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Residential HVAC Design

mega_pointe

I recently began working for a newer residential design-build practice and am trying to identify methods for improving our understanding of the HVAC systems we need to put into our homes. Before this job I worked at a commercial AE practice where I enjoyed the convenience of having mechanical engineers to design ductwork and run load calculations. 

Because we are a design-build practice I would like to have some rudimentary information in our drawings (schedules, schematic duct layouts, etc) to have informed discussions with potential HVAC subs about the sizing requirements of the systems we are putting into our projects. To make things more challenging, we only subscribe to Revit LT and do not have the Systems tab available in the full version of Revit. 

I'm not trying to necessarily do entire Manual J calculations but am looking for other ways to have these basic but informed conversations. What methods do you employ at your residential practice, if any? Thanks for your comments ahead of time. 

 
May 4, 22 2:39 pm
Wood Guy

I do high-performance residential design and for my colleagues and I, mechanicals seem to be one of the trickier aspects. I don't have great advice other than to learn the basics yourself. I spend a lot of time on Green Building Advisor, go to conferences--I just went to one in Vermont and had a session on duct design--buy ASHRAE Fundamentals, etc.. Most importantly, find an independent ME who focuses on residential HVAC. They are very hard to find and always busy if they are any good, but they are out there.

May 4, 22 4:20 pm  · 
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mega_pointe

Thanks Wood Guy! We'd love to hire an ME - full time or as a consultant - but in an attempt to keep prices down for our clients we're trying to find ways to do some of this ourselves. I agree, this is definitely one of the trickier things when it comes to residential design. We definitely want to design high performance homes but I just don't feel great leaving it to an HVAC contractor to be the majority decision maker on what that means when it comes to selecting and sizing equipment. Besides the book you mentioned, are there other specific books, websites, conferences you would recommend? I've definitely become a fan of GBA.

May 4, 22 5:30 pm  · 
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Wood Guy

Most equipment on residential projects is sized by unlicensed engineers at supply houses who don't ask or care about things like insulation levels, window size and performance, or air leakage--they use the lowest common denominators because they are terrified of having under-sized equipment. The result in high performance homes or even average-performance homes is equipment that is 2-3 times as large as necessary. High-end equipment can often modulate down so you aren't wasting a huge amount of energy, but the up-front cost is higher than necessary and it often doesn't work as well as right-sized equipment.

You should consider following my friend Dr. Allison Bailes III: https://www.energyvanguard.com.... He writes prolifically about all things energy, but especially mechanical systems. He just finished writing a book which I preordered and I'm sure it will be great. 

Shameless plug: for the basics, you might consider pre-ordering a book I just finished co-writing: https://www.tauntonstore.com/p....

I just had lunch with John Siegenthaler, a superstar when it comes to hydronic systems: https://www.hydronicpros.com/.

Another shameless self-plug, the Zoom-based talk show I started and co-host: https://www.thebsandbeershow.c.... All past shows are here: https://www.youtube.com/channe...

Maybe it goes without saying, but maybe not--I highly recommend going through Passive House training. I learned a lot doing that, including basic mechanical design. 

May 5, 22 8:31 am  · 
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mega_pointe

Whoa, thanks so much! I literally preordered your Pretty Good House book yesterday before this conversation. I'm excited to get it sometime this summer! I've watched a couple episodes of the talk show and will definitely tune in more. I've been really interested in Passive House training and will hopefully do so in the near future... but I love the realistic principles of the PGH! Thanks so much for the thoughtful replies.

May 5, 22 9:14 am  · 
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mega_pointe

Do you have a link for pre-ordering Dr. Bailes book? Looks like there was a pre-order campaign a couple years ago but I can't find a link to pre-order today.

May 5, 22 9:18 am  · 
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Wood Guy

You're welcome! My initials are MM; I just use a screen name here so I can bitch about clients when necessary ;-)

It does look like Allison's pre-order is closed for now, but here is a sign-up to be notified when it's open again: https://www.energyvanguard.com/book-house-needs-breathe-or-does-it.

May 5, 22 9:51 am  · 
1  · 

since you're design-build, just reach out to a local potential supplier/installer of the HVAC equipment. Some of them are used to working off drawings and can advise on equipment, best practices, run a manual j, etc. 

May 4, 22 9:57 pm  · 
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atelier nobody

I'm an architect, not an engineer and not very "mathy", but I didn't find doing Manual J, Manual D, or basic Energy Code calcs very taxing. Of course, that just gets you to code compliant - if you're after high performance it gets trickier.

May 5, 22 2:00 pm  · 
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mega_pointe

I have not dove into any of these calculations myself but it's good to hear they weren't especially difficult for you. Did you use a software to help you or do this manually? Are you referencing any literature or websites? Thanks for the input!

May 5, 22 6:45 pm  · 
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