There is a new guidance due to be released around the deployment and use of HEPA filtration within the healthcare environment. This will lay out a basis whereby equivalent air changes per hour (eACH) can be utilised by engineers to provide part of the total air changes per hour for ventilation (ACH). Recirculation of air has always been problematic under Htm03 and this new guidance will lay out the basis on how this can be achieved. The proposed talk is aimed at CP, AP, AE etc ventilation to lay out information around how filtration is tested and can be evaluated. This will expand on information contained within the new guidance, which it is expected will be released by HCE2023. The talk will also cover comparisons between mobile and fixed systems using generalised case studies. The objective will be to give attending engineers the basic information they require to safely assess, deploy and maintain filtration units within their built environments. It will close laying out how these approaches can be successfully utilised to aid in the delivery of net zero.