40 CFR § 1066.710 - Cold temperature testing procedures for measuring CO and NMHC emissions and determining fuel economy.
The heater
is used at 72 °F on front window defrost, in vehicles with automatic climate control, when on the Cold FTP test cycle, at least on ICEs.
Note that in most ICE vehicles, the heater core is on a part of the coolant loop that isn't blocked by the thermostat when the engine is cold, so there is a potential emissions impact (slower warmup). Additionally, on some ICE vehicle designs, there's supplementary heaters used in those conditions that increase load - a kilowatt or so of PTC electric heat is common on higher efficiency vehicles, and I've even heard of diesel-fired supplementary heaters on one diesel ICE vehicle sold in the US market - the consumption from those devices would affect things as well.
Agreed, the following is misinformation:
"Heat pump would have no impact on measured results, even if using 5-cycle testing - the 5-cycle testing only engages A/C in the hot test and never turns on cabin heat in the cold temp test (there is no reason to, since that would have no significant impact on results in an ICE vehicle)."
Thanks for the info. This has been pretty confusing for me to track down - I was reading a publication from the EPA (but I guess it was quite dated) indicating that it wasn't needed. Thank you for your link.
But this makes a lot more sense...looking at some cold weather test data from Teslas and it does look like it significantly impacts the efficiency...which is great as at least it means 5-cycle testing might actually have some significant impact on the results...
Here is the
erroneous table I was looking at in an old document:
But doing a search for "heater" in that document...
I've recently learned that cabin heat is never active in EPA test cycles, so heat pump instead of PTC heat wouldn't help tested range, but might help real world range in cold.
Sorry for misinforming you. As you can see above, I was going off this table, which is apparently dated...
I guess it remains to be seen whether the Model Y has a heat pump? I'm having a hard time understanding how that scalar of 0.756 could have gotten so large without one, but who knows. I'm stumbling around like a blind man on this stuff, gradually learning my way as I go.
Sadly, even the "Test Details" tab in this EPA link is ambiguous/does not speak about heat - but I will trust the link provided above in
@bhtooefr's post.
Detailed Test Information