Calculate Total Heat Load?

Is there a way to calculate the full heat load on the entire model after solving? (in Watts) It’s always nice to do a double check after the solve, just to make sure…

I tried looking in the output file, but I did not see it. Also, I don’t know French. :slight_smile:

Also, quick request - It would be AWESOME if we were able to just input the volumetric heat load in Watts (just have Simscale calculate the W/m^3.)

1 Like

@rszoeke/@ahmedhussain18 is this possible?

Hi @fastwayjim,
currently this is not possible on the platform since we would need a result control item that can do an integration operation (besides min/max, nodal average and sum) and a dot product with the surface normals. We could either provide a general integration option for fields. This would be a general tool for integrating variables over a surface, but with this you would only get correct results for plane surfaces. On the other hand we could add a specific total surface flux result control which would specifically compute the total normal heat flux through the assigned surfaces. Which one would you prefer? Would the general approach with the simple field integration be enough?

For the time being this could also be achieved with a chain of filters in paraview:

  • (optional) use extract blocks such that you can restrict the computation to specific volumes or faces
  • extract surface
  • surface flux (it essentially does compute the dot product Normals.heat_flux and integrates over the surface)

You should get a variable Surface Flow which shows the total heatflux through the specified block’s surface.


It comes down to giving the user the confidence that they have set up the thermal model using the correct amount of power. More often than not, this value is known as watts (for electronics, this is an output of an electrical power analysis done by the Electrical Engineers).

The current workflow involves extracting the volume from CAD, and putting that in a spreadsheet along with the power (output from the EE), and calculate the Watt/m^3. This introduces an extra step, with the potential for human error.

If you can’t provide an output easily, then can we at least allow the user to just input a “body heat load” in Watts?

Hi @fastwayjim,
now I understand the actual problem.

this would be definitely possible. I’ll add this feature request. If accepted it shouldn’t take much to implement it.


1 Like

Awesome, thanks! In general, I think anytime there is an opportunity to “remove another calculator” (i.e. omit the use of excel during pre-processing), we should take advantage of it!


Couldn’t agree more! Initial condition values for turbulent quantities (k, Omega) is another example for that! We working on moving more and more of these calculations into SimScale!

Calculating the total heat load for a building requires taking into account several factors, including the size of the building, the number of occupants, the climate conditions, and the type and efficiency of the HVAC equipment being used.

Here is a basic formula to calculate the total heat load:

Total Heat Load = Sensible Heat Load + Latent Heat Load


Sensible Heat Load: This is the amount of heat energy that is required to increase or decrease the temperature of the air in the building without changing its moisture content. It can be calculated using the following formula:
Sensible Heat Load = 1.08 x CFM x Delta T


1.08 is the specific heat of air (in BTU/lb.F)

CFM is the airflow rate (in cubic feet per minute)

Delta T is the temperature difference between the supply and return air (in Fahrenheit)

Latent Heat Load: This is the amount of heat energy that is required to remove or add moisture to the air in the building without changing its temperature. It can be calculated using the following formula:

Latent Heat Load = 0.68 x CFM x Delta W


0.68 is the latent heat of vaporization (in BTU/lb)
CFM is the airflow rate (in cubic feet per minute)
Delta W is the difference in moisture content (in grains of moisture per pound of dry air)
Once you have calculated the sensible and latent heat loads, you can add them together to get the total heat load for the building.

It is important to note that this is a simplified formula and that there may be additional factors that need to be taken into account for a more accurate calculation. It is always best to consult with a qualified HVAC professional to determine the specific heat load requirements for a particular building.