https://wiki.kanthaus.online/index.php?action=history&feed=atom&title=Reducing_heat_absorption_through_windowsReducing heat absorption through windows - Revision history2026-05-02T01:17:59ZRevision history for this page on the wikiMediaWiki 1.42.5https://wiki.kanthaus.online/index.php?title=Reducing_heat_absorption_through_windows&diff=12&oldid=prevDoug: Init2024-07-21T15:26:55Z<p>Init</p>
<p><b>New page</b></p><div>During [[Summer]] it gets warm, and a lot of heat comes through our windows.<br />
<br />
Our windows each have an area of ~1,5m², meaning up to ~800W of heating power. The German norm DIN 4108-2 defines the Fc value of a sun protection mechanism as a factor for the "incoming" power, where 1.0 is "nothing" and 0.0 is perfect deflection.<br />
<br />
A dark curtain on the inside reaches an Fc of 0.9, a semi-transparent textile screen on the outside (e.g. lets light pass through) reaches an Fc of 0.25.<br />
<br />
Rules of thumb:<br />
<br />
* outside better than inside (since once heat is internally absorbed, any outgoing heat will reabsorb in the window glass by ~40%)<br />
* if inside, reflecting better than absorbing<br />
* anything better than nothing (as the room "feels" cooler when energy is just absorbed in the window region and not on most of the room surfaces)</div>Doug