![Joseph Allen on Twitter: "Our rec: "Target 4-6 ACH, through any combo of the following: 1. outdoor air ventilation 2. recirculated air that passes through a filter with at least a minimum Joseph Allen on Twitter: "Our rec: "Target 4-6 ACH, through any combo of the following: 1. outdoor air ventilation 2. recirculated air that passes through a filter with at least a minimum](https://pbs.twimg.com/media/FO2y0J7XoAgppqr.jpg:large)
Joseph Allen on Twitter: "Our rec: "Target 4-6 ACH, through any combo of the following: 1. outdoor air ventilation 2. recirculated air that passes through a filter with at least a minimum
![Why do some ASHRAE 170 ventilation rates appear as people and area based ventilation instead of cooling and heating air changes per hour? Why do some ASHRAE 170 ventilation rates appear as people and area based ventilation instead of cooling and heating air changes per hour?](http://software.trane.com/RightNow/0716-ASHRAE170/7161.png)
Why do some ASHRAE 170 ventilation rates appear as people and area based ventilation instead of cooling and heating air changes per hour?
![Making Classroom Air Safer During the Pandemic: A Step-by-Step Path to Optimal Air Changes for COVID-19 Mitigation – enVerid Making Classroom Air Safer During the Pandemic: A Step-by-Step Path to Optimal Air Changes for COVID-19 Mitigation – enVerid](https://enverid.com/wp-content/uploads/2020/12/How-to-Achieve-5-ACH-in-Classrooms-enVerid-Systems-1024x538.jpg)
Making Classroom Air Safer During the Pandemic: A Step-by-Step Path to Optimal Air Changes for COVID-19 Mitigation – enVerid
![What are Air Changes per Hour (ACH) and how do they relate to UV disinfection in Building Ventilation Systems? – Luminus Devices What are Air Changes per Hour (ACH) and how do they relate to UV disinfection in Building Ventilation Systems? – Luminus Devices](https://luminusdevices.zendesk.com/hc/article_attachments/4442846495501/mceclip9.png)