[Greenbuilding] The role of PV in achieving NZE

[Sacie Lambertson]

What a fabulous list, although at times I feel I'm in an engineering class
and am waay over my head.  Thanks for the excellent back and forth, all of
it educational.  Challenges offered with respect and coming from learned
sources are important and useful (unlike what is currently happening in
Egypt).   Great intellectual ROI here.    Sacie

On Wed, Jan 26, 2011 at 3:53 PM, Gordon Howell -- Howell Mayhew Engineering
<ghowell at hme.ca> wrote:

> Hello John:
>
> a) Thanks for your comments.  I am appreciating the GBL list and the people
> expressing their expertise.  I wasn't wanting to be obstructing... but I
> felt that Ross used a few hot words that I suggest needed to be challenged.
>  That's why I addressed my comments to him directly, rather than comment on
> the expertise of people on the list generally.  I apologise for being
> derogatory.  I should have been clearer.
>
> b) Re the Riverdale NZE house energy consumption, as viewed on page 7 of
> its profile <
> http://www.riverdalenetzero.ca/Riverdale_NetZero_house_--_project_profile.pdf>
> .
>   ----- May I suggest that it is important to clarify what the term "energy
> use" means.  The PassivHaus standard is NOT 15 kWh/year/m2 of space heating,
> but rather it is 15 kWh/year/m2 of net energy consumption for space heating
> from the grid (if I am understanding correctly) -- a biiiiig difference.
>  The PassivHaus net energy consumption is net of its internal gains and
> passive solar gains (please provide any correction on this).
>   ----- The RNZ house uses 33 kWh/year/m2 of space heating -- this is how
> much energy passes out through the house envelope regardless of where the
> energy is source.  The RNZ space heating is provided by a number of factors,
> as shown on the profile:  this includes internal electricity gains, internal
> people gains and passive solar.  So the net space heating requirements for
> RNZ are: Space heating incl fans = 33.65 kWh/m2 plus mechanical ventilation
> = 2.02 minus usable passive solar space heating = 6.88 (37% is useable)
> minus useable internal gains = 4.13 (25% is useable), minus active solar
> space heating = 9.57 giving a net space heating requirement of 15.08
> kWh/year/m2.
>   ----- How would a PH house do this same type of accounting in order to
> achieve 15 kWh/year/m2?
>   ----- So may I suggest that an apples and apples comparison be made.
>   ----- I can't imagine a NZE house being rationally made without being at
> least really close to the PH standard.
>
> c) I agree with you re the Kamloops DreamHome COP...  time will tell, I am
> sure.
>
> I appreciate your viewpoints and challenge.
>
> +Gordon
>
>
>
> Date: Wed, 26 Jan 2011 13:58:23 -0500
>
>> From: jfstraube <jfstraube at gmail.com>
>> To: Gordon Howell -- Howell Mayhew Engineering <ghowell at hme.ca>
>> Cc: Ross Elliott <relliott at homesol.ca>,
>>        greenbuilding at lists.bioenergylists.org
>> Subject: Re: [Greenbuilding] PassivHaus and NZE comparison
>>
>> Sheesh Gordon, not sure what you meant by the "the company of facts and
>> knowledge" but I would say there is quite a bit of that on this list.
>>  Sounds kind of derogatory, and yet Ross is one of the "good guys" (eg he is
>> willing to have a rational conversation) and I basically said what you said.
>> Most of the "facts" you provided are available to anyone surfing the web
>> and/or talking to CMHC folks.  All of them were built into my commentary.
>>
>> However, it is not true that NZE homes meet the PH standard.  That is my
>> point.
>> I attach a table of 5 of the houses I compared recently at the bottom of
>> this message.
>> According to CMHC, the Riverdale Duplex (eg one wall less than a single
>> family house to loose heat) uses 33 kWh/m2/yr.  This is over twice the PH
>> standard, eg no where near the target.  I think the Riverdale house is a
>> exemplary cold climate home, a real step forward.  And that is my point: you
>> met the 0.5, but not the 15 heating target and yet use less energy than a PH
>> by about 120 kWh/m2/yr. The Ottawa ecoHome fails the 0.6 test and the 15
>> test, and the GreenDream meets the 7 and fails the 0.6.  (Note the Kamloops
>> gets this low by using a ground source heat pump and using a COP = 5.1,
>> which is crazy, and reality will certainly be closer to COP=3.5).
>> The 120 primary target is an arbitrary but sensible target. By beef is the
>> 15 and 0.6 numbers, and the lack of climate response and renewable energy
>> sources.
>>
>>
>>                  Avalon    Riverdale ecohome GreenDream Now
>> Location            Red Deer  Edmonton  Ottawa  Kamploops  Toronto
>> HDD (18C)               5500    5600    4600    3650    4000
>> Floor Area (heated m2) 240      234     310     284     139
>> Total Site Energy (ekWh)13094   14391   20646   11031   13475
>> Heat Energy (kWh/m2)    23.9    33.7    40.2    7       23.1
>> Roof (R)                87      100     60      60      36
>> Wall                    70      56      44      44      40
>> Window          5       7.3/10  5.7     4.5     5.7
>> Basement walls  none    54      40      44      25
>> Slab                    60      24      15      20      25
>> ACH at 50          0.5     0.5     0.65    0.68    2.6
>> PV Installed (kWp)      8.6     5.6     6.2     6.8     2.7
>> SHW produced (kWh)      3886    1907    6665    2099    1824
>> PV produced (kWh/yr)    9569    6224    8184    9963    2800
>>
>
>
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