Overview

The CIBSE gain calculation contains an option to allow the temperature to rise. This allows the "peak cooling capacity to be reduced if the room temperature is allowed to rise above the room set point for a period sufficiently short that the effect on the mean temperature is small." (CIBSE Guide A, Section 5.A2.5)

Notes

• The permitted temperature rise should be used with care. The method is only accurate for a rises of up to 2 or 3°C

If temperature is allowed to rise by 2°C, why are the calculated room loads different to increasing room design temperature by 2°C?

• Allowing a swing of 2°C will generate a different peak cooling load than changing the room set point by 2°C as in each case,  the mean room temperature will be different. For example, a room set point of 24°C will be controlled to 24°C, when allowing a 2°C swing, the room will be controlled.

Why do I only see a single sensible load rather than separate component loads in results?

• While calculating, sensible gains are combined as they are passed through the equations noted in CIBSE Guide A, Section 5.A2.5. This is reflected on the results page, with a single sensible gain column showing combined figures.

Why does the room peak appear at the same time for each room, regardless of actual room peak?

• The room peak indicated in the results will indicate the plant peak cooling load hour, and not the room peak hour.