ArchiCADDavid Bitter is sole proprietor of Solera Studios in Atlanta, Georgia. As such, he combines his passion for social responsibility and sustainable living to create homes that are among some of the most environmentally responsible dwellings possible – designed per the “Passive House” standard. The South Carolina home featured in this story is currently pending final Passive House certification, but was designed to those exacting specifications. Passive House certified homes are built to the world’s most stringent energy standards and boast a reduction of annual heating and cooling energy consumption by an average of 80% – 90%. Bitter uses ArchiCAD to be certain his homes use as little energy as possible and have unparalleled comfort conditions and superior air quality – the hallmarks of Passive House design.

ArchiCAD Passive HouseThough super insulated, and virtually air-tight, Passive House can claim superior air quality and comfort levels relative to traditionally built homes because all ventilation air is filtered of airborne pollutants (pollen, etc.) rather than being accidentally admitted through random pathways in building crevices. Additionally, the extremely low amount of conditioned air required for a Passive House means there is no longer the constant background sound of a forced air system at work.

Since the building energy loads are so low the size of the heating and cooling systems can be dramatically reduced; the savings for active systems are invested in the passive envelope of the building. “You might say we bundle up the building in a nice cozy coat.”

Owner Deb Tucker says she’s very happy with the way the home’s energy efficiency is performing – and her energy costs are proof that the home is meeting its Passive House goal.

“The home is exceeding expectations in terms of savings on my utility bills, last month’s utility costs were $58.00 – the standard in this area is several hundred a month for heating costs.” Bruce Kitchell of Airedale Energy Consultants, the Phius Plus Rater for the project, expects those numbers to drop once the fine-tuning of the mechanical systems is completed.

While the home is designed with a small envelope, the interior is set up to feel spacious and be highly functional, according to Tucker, it is a perfect fit.

ArchiCAD Passive House“We’re not talking “McMansion” here – there is no wasted space and every inch of the home has a purpose.”

Bitter says he used ArchiCAD to its fullest extent in creating the design for the home, managing the MEP systems and utilizing data from the model for use with PHPP (Passive House Planning Package). Jeff Dinkle, of Eco Custom Homes, was the Passive House Consultant for the project who made sure the design met the stringent performance criteria outlined in PHPP – which Bitter points out, is not a small task when you are dealing with a 30 tab excel spreadsheet of calculations, yet simplified through the use of ArchiCAD.

“ArchiCAD was a big asset, the advantages of BIM in general is interrelated and reflected throughout the documents. The most obvious benefit was the time savings that all the coordination provided me, I’m able to be fully productive every time I access the model.”

“Given that it is a south-eastern US climate zone 3A, extremes of temperature and humidity have to be considered.”

ArchiCAD Passive HouseAccording to Bitter, the project also utilized ArchiCAD to optimize the MEP systems used for the Passive House design. ArchiCAD was used to model the novel conditioned energy recovery ventilator (CERV), by Build Equinox, which enhanced comfort levels even further by providing controls for monitoring of VOC and CO2 levels directly interfaced with the conditioned ventilation air requirements.

“I created a 3D of the mechanical distribution system to keep tabs on the supply and return of air. ArchiCAD allows me to turn layers on and off – so I was able to see all the duct work snaking through the webs of the trusses. It was a fantastic advantage for all the team members working on the project, in terms of coordination.”

Bitter says he made full use of BIMx to keep his client informed of changes and options as the design progressed forward. There were many instances during the design process where the BIMx file was exchanged between Bitter and Tucker – as they made decisions about the look of the interior, especially.

“My client loved being able to walk through the BIMx files. I would send her updates in the way so she could visualize each change we had discussed and really get a feel for what living in the home would be like. Hands down, BIMx is the biggest plus in terms of working with the client.”

Tucker was able to show the home’s design in BIMx on her iPhone to friends and agrees wholeheartedly, “I cannot see designing a house without BIMx, from the customer’s perspective, and it really does give you the feel of what the house is going to be.”

Passive House ArchiCADThe client embraced BIMx so well, she was able to take it upon herself to share the model with the contractor she had brought in on the project. Tucker reports that the use of BIMx helped eliminate confusion from the contractors and sub-contractors. Access to BIMx made it possible for her to communicate to the construction team, in Bitter’s stead, the design intent of the project.

“William Ashley has been around a long time and still does his job the old fashioned way. He doesn’t use a computer, but was able to absorb what my client showed him through the BIMx file. A BIMx picture is worth a thousand words. ”

Bitter notes that there is more to come. The client hopes to eventually implement the design prepared by permaculture designer Brandy Hall of Shades of Green which features around 65 kinds of herbs, bulbs, fungi, shrubs, trees and vines most of which are edible. Bitter laments that he did not have the time (or library) to make Brandy’s design come alive in ArchiCAD but conceded that it was still nice to have a hand colored rendered design in the document set.

“I was blessed to have a client who wished to showcase energy efficient and sustainable practices that others may be inspired to learn from and to be able to leverage ArchiCAD to help make that possible.”




  1. Geoff Briggs

    Great project! Can you tell me if ArchiCAD MEP modeler was used for the HVAC system. If not please tell me how the ductwork was modeled. Thanks.

  2. Don Armstrong

    Good for you Dave, a step in the right direction…

  3. Jack Robinson

    Were the 3D AXONS showing the ducts (in color) actually used in the construction documents? Usually construction documents are made at the printer’s in black & white.
    I like the use of color in construction sets. It can convey so much more information than black & white. Is this going to be a new trend?

    • David Bitter

      Yes…they were in color. Certainly is easy enough to do…especially with BIMx Docs…expect less and less use of paper docs.

  4. Bob Woodhurst

    Hey, Dave, that’s an impressive project, especially for our southeastern climate. I look forward to reports on how the house performs in an annual cycle.

    • David Bitter -AIA, CPHC

      Good to hear from you. Are fine tuning the systems…have a scheduled June 2 on-site visit by Build Equinox (makers of the conditioned energy recovery ventilator) to tweak the units logic. Will be posting final project pics hopefully in the near future.

  5. Douglas Clark

    Congrats on this project, well done.
    Do you prefer ArchiCad to Revit?
    What made using ArchiCAD advantageous in a Passive House project?
    Compared to Revit?
    Compared to AutoCAD?
    How did the HVAC system tuning.validation turn out?
    Can you overview the HVAC and building envelope systems in more detail?

    • David Bitter -AIA, CPHC

      I definitely prefer ArchiCAD…did a lot of “research” up front on ArchiCAD vs Revit…took formal training in Revit through intermediate level…ArchiCAD or Revit (BIM tools) should not be compared to AutoCAD…both are far superior. Revit’s big plus is that most folks use it (Autodesk had there foot in the door with AutoCAD). Happy to have taken the road less traveled.
      Did final blower door testing…did much better than the required .60 ACH @ 50 paschals.
      Used Build Equinox’s CERV unit(conditioned energy recovery ventilator with CO2 and VOC monitoring provide “demand controlled” performance ) plus a non-ducted Mitsubishi 9000 BTU mini-split as back-up.
      R37 walls: 5/8″ GWB, 2×6’s w/ JM “hybrid system” (3.5″ fiberglass + 2″ foam), Zip system sheathing, Dryvit’s EIFS (2.5″ polyiso) ; R60 roof: 5/8″ GWB, 14″ scissor trusses w/ JM’s hybrid system (12″ fiberglass + 2″ foam), Zip system sheathing; R31 slab system: 6″ XPS (Atlas Thermal Star X-Grade 25) + concrete slab.
      Think I will opt for dense pack cellulose in lieu of JM hybrid system next time (with some other refinements)…recommend “Builder’s Guide to Mixed-Humid Climates” by Joseph Lstiburek for this climate zone.


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