Replies

1. 
   Guest_ | Mar 19, 1999 06:11pm | #18

   *
   After you mentioned in the "Heat/Etc.
   Software" thread that you had done your
   own spreadsheet for heat loss
   calculations, I started looking for
   examples, and trying better to
   understand my (Clarisworks) spreadsheet
   program. I found a sample worksheet,
   which helped. You basically have a
   column for each sq. area of
   ceiling/wall/floor/window/door, along
   with insulative qualities of each, and
   you tote it all up. But....

   You are to assign an "RSI" value to the
   insulative qualities of each area (wall,
   ceiling, etc). I think "RSI" has to do
   with total performance: fiberglas
   rating, for instance, minus thermal
   bridging, air leaks, etc. (Most wall
   systems, for instance, are 20-50% less
   effective than their R-rating.) Also, the
   worksheet I saw used an unexplained
   multiplier that you multiplied the area
   by, before dividing by RSI, to get Watts
   of loss.

   So, Fred, how is your spreadsheet set
   up? And am I trying to get too tricky?

   I found some very interesting sites:

   http://www.ornl.gov/ORNL/BTC/

   http://www.aud.ucla.edu/energy-design-to
   ols/

   http://www.eren.doe.gov/buildings/tools_
   directory/index.cgi

   For those of you with strong PC's, there
   are some nifty looking, downloadable
   calculators. And the Oak Ridge Labs
   (ORNL) has incredible testing
   facilities, if you've come up with a
   wall system you want analyzed.

   One thing I found out a little about at
   ORNL is Larsen Trusses, which probably
   everyone else already knows about and I
   thought I thought of the idea first.
   (Usually happens: I think of a great
   shop idea, and my neighbor sez he's
   been doing it for 27 years.)

   Jim

1. 
   Guest_ | Mar 15, 1999 02:59am | #2

   *Divide metric RSI by .1761 to get real imperialistic R-values. Thanks for the web sites! I found something on AUDIT 2000, go to http://www.nrcan.gc.ca/es/etb/cetc/cetc04a.htm and I think you'll find that's the computer program that does what you want.

1. 
   Guest_ | Mar 01, 1999 12:23pm | #1

   *Ross,I gotta admit dumb on both (excuse me, ALL) accounts. What does "RSI" stand for? And "imperialistic"? And I'm having difficulty seeing the differences between Audit 2000, Base 2000, and BaseCalc, other than that the latter is $600. And will either of the others run on a mac--which was my on-going problem through the various threads?Now that I understand spreadsheet function a little better, I think I can (fairly easily) rig up a calculator, if I could just get a better handle on all the terms, and figure out how to make the final computation mean something. (I remember a Gary Larson cartoon entitled "Man's Early Experiments With The Wheel": they had a guy strapped around the outside of a stone tire and were rolling him down the side of a mountain.)Or, to be clearer: it's fairly easy to set up a calculator that will total up various sets of numbers,and then let you introduce variables that will give younew sets of numbers, but I'm not sure there will be anybeef. Fred, where are you??Jim

1. 
   Guest_ | Mar 16, 1999 03:25am | #3

   *RSI according to my book here means Resistance Value... okay, that doesn't make any sense, they're lying, that's what R-Value stands for, so my guess is that it stands for Resistance Something International. RSI is a metric measurement of thermal resistance, and the definition is unintelligible even to Canadians, so we just convert to American (also called Imperial)R-Value. A Canadian 2x6 wall has an RSI of 3.5, which doesn't sound near as good as R-20, so nobody uses RSI unless they work for the government. And sorry I missed that Mac problem, I have no idea if AUDIT 2000 runs on a Mac. As a former energy auditor, I can see trying to create a spreadsheet as being an excercise in mathematical frustration, because everything relates to everything else (R-values, numerous different surfaces, thermal bridging, air infiltration, solar gain, thermal mass, heating systems, occupant loads, lighting and incidental heat gains, etc. etc...). Sounds like you're probably way ahead of me though, if you're even attempting it! Good luck, if you succeed in creating something simple that can run what-ifs for heat loss without losing your mind, then you'll have done well!

1. 
   Guest_ | Mar 16, 1999 06:55pm | #4

   *Ross,Actually, spreadsheets baffled me until recently, mainly because of the (usual) bad/frustrating/geeky "help" manual that came w/ my Clarisworks program. But after finding a user group, and various dedicated websites, I see that it's fairly simple to set up a basic calculator. And I'm not looking to achieve anything terribly complicated.Whether I use R-rating or RSI, I think I just need to use common denominator terms for heat loss. Then, I set up a spreadsheet where I define one line each of square footage for floor, walls, ceiling, windows, exterior door, then one line each for R-rating of each element, and formula areas (cells) to tote this all up. Then I can change walls, say, from R-15 to R-25, to see what it does to total heat loss.ORNL has an area that shows how different wall systems perform (the difference, for instance, between 3 1/2" wall framed w/ steel studs as opposed to wood studs, all other insulation/sheathing factors being equal) , but not for floor/roof/windows. If I could find an index that gave R-ratings in all these areas, then the rest would be straight-forward. But of course no such index probably exists.But then, if one COULD arrive at a total heat loss amount (and one sample worksheet I saw expressed the result in watts), how could you convert this into usable information? In other words, how much heating/cooling BTUs would you need? I've found with various online calculators I've found--like mortgage calculators that will show you results for any combination/amount of prepayments--that seeing what happens w/ various if/then scenarios helps you make decisions. I'm about to build a small (200 SF), free-standing studio for my wife, not w/ permit, so I can be experimental. (The ORNL has some heat loss figures for Larsen trusses, whose design/premise intrigues me.) I'd love to see what it would cost to build a Leger-style structure that could practically heat itself w/ body heat. (And cool itself w/ samllfan blowing across glass of iced tea?)Jim

2. 
   Guest_ | Mar 16, 1999 07:45pm | #5

   *Hi Jim,Most of those calculator progarams are just spreadsheets in disguise. Many very powerful custom programs are created either in spreadsheets or database programs. As you say, once you have all the variables it's just a matter of plugging in changes for what-ifs.If you dead end on trying to work out the spreadsheet, you can always spend 100 bucks for Virtual PC for your Mac (I'm a Mac user). It's got a fairly hefty system overhead. Takes 300 megs of disk space or so, plus it needs a good chunk of RAM, but it works, and is said to be easier to use than a real PC. You've still gotta look at that butt-ugly interface though, and learn to think in Windows-speak, which is trying to those of us who have come to expect our computers to behave rationally.If you work out such a spreadsheet, I might be interested in buying a copy of it from you.Steve

3. 
   Guest_ | Mar 16, 1999 08:05pm | #6

   *My HVAC supply houses all have software to do heat calcs and years worth of trial and error experience....Aren't you trying to reinvent the wheel????J

4. 
   Guest_ | Mar 16, 1999 08:36pm | #7

   *What's a wheel?

5. 
   Guest_ | Mar 16, 1999 08:43pm | #8

   *Jack,Please ask one of your HVAC guys to email me a copy of their software, suitable for mac.But seriously, I know this stuff already exists, especially for PCs, but it's pretty expensive. And I doubt somebody at an HVAC house is going to want to waste a lot of time sitting down with me, running through all sorts of what-if's for a 200 SF structure that he ain't likely to sell me anything for.And I need something to keep my spare time occupied; better to reinvent the wheel than grow marijuana. I think....Ji

6. 
   Guest_ | Mar 16, 1999 08:51pm | #9

   *Steve,I've been tempted to get Virtual PC, but read that it can really gum up with some software, and is pretty slow with most, especially if, like me, you have a slow (160) processor. If you've got it, why not get one of those downloadables and let us know how it runs?Or, why don't we all pool resources; maybe form an off-line group, if necessary, then give results back to Breaktime.

7. 
   Guest_ | Mar 16, 1999 08:59pm | #10

   *Two wrongs....kinda make you feel pretty rightous there dude.....There are thing that should be grown besides tomato plants...I hate smoking tomato stem....And as far as your spare time, then go ahead and write the software....kids should be entertained.You're not invited to the Fest yet are you????Trying for an invitation?J

8. 
   Guest_ | Mar 16, 1999 09:05pm | #11

   *Jim,I have a killer pentium two pc to run pc software on, but no interest in surfing the web jungle....What specific site has a free heat loss software program that I should try and yak back here about?Fest Invitation with a slap and a beer waiting...no pot.J

9. 
   Sherri_Zann_Rosenthal | Mar 16, 1999 10:55pm | #12

   *Re-check my post about Energy-10. It's for the PC, but I swear it does what you want, is fast and easy, and is available through the American Solar Energy Association (ASES), which has a web site. It does a lot more than you'll be able to do with a homemade spread sheet, like calculate the difference in energy use from things like shifting windows and overhangs (for solar gain in winter and shading in summer) and use of thermal mass, as well as including all the insulation/roofing materials variables. If you only want it for one project, ASES or someone in your own state (look for a solar center, or some university department interested in energy use) will probably run the calculations on a building for you. Here in NC, we've got a solar center associated with NC State U., and their staff person ran the numbers on one of my projects.-Sherri

10. 
    Guest_ | Mar 16, 1999 11:06pm | #13

    *Hi Jim,I've thought about getting it. I had a hard time finding a beam-calculating app for the Mac and nearly caved and bought it then. Now my hard drive is maxed out and I couldn't put it on if I wanted to.My wife ran it at work for awhile. She didn't like it, but mostly what she didn't like was that it was like using a PC. She had version 1.0 and it was troublesome printing stuff sometimes, but ran the programs just fine. She was using it to run Access database. As soon as she got everything she needed from the database she tossed it off her computer because it was such a space hog.Speed shouldn't really be an issue with these little vertical market number-cranking apps.Steve

11. 
    Guest_ | Mar 16, 1999 11:08pm | #14

    *Hi Jack,I was looking for a Mac version of a heat loss program once, and people kept mentioning one for wWindows called J-works. I don't know where to get it or how much it costs. Mostly what I got was a lot of abuse from HVAC guys who thought it was incredulous that anyone other than an HVAC professional would have the brainpower to try and attempt a heat-loss calculation. Hey, at least I know what sticks not to cut in order to keep my house from falling down.Steve

12. 
    Guest_ | Mar 17, 1999 06:20pm | #15

    *Jack,The last of the three web sites up on my first post has 'em. The second on has some pretty space-agey looking ones, too.I ain't coming back east for no beer slap.

13. 
    Guest_ | Mar 17, 1999 06:29pm | #16

    *Sherri,I'm ashamed to admit how many hours I've spent looking for some place, here in CA or anywhere else, that had either online or telephone assistance.The reason I started building furniture is because I couldn't find what I wanted/liked/needed. So, heck, why not get in the spreadsheet business? Less dust, anyway.Maybe, though, combining what you and Steve are saying, I should spring for Virtual-PC, and use Energy-10. Now I gotta find that website. (The post you mentioned it in no longer comes up on this thread, on my machine.J

14. 
    Guest_ | Mar 19, 1999 08:18am | #17

    *JimI,ve been following this thread with interest. . . I'm not a Mac user, but if what Steve says about this Virtual P.C. taking up excessive hard drive space & Ram, why not buy an older P.C. to run it on.. . . dedicate it to this one program. . . 486's are goingi dirtcheap, you wouldn't really need a 2nd keyboard or monitor except for convenience! 'Cross platforming' sounds like the worst of both worlds!!!-Patrick

15. 
    Guest_ | Mar 19, 1999 06:11pm | #19

    *Patrick,I've thought about picking up a cheap PC for this very reason, but there are several things tha weigh against it, not the least of which is my office hasn't got room for two computers in it. One advantage to using Virtual PC is that you can use all your MAC peripherals in the Virtual PC environment. For those of us with lots of money in external drives, scanners and printers, that's a big plus.Plus you can copy and paste between the two environments. Also, the hardware maintainance issues are minimized. You only have to be able to take care of the machinery you already know well.Steve