{"id":517,"date":"2019-01-15T09:01:28","date_gmt":"2019-01-15T09:01:28","guid":{"rendered":"https:\/\/smartairfilters.com\/mn\/?p=517"},"modified":"2019-06-01T07:06:20","modified_gmt":"2019-06-01T07:06:20","slug":"hepa-longevity-test-170-days","status":"publish","type":"post","link":"https:\/\/smartairfilters.com\/mn\/en\/blog\/hepa-longevity-test-170-days\/","title":{"rendered":"HEPA Longevity Test: 170 Days"},"content":{"rendered":"

When I started\u00a0<\/span>Smart Air<\/a>, a lot of people asked me how long the HEPAs last. Several people criticized the DIY\u00a0<\/span>on Zhihu<\/a>\u00a0<\/span>because they said you\u2019d probably have to change the HEPA so often that it\u2019d end up being more expensive than the expensive brands.<\/p>\n

At the time, I really wanted to pull out a nice round number, but I couldn\u2019t think of any way to answer the question without getting hard data first, so I started doing tests (well, actually\u00a0<\/span>Gus<\/a>\u00a0<\/span>did).\u00a0<\/span>At 90 days<\/a>, we found it worked as well as in the beginning.\u00a0<\/span>At day 130<\/a>, we found a 4% decline. Now we\u2019ve finished 170 days!<\/p>\n

Methods:\u00a0<\/strong><\/p>\n

Gus used\u00a0the Original DIY<\/a>\u00a0and\u00a0the same HEPAs we ship from\u00a0Smart Air<\/a>\u00a0every night in the 12.3 m2<\/sup>\u00a0<\/span>bedroom in his Beijing apartment.\u00a0Gus used\u00a0the same method as my previous tests<\/a>\u00a0to\u00a0calculate effectiveness\u2014the percentage reduction of particles .5 microns and above from the room air overnight.<\/p>\n

To smooth out the variability in any single datapoint, I averaged the effectiveness over each 10-day period. (More details on the methods here<\/a>.) Here\u2019s what a single test day looks like:<\/p>\n

\"3\"<\/p>\n

Results:\u00a0<\/strong><\/p>\n

At day 100, the effectiveness dropped by about 4%. It stayed at around that level, until day 140, when it dropped 5-10%. After that point, the total effectiveness has bounced between 65-80%.<\/p>\n

\"4\"<\/p>\n

Conclusion:<\/strong><\/p>\n

In this test with real-life Beijing air, the\u00a0<\/span>Smart Air HEPA<\/a>\u00a0<\/span>lasted 100 days at about 8 hours a day at full effectiveness (729 hours to be precise).\u00a0People who want every percent of effectiveness should change HEPAs after\u00a0<\/span>100 days<\/strong>.\u00a0People who don\u2019t mind the 4% drop, I\u2019d recommend replacing it by\u00a0<\/span>140 days<\/strong>\u00a0<\/span>(1,028 hours).<\/p>\n

For now, the test continues! I\u2019ll post the final results when we finally run this HEPA into the ground.<\/p>\n

As always, I\u2019m posting the raw data as a download\u00a0<\/span>here<\/a>, and there are more details on the methods in\u00a0<\/span>my earlier post<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"

When I started\u00a0Smart Air, a lot of people asked me how long the HEPAs last. Several people criticized the DIY\u00a0on Zhihu\u00a0because they said you\u2019d probably have to change the HEPA so often that it\u2019d end up being more expensive than the expensive brands. At the time, I really wanted to … Read more<\/a><\/p>\n","protected":false},"author":4580,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-517","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/posts\/517","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/users\/4580"}],"replies":[{"embeddable":true,"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/comments?post=517"}],"version-history":[{"count":1,"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/posts\/517\/revisions"}],"predecessor-version":[{"id":518,"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/posts\/517\/revisions\/518"}],"wp:attachment":[{"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/media?parent=517"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/categories?post=517"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/smartairfilters.com\/mn\/en\/wp-json\/wp\/v2\/tags?post=517"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}