We're just coming off a few days of the kind of cold that makes me think about survival. It was a bit unusual because there was wind as well as cold, with wind chill values around -40 to -50ºC. Today I was out running errands around noon, and it was only about -20º, and by late afternoon it was maybe -10.
Working in the sunroom this afternoon, Dad and I took off our jackets because it got too warm. There is some heat that leaks into that space from the rest of the house, but we keep the doors closed, and the one heating duct that feeds into it is closed off. Mostly the space is heated by the sun through the windows. Even during the extreme cold over the past few days, the sunroom has been cooling to only a couple of degrees below freezing over night, and warming nicely during the days. Today the heat flow was reversed: Garth opened up the doors into the rest of the house and turned the furnace off for a couple of hours.
The thermal performance of the new space has been improving bit by bit as we insulated the outside walls, closed in the gaps where warm air could rise right into the attic and away (big improvement there!), and finally started sealing all the walls up with vapour barrier. Today we were applying the last big sheets of poly and finishing the seams around windows. As we got down to the last little details, I noticed the sound of a big truck, engine braking somewhere nearby, and realized that the sound was much fainter than usual. With that thought, I also realized that the room had been feeling different over the last few hours. If someone had asked me, I might have said that I sensed it becoming more airtight, but in reality, what I sensed was probably just the gradual reduction in sound.
We are very pleased with the sunroom so far. Over the next couple of years, I hope to add a rock wall or perhaps water containers as thermal mass, to smooth out the heating and cooling cycle a bit. Insulated blinds or shutters are a big priority, too. If we can slow the heat loss overnight, I am hoping the room may become a significant heat source for the rest of the house.
And if you're wondering what it will be like in July, check out my post from 2006 about designing window overhangs. From what I saw of the rafter shadows on the window framing last summer, it looks like this is going to work, folks!
6 days ago