[esp-r] Fwd: [ESP-r] night cooling / ventilation (a revised response)

[Jon Hand (clcv10)]

This is a message sent out in 2004. Since that time flow controls  
have evolved
and the message has been edited to reflect this....

A recent comment on flow components for night ventilation
control:

> A question on this control-scheme:
>
> Night ventilation often is realized via natural ventilation -
> i.e. simply by an opened window during night.
> For modelling an opened window usually a flow component is
> required, which enables a bidirectional air flow (the
> "door" component in ESP-r).
>
> For modelling a control scheme described below for natural
> night ventilation (which can be realized by automatically
> controlled windows) you have to split the window opening
> into two flow components.
> In which way should this be done for a bidirectional air
> flow component representing an opened window ?
>
The are many flow components which can have a control
applied to them e.g. air flow opengins, common orifice, constant
volume flow component bi-directional controls. Control acts to alter  
the effective area
or flow rate on these components.

The bi-directional component control is applied to the width of
the opening.

Cracks are a component type which is not controlled.

Many components can be further controlled via an additional
parameter in the ON/OFF controller which stipulates the fraction
of the nominal area/flow rate which is considered ON for
a particular period.  Thus you can define a component such
as a constant volume flow device with a flow rate of, say 0.5m^3/s
and then instruct it to be ON at 0.3 of this value during one period
and 0.6 of this value during another period.  You could use this
to represent different ventilation rates for different occupancy
levels without the need for setting up multiple fixed volume
flow components in parallel.

Regards, ESRU