Modelling Atriums for Part L

[marcus_dea]

I am modelling (DSM) a building with a large atrium. The ground floor of the atrium is a reception/entrance.
The 4 upper floors have an open corridor which overlooks the atrium. The roof of the atrium is 100% glazed (Approx 400m2 with 600m2 of floor area).

Currently I have modeled the space as one whole zone, floor to ceiling, and defined this as reception.
As you can imagine, because of this I have a severe issue with Solar Gains and the space is failing the Criterion 3 Check.

I just want to check if I should model the building as I have, or should the space be split up by floor level, and joined up using holes. The upper floors should then be defined as circulation rather than reception to best define the nature of the space?

[Complex Potential]

I'd probably divide by floor and then subdivide the actual reception as a separate zone on the ground floor (adding holes where appropriate of course). To be in line with the SBEM guidance and NCM you do still need to apply the same space type and conditioning to the rest of it however, probably circulation. This is normally fine for voids because they have no floor area and thus no additional internal gains will be added beyond the ground floor and walkways.

As long as the atrium is not being cooled it should then be omitted from the C3 check.

Don't forget that if the atrium is to be naturally ventilated in the summer, be sure to add 5AC/H to the free cooling to all zones to avoid it getting unrealistically hot.

CP