What does it mean to model an underfloor space as “very open”?
Until recently there were some restrictions in how underfloor spaces could be modelled, (See Q46). These restrictions have been lifted so that “very open” at any level means that the underfloor space is considered to be at ambient air temperature. “Open” assumes a high air flow rate but models convective and radiative transfer between the ground and the floor. “Enclosed” assumes walls around the underfloor space reduce airflow to that allowed by the vent size nominated.
