Replies

1. 
   Trevor Lambert|Jun 20, 2019 12:21pm|#1

   我不确定,但我相信它是energy required to heat the space. In other words, it doesn't take into account the COP of the heating source. The reason I think this is that our PHPP report doesn't include any place to specify the particular heating equipment being used, or its COP. At least not that I could find.

   Note however that the two requirements you listed (15kW/m^2a and 10W/m^2 peak) are alternative requirements. You only have to meet one of them, not both.

2. 
   Peter_R|Jun 20, 2019 12:36pm|#2

   Thanks Trevor. My impression is also that the COP of the heating source is not included, but I haven't seen this written explicitly anywhere.

   Thanks for the correction about the OR vs AND for heat loads. For the max heat load, do you know if buffering from thermal mass "counts" towards the 10W/m^2, or if heat consumption must be modelled in steady state? For example, let's say the time constant for your house was ~15 days, and so you can whether through a cold snap consuming less than 10W/m^2, but not if the cold snap continued indefinitely.

3. 
   Trevor Lambert|Jun 20, 2019 01:03pm|#3

   I don't think thermal mass is factored in anywhere. When you're talking about peak heating load, you're typically looking at a diurnal cycle, not ~15 days. A thermal mass capable of retaining surplus heat ~15 days is going to be huge. I know there are practical problems with dealing with a mass that size, but that's way above my pay grade. I can tell you that my house has a pretty substantial thermal mass (1600ft^2, 8" thick concrete slab), passive house level insulation and glazing, and it can't maintain the temperature overnight in the dead of winter, let alone multiple days.