Recently it occured to me that this 20KRPM brushless turbine i have that i can buy rather cheap too, incredibly efficiently consumes 300W of power. On paper, a 12″ x 24″ (~30x60cm) H14 Hepa can operate above the required 0.5m/s airflow with a mere 50-80W fan. One of the downsides of induction fans, the most common high power fans, is you cant change their speed unless they were designed with that functionality in mind. Ones that are, usually are incredibly expensive, offsetting their value. Usually a flowhood motor costs more than it needs to because it needs to work unregulated matched perfectly to your filter, producing more than 0.5m/s airflow while also not exceeding the pressure rating of the filter.