As someone who lives where temps near or exceed 100F almost every day from late May to late September, the thought of having something attached to the house that heats up an additional 30 to 70 degrees and then radiates that heat to the nearby surroundings isn't appealing. It would be nice to have the reduced maintenance synthetic decking provides, but I'm just not hot on the idea.
Now that gets me thinking.
The same amount of sunlight hits both wood and PVC decks. I don't see a lot of reflection from wood decks so I doubt that there is a lot of energy reflection in the visible spectrum. I suppose there could be much more reflection outside of the visible spectrum, but I'd be surprised by that.
I suspect that both type of decks convert a similar amount of sunlight to heat and that the amount depends substantially on the color of the deck. Dark decks will, I suspect, convert more light to heat, all other things being equal.
Even at the same temperature, wood may
seem less hot than PVC because wood conducts heat to the foot more slowly. (Metal, for example, at 150 deg 'feels' much warmer than wood at 150 deg.) Also, wood probably has a lower heat capacity than PVC and stores less heat, so there is less stored heat to conduct to the foot. Wood may feel cooler without actually being at a lower temperature.
Conservation of energy suggests that wood (or paint/stain) and PVC, depending on color, must dissipate equal amounts of heat (unless one is more reflective). That heat can be radiated or conducted to the air.
Hot wood may be more comfortable to walk on than PVC but I'm not sure that either causes less heating of the local environment. (But, I've been wrong many times before.)
