John C. Semmelhack
  • Charlottesville, VA
  • United States
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Latest Activity

John C. Semmelhack replied to David Holtzclaw's discussion GSHP for domestic Hot water
"Mitsubishi has a refrigerant-to-water heat exchanger in their City-multi VRF lineup, but you have to add an additional heat exchanger (probably in the tank) to move the heat from Mitsubishi's non-potable rated heat exchanger into the potable…"
Jun 13
John C. Semmelhack replied to Robert Bean's discussion Low velocity consequences in the group Kitchen Ventilation
"I'm not familiar with any recommended minimum velocity for residential range hood exhaust ductwork. I suspect that long-term grease deposition in the ducts is minimal for most residential applications, given the intermittent use of the cooktop…"
Jun 7
John C. Semmelhack liked Diane Chojnowski's discussion Everything you need to know about California's new solar roof mandate
May 25
John C. Semmelhack replied to Gary Hall's discussion HERS score with HRV
"I agree with David really depends on the inputs into the model as well as the efficiency of the HRV. There's a big range of heat transfer and fan motor efficiency in the HRV/ERV world. If the ASHRAE 62.2-2013 ventilation rate…"
May 19
John C. Semmelhack replied to Diane Chojnowski's discussion Portland home energy scores not so hot
"From the article: "Lynae Forbes, president and principal broker at Hasson Company Realtors, said her industry is still facing some challenges with the new mandate. From what she's heard from her brokers, large houses are prone to low…"
May 10
John C. Semmelhack liked Diane Chojnowski's discussion Portland home energy scores not so hot
May 10
John C. Semmelhack replied to Andy Wahl's discussion Fire Rated High Performance Doors
"I agree with David. All of the tightest houses I've tested have used Therma-tru doors (including a fire-rated door to garage in a couple of houses) and we've seen near-zero noticeable leakage around the doors when properly installed,…"
May 2
David Butler replied to John C. Semmelhack's discussion ACCA: Call for Volunteers to Aid the Development of a New Design Manual for Low-Load Homes
"It's about damn time."
Apr 16
John C. Semmelhack posted a discussion
Apr 16
John C. Semmelhack replied to Dav Camras's discussion Experience with new energy monitoring tools such as Curb, Sense, Nerio and Smapee
"I've tried out most of the available residential energy monitors over the years and am satisfied with none of them. The ones that monitor just a single circuit don't provide enough detail, the "learning" devices (such as Sense)…"
Jan 9
John C. Semmelhack replied to Blake Shurtz's discussion Replacement for Energy Conservatory Flow-blaster
Oct 24, 2017
John C. Semmelhack joined Allison A. Bailes III's group


HVAC design, Manuals J, S, T, & D, Duct leakage, Air flow, ENERGY STAR new home requirements, and more. Since heating & cooling are such a big part of home energy use, understanding HVAC is critical.See More
Oct 1, 2017
John C. Semmelhack replied to Rob Buchanan's discussion Whole-house Ductless Mini-split install costs
"For multi-split systems, plan on roughly $2,500-3,000 per indoor "head"....on the lower side if it's 4-5 heads...on the higher side if it's just two heads. This will also vary up or down up to $500 per head depending on if…"
Feb 12, 2015
John C. Semmelhack replied to George Kopf's discussion How does efficiency factor into a grid parity world?
"Graham, The U.S. is catching up to Germany very quickly on solar installs. As of the end of 2013, the Germany-to-U.S. cumulative installed solar capacity ratio was about 2.6 to 1. At the end of 2014, it will be closer to 2 to 1. The U.S. will likely…"
Oct 23, 2014
John C. Semmelhack replied to Jack Baikoff's discussion Measuring fresh air intake ducted to a return and no way of measuring from outside.
"HVAC contractor (ideally) drills the 1" hole, then tapes over afterward.  I invested about $250 for 4", 5", 6", 7" and 8" versions of the device. "
Jan 24, 2013
John C. Semmelhack replied to Jack Baikoff's discussion Measuring fresh air intake ducted to a return and no way of measuring from outside.
"By the way...not sure what climate you're in, but someone should probably should insulate that fresh air duct!"
Jan 24, 2013

Profile Information

Think Little
Professional Certification
Certified Passive House Consultant, HERS Rater, EarthCraft Virginia Technical Advisor, BPI Building Analyst
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At 4:19pm on October 11, 2011, Diane Chojnowski said…

Hi John,

Welcome to Home Energy Pros! Feel free to join the conversation in the Forum and Groups. And share your energy efficiency photos, videos and upcoming events. If you're blogging about home performance, this is the place for you!

Don't forget to upload your profile photo. And add your location on our Member Map!

Diane, HEP Moderator


Forum Discussions

Overheating garage

Started by Chris Bellanca in Best Practices 1 hour ago. 0 Replies

GSHP for domestic hot water

Started by David Holtzclaw in General Forum. Last reply by David Holtzclaw 4 hours ago. 3 Replies

Log home roof insulation

Started by Bob Reuther in Best Practices. Last reply by Daniel Baur-McGuire yesterday. 8 Replies

Latest Activity

Chris Bellanca posted a discussion

Overheating garage

Hi all, I'm looking for potential solutions to a problem at a client's house.  The south facing 2…See More
1 hour ago
Landon added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase

Brand new retrotec blower door system $3000

Hi, I’ve got a brand new blower door system from retrotec that I got 2 months ago, and never got…See More
1 hour ago
John Redmond posted discussions
1 hour ago
David Holtzclaw replied to David Holtzclaw's discussion GSHP for domestic hot water
"Thanks John & Bill. Bill your experience is one reason why I wanted a larger heat pump with…"
4 hours ago
John White posted photos
13 hours ago
Diane Chojnowski posted events
Rob commented on Bob Krell's group Healthy Indoors (IAQ)
"Hello, Has anyone tried custom filtering of window AC units? Specifically concerned with…"
Michael Dunseith's 2 photos were featured
Franco Oyuela commented on Perry Ning's blog post Warnings About Portable Air Conditioners
"Here are the top five benefits of owning a portable air conditioner: 1. Low Price – All…"
Daniel Baur-McGuire commented on Kurt Shafer's status
"Whole house fans are a scam if you use air conditioning. Seriously "
Daniel Baur-McGuire commented on Michael Dunseith's photo


"Looks fun. How did you connect all the fans together or did you adjust the flows manually? The…"
Daniel Baur-McGuire replied to Bob Reuther's discussion log home roof insulation
"I would look to stop air from penetrating the ceiling. I would guess hot air is able to rise…"
Jay Lillien posted a blog post

How Changing Temps Affect Your Home’s Windows

In Colorado, there’s a time-honored saying:“If you don’t like the weather, just wait a few minutes……See More
Matt Peiris replied to H.O. Electric's discussion Stop Drinking Bottled Water! in the group News & Announcements
"Cities like Los Angeles now use chlorine AND chloramine to treat their water. While chlorine can be…"
Matt Peiris joined Diane Chojnowski's group

News & Announcements

Share your news and announcements with the community in this group.To post news or an announcement,…See More
Michael Dunseith posted photos
Ron Jones added a discussion to the group Job Board

Residential Construction Superintendent for Net Zero Energy Homes: Northern California

At Acre Designs (, we're bringing Net Zero Energy homes into the 21st century, and we're…See More
Kim added a discussion to the group Job Board

Job Opening - New Construction Specialist - Philadelphia or Pittsburgh, PA Location

New Construction SpecialistAre you looking for a collaborative work environment, colleagues who are…See More
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Steve liked Alex Jonson's discussion Constant Airflow Regulator


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