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How can I find an energy modeler?

Michael Schonlau | Posted in General Questions on

I’m looking for advice on how to find an energy modeler. I’ve spoken with various consultants (all out of towners) who tell me they can provide these services. Some are Passive House consultants, even though I’m not going for that certification I do like their detailed modeling process. Others are simply HVAC “experts” who seem to know heating/cooling load calculations.

Does anyone have advice on how to select a modeler? Should I be looking for specific experience, certifications/licenses, services offered? My goals are to get independent heating and cooling load calculations, advice on insulation levels, windows, and ventilation.


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  1. J Chesnut | | #1

    I think I recall earlier posts from you. For your situation ideally there is a calculation not as detailed as the Passivhaus PHPP but more detailed than HVAC heating and cooling load calculations. Unfortunately I'm not personally aware of professionals who are working in this middle ground.

    As a designer I've worked on designs to meet the Passivhaus standard. This type of energy modeling is most effective when used by the designer in during the design process. You would get meaningful quantified info from running calcs on an existing design in the PHPP software but that takes time and would require making some rough assumptions about overall performance because you stated you are not intending to meet the standard.

    If you were to hire a HVAC contractor I would wonder if their calculation could adequately account for passive solar heat gains. HVAC heating cooling loads are usually simplified because typically there is a factor of safety inherent when using conventional boilers/furnaces which are usually over sized to error on the safe side.

    I would ask the consultants you are talking to to show you examples of the output of the calculations to help give you a sense what value you will get from them.

  2. David Meiland | | #2

    You probably want a HERS Rater. I believe you can search the RESNET directory for people in your area.

  3. Lucas Durand - 7A | | #3

    If you want to try and DIY, here are some free programs you can try:
    "Home heat loss calculator" from the "Build it solar" website - simplistic, but kind of fun to play around with.
    "HOT2000" - a free download from NRC. I have played around with this program as well and it seems fairly powerful but I never seem to have time to get into it fully.

  4. Lucas Durand - 7A | | #4

    It seems there is a "HOT3000" energy modelling program now as well.
    Never tried it, but the write up makes it sound "hot" - or maybe "cool" as the case may be.
    It's a free download.

  5. Dick Russell | | #5

    If you are willing to spend the time to educate yourself on the fundamentals of heat transfer (something you may have done already) and to build a detailed model by spreadsheet, you can build the model yourself. The advantages to doing that are several. You can tweak the design as often as you wish without incurring continual consultant fees. You can be sure you have the model as detailed as you require, and not have to wonder about what things have been lumped together for simplicity and what other shortcuts have been taken. You'll know what goes into the bottom line, so you can target changes that have significant effect.

    Making a good model takes a considerable amount of time, something not every energy modeler may be willing to invest. Using a canned program, with calculations hidden behind the interface, leaves you with a certain degree of uncertainty as to accuracy of the results. If you do go the route of engaging someone's services, make sure your report is as highly detailed as possible, so you can verify the calculations.

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