Berkeley Lab
2 HN recommenders · recommended in 4 months, 2019–2021
1:09:53 · 185K views · Oct 6, 2010
A Berkeley Lab Distinguished Lecturer talk on building science, with an expert covering control layers, insulation and vapour barrier placement, and how buildings fail. The delivery is humorous.
HN commenters cite it as an authoritative, entertaining source on building science, such as insulation placement and why LEED point priorities miss the mark.
6 comments from Hacker News
You got the gist of what I was saying which is physics is at play and the answer is always "it depends". But people don't like that. Hence, AC off I'm a good person. Green roof I'm a good person. 'etc. > I agree to a certain extent with his points, but found his tone incredibly condescending and offputting That kind of says it all, doesn't it? Personally I found it good natured tongue-firmly-in-cheek conspiratorial humour. Considering he is an actual authority on the subject and has seen a lot of incredibly idiotic behaviour and expensive and downright dangerous mistakes I think you can forgive him if his comedy schtick is not to your taste as long as the info is good. This talk is even better: this video He seems like the grumpy Linus of the building science world and if he is a jerk he is my kind of jerk.
A house should not breathe. A catchy mantra I've run across is "seal tight, ventilate right": * [LINK] Mold is not a ventilation problem, but rather a moisture control problem. Keep the humidity down (especially with whole house dehumidifiers), and eliminate condensation points (by eliminating thermal bridging), and it goes away. While the above video, which is from the really good channel by Matt Risinger, is a good introduction, I recommend you also check out the building science stuff put out by Joseph Lstiburek for a more science-y explanation: * [LINK] On the "perfect wall": * [LINK] Presentation on control layer (especially starting around 15m): * this video Good webinar: * [LINK]
> Certain building materials need to breath. As explained in the linked video, they actually need to dry . This does not need to happen to the outside environment. IMHO, using the two terms (dry/breathe) interchangeably is causing confusion, as each has certain connotations in many people's minds. The person in that video lives in Austin, Texas, and when he builds or renovates structures he has a stand-alone, whole-house dehumidifier designed into the HVAC system (the client can of course reject the suggestion): * [LINK] > If the there are discontinuities it is possible to get condensation when the temperature / dew point align just wrong. Which, as explained in the first link (BSI-001), is why you want external insulation (if possible); some portion of the insulation being continuous is code in many places nowadays. That way the condensation occurs on the outside of the water/vapour control layer. Joe Lstiburek: * this video This is harder to do with renovations, but is code in most places. In Ontario, Canada the code (IIRC) also specifics what minimum portion of the insulation that should be on the 'outside' of the vapour control layer: the colder the region the more has to be external, so that condensation happens on the outside of the structure. Having it 100% external is ideal, but would cause trade-offs in other aspects of the building, which may not be desirable. An example of such a structure: * During construction: [LINK] * Finished: [LINK] Sadly, last time I checked, t
The order of importance is not the order in which they are layered: * [LINK] If you wish to argue against Joe Lstiburek, a PhD who has been doing building science for probably over thirty years (both academic research and field work/consulting), go right ahead. He has taken failures into account because a good portion of his career has been studying / consulting on failures: * this video
Not necessarily. Mold grows in certain conditions: food availability, right temperature, water/moisture. Ideally you would want your insulation outside of vapour barrier: * [LINK] * this video * [LINK]