@ShadSterling@mastodon.social @Sea1Am@mastodon.social @jblue@mastodon.world Not from the cost of a specialty product marketed to consumers but from the actual materials cost to manufacture it at scale, which is basically zero. Passive venting is unlikely to get you significantly lower than just leaving windows cracked already does. Active venting with both intake and exhaust fans powered off of solar might do a decent job. But nothing short of RSC or a heat pump of some sort will get you down to even near much less below ambient outside air temperature.