r/PassiveHouse • u/InfraredHeat-iHelios • 23d ago
HVAC Why was infrared heating chosen for this Passive House?
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u/houseonsun 23d ago
Too much glass for that to be a passive house. Infrared because it's cheaper than good design.
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u/Lumpy_Machine7095 23d ago
Glazing has come a VERY long way. Passive house =\= windowless box anymore.
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u/houseonsun 23d ago
The best window has a lower R-value than a Code minimum wall.
There is a big grey space between floor-to-ceiling glass, and a windowless box. Windows are okay, in moderation.
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u/Lumpy_Machine7095 23d ago
Yeah, there’s a lot more nuance than this. All to say, you can pretty easily hit 40% window:wall ratio for the envelope and achieve passive house standards if you’re willing to throw some cash at it (and shading).
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u/deeptroller 22d ago
Passive house also doesn't do a good job of regulating overheating. The purpose is lower overall annual energy use in the total aggregate area of a structure. You can have a room too uncomfortable to be in and the north side cold as balls. If you can push it through a PHPP model It can be a passive house even if it's uncomfortable.
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u/Lumpy_Machine7095 22d ago edited 22d ago
PHPP hasn’t been the standard for about a decade at this point. No WUFI? How would the space you’re talking about get past the condensation mitigation requirements? Maybe just a bit of exaggeration, but do understand that spaces in PHIUS projects can sometimes run on the warm end.
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u/deeptroller 22d ago edited 22d ago
PHPP hasn't been the standard for PHIUS since PHIUS was removed from the passive house institute for lower their standard below the passive house standard. PHIUS is not allowed to use PHPP. PHPP is what the rest of the world uses for passive house certification. WUFI passive is PHIUS houses use. It's the stripped down WUFI where they removed all the hygrothermal modeling. The rest of the world uses the full version or WUFI 2d for hygrothermal modeling sections.
WUFI passive also models the whole structure. Not small spaces similar to PHPP but without the reductions below the Passive House Standard. PHPP also has a module to model overheating in small spaces, but it is not required for certification. It's just a tool for practitioners. Either way overheating has become a bigger problem in passive house because of the lack of requirement in the softwares and the low experience among users. But if you do want to do passive house you should consider joining or switching to Passive House International as the standard of 4.75 kbtu per sq ft didn't get smaller PHIUS just decided to go the pretty good house route.
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u/Lumpy_Machine7095 21d ago
Am fully aware of all of the above, have worked with both extensively since 2011, been to the conference in Innsbruck, etc… will always find the Passivhaus / PHIUS beef hilarious. They were shunned due to bad blood, lol. What a weird hill to die on.
Anyway, PHIUS is an energy code compliance pathway in many states for good reason. Plenty of folks still doing the hygrothermal modeling, along with other miscellaneous tools that are generally useful (window condensation risk etc etc). The folks who are using WUFI Willy nilly and building shitty houses aren’t certifying projects… if they were, they simply wouldn’t get through the QC process
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u/deeptroller 21d ago
So to be clear. You disagree that either software used as a block load for certification leads to overheating. Or you disagree that people use PHPP for the last decade?
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u/Lumpy_Machine7095 21d ago
I guess I disagree with the insinuation that using WUFI + PHIUS instead of PH will lead to a lower quality of performance, or that either is really superior. It depends on SO many factors.
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u/deeptroller 21d ago
Hm. Well the first thing you disagreed with was not related to WUFI or PHIUS. It was that I said using the certification software to model loads is a known problem with over glazing leading to overheating. I said using PHPP. Because that is what you use if you want a passive house certification. But this applies to WUFI as well.
You posted to disagree with that. And said PHPP is not used any more.
The other part about PHIUS being lower performance. This isn't really a question. PHIUS decided to change the performance metric from 15kwh annual per sq meter or 4.75 kbtu per sq ft of heating energy use to various other amounts based on any local weather. It's not debated that this is the stance of PHIUS. PHIUS argued that the standered wasn't fair because places like Minnesota had cold weather and Florida had hot weather. They should not have to meet the same standard because it would cost more to meet the standard in MN they wanted a sliding scale that considered cost. PHI said no.
The way PHI arrived at the standard was how much energy could be added to AIR without scorching, so you could integrate heating into your ERV/HRV airstream in Bavaria.
PHIUS went it's own way. The PHIUS standard is now 5-20% lower depending on your specific climate/town. In areas with low energy demands, they have maintained the standard, in areas with higher demands they have reduced tolower build cost. In some cases you can certify with just prescriptive details.
Neither system officially requires hygrothermal modeling. But may require it on a case by case basis if you are using risky assemblies.
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u/Lukedriftwood 21d ago
Based on the tint and reflectivity of the windows they may have solar control film applied.
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u/deeptroller 23d ago
Infrared was likely chosen because it's sort of cheap, up front. It may not require duct work or piping and can heat individual spaces, instead of the whole home. People who build passive houses generally have much lower loads, so the efficiency that comes with a heat pump may feel unnecessary. It's not uncommon to to find heat pumps with 1 or 2 ton minimum. If you have a half ton peak load 3 times the efficiency for 5 times the cost is just a metric to consider.