Replies

1. Expert Member
   Akos | Nov 25, 2024 08:47pm | #1

   I don't think the semi geo loop return will work. No ducted unit will pull enough CFM through such a long 6" return. You are also essentially taking the heat from the house and warming/cooling the soil around the house. Never mind the potential issues you can have with moisture in such a setup.

   If you want geo, simpler is a brine loop around the house to an air to water coil on the outside fresh air supply to the ERV.

   Sloped bellow grade garage/basement entrances were a thing for a while around me and now are specifically banned. Too many issues trying to keep water out of the house. If you want burmed, build in a way that you can still slope away from the house.

   Most codes need R20 or R5/R10+2x4 with batts for interior insulation for a basement. Won't change your design or heat loss much plus studs are a good spot for utilities.

   I would bump up the roof slope so you can use regular snap lock metal panels. 0.75/12 is possible but you rely on sealants to keep the water out, at 2:12 everything is simpler. This would increase the peak ceiling height and also let you install some high windows to bring more light into the space.

   Due to the risk of back drafting, some codes also don't allow bellow grade wood burning stoves.

   More a personal preference (don't like them), but if you have AC, ceiling fans won't do much. Your cooling loads are already so low that running the AC VS ceiling fans the cost delta is pretty much noise. Depending on your local climate, you might also need a dehumidifier as low load AC systems tend not to remove enough moisture.

   You might want to put a set of doors to your laundry room.

   P.S. Do the future a solid and size your footings to be able to support at least 1 more story.

1. 
   krackadile | Nov 25, 2024 09:32pm | #2

   Thanks for the reply.

   Comments/ clarifications:

   For the geo loop the concept is to open the return in the summer to allow air to circulate underground to cool and close the return (and open the damper near the stove) in the winter so that air does not circulate underground but is drawn from near the stove. With regards to condensation the piping is sloped downhill toward the stove with a plug at the end that I would crack open in the summer when condensation would occur (or just leave cracked all year long). The other function of the tube would be to temper outside air which would always remain open to help the drive to draft as well as allow the kichen and restroom exhauat fans to bring fresh air into the house. I think I did the pressure drop calcs to make sure the fans and minisplit can push the air through the ducts and piping but that's a good thing for me to double check.

   Water is a big concern so I figured I'd look at the site and depending on the risk of water intrusion I might go with burmed. I did include a sump for a pump just in case. The reason for this depth is to balance the soil so that all soil removed is used for berming (although that depends on the slope of the site).

   The current IECC requires r10 for continuous insulation for below grade mass walls. You want to hear something funny? The IECC only requires r8 for continuous insulation for above ground mass walls. Crazy no? I still don't quite uunderstand why. This is zone 4A.

   Back drafting is a concern. Do you think the always open outside air portion of the geo loop will counteract this?

   I did consider a higher slope for the roof. I'll think on this one.... there are some benefits and adding a little slope wouldn't add much cost.

   I included the fans to try to help keep air moving to help avoid any condensation but you're probably right that they won't really do much. I guess if I plan to run the minisplit frequently that it may be more cost effective to just remove them....

   Lol, I actually almost kicked myself when I initially didn't oversize the foundations. It all depends on the soil but for what I've got planned the foundation can support one additional story and I thought of maybe enlarging them more to allow a third story.

   I'll have to read up on stoves and drafts.

   Thanks.

2. 
   Malcolm_Taylor | Nov 26, 2024 12:02pm | #3

   Krakadile,

   GBA is all about high-performance building, and I think you are doing a good job trying to make the structure as efficient as possible, but in prioritizing that pursuit I think you have ended up with what is largely a machine for living in. What it lacks in any joy. Something that makes you and others look at and experience the house as a place that is an interesting and pleasant space to spend time in. That's what I think this design needs to go towards now.

1. Expert Member
   DCcontrarian | Nov 26, 2024 03:10pm | #4

   One of Joe Lstiburek's talking points is that all buildings need maintenance, attractive buildings are more likely to get the maintenance they need and therefore last longer, and buildings that last longer are inherently greener. So most utilitarian isn't necessarily green.

1. 
   krackadile | Nov 27, 2024 07:47am | #5

   That is very interesting. I will have to look into this aspect of design a little further as I think I may be lacking in this area.

   Thank you.

3. 
   nynick | Nov 27, 2024 08:23am | #6

   There is so much experience and technology out there that it is unnecessary to reinvent the wheel. While I'm a true believer in building a house to please yourself, you need to always bear in mind that the home will be sold sooner or later. The broad real estate market doesn't like unique and a unique house affects price and appeal.

   Do what you want but keep that in mind.

1. 
   krackadile | Nov 27, 2024 01:11pm | #7

   Yeah. That's a good point. People really become accustomed to how they live.
   Thanks.