RE: RE: [EnergyPlus_Support] Calculated design heating load difference

We agree on that, but what load is then reported in HTML output file? In my opinion design heating load is characteristic of building, and interior and exterior conditions, and not the systems, so it is the demand. It should change only when building geometry, materials, indoor conditions change, and not when the system changes. The main reason I'm interested in this is that I am trying to calibrate real building and its systems. So, my model with ideal loads (demand) matches very well with the project data for this building (for winter design day), but when I introduce systems and equipment with all fields set to autosize and efficiencies to 1, I get significant differences.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, <energyplus_support@xxxxxxxxxxxxxxx> wrote:

Ideal Load gives as result the energy DEMAND and any simulation including HVAC system gives the FINAL energy.

Energy demand and Final Energy are never identical due to System inefficiency

Josep SolÃ©
URSA Insulation S.A-

Sustainibility & Technical Manager

MÃ³vil +34 606 42 32 14

www.ursa.es

www.ursainsulation.com

www.uralita.com

P URALITA / URSA se compromete con el ahorro de energÃa. Antes de imprimir este mensaje asegÃºrese de que es necesario.

De: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] En nombre de marko.ignjatovic1980@...
Enviado el: jueves, 05 de septiembre de 2013 10:44
Para: EnergyPlus_Support@xxxxxxxxxxxxxxx
Asunto: [EnergyPlus_Support] Calculated design heating load difference

Hi guys,

I'm having trouble in finding the reason why there is a difference in calculated design heating load for my models. This is the problem. Both models have the same building with the same envelope and same WinterDesignDay schedules for indoor temperatures for sizing. In first model i used IdealLoadsAir system and the obtained design heating loads comply with the real buiding. But when I modeled HVAC systems, there was a great difference in calculated heating load. As we all know design heating load for zone is not dependent of HVAC systems serving it, but is function of envelope properties, interior and exterior conditions. Does any of You have any idea what could be the cause for this difference. I double checked all common objects for both models and they are the same.

Thanks in advance

Marko