<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>Animats</author><text>This is another way to do IoT wrong - collecting data but just displaying it.&lt;p&gt;The idea is to use CO₂ levels to control your HVAC system. The HVAC system should be able to draw fresh air from outside or recirculate air from inside, depending on CO₂ level. This is a standard option on modern HVAC systems, and there are standard sensors for it.  Better systems sense temperature, CO₂, CO, humidity, and smoke.  This is a huge win for rooms where the people load varies widely, such as hotel function rooms and classrooms. Such control systems save money, because, when nobody is using the room, they detect that CO₂ is low and cut down the ventilation rate. When the room fills up, the CO₂ level goes up, the fans speed up and the outside air intakes open until the CO₂ level comes down.[2] There are smart control units which manage heat, fans, vents, and air conditioning compressors.  The hardware pays for itself in power consumption.&lt;p&gt;And yes, you can get this stuff Internet-enabled, although that&amp;#x27;s mostly for remote maintenance. The HVAC works just fine without connectivity.&lt;p&gt;Surprisingly, this technology is a tough sell. Except for convention hotels. They get this. They&amp;#x27;re in the competitive business of keeping large numbers of people comfortable and coming back. They have big rooms where the people load may go from zero to a thousand in minutes, and go back down an hour later. It&amp;#x27;s a huge win for them.&lt;p&gt;[1] &lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;www.airtesttechnologies.com&amp;#x2F;support&amp;#x2F;reference&amp;#x2F;CO2SeqOfOperation.pdf&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;www.airtesttechnologies.com&amp;#x2F;support&amp;#x2F;reference&amp;#x2F;CO2SeqO...&lt;/a&gt;
[2] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;buildingcontrols.honeywell.com&amp;#x2F;literature&amp;#x2F;Advanced_RTU_Retrofit_Solution_Program_Sell_Sheet-01-00041.pdf&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;buildingcontrols.honeywell.com&amp;#x2F;literature&amp;#x2F;Advanced_R...&lt;/a&gt;</text><parent_chain></parent_chain></comment><story><title>Show HN: Low cost CO₂ monitoring (your office) with Prometheus and Go</title><url>https://github.com/larsp/co2monitor</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>Hasz</author><text>If you&amp;#x27;re interested in a hardware solution, I&amp;#x27;ve used the MH-Z19 CO2 sensor to great results. It&amp;#x27;s an NDIR (read:not electrochemical) sensor with a UART interface and temperature compensation. It will report up to 5000ppm and comes factory calibrated.&lt;p&gt;It&amp;#x27;s also $20 in singles from China. Coupled with whatever microcontroller you want, it&amp;#x27;s totally possible to have a distributed net of CO2 sensors for a low cost per node.&lt;p&gt;That being said, it&amp;#x27;s a ton of work and this is an excellent solution with much quicker results.</text><parent_chain></parent_chain></comment><story><title>Show HN: Low cost CO₂ monitoring (your office) with Prometheus and Go</title><url>https://github.com/larsp/co2monitor</url></story>