Best HVAC system and suggested improvements
My wife and I are seriously considering building a home on a large lot in a rural area near Rochester, NY (Zone 5). Our general plan is a single story house slab-on-grade house with a partially enclosed courtyard. It poses some challenges, because for its floor area, it has a large and long footprint. I’ve attached my rough plan for the house, with the hope that I can get some good insight from the GBA crowd.
I would like advice on how to efficiently heat, cool and ventilate it. I am concerned about keeping the heat running when the power goes out. Furthermore, I would welcome general suggestions on how to improve the design. I’m also curious if there are any efficiency standards that would be worth pursuing,
Current plans:
We’re building at the high point of a open mostly flat lot (a portion of a field). The courtyard opens southward. The best views are east and west. There are no nearby trees at present. There will be a detached garage south of the house.
Building on an EPS insulated monolithic slab.
Exterior walls are going to be R-40 double stud walls, air sealed at the WRB, with a rainscreen and wood siding.
The ceilings will be 10′ tall. Ceilings will be framed with 2x8s or 2x10s with a plywood air barrier above the framing. The attic floor will be covered with R-60 cellulose.
Roofs will be 4:12 shed roofs with ample overhangs. The roofs will slope away from the courtyard to reduce the snow and water that ends up there. The roofs will likely be framed with trusses held off the attic floor by 2x lumber around the edge.
Around the inside of the courtyard, a lower roof will protect a walkway.
The door between the family room and study will always be closed to keep pets out of the bedrooms.
The lot has no natural gas, but has lots of open space to install solar.
The kitchen will have a Stiebel Eltron mini tank water heater, and the bathroom off the kitchen will have a Stiebel Eltron mini tankless water heater. Everything else will get hot water from a large electric tank heater.
–John
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Replies
John,
This type of house -- one that has many corners and that is not compact -- will never be particularly energy-efficient. I urge you to create a courtyard with hedges rather than with a U-shaped house.
Ideally, you want to design a simple rectangle. You can deviate from a rectangle somewhat, but your design has a terrible surface-to-volume ratio.
A related point: Your design does a bad job of planning for foot traffic inside the house. The passageways through the family room and study are particularly awkward. If you keep the U-shaped house -- and I don't think you should -- you need to think about proper hallways. Of course, the hallways will take up a significant portion of this type of plan -- another reason to abandon the U.
John,
Check out this thread: https://www.greenbuildingadvisor.com/community/forum/plans-review/58526/ideas-floorplan I bet you'll find some ideas and answers to layout efficiency in this thread. Many good people patiently contributed answers to my questions.
I'm still trying to come up with a plan as well. I like the plan I have now but I may add a bump out for a little character and living area. I'm happy to share my latest with you. You'll find my email in the thread. Just drop me a note.
In Rochester's lake effect snow-pummeling location you'll have a heluva snow removal problem in the yard with a closed or semi-enclosed courtyard configuration.
You'll also probably end up with some big valleys in the roof that need hand remediation after big storms.
Average annual snowfall is between 90-100", but that's "average". Non-average years can see more than 10' of snow, and it's not nicely distributed in time- it often comes in big lumps of 2' or more in one go, with drifts of 5'+, which you absolutely don't want to see captured in the courtyard of your U-shape, since you'll also have to shovel off the 5'+ depths out of the roof valleys to keep the weight and ice damming risks bounded. This footprint might work just fine in San Diego, but it's rife with issues in your location & climate.
Shoot for at worst an L-configuration, and think long & hard about rooflines. A simple single gable would have the least amount of snow trapping, steeper pitches shed snow better than shallow pitches. An L-configuration with the ridge lines closer to the inside of the L for a short valley and a long hip might not be too bad, especially if the valley side is steep enough to reliably avalanche quickly after a storm (steeper than a 12:12 pitch on that side.)
Dana,
You missed John's description of his roof: "Roofs will be 4:12 shed roofs with ample overhangs. The roofs will slope away from the courtyard to reduce the snow and water that ends up there."
That means two hips and no valleys.
BTW: On the HVAC recommendation front: It's WAY too early to be able to weigh in on good/better/best approaches. At the very least a preliminary heating & load calculation is in order, and if the footprint is in a state of flux those estimates cannot be done.
Thanks, Martin- I indeed missed the shed-roof description!
Something steeper than 4:12 is still recommended for that amount of annual snowfall.
The U-shape is still going to be a snow-trap with major courtyard drift accumulations, no matter which way you orient the house relative to the prevailing lake-effect snow wind.
John,
In addition to the great information you will get here, you may want to reach out to Matt Bowers who recently completed a Passive House in Rochester, and his site is appropriately named http://www.rochesterpassivehouse.blogspot.com.
John,
Not knowing the thought processes that lead to your design, I'll just suggest some small tweaks:
- The circulation between the public areas of your house (the main entry and living rooms) is a bit circuitous and leads you through the kitchen. Most contemporary houses have the kitchen open to the dining and living spaces but If you don't like that approach, moving the powder room up so that the corridor is against the courtyard exterior wall will help. I would suggest moving the doors to the study down to this wall too, but I think you may be planning bookshelves there?
- The family room seems shoehorned in. This is made worse by having access to both bedrooms on one of the walls. Moving the doors to what is now a storage closet between them would help and also provide them with more privacy as they would be accessed from an alcove.
- The long hallway leading to the master bedroom could be shortened by moving the door up either to align with the wall of the en-suite bath, or further to just before the entry to the main bathroom. This will make the master bedroom feel a lot more private.
Good luck!
Hi Malcolm,
The automatic labeling is misleading. The door off the living room next to the coat racks is intended as the main guest entrance. The room labeled entry is actually intended for quick access to the courtyard (grill) from the kitchen. This keeps guests largely out of the kitchen, except when they're heading to the bathroom.
I cook a lot, and I don't like open kitchens. It's my personal preference. I want to be able to close doors to deal with smoke or hot pepper fumes.
I love the ideas for the alcove in the family room and pulling the hallway into the master bedroom.
The suggestion for moving the hallway down I find attractive, except that I like the study as-is. The pass through gives access space around the stacks.
I'm coming up with an alternative plan that doesn't have a U-shape. My wife really likes the courtyard, but being engineers, we both understand that the large surface area to volume ratio is not optimal. We'll see what I can come up with for a box with a hip roof.
Thanks much!
--John
Hi Martin,
My wife really likes the courtyard, but she's open to a design that creates a courtyard through other means. I'm working on folding the house into a hip-roofed box. Once we agree on a layout, I'll post a revision.
I agree that the family room is awkward, and I think Malcolm's suggestion works well to improve it. I actually like the study, but it's probably going to change anyway. Regarding foot traffic, it's unclear from the drawing, but the main guest entry is off the living room, limiting guest traffic to the west wing.
--John
Hi Dana,
I understand the concerns about snow. To my eyes, this layout is a huge improvement over my past houses. The open side of the courtyard, while admitting blowing snow, also provides a path to clear it. I have a maneuverable but heavy-duty gas snowblower that held up to the snow in Boston two years ago. (Damned lucky purchase. I bought it about a month before the first snow, thought I was buying a stronger machine than I needed, and then had the only snowblower on my block that worked.)
I've shoveled compacted 5' drifts off a rickety barn, which is why I designed this roof to have no valleys and slope toward the exterior. That's pretty much a requirement for me. I'll definitely consider increasing the slope of the roof.
Thanks!
--John
John,
As an architect I probably have different starting point than many other posters whose primary concern is efficiency. The primary generator of form should be how you want to live on that site in that climate. If what you came up with is a courthouse then I wouldn't be too quick to change that.
Houses are primarily cultural artifacts. They don't look like they do because of logical reasons any more than our clothes or cars do. They are not machines for living in. You have increased the area of exterior walls over that of a more efficient rectangle, but your roof area remains the same, and the building assemblies you are proposing will yield a very efficient house.
Any changes I suggested are just that: suggestions. Build a house you and your wife will be happy in. That's a huge achievement in itself.
I live in a house that has an even smaller U-shape on one side than the one in your floor plan, with a deck in the middle. My back definitely feels it those winters where we get over 95" of snow (the average in Rochester). Just sayin'...
Part of the pain is also digging out the roof valleys, but there is literally a ton of snow on the deck after every decemt nor'easter. If I didn't regularly clear the deck of snow would be above the window sills in an average snow year ( a mere 60" in my neighborhood), and would be in contact with the siding despite 2' overhangs. Other parts of the walls can sometimes get a drift that needs to be dug out in a big snow year, but it's nothing like what happens in that snow-trap.