Overview

This document provides guidance on the Additional fresh air option in Hevacomp Simulator.

Method

Many of the Simulation calculations within the Desin Simulator contain an option to include Addition Fresh Air into your design.

In Hevacomp v26, this will only affect results if you have chosen the Simple air change rate option, within the Simulator > Design Data > Model menu:

If Multi-zone air flow model is selected on the other hand, results will not be affected by this Additional fresh air. This is because the purpose of the Multi-zone air flow model is to analyse detailed flow paths such as openable windows, rather than the affect of simple air change figures.

Should you need to specify additional fresh air while using the Multi-zone air flow model, then you can do so by defining the HVAC system that supplies your additional airflow, using Fresh air only, and assign it to the relevant rooms.

Explanation

Design Simulation uses the EnergyPlus Engine which has been updated in Version 26

• With Hevacomp v25 (which used V4 of EnergyPlus) - additional fresh air is considered, regardless of whether Multi-Zone or Simple air flow models are selected.
  
  
• With Hevacomp v26 (which uses V8 of EnergyPlus) - additional fresh air is only considered with the Simple air flow model.