[Strawbale] Alternative tightening materials

Sara Tommerup stommerup at gmail...
Mon Mar 7 20:44:50 CET 2011

All who have joined this discussion, do you have any pictures of such
details that you would be so kind to share with me?

I will be using them for an essay for my studies comparing them with
convential details. Please provide source for the photo, so i can
accredit it.



On Mon, Mar 7, 2011 at 5:28 PM, RT <ArchiLogic at yahoo...> wrote:
> On Mon, 07 Mar 2011 01:14:52 -0500, David Neeley <dbneeley at gmail...> wrote:
>> On a well detailed straw bale in which you have paid attention to air
>> sealing, don't you then run the opposite problem--having inadequate air
>> changes?
>> Would it not in such case be prudent to also install an energy recovery
>> ventilator?
>> On 03/06/2011 11:02 PM, RT wrote:
>>> strawbale construction methodology is inherently conducive to yielding
>>> air-tight buildings
> I don't think that there is any question of the necessity of paying careful
> attention to air-sealing
> with any well-insulated building, whether it has straw in the walls or not.
> Any air-leakage point is a point where bulk moisture from conditioned
> interiors will find its way into the envelope materials and condense
> somewhere within the cross section.
> Once that moisture is in liquid form, it becomes more difficult (than if it
> were in vapour phase) for that moisture to get out again even if the skin
> materials are vapour permeable. (ie vapour permeable is not liquid
> permeable).
> So what you have is moisture hanging around for a long time and like
> teenagers with too much time on their hands, trouble (in the case of
> building materials, microbial activity) is sure to ensue.
> If one is relying upon air leakage through the envelope materials to provide
> the necessary ventilation air changes, then that ventilation air is going to
> be passing through mould/mildew/crud infested materials before entering the
> indoor air environment -- certainly not a scenario that is conducive to
> creating healthful living space.
> So if air-tight construction is a necessity with well-insulated buildings to
> preserve the integrity of the materials and avoid potential deleterious
> health consequences to the building's occupants, then it necessarily follows
> that a ventilation strategy be implemented as well to ensure the necessary
> air changes to provide good indoor air quality.
> And since the minimum (ie the worst that the Codes will allow) ventilation
> rate requires that the entire
> volume of air inside the house (air which you have spent energy to
> condition) be changed a minimum of ~8.4 times a day  ... (ie you need to the
> empty the house of air that has been heated/humidified to 18-21 degC /~20 -
> 25% RH and replace it with fresh outdoor air (which might be at minus 20 or
> minus 40 degC and containing almost no moisture) that has to be warmed up to
> 18 - 21 degC at least eight and a half times every day ... and since any
> energy recovery ventilator worth considering will recover 75 to 95 percent
> of the energy from the stale air exhaust stream, I think that the choice is
> a no-brainer (and a Code requirement here in Ontario).
> --
> === * ===
> Rob Tom
> 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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