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Black exterior walls confusion

Big__O | Posted in Energy Efficiency and Durability on

We are building a passive solar house. .

We are close to Dallas Texas
we have approx 2644 Heating Degree days and 2811 Cooling Degree days.

here is the problem. In BEopt 2.8 I compared a very black exterior to a very white one, everything else being the same and its showing that the black cladding actually uses less energy over a full year than the white cladding.
could this be possible for DFW tx?

cooling setpoint was 74 and heating was 71
am I doing something wrong or should I get the black wall since both my spouse and I prefer the esthetics of black over white

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Replies

  1. Big__O | | #1

    I can answer my own question - BEopt is WRONG.

    I modelled a very hot city with the same parameters, PHX AZ, and it still said the black walls are more energy efficient.

    then I modelled a black ROOF vs white roof for phx. I personally know someone in phoenix who painted their roof white and dropped their energy bill almost by half.

    guess what. BEOPT still says a black roof is cheaper than a white roof so I know for sure the program is junk

  2. Expert Member
    MALCOLM TAYLOR | | #2

    Max,

    There isn't enough in it either way to choose the colour of your cladding for considerations of energy use. I'd decide what you would prefer to live with and go with that.

    Just as a side note: The fashion for black exteriors is already on the wane. They are disappearing from architectural periodicals, much as open-cladding has in the past several years. That's no reason not to use black, but I'd pause to consider if part of the appeal might be it's recent popularity am0ng designers. Things chosen based on that don't generally age well.

    1. Big__O | | #3

      I think you are right Malcolm , in that the savings are not big enough to choose one color over another.
      We prefer a dark gray blue vs a true black . unless its a true charred cedar . Im ok if they fall out of fashion. I was just reading a book on bungalows and it showed a bunglalow built in 1918 that was painted black and that was over 100 years ago.

      1. Expert Member
        MALCOLM TAYLOR | | #4

        Max,

        Choose what appeals to you. The best indicator of the longevity of a house is how it is maintained over time. Houses that the owners love generally have a better chance of being cared for.

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