[Greenbuilding] PassivHaus and NZE comparison

[Ross Elliott]

Hi John,

As my previous post stated, most of the problem is in the EnerGuide rating
system, although the software itself has some issues - The way it calculates
energy loss from air leakage is baffling, sometimes raising the energy use
of the house when you give it slightly tighter numbers (don't ask me why, as
I said it's a black box so although I'm sure a guy like Bruce Gough
understands how the software thinks, it's not my passion to understand these
things, I just have to assume all the air leakage energy calculations may be
suspect). Window modeling, compared to PHPP, is dismal, and I don't know if
I can trust its numbers even when I create a custom assembly. Figuring out
if a house overheats consists of checking whether the imaginary air
conditioner is coming on in March, and I'm not sure if it really handles
solar accurately. Of course all the default values running in anything other
than General skews things; for example, assumed electrical baseload and hot
water consumption means you can only get so far in dialing back the energy,
after a certain point it keeps you from getting to zero (I'm sure HOT2K is a
lousy modeling tool for NZ). And as I said about the rating system, you can
put in R-100 everywhere and triple glazed high performance windows and 0.2
ACH50 and a 98% AFUE combo instantaneous gas unit and 75% efficient HRV and
you'll be no more than eight points above the 2012 Ontario Building Code of
ERS 80 (without a heat pump, which regardless of efficiency still uses
electricity, an energy carrier we should be reserving for motors,
electronics and maybe transportation, but not heating houses!) - how does
the rating define how much better the aforementioned house is, compared to
the worst efficiency allowable by law? 

But other than that it's a good tool for comparing different upgrade
options, it gives a good Design Heat Loss, and it's even fairly decent at
calculating room by room heating, cooling and ventilation. I use it every
day, but sometimes other software does a better job of telling me what I
need to know. 

Ross

-----Original Message-----
From: John Straube [mailto:jfstraube at gmail.com] 
Sent: Wednesday, January 26, 2011 5:49 PM
To: relliott at homesol.ca; Green Building; 'Gordon Howell -- Howell Mayhew
Engineering'
Subject: Re: [Greenbuilding] PassivHaus and NZE comparison

Ross
Can you tell us more about the problems with HOT2000 for low energy houses?