IES-VE User Forum

Hi guys,

I am running a glazed box building in NZ. apparently when reducing r-value of the glazing window, the cooling energy actually dropped. (the heating energy increased, so it makes sense.)

anyone can explain why the cooling energy goes up?

Hi,

When you edit the window construction or assign a new one have a look at other parameters (g-value etc) to ensure you aren't introducing other unexpected effects. Use Derived Parameters for this as well, it provides a useful summary base don the whole window arrangement you defined

You can compare your results files side by side in VistaPro and plot typical winter and summer days when there is a large discrepancy to better see the effects of the change and understand why they perhaps don't meet your expectation

Phil

In instances where the external air temperature is greater than the internal air temperature, more insulation actually helps to reduce cooling demand, in the same way that an insulated cool box keeps your drinks cold in summer.

When the external air temperature is lower than the internal air temperature, more insulation will increase cooling demand.

So the relationship between insulation levels and cooling demand will depend very much on your individual building, particularly the internal gains pattern and local climate. In buildings with high internal gains (from computers, equipment etc) I would usually expect to see annual cooling demand decrease with more insulation, but for buildings with low internal gains the opposite can be true - especially if they are in a hot country.

That is assuming all other factors are the same of course...