Natural ventilation

miguelnery · Posts: 72

Hi Andy,

I´m trying to simulate a natural ventilation strategy
for a single zone office building, and i'm having some problems with it:
1-when, in model options, I pass from a sheduled to calculated ventilation I don't get any output of natural ventilation?
2-How can I setup a night ventilation strategy, just when Tint>Text, keeping internal gains during the day?
3-Can I use existing windows or should I use vents?

Best regards,

miguel

Andy Tindale · Posts: 1165 Location: Stroud

Hi Miguel,

When the Natural ventilation model option is set to Calculated, all infiltration and natural ventilation heat loss is accounted for under ‘External air’.

To model night-time ventilation, open the Openings tab at building level, open the External glazing header and the Operation header. You can set the operation of the windows by giving an appropriate schedule. The typical workday Timing option only allows on/off operation with a single on period and, to get more flexibility with the schedule definition you may prefer to use the 7/12 Schedules Timing option on the building model options dialog.

This will give you a model which has windows opening according to your schedule but only if:

Tin > Tout and Tin > Tsetpoint

Where:

Tsetpoint is the ventilation setpoint temperature on the Activity tab under the Environmental Conditions header.
Tin is the inside air temperature.
Tout is the outside air temperature.

You can also control doors and vents in the same way. You could use windows to define daytime ventilation and vents to define night-time ventilation for example.

Best regards
Andy

zt99 · Posts: 1

why I cannot find the "operation" tab under the "external glazing" section but I can find it in the "internal glazing"?

Andy Tindale · Posts: 1165 Location: Stroud

You will only find the Operation header for External Windows when the Natural ventilation mode is set to 'Calculated'. In 'Scheduled' natural ventilation, the ventilation rate is set explicitly on the HVAC tab under the 'Natural Ventilation' header.

Operation for internal Windows ,when using 'Scheduled' natural ventilation, models mixing of air between zones.

Andy

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