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GSBN: Digest for 1/24/03



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-> Re: GSBN:HRVs and SB
     by "Rene Dalmeijer" rened@...
-> Re: GSBN:HRVs and SB
     by Paul Lacinski paul@...
-> HRVs ERVs and SB
     by bainbridge bainbrid@...
-> Re: GSBN:HRVs and SB
     by Derek Roff derek@...


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Date: 24 Jan 2003 16:43:02 -0600
From: "Rene Dalmeijer" rened@...
Subject: Re: GSBN:HRVs and SB

Chris,

I would have a good look at the HRV but then taking the following into
account:

A good HRV unit will recover at least 85% of the exhaust heat in a well
insulated house this can build up to rapidly. Commercial balanced units here
95% are about $1500 the air coming in is about 1-2 C below inside air temp
during winter. You easily save the energy required for the ventilator.

ie 250m^3/h at delta T 28C=1.2*28*250/3.6=2333W if you recover 85% means the
HRV saves 2333*.85=1983W not bad

In a properly designed system the ventilator should not require more then
400W leaving you a saving of 1583W

If you design carefully you don't need much ducting besides this also saves
on resistance and noise. In summer you can switch off and just open the
windows. To keep noise and losses down keep the flow rate below 2.5m/s in
the ducting. I used to work at a HVAC engineering buro and before this I did
an apprenticship at an alternative energy consultancy buro. Besides
fluorescent lighting the next best energy saving measure is balanced
ventilation with a HRV unit. If you want you can keep it running on energy
collected with solar panels. But then again this costs more money then you
save by not using the grid. It is much better to limit the amount of energy
required for moving the air. If the system is designed well 150W would
already move enough air. An efficient system also cuts back on noise.

I must confess I live in a house that is so leaky that we don't need a
ventilation system. But I should do something about it. HRV is a good thing
if done properly. Maybe running a ventilator doesn't seem right but it is
very sensible energy saving measure.

Rene

- ----- Original Message -----
From: "Chris Magwood" TLSEditor@...
To: "GSBN" GSBN@...
Sent: Wednesday, January 22, 2003 8:18 PM
Subject: GSBN:HRVs and SB


> Hello All,
>
> In the past month, I've had numerous enquiries like the following:
>
> >> Has anyone with a strawbale home NOT installed a heat recovery
ventilation
> >sytem (HRV) and if so do you have a problem with condensation? I'm trying
to
> >decide whether to install one before my interior walls are closed in.
>
> Now that HRVs are part of our building code, it seems inspectors are not
> giving owners any options other than installing the full systems ($3-6000
> and require constant fan noise and energy, plus ductwork everywhere). Does
> anybody know of an indoor air quality expert who might have
> options/opinions other than the installation of full HRVs? My own home was
> built without one, and we don't have any moisture problems, which I
> attribute to the amount of porous, unsealed natural materials in the house
> (barn board, beams, unpainted gypsum plaster, etc) which are capable of a
> lot of storage when conditions are humid, and release when conditions are
> dry.
>
> Thanks!
>
>
> Chris
>
>
> ***************************
>
> Chris Magwood / Camel's Back Straw Bale Construction
> http://www.strawhomes.ca
>
> Interested in bale building? Have you subscribed to
> The Last Straw Journal?
> You should!
>  http://www.strawhomes.com

>
>



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Date: 24 Jan 2003 17:34:56 -0600
From: Paul Lacinski paul@...
Subject: Re: GSBN:HRVs and SB

Chris,

I would agree  with what Derek and others have said about indoor air 
quality, etc.  I would even go so far as to say that I wish our codes 
would follow yours and require HRV's, because then I could actually 
get people to use them, instead of cutting them at the last minute, 
as is generally the case.  I say "almost" wish because requiring them 
flat-out would be an excessive expense for some people who are 
building small houses on a very tight budget.  (So now we come back 
to the heart of your question.)  I assume that the generally 
enlightened Canadian codes make provision for use of energy modelling 
software, so that if you can show that a given design will meet the 
overall intention of the code with the use of exhaust-only 
ventilation (bathroom fans with timers) rather than an HRV, I would 
imagine that you would be OK.  Of course, it may turn out that an HRV 
is a less expensive way to meet the code than having to bump up to 
(for example) those Canadian triple-paned fiberglass windows.  (Which 
we have only used once so far, but which work supremely well, in 
terms of both heat loss and noise reduction.)  Such provisions 
sometimes also account for size, allowing a slightly less efficient 
envolpe and sysstems for small houses, since small houses use so much 
less heating energy than large ones.

So now that I've gone in a bit of a circle about that, I will 
disagress with Derek's assertion that "current heat recovery 
ventilation systems are primitive and expensive."  They are somewhat 
expensive, but I would certainly not call them primitive.  They 
ventilate an entire house with only a 30% heat loss, using 1 moving 
part- a very high quality fan.  They have filters for incoming and 
outgoing air which can be specified to remove pollen, dust, urban 
pollutants, and other matters of concern to allergy sufferers, 
chemically sensitive people, children, etc.  They replace the 
bathroom fans, so there is no noise in the bathrooms.  They provide 
some circulation of interior air.  And they lead to houses in which 
the air is warm but also always fresh and clean.  Regardlesss of 
building materials, I have never been in a house with an HRV that 
didn't have sparkling air quality.  So given all of that, and 
considering that they are built to last indefinately, I don't think 
they're very expensive.

Cheers,

Paul




>Lacking comments from Rob Tom and Paula Baker Laporte, here is what 
>I think about indoor air quality.  Moisture buildup is not the only 
>problem.  It may be the most serious issue for the physical 
>structure of the home, but it is probably secondary for the health 
>of the inhabitants.
>
>For good indoor air quality, a home needs significant, continuous 
>air exchange in all rooms.  This is hard to achieve.  If a building 
>has lots of air infiltration, it wastes energy and can lead to 
>invisible moistuure problems in the walls.  A loose home is also 
>likely to have very uneven air exchange.  If a building is tight, 
>then air exchange needs to be designed in, in order to have healthy 
>air quality in all rooms, regardless of moisture levels.
>
>Current heat recovery ventilation systems are primitive and 
>expensive, which is why we don't want to use them.  But to ignore 
>the problem and subject ourselves, our families and our clients to 
>unhealthy indoor air is irresponsible.
>
>Derek
>
>--On Thursday, January 23, 2003 10:03 AM +0200 Evgeny Shirokov 
>iae@... wrote:
>
>>From my experience with straw-clay houses: moisture is not a problem
>>in bathroom, if you use clay stucco and protect walls from "direct
>>water flow" by ceramic or other with ordinary system of ventilation.
>
>And Chris Magwood relayed:
>>>Has anyone with a strawbale home NOT installed a heat recovery
>>>ventilation
>>>sytem (HRV) and if so do you have a problem with condensation?
>>>I'm trying to decide whether to install one before my interior
>>>walls are closed in.
>>
>>>Now that HRVs are part of our building code, it seems
>>>inspectors are not giving owners any options other than
>>>installing the full systems ($3-6000 and require constant fan
>>>noise and energy, plus ductwork everywhere). Does anybody know
>>>of an indoor air quality expert who might have options/opinions
>>>other than the installation of full HRVs? My own home was built
>>>without one, and we don't have any moisture problems, which I
>>>attribute to the amount of porous, unsealed natural materials in
>>>the house (barn board, beams, unpainted gypsum plaster, etc)
>>>which are capable of a lot of storage when conditions are
>>>humid, and release when conditions are dry.
>
>Derek Roff
>Language Learning Center, Ortega Hall Rm 129, University of New Mexico
>Albuquerque, NM 87131  505/277-7368, fax 505/277-3885
>Internet: derek@...
>----
>For instructions on joining, leaving, or otherwise using the GSBN 
>list, send email to GSBN@...HELP in the 
>SUBJECT line.  ----


- -- 
Paul Lacinski
Amy Klippenstein
GreenSpace Collaborative
Sidehill Farm
PO Box 107
463 Main St.
Ashfield, MA 01330 USA
01-413-628-3800


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Date: 24 Jan 2003 18:03:40 -0600
From: bainbridge bainbrid@...
Subject: HRVs ERVs and SB

Adding a bit from SD where we don't even really need houses to be 
comfortable -- I see that there are now ERVs for cooling recovery 
while summer venting. These might make sense for some people in hot 
summer/cold winter climates.

Here is a commercial explanation with map of application recommendation...

http://www.la-air.com/html/erv.html

Cheers

d
- -- 
David Bainbridge
Environmental Studies Coordinator
CAS
Alliant International University
10455 Pomerado Road
San Diego, CA 92131

Fax (858) 635-4730
Ph (858) 635-4616
http://academic.alliant.edu/bainbridge/
http://www.sustainableenergy.org/resources/technologies/solar_passive.htm
http:SustainableSources.com

The future isn't something hidden in a corner. The future is 
something we build in the present. Paulo Freire


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Date: 24 Jan 2003 18:34:51 -0600
From: Derek Roff derek@...
Subject: Re: GSBN:HRVs and SB

- --On Friday, January 24, 2003 7:54 AM -0500 Paul Lacinski 
paul@... wrote:

> So now that I've gone in a bit of a circle about that, I will
> disagress with Derek's assertion that "current heat recovery
> ventilation systems are primitive and expensive."  They are
> somewhat expensive, but I would certainly not call them primitive.

I appreciate Paul's comments and the misleading nature of my earlier 
unqualified assertion.  From a practical point of view, current HRV 
systems are pretty impressive in recovering 70% of the heat.  And 
averaged over the life of the home, their value to health is high and 
their cost is small.

What I had in mind when I wrote before was comparing current HRVs to 
what we will see in the market very soon, after use has become high 
enough to drive research, innovation and competition on a much larger 
scale.  I think that within five years, we will see large increases 
in efficiency, combined with large drops in price and easier/better 
installation protocols.  "Primitive" doesn't always mean bad, but I 
expect to see a lot of improvement and optimization in HRV systems.

Derelict

Derek Roff
Language Learning Center, Ortega Hall Rm 129, University of New Mexico
Albuquerque, NM 87131  505/277-7368, fax 505/277-3885
Internet: derek@...


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