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Energy Assessment: Heat flux measurements

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1 to 17 of 17

  1.  
    • CommentAuthortony
    • CommentTimeDec 5th 2025
     
    I have been dreaming about a project that measures heat flux through walls

    The big news is that my dream is about to come true

    I would be keen to from any others who have heat flux data for walls of any type please
    •  
      CommentAuthordjh
    • CommentTimeDec 5th 2025
     
    I'd be interested to learn more about the approach. Something like the PHFS-09e heat flux sensor?
  3.  
    Didn't Historic Scotland do a lot of in situ U value testing? (I understood that it was these tests which gave rise to the amendment of the SAP assumption for an uninsulated 225mm solid brick wall from 2.1 to 1.7W/m2K).
    • CommentAuthortony
    • CommentTimeDec 15th 2025
     
    Not sure which heat flux sensor we will be using, we will install it and data log results for three days - add weather data and compare real world with as designed assumptions

    I have a few building types lined up and am about to start a list
    •  
      CommentAuthorfostertom
    • CommentTimeDec 15th 2025 edited
     
    Will be exceeding interesting.
    • CommentAuthortony
    • CommentTimeDec 15th 2025
     
    Yep
    • CommentAuthortony
    • CommentTimeJan 27th 2026
     
    Started, high level note on second property monitored

    Dot and dabbed on medium density blocks, cavity with “fluff” rendered blockwork outside skin.

    U -value as found 0.54, after retro filling in void between blocks and plasterboard with fire retarded EPS beads = 0.37

    I think this delivers a 30% saving on heating demand and has the added benefit of fewer draughts.

    Property was built in 1986 - uncertain about the as designed u-value but suspect 0.6
  8.  
    I have used this kit previously:
    https://www.buildtestsolutions.com/u-value-measurement/heat3d-infrared-thermography

    which uses the FLIR One and iPhone to monitor heat flux and establish a u-value.

    The kit was fiddly to set up (easily disturbed), but delivered results after a few days of monitoring. Generally measured u-values of older solid walls were better than 'on paper' and newer walls were a bit worse.

    We also found that the u-value varied in different spots of the wall, so you need to do a few 'takes' to get a reliable figure.
    • CommentAuthortony
    • CommentTimeFeb 26th 2026
     
    More results are being obtained

    16 year old timber framed house - 30% underperforming

    Brand new 0.1 timber frame with designed U value 0.1 measured at 0.09 likely result of careful workmanship

    1950’s cavity wall was 1.6, when filled with ‘fluff” 0.68 and after internally thermally lining it with 50mm eps/plasterboard laminate 0.34.

    The odd result was a 1960’s mansard wall with no insulation at 0.09????? Under further investigation

    More monitoring is ongoing.

    We are using a heat flux detector, indoor and outdoor temperature sensors and internal and external wall surface temperature , data logging for seven to ten days
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 26th 2026 edited
     
    So what heat flux monitor are you using?
    • CommentAuthortony
    • CommentTimeFeb 27th 2026
     
    A proper heat flux pad , £ thousands
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 27th 2026
     
    I'd like to look it up?
    • CommentAuthortony
    • CommentTimeFeb 28th 2026
     
    Huskeflux heatflux plate is the name of our sensor , it is connected to a data logger with the other input sensors
    •  
      CommentAuthordjh
    • CommentTimeFeb 28th 2026
     
    • CommentAuthortony
    • CommentTimeMar 1st 2026
     
    Yea
    • CommentAuthortony
    • CommentTimeMar 7th 2026
     
    Just did my house, from the data the U-value of the SW side wall of my house was 0.08W/m²/K which is much better than the design value of 0.1W/m²/K.

    The flank wall value most likely benefited from three factors that help improve the U-value, a) careful installation of the fibreglass batts with no gaps, b) using basalt fibre wall ties to reduce thermal the bridging of the more common metal wall ties assumed in the U-value calcs, and c) highly air-tight construction. But a 20% improvement on design was very satisfying to find.
    •  
      CommentAuthordjh
    • CommentTimeMar 8th 2026
     
    Congratulations :bigsmile:

    It's all stuff I'd be interested to do on my own house if it wasn't so expensive. I can't really even justify doing a repeat airtightness test just for interest, and that (I hope) is a lot less expensive.

    It's a pity there aren't (a lot) more of community ventures that share the cost of the equipment and the desire.

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