Single Story Passive Homes?
jackofalltrades777
| Posted in PassivHaus on
Is it possible to make a viable single story passive home? Most are two-story designs since you can fit more glazing on the south elevation with two floors.
The other question I have is can one find any “public domain” single story passive house designs to those who want a PH but can’t afford to hire an architect to design one?
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Replies
Hi Peter L.
I think you have raised an Excellent Question.
I see NO reason why a Passivhaus or an Affordable "Low Energy Home" can not be One Story.
Especially since there is now the realization that Maximizing Equator facing glazing is not ALWAYS the best strategy.....
It's not only Passivhaus that seems to favor Two Story Designs.
Almost every "Building America" Example is also Two Story.
The assumption has been ... since a two story design has less TOTAL surface area...there will be less "heat transfer".
The focus has been on reducing TOTAL surface area... and the forms tend to be more "cubic".
It's true that High R-value Basements and Foundations are very costly per square foot.
... so a Two Story "Seems" to have an advantage....
I don't think it's so simple.
We must also consider that Extremely High R-Value walls are also Very Pricey...and that High R-value walls are VERY thick which increases the total footprint of the house.
A stair also adds to the total footprint....A big factor in a small "right-sized" home.
And consider that THE most affordable High R-Value Assembly is the humble Vented Attic with "Cellulose Galore on an Airtight Attic Floor"
Other reasons to favor a One Story ...
1. Universal Design and "Aging in Place"
2. Easier (and safer) to construct.
3. Easier (and safer) maintenance (painting, gutter & window cleaning)
4. with an ample roof overhang ... FAR LESS wall area exposed to Rain and UV.
Peter,
The reason that there aren't (to my knowledge) any "public domain" Passivhaus designs is that meeting the standard is very site-specific. The same design won't be certifiable if the amount of available sunlight or the climate is slightly different from that at the site for which the house was originally designed.
Q. "Is it possible to make a viable single story passive home?"
A. Yes, of course. But in many climates, such a house wouldn't make much sense, because it would require insulation levels that aren't cost-effective.
Every time that a Passivhaus design deviates from the "stacked shoeboxes" shape, you need to add more insulation to compensate for the less-than-ideal shape. So, you can have an ell or a bump-out, but you'll pay for it in some way -- usually by having to crank up your required R-values another notch. Similarly, a one-story Passivhaus can be designed -- it's just going to require a lot more insulation than a two-story Passivhaus.
This raises the question: why would you want to hit the 15 kWh/m2*year target if the insulation levels aren't cost-effective?
My advice: if you want a one-story house, by all means build it. But it doesn't need to be a Passivhaus. It can be a Pretty Good House.
Maybe Peter isn't looking for a "certified" house ...just a Darn Good one
Martin wrote:"Similarly, a one-story Passivhaus can be designed -- it's just going to require a lot more insulation than a two-story Passivhaus."
A Two Story will Obviously require "a lot more" Ceiling Insulation(potentially very affordable cellulose).
But not "a lot more" or even "more" Wall Insulation....
A One Story has LESS wall area.
Just imagine 2 shoeboxes that have been "joined" on the ground...instead of "stacked".
There will obviously be more foundation area with a One Story....
But the amount of Required Foundation Insulation will depend on the Climate and the Average Ground Temperature.
And a larger footprint may also help "store" some heat/coolth in the earth.
The real question here is :
Why are you seeking Passivehaus standard ??
you then face 2 choices :
1- pushing to get PH certificate ( $$$$ )
2- using PH as guidelines/learning ( my choice )
I don't see why a single story building would have any problems with being energy efficient.
Doesn't change much...it all depends on your goals
Setting the right goal is much more important .
Peter,
As the others have said, it's certainly easy to take a stock floor plan and make it into an energy-efficient house that's damn good, if not PH. There are some really good plans out there on the Internet. In our case, my wife and I have been downsizing our house design since the Crash of 2008. Now it's at 1900 sf on one story: still huge by world standards, but decent for the US. Knock wood, we'll break ground next month. But the point is, we designed it ourselves at the kitchen table, and so can you. Floor plans aren't rocket science, especially if you go to sites online and see what works. The rest is just making the walls thick, plugging the leaks, and spending a lot of time learning what's on this site. And be realistic for your climate. In my case we drew the walls at 12" but went down to 10" when twelve seemed too much for our zone.
I think I will make my own plans and start one some time next year it is NOT Rocket science. My house of 47 years ago was as good as you could build then to the code this one will be in SC, on a slab and as conservative as I can make it. That's why I am looking at all this GREEN info!!!!
I hope so! Take a look at our project/adventure esp. the extension. All the details at pcb.uk.pn
We gave up with architects, just use a good building firm and common sense. Build by eye, and feel.
Those darn useless Architects and Home Designers ...who needs um
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