Well, it will drop as fast as it drops. "Should" doesn't enter in. You are
talking about very modest low temps (my god, -15C is only like +5F), and
your insulation is thoroughly adequate for that kind of cold, if indeed it
meets code, which you are assuming. I doubt you have ripped a wall open.

There are only two considerations in my opinion:

1. Don't let it get so cold in the house that you get massive condensation
on the windows
2. Don't let it get so cold that the furnace can't restore comfort in a
reasonable length of time.

And if you are waiting till you get up to turn on the furnace, that time is
probably shorter. In a well-insulated house (if yours is code, it is
well-insulated), there is very little payoff in letting the place get way
cold. A 5 degree setback day to night is plenty. You should buy yourself a
setback thermostat and learn how to run it, and let it take care of things
for you.


"kevins_news" wrote in message
...
I know that question is too open ended to really answer. Each house
will behave different. Each room will behave different depending on
windows, exterior walls, etc. But I'm just looking for some sort of
estimate.

Say it's -15C outside and +20C inside at midnight. If i left the
furnace off (gas forced air) all night, what kind of temperature could
be expected at 8am? I guess a "If it drops lower than X then you may
have issues" is the kind of answer i'm looking for.

The reason i ask is because i'm an insanely over-critical person who
wants to squeeze every bit of efficiency out of this house until the
next one which i will have built properly. :-)

I'm in the middle unit of a 3 unit townhouse. So i share a wall with
each nieghbour on the sides and only my front/back walls are exposed
to the elements. However I have a 2nd story which neither of my
neighbours do, so upstairs is exposed on all four sides. Because the
vast majority of my main floor walls are shared with neighbours i
figured that my heat loss should be significantly better than any
detached house. But i have nothing to compare against. Buit new in
2001 according to ontario building code. I think that's r-34 in the
attic and only r18 in the walls. All the windows are double paned. I
can't feel any air leakage and no condensation or ice ever forms
between panes but the bedroom windows ice up like hell every night
along the bottom edge. (35% humidity inside at 19C with -15C outside).

I haven't done any tests to see how quickly the temperature drops but
i was just looking for some sort of general numbers to compare against
once i do.

any thoughts appreciated.