Sustainable house day 2026

We had about a dozen or so people through for Sustainable House Day 2026. Always a great day with lots of conversations with very interesting people.

A couple different people asked about house performance relative to the PassivHaus design spec:

Temperature performance (based on just over 6 years of data): Keep in mind that we aim for 18 - 25 °C rather than 20 - 25 °C. At the hot end, we have experience 1.1% of hours above 25 °C. Indoor, our maximum recorded temperature was 26.6 °C, and in comparison the outside max was 42 °C. I would translate as... 26°C inside feels really nice when it is 42 °C outside. Less than 0.03% of hours have a temperature < 18 °C, and 5.6% of hours have been between 18 and 25 °C. 

Energy Use: Again over the same timeframe (minus a few months with some data issues associated with reconfiguring the system for batteries). Mean energy usage is 13.3kWh per day. Mean production is 13.0kWh per day, with half of our energy use being met by onsite production (51%). Over the course of the last 6 years we have produced 107% of the energy that we have used, although we have imported & exported over that time. These figures are slightly complicated as the house batteries were added last year. Since the initial battery install the energy independence metric has jumped, but we are only now getting the point where we have a full year of data with house batteries.


Popular posts from this blog

Temperature (Out vs. Old vs. New)

Image
I have fielded more than a few questions about the temperature of our passive house versus the temperature of the house that we lived in prior (on the same lot).  So I've used the data I had on hand which is temperature (°C) recorded every 5 minutes over since October 2012. For the sake of consistency I am only using the NetAtmo sensors that I have had for that entire period. So I only have one outside sensor and one inside sensor located in the the respective living room. The outside sensor moved around a bit, but it should be good enough.  I've converted those measurements to hourly averages.  This ends up being ~ 66,955 hours to play with (52,232 hours from the original house, 14,723 hours from the passive house). I've left the rental house out of this comparison, but it was disturbing like the original house despite being ~ 20 years old. The key take-home messages: The passive house a much less variation in temperature than the original house (or outside).  ...
Read more

Carbon dioxide (Old vs. New)

Image
I one of the things I've noticed is the carbon dioxide levels in our passive house compared to our old house which had plenty of draughts but no ventilation aside from a bathroom exhaust fan.  So I've used the NetAtmo carbon dioxide data collected every 5 minutes since October 2012 to quantifiy the differences.  I only have a single sensor located in the respective living room of each house.  I averaged the raw measurements to get hourly averages.  Because I most interested in peak carbon dioxide - I've taken the maximum hourly average for each day. This ends up being 2,192 days from the original house, 615 days from the passive house. I've left the rental house out of this comparison, but it was disturbing like the original house despite being ~ 20 years old. By way of standards: 420ppm is typical CO2 level outside, less than ~ 1000ppm is considered to be good, levels greater than 2000ppm are often associated with headaches and drowsiness. The key take-home mes...
Read more

2025 May

Image
May was decidely cool and wet (median temperature 15 °C). Outside temperatures ranged from 7 to 26 °C, while inside we were a comfortable 19 to 24 °C. The HRV was between seasons until the end of the month when it entered the heating season and the split system was set to heat to 19 °C. Now that we have solar house batteries we no longer need to schedule the split system as we have done prevously. 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...
Read more