Thornleigh Passivhaus

We did it. It is not clear that the batteries will save us money, although with the way electrical prices are going, they might, and it isn't clear that they won't save us money either. At some point, we wanted to be part of the solution, so the likely breakeven-ish economics were good enough. Call it an investment in the future stability and sustainability of the Australian electricity grid. In terms of economics. Relative to my last statement on the topic, back in 2021 , four years is a long time. Batteries have gotten better, the cost of electricity is up (and demand pricing has arrived), solar feed-in tariffs are down, and NSW has a battery rebate at the moment. The cost of electricity has become increasingly complicated, making modeling costs/savings more tedious as the costs vary by time of day with times of day changing seasonally. Which also means there are more ways that electricity costs will likely change in the future. Minimally, with the battery system, we shou...

Every so often I find myself chatting with someone about the performance of the house and I am caught out with not actually having looked at the numbers except on a month-by-month basis. So here is a bit of a look at 5 years of data. March 2020 - February 2025. Hard to believe that we have been living here for over 5 years, but we have been (actually longer than that, but the data are consistent back to mid-February 2020). For the record, I am using data spanning the 1st of March 2020 through 28th of February 2025. A few things of note. In winter months, we aim for a house temperature at or above 18 °C inline with the WHO recommendations and a general happiness with sleeping / waking up to a house that is ~ 18 °C. Using the hourly averages, the outside temperature ranged from 0.2 to 42.4 °C with a median temperature of 17.1 °C. The inside temperature ranged from 17.6 to 26.6 °C with a median temperature of 22.2 °C. Over the past 5 years, we have been in the passivhaus temperature t...

February was summer (median temperature 22 °C). Outside temperatures ranged from 12 to 36 °C, while inside we were a comfortable 20 to 26 °C. The HRV was in the cooling season and the split system was on during the solar generation period. For about half of the month overnight temperatures did not drop below 20 °C, so openning windows in the evening wasn't an option for cooling the house. Temperature from inside and outside the house as the percentage of hours in 0.5 °C bins. I've scaled the temperature in hope that I will be able to use the temperature range for all months. Methods:  I have taken the 5 minutely data from the wirelessTag sensors and calculated the median temperature for each hour and determined the proportion of hours falling inside of the 20 - 25 °C target temperature (using the R functions 'aggregate' and 'hist'). Inside includes data from the wirelessTag sensors spread across nearly every room of the house. Outside is the data from the ...