FYI, the guys at the Filterwatch Kickstarter campaign just added a simple unit that you can connect to an Arduino to measure/alert airflow. Perfect to let you know when your A/C filter or your dryer vent is clogged (which could lead to fire).
The campaign is a bit unclear, but it’s worth it… I’ve pledged, but the campaign needs a boost if it’s going to meet its target. Search for “filterwatch” on Kickstarter, or follow this link:
I plan to use this with my Spark Cores to monitor my dryer vent (I don’t like the thought of fire), my A/C filter (so I can sneeze less), and to monitor my attic fan (last one died and smoked for a while before finally tripping the breaker).