Replies

1. 
   johngfc | Nov 27, 2020 11:47pm | #1

   I've briefly looked into this - not at all deeply - and found the sites below to be useful. Having said that, so far it's been most insightful to build my own simple spreadsheet model, because (1) the simple programs make assumptions that are either too crude (e.g. categorical selections), or (2) the detailed models require very extensive data input, and it's too much trouble to enter all that stuff for the stage of design that I'm at. It's not difficult to build your own model, it requires that you learn the basic calculations, and you have to think carefully about what you're doing.

   I'm wondering if BeOpt would be useful when I'm further along with the design (https://beopt.nrel.gov/home), but suspect the detailed data entry requirements and learning needed to use the program and OpenView environment will require more work than I'm willing to put into it.

   For others with more experience, I think it would be helpful to know why you want to do the modelling (e.g. roughly identify energy losses in an existing house, optimize new construction, meeting PH or other standards, etc.), level of effort you expect to put into this (casual, deep dive), the level of complexity and level of resolution you need, and perhaps your "quantitative bent" (are you an engineer?). If you want to model an existing structure, it would be useful to know what you actually know about the building - have you had a blower door test, know the wall structure, etc? When you do your first model, you'll immediately understand why people on this site put so much emphasis on blower door tests ... No sense trying to use a detailed model if all your inputs are guesses.

   A quick web search will reveal many commercial models and some free ones.

   There are a number of good articles and links here:
   https://www.greenbuildingadvisor.com/article/how-to-do-everything
   - see: how to decide whether to use energy modelling software, whether to use Man. J, etc.

   I also found these were a good start:
   http://www.sensiblehouse.org/nrg_heatloss.htm - excellent introduction to principles, formulas, and calculations
   https://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm - good, very basic calculator and associated info
   https://www.loadcalc.net/ - simple "Manual J" model (with assumptions ...)

2. 
   7036905 | Nov 28, 2020 04:48pm | #2

   Thanks for your reply, John. I have mid-life architectural degrees but mostly consider myself a seasoned builder - since 1978. I am building a house for myself in Midcoast Maine and am at a point in that construction where I can fine tune insulation levels. The house is a 1400 sf, largely open floor plan and passive solar. It is currently an "airtight" (Blueskin) shell with 2x4 frame 16"oc, 16"TJI rafters, and with full basement. No blower door test has yet been done. I have "modeled" the project after being inspired by a GBA article on a house being built by Rick Meyers with its hybrid exterior and interior insulation strategy. I have the time to learn to do energy modeling at this point in my project: Obviously this is different than the usual "all done" design before construction started. Building it myself and with my own wallet has given me this opportunity. So far so good. I will check out your links. Thanks again.

3. 
   Rickgrnv | Nov 28, 2020 09:11pm | #3

   I think the freeware Climate Constant developed by UCLA is a great place to start for architects and builders who are new to energy modeling.
   http://www.energy-design-tools.aud.ucla.edu/climate-consultant/request-climate-consultant.php

4. 
   walta100 | Nov 29, 2020 06:09am | #4

   I am a fan of BEopt yes it takes time to watch the training videos and learn how to enter the data. I think by the time you got to house 4 a person would be moving very quickly. It is a very powerful tool because it has so much data specifically about your house, any program that uses less data has the problem of garbage in equals garbage out.

   It seems to me the choices have already been made in your project I do not see any value in building a model with the goal of confirming your gut feelings were or were not correct. The point of the model is to allow you to make the optimal choices and get the maximum return on your investments. When I run my BEopt model the code minimum house and the passive house have very similar monthly costs when you borrow the money to buy the insulation that will never pay for itself in my lifetime.

   Walta