Dear All,

We're currently trying to certify an office building project with the following characteristics:

  1. the building has a narrow plan and high ceiling height;
  2. noise and air pollution levels are acceptable;
  3. occupants can adapt conditions with weather changes;
  4. the vast majority of spaces are only naturally ventilated, and meet the minimum requirements of ASHRAE Standard 62.1–2010, Sections 4–7.
  5. Most of the naturally ventilated spaces referred above have heat gains lower than 40 W/m2, but some are slightly higher.
  6. all spaces are fitted with mechanical cooling/heating systems (VRF’s).

According to CIBSE definition, these characteristics correspond to mixed-mode solution (combination of natural ventilation with mechanical cooling/heating)

The question is: in order to confirm that natural ventilation is an effective strategy for the project by following the flow diagram in the Chartered Institution of Building Services Engineers (CIBSE) Applications Manual AM10, March 2005, Natural Ventilation in Nondomestic Buildings, Figure 2.8, is it acceptable to follow the path that leads to mixed-mode (CIBSE AM 13)?