frequent. In coming years, we think we will have to look at the pollen count and then decide whether to open windows to vent heat, or keep them closed to minimise sneezing.
Summer
Our previous house (passive solar design) performed very well in summer so I really didn’t even think about what summer would be like in a passive house. Scott had, of course, but all I could think about was how much warmer it would be in winter. So I was a bit frustrated when I felt the temperature rising to 23-24 degrees inside most days. That temperature is lovely during the day, but quite warm overnight and it did not naturally drop overnight as we were used to. I soon began to bug Scott to put screens on the windows as opening them at night helped to vent the excess heat. This worked, and we also started running the aircon gently during the day to keep the place cooler in preparation for evenings. Since we have solar power, we were simply using excess power generated and had not paid for power from the grid for about 6 months anyway (we use a bit in winter when there is not enough power generated). This approach made summer comfortable and hopefully when our grape vine grows up, the shading on the north and east windows will also help keep the temperatures down. It was a mild summer so we cannot really comment on the performance on days over 40 degrees, but Scott reckons most of our heat load is from internal energy use and direct solar access on the still-unshaded windows. Our strategy of running the air-con on it lowest energy setting worked regardless of the outside temperature and the interior temperature in the house didn’t really go above 25 degrees. So there is no concern about high temperatures in the house in summer, but the indoor climate shifts very slowly which makes it harder to achieve the cooler sleeping temperature that we would prefer. Opening the windows at night generally addresses this on all but those hot nights, however it also shows us how well the triple glazed windows work in cutting out the sound of the noisy nocturnal birds! One recommendation is that you choose windows that can be propped/latched open for summer evenings.
Autumn
In Autumn we finally managed to get our retractable screen for the deck/outdoor room so were able to have the doors open on days that were pleasant, which gave us an additional way to create the perfect indoor environment.
A surprising thing that we have learned is how much heat 5 people (and a dog) generate, and when you add some cooking/washing appliances and an internal hot water tank, we are responsible for heating the house from the inside with people power. We have also grown our stock of indoor plants which are thriving in the light and warm environment!
I think I would struggle to live in another house now, and the annual cost savings are considerable. We are 100% reliant on electricity so we are also shielded from the current gas price rises and supply shortages.
Some technical stuff from Scott:
Our old house consumed an average of 13 kWh of electricity per day plus the equivalent of another 9 kWh in gas. In winter gas consumption doubled to the equivalent of 19 kWh per day, increasing total energy consumption to 32 kWh per day - and the house was still cold in more than half the house. Our new (bigger) all-electric house requires only half that energy consumption - an average of 17 kWh in June and yet it is so much more comfortable throughout the entire house (previous winter inside temperatures were around 15 degrees in the bedrooms and we would keep the heater running all day in winter on a 19-20 degree thermostat). Even on a nice sunny winter’s day like yesterday, the solar panels still provided almost two-thirds of the power consumed.
The HRV and it's tentacles
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