WUFI

Hi:

In the results report of WUFI Plus, I would like to know how you calculate the values for "opaque areas" in the "Energy Balance" table. I am trying to obtain these from the sum of heat gains/losses at all indoor surfaces of the zone (except windows), the results are of similar proportion but never the same.

Additionally what is the criteria you use to differentiate heating days from cooling days?

Your help will be appreciated

Thanks for this question. Short answer: the energy balance (table above) sum each timestep the gain and loss off all opaque components. The component results sum the gain and loss for the named component (or component group).

Long answer: I will start with the component results:

the gains (green bars) are the summed up heat flow results with a positive sign for the named component, regarding the inner surface of the component pointing to the zone, e.g. over all timesteps, for the total calculation period. Respectively the losses (blue) are the summed up negative signed heat flows. For transparent components the gain also include the incoming solar radiation.

For the energy balance table the gains and losses for all opaque areas for each timestep are summed up first. If then the sum has an positive sign, it is summed as gain. If the sum is negative it is summed as loss. In this sum for the energy balance, inner walls (components with the same Zone on inner and outer side) are also regarded, respectively the the heat flow on both sides including the outer surface (if it is the same zone).

I'll try to give an example for two walls:

The heating period and the cooling period depend on heating demand, or cooling demand.

If there was heating/cooling neccessary in one timestep, the timestep is regarded for the heating/cooling period.