Heat gain originating from hooded equipment in energy modeling

I am doing energy simulations for a factory. I am seeking advice as to the following situation: 1.) Part 1: Load Estimating, Chapter 7 of the classic Carrier Manual states that “a properly designed positive exhaust hood reduces the sensible and the latent heat gains by 50%”. Supplemental data is shown in table 7 – Heat gain from miscellaneous appliances. Inquiry: Could I simply multiply the appliance wattage by 0.5 to obtain room sensible heat gain? 2.) The factory equipment takes a substantial portion of cooling demand. Therefore, the HVAC designer proposes once-through configuration of supply airflow to equipment room. That is, no room air in equipment room will return to the air handler and end up as a load on the chiller plant. The designer calculated the amounts of exhaust air and make-up air associated with the hood that will keep up desired pressure differential across the room enclosure. For instance, 4-kW equipment should impose 2-kW heat gain. Suppose that the 2-kW heat gain will warm up the supply air temperature from 13.9 ⁰C (57 ⁰F) to 25 ⁰C (78 ⁰F). The room air at 25 ⁰C (78 ⁰F) will be constantly discharged through the hood whenever the hooded equipment runs. Inquiry: Regarding energy simulations, could I entirely eliminate the heat gain from hooded equipment as the once through configuration is utilized together with hood? Just additional fresh air load is relevant because, for example, 250 l/s (500 cfm) of once-through make-up air to equipment room is equivalent to 250 l/s (500 cfm) of fresh air to the air handler. I am grateful for all the advice.