At this time in 2014 there was a temperature and humidity sensor in the daughter’s upstairs bedroom and a CO2 sensor was added in March. Our children are a big reason why we want to renovate and why we want to do it right so this section of Nichole’s report is of special interest.
For the complete story on Nichole’s project on our house with BCIT, click on the BCIT category on the right hand column.
I love Nichole’s graphs which show temperature, relative humidity (RH%) and CO2 level (in parts per million) all on the same graph. What does this information tell us about how we should renovate? How is the air quality in the upstairs bedrooms affecting our children’s health?
2nd Floor Child’s Bedroom
Temperature, relative humidity, and carbon dioxide concentration data is plotted in Figure 3 below. CO2 data was only available after February 25.
[James’ Note: I have added the BCHydro data for electrical consumption and outside temperature below Figure 3 for comparison.]
While the average CO2 concentration was approximately 1,100ppm, higher “spikes” are regularly occurring at night time, when the bedroom is occupied. Figure 4 provides a closer view of the data over a three day period, from March 5 to March 8. As expected, the CO2 levels increase sharply around 7:30pm, which is around the time that the child goes to bed; interestingly, the CO2 concentration decreases shortly after the child goes to bed, and continues to decline throughout the night. This appears to be a result of the exterior temperatures decreasing over night, driving greater stack effect ventilation.
Thank you Nichole!
This last graph gives you a picture of our bedtime routine. The CO2 spikes when the kids, Leanne and I snuggled into the big bed in the room with the sensors to read bedtime stories. At lights-out time I would typically go downstairs (not enough room in the bed) and Leanne would fall asleep with the kids. At that point there is not so much breathing in the room and CO2 drops. Leanne usually woke up in an hour or two and came downstairs, leading to a further drop in CO2 and a much happier husband.
I’m proud of how consistent we are with bedtimes and this graph reflects that consistency.
There is little air circulation in the upstairs bedrooms. Dave the father-in-law helped us install a new heating duct in each room, but they do not seem to be very effective. Perhaps this is because they are smaller ducts, but perhaps, without a coresponding duct to take cold air down to the basement, the warm air has nowhere to go. Certainly the BCIT results suggest that air is not moving. However, it looks like the oil furnace combined with the electric space heater in the room were keeping the temperature pretty steady at least.
Do Nichole’s results prove that our efforts to seal and insulate the upstairs worked? Every exterior wall was covered with vapour barrier before the drywall was put up. The only leaks would be through gaps at the windows, attic entrances and holes made for climbing wall gromits, ladders, etc. If so, we can see here the effects of sealing an old house without installing the necessary ventilation system at the same time: CO2 spikes.
So should we be worried? 2000 parts per million of CO2 is not desireable. Carbon dioxide is not dangerous in a room except as an indicator that there is a less-than-ideal amount of oxygen (and that there may be other air problems). However, the spikes of CO2 are short-lived, lasting about an hour, so there is no need to panic. When we renovate we will install an effective ventilation system that will circulate fresh air throughout the house.
It’s a good thing we expect to be finally renovating in 2015. We expect to sign the final Heritage Revitalization Agreement on Tuesday and I’m meeting another contractor today. More on these developments later!