Passive House Brownstone
beckyv
| Posted in General Questions on
Hi-
I’m on a deadline (today) to do a schematic design for a 4.5 story brownstone- new building, ground up. We’d like it to be Passive house and will reach out to a consultant later, but first hope to clarify some general parameters for our initial design. Would it be possible to get advice on:
-Thickness of insulation added to existing party walls (1′-0″ +/- brick)
-Thickness of front and rear facades (and is rain screen preferred? And must windows be minimized?)
– Heating/Cooling: can mini splits be used and still be passive, using lower capacity units? Each floor will have single or double apartments.
Thank you!
Becky
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
More information is needed to provide sensible answers. I'm thinking you left this a little late to be asking advice, the day the design is due.
Becky,
You can't design a Passive House without using sophisticated energy modeling software called the Passive House Planning Package (PHPP). Entering the data for a PHPP run takes more than 24 hours, so you are in trouble.
I don't understand how the design process for a multi-million dollar building led to a question like yours.
I"m not a certified Passive House designer, but its likely that the thickness of party walls would be determined by sound attenuation for a luxury home, rather than insulation. You likely can assume that heat losses or gains are zero or minimal through party walls to other conditioned living spaces of neighbors. You could get excellent sound attenuation with walls as thin as 2-3".
To remain below Passive House total heating energy maximum, you budget your heating losses among various parts of the building envelope, as you choose. Assuming you choose about R-40 walls, that would require a wall about 11-13" thick including cladding, sheathing, insulated stud walls, and interior drywall.
You could use two mini splits, but they likely would be overkill, and would be best to be low capacity. The real problem is that your total use of energy, total heating energy etc must be below very stringent targets. That has to do with a highly efficient shell, requiring little or no heating or AC.
Thank you Robert-
Hi Becky -
You need help: David White of Right Environments (https://www.rightenvironments.com/about). He has done more brownstone passive house projects than anyone. Plus, besides being brilliant, he is a really wonderful person.
Peter
I'll check this out. Thank you Peter-
Thank you for your constructive responses. My original post didn't tell the full story, actually wasn't really accurate- question was for a design competition, not brick and mortar project. I'll contact a green consultant during the week, just looking for any helpful feedback over the weekend, as I'm beginning to design-
Consider you may have selected the wrong goal.
Passive house has a nice ring to it but its goal is xBTU per square foot, my problem is there is no dollar sign in this goal. So it is a blank check depending on your climate.
Consider a “net zero goal” where you stop spending craze money on insulation that can never save enough energy to pay for itself and instead use some of that money to buy solar panels. So your insulation levels are set by the current price of solar panels and your climate.
The “pretty good house” goal is a very common sense goal.
Walta