[GSBN] Can bale buildings be air tight?- How to ventilate

Thu Mar 14 23:05:28 UTC 2013

Thank you Graeme for expressing my sentiments so well!

On Thu, Mar 14, 2013 at 3:51 PM, Graeme North <graeme at ecodesign.co.nz>wrote:

> Well my 2c worth is that in NZ we have a long history of cold damp houses,
> in a very humid mostly temperate climate.  (As it is at the moment we are
> in the grip of the worst drought for over 70 years so any hint of damp
> would be welcome.)
>
> That aside - the best strategy I have found for drying out damp houses is
> to use hygroscopic materials in the fabric of the house - and the best and
> easiest is earthen walls or at least earthen plasters on any suitable
> substrate such as dry wall.  Of course to help get over cold we insulate
> and that's where sheep's wool, or strawbale,  or low density earthen
> materials, come into their own.  Condensation on windows and the
> accompanying wet window sill syndrome simply vanishes.  Needless to say we
> don't have several cm of snow lying around but we do get some pretty good
> frosts.  Then reducing the size of houses and the size of windows in them
> also helps. Lets face it, oversized badly orientated triple or quadruple
> glazed self ventilating thermally broken windows are still not nearly as
> good as a bit of well insulated wall at keeping heat in or out.
>
> I suggest that the approach of using more and more of the earth's
> resources to sort out these building issues  may not be a good primary
> design strategy, especially when it leads to oversize buildings, with
> oversized windows needing mechanical ventilation systems etc., -
>  mechanical systems that are only as good as their energy supply.  I don't
> want to wake up dead of asphyxiation in an air tight building because the
> electricity failed while I slept.
> *
> *
> This is not to dismiss some very good building science and its associated
> research, but I am finding this conversation on interior air quality in air
> tight buildings a bit disturbing when we end up with buildings so tightly
> sealed that the occupants are at risk from either the building fabric
> itself, or even more alarming, from their own breathing!   People would be
> much healthier outside the building under these circumstances.
>  Interesting, isn't it, how, if a person feels ill we often take them
> outside, where they usually feel much better?  We really do need protection
> from the built environment.
>
> I prefer a design approach that minimises the use of expensive, resource
> gobbling, and complicated materials and systems.  A colleague of mine sums
> it up thus:
> *The.... division is between those who fling open their doors to embrace
> the day, and those who huddle behind triple glazing worrying whether they
> are going to be comfortable**.   *Tony Watkins FNZIA
>
>
>
> Graeme "Stirrer"
>
> Graeme North Architects
> 49 Matthew Road
> RD1
> Warkworth 0981
>
> www.ecodesign.co.nz
>
>
>
>
>
>
>
>
>
> On 13/03/2013, at 5:04 AM, RT <ArchiLogic at yahoo.ca> wrote:
>
> Tony wrote:
>
> Is there a window sill detail for the interior that could accommodate the
> inevitable moisture present?
>
>
> Carolyn wrote:
>
> "ventilation window" ...two glass panes with space in
> between - like 3-4 inches.
>
>
> Tony;
>
> Condensation on glass and subsequent puddling on window sills would of
> course, best be addressed at the source of the problem (in most cases just
> providing proper ventilation) but for small amounts of water accumulation,
> a gutter detail can be useful.  In the commercial window industry, the
> aluminum extrusions (especially with sloped glazing) typically include a
> condensation gutter.
>
> For residential windows it would be a matter of bending some
> corrosion-resistant sheet metal flat stock to mimic the profile of the sash
> and glass stops of the bottom rails to function as flashing to direct the
> runoff into a collection gutter which may be integral to the flashing or a
> separate piece of off-the shelf stock (ie J-trim ).
>
> Also, for the sills themselves, tile or stone set in a mortar bed rather
> than a moisture-susceptible material such as wood.
>
>
> Carolyn;
>
> I don't see a file attachment for the windows you mentioned but they sound
> like the "laminar flow" windows that were marketed over on this side of the
> pond in the early 1990s.
>
> My objections to them back then were:
>
> (1) Solar pre-heating of ventilation supply air by the windows would only
> be happening when the sun is shining and striking the equator-facing glass.
>
> In winter, at my latitude here near Ottawa, Ontario Canada that would be
> be limited to effectively about the 4 hours around 10:00 to 14:00 hrs.
>
> Problem is, in most normal households, there is no one home during that
> time.
>
> "Okay, so we'll just store that fresh air inside until people get home to
> use it. Right ?"
>
> I don't know if Denmark has ventilation requirements written into the Code
> but there are minimal flow volume guidelines in existence intended to
> ensure good indoor air quality (see handbooks put out by ASHRAE or IHVE
> etc).  These, like building codes are minimal standards intended to provide
> a minimum level of health safety. I assume that we on the GSBN list aim
> higher than the worst buildings allowed by law.
>
> Here in Canada we've had considerable experience with trying to make
> well-insulated buildings and learned very early in the process that making
> such buildings air-tight was an absolute necessity and of course, the
> corollary being that proving an effective ventilation strategy is also
> absolutely necessary and the R-2000 program from the early 1980s taught us
> many lessons that are still valid today.
>
> The PassivHaus standard utilises most of the same principles (with some
> variations on targets) but PH strikes me as being confused so I won't talk
> about it here.
>
> The CAN/CSA-F326 Standard (first published in 1989 and revised in 1991) is
> one of most comprehensive available on the subject of ventilation
> requirements and it lists the following:
>
> ==============Copied material =================
> Table 1. Ventilation Capacity
>
> Room   Capacity, L/s
> Master bedroom  10
> Other bedrooms  5
> Living room   5
> Dining room   5
> Family room   5
> Recreation room  5
> Basement   10
> Other habitable rooms  5
> Kitchen  5
> Bathroom or
> water closet room  5
> Laundry  5
> Utility room   5
> =================== end of copied material =================
>
> In 1994, a study was done for the Energy Efficiency Div., Residential
> Program, Energy Technology Branch CANMET, Dept of Natural Resources Canada
> (now NRCan)
>
> "Indoor Air Quality and Ventilation Rates in R-200 Houses"
>
> which found that most owners of R-2000 certified homes were operating
> their heat recovery ventilators (HRVs) at 75% the rate specified by the
> F326 Standard with no deterioration in IAQ and recommended that the lower
> rate be adopted for R-2000 certified homes.
>
> Recently on the Greenbuilding list in a thread on the topic of
> ventilation, WatJohn mentioned some similar numbers (ie lower rate than
> those specified by F326) as a guideline:
>
>    (per WatJohn)  7.5 cfm (~3.6 L/s) per occupant + 0.1 cfm per sq foot
> floor area
>
> ... which, if you crunch the numbers will yield a "NO!" to the question
> posed (re: storing solar pre-heated fresh air) -- the point being that
> depending upon the degree of air-tightness of the building, there are
> certain minimal ventilation requirements that must be met or there will be
> unacceptably high levels of pollutants which will have deleterious effects
> on the health of the building's occupants.
>
> Condensation on windows is just the most visual and most easily-addressed
> indicator that the house is suffering from poor ventilation.  It is the
> "invisible" pollutants that are more worrisome -- CO2 and VOCs.
>
> The other thing that is troubling (to me anyway) is that we're only just
> now having this discussion on this List when the resources to address these
> questions have been readily available for the past three decades or so,
> pretty much pre-dating the current "SB Revival".
>
> The need for air-tight construction with well-insulated buildings and the
> need for effective ventilation strategies for air-tight buildings does not
> have one set of requirements for buildings made of conventional materials
> and another set for buildings made of natural materials simply because the
> natural processes involved don't make the distinction.
>
> That is to say, since the resources to address these issues already exist
> and these days are quite likely accessible with a few mouse clicks, there
> is no need for willful naivite or missions to re-invent the wheel. It's
> okay to transfer that knowledge to SBC and NatBuild.
>
> No doubt there will be arguments to the effect "We don't want no stinking
> mechanical ventilation gizmos just so we can breathe ..." but that's a
> non-starter.
>
> What's necessary are the ventilation rates to ensure health.
>
> It doesn't matter how those rates are provided.
>
> In milder (than Canada) climates and smaller, single-storey homes (ie
> under 160 sq metres) exhaust-only/passive-inlet ventilation strategies
> (EOPIVS) are an alternative to HRVs. The downside to EOPIVS is that there
> will likely be no heat recovery capacity on the exhaust air stream which
> means that energy consumption for space conditioning will likely be up to
> 40% higher than it needs to be and for any building aspiring to be "Green"
> in 2013, is that acceptable ?
>
> But enough of that (and apologies to those who have had to endure this
> rant on numerous occasions previously).
>
>
>
>
> --
> === * ===
> Rob Tom   AOD257
> Kanata, Ontario, Canada
>
> < A r c h i L o g i c  at  Y a h o o  dot  c a  >
> (manually winnow the chaff from my edress if you hit "reply")
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-- 
Paula Baker-Laporte FAIA,BBP
Econest Architecture Inc.
www.EcoNest.com
paula at econest.com
Phone: 541.488.9508
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