Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Is there a internet free nicely organized table of R values or U values for Heat Loss calculations

As the title says, it would be helpful to have a table, listed with great number of standard construction elements, so one could do a rough Heat Loss for the whole building to get an estimate for the size of the boiler (or furnace). [I have seen some computer programs that want to break everything down into rooms etc. and that is a good idea if you are starting from scratch]--but if you want a quick estimate on-the-go, it would be nice to do the arithmetic by hand or calculator.


  • Jamie Hall
    Jamie Hall Member Posts: 22,100
    You mean something like "wall with windows" or "roof"? I frankly hope not. You might find one which gives the net R value (or u value) for certain common wall cross sections or roof cross sections, for instance, but you are still going to have to do some measuring and figuring.

    Without that, you are doing back of the envelope WAG figuring.

    Engineer's toolbox has R values for common building materials and insulation types.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 6,695
    edited February 25


    I'm sure there is a more detailed and comprehensive list somewhere, but for the average HVAC guy, the standard list that comes with what ever software or hand written form you have is usually close enough.

    You got to use a little common sense if for example you have 2 layers of 3.5" fiberglass insulation on your attic floor in leu of 1 layer of 6" fiberglass.

    EDIT: here is a website with a list of common building materials. you can make construction assemblies based on the numbers on this website. https://www.archtoolbox.com/r-values/

    For example:
    1/2" plywood exterior sheathing..........................................0.62
    Wood frame construction with R-11 insulation...............12.44
    1/2" gypsum interior wall......................................................0.45
    Vinyl exterior siding with foam insulation..........................1.80
    Over a covering of Tyvek or other exterior film.................0.17
    Total R value of this assembly........................................15.48
    U value = .0646

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 6,695
    edited February 25
    There are several whole house heat loss calculators available on line. This is one I used and made a spread sheet so I didn't need to actually do the math. The spread sheet did it for me. I just entered the measurements and the factors.https://docs.google.com/spreadsheets/d/1PFPIx3655H7xFTUc2HwuhJa4PCOqAcqw8E5F6woKdN4/edit?usp=sharing. There are some little bugs that I might have never completely addressed but for the standard 4 sided home with no additions it works great. If there is an addition that is completely different from the original construction there are tweaks that I can talk you thru.

    Not good for air conditioning heat gain.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • john123
    john123 Member Posts: 51
    Thanks Ed for your referrals. I can work with them. I guess I was looking for someone to do the work for me--like double brick with lath and plaster----or 2x6 stud wall with brick facing and vapor barrier and 1/2" drywall. But once you figure it out from the tables you referenced, one could simply make a note of them for the next time!
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 6,695
    Yes. And the difference between new housing development from the 1930 until today is only a small U-value each year. But when you add them all together and compare those balloon constructions of that time to the Tyvek wrapped germ traps they are building today, there is a big difference. that is why we need to do out jobs and be the best load calculators we can be.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics