Nichole’s Results II Bathroom

This is where the data starts getting juicy.

Master bedroom below, bathroom above
Master bedroom below, bathroom above

Sunday was bath day but we forgot so yesterday after school and the kids had their half-hour of iPad time I filled the tub. They used to bathe together all the time but now sometimes the daughter prefers to wait so she can bathe alone.

Iron bathtubs cool quickly
Iron bathtubs cool quickly

While the son bathed the daughter passed out in the master bedroom and I let her sleep until it was time for dinner before we headed out for Beavers (him) and Cubs (her). She had a mild fever last night and lost some sleep hallucinating and wandering around the house demanding, “It’s snuggle time!” I thought sleep was more important than bath.

The result was a full tub of warm water washing only one kid (a scandalous waste in our house). The other result, as usual, was a lot of humidity in that corner of the house. With no central heating fan blowing air around I am reluctant to drain the tub when the water is still warm. I don’t know how good the moist air is for us, but I just want to suck all the warmth out of it I can before I let it go down to warm the sanitary sewer.

Another thing I don’t like doing is living in a leaky, badly insulated house and burning wood and oil to heat the neighbourhood.

Anyway, here is part two of “Nichole’s Results” in which she comments on the fact that, in winter, we don’t like opening the windows in the bathroom to let the humidity out–especially now that we’re refusing to turn the heating on!

For the complete story on Nichole’s project on our house with BCIT, click on the BCIT category on the right hand column.


Temperature and relative humidity data is plotted in Figure 1 below.

The bathroom window
The bathroom window

The bathroom does not have a dedicated exhaust ventilation system, and the homeowners do not consistently open the window for ventilation due to cooler exterior temperatures, so the humidity levels in the bathroom are often very high. Figure 2 illustrates the spread of hourly data points on a psychrometric chart, prepared using the Ecotect software; a comfort zone is indicated in yellow, assuming a “sedentary” activity level. For a large portion of the time, the conditions in the bathroom fall outside the comfort range, and are primarily too cold. This helps to explain why  occupants are reluctant to open the windows to increase ventilation, as this would also decrease the air temperature further.The change in temperature profile from about March 16 to March 23 is due to the house being unoccupied during the family’s vacation.


It’s true. We took the kids to Disneyland for the first time. We wanted to do something special with the small inheritance Leanne’s Grandma had left her.

Anyway WHAT A COOL GRAPH! AmIright? You can tell exactly when we bathed. Awesome.

The temperature in there is bouncing up and down by 3 or 4 degrees Celsius every day, dictated, I guess, by the programmed thermostat, the amount of sunshine coming in the windows and the number of people in the house. I imagine in a really comfortable home, a good ventilator is circulating the air and controlling the humidity so those spikes become a nice gentle wave. After feeling pretty smug about how well we sealed the house in 2008, this graph is pretty sobering.

imageSpeaking of our vacation, it looks like I set the thermostat for 18 degrees celsius in the day and 16.5 at night. That is how far the blue line bounces up and down in the third week of March. It is pretty regular there until around March 20th. That is when a movie crew filmed at the house and turned off the furnace completely for hours at a time (they do that for sound recording). I guess that tells us how fast the house will lose heat without any source at all.

How do you think your house compares? I would love to hear your comments because I have heard that, even using “modern” building codes of 30 or even 20 years ago, similar problems exist in more recent homes. Remember that this data was collected AFTER we insulated the attic spaces and pumped foam into the walls.

Let me add a graph from BC Hydro for the same time period.

Electricity Consumption and outisde temperature
Electricity Consumption and outisde temperature

One thing that is fun to note is the bathroom humidity went down when it was cold outside. I suppose you should also see our electricity consumption go up when the humidity spikes because we use electricity to heat the water for the bath and shower. Finally, when we were on holiday, the fridge, freezer and furnace fan  were pretty much all that was drawing power. I wonder how that baseline would drop if we got super efficient appliances.

As I noted when I first shared a graph from our Smart meter, since we were using oil to heat the house, not electricity, we don’t consume more of it when it is cold outside, but we do on bath and laundry days.

Nichole finishes this section up with an impressive psychrometric chart.

The bathroom ceiling finishes are tongue-in-groove wood boards, which are likely not providing a reasonable level of airtightness. It’s likely that high volumes of warm, moist air are travelling into the attic space, where they may be able to condense and cause deterioration to the wood framing.

What a cliff-hanger! Will we find deterioration in the wood framing when we open the walls up? How many carpenter ant nests are there? Will James and Leanne find a way to live inside the Yellow Comfort Box?  Tune in next week on Hammond Forever House!

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James Rowley

James lives in Maple Ridge, BC, Canada with his amazing partner, Leanne Koehn, and their two amazing kids in their beautiful house. He studied Science and English Literature at the University of British Columbia where he met Leanne. He also studied acting for a while at Studio 58 in Vancouver. He works as a teacher of English and curriculum writer for new Canadians.

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