This is in regards to Eap2 Minimum Energy Performance and Eac1 Optimized Energy Performance.

We need help with choosing the baseline system for a v4 BD+C residential project in Sweden (climate zone 6A). 

Most residential projects in Sweden have a hydronic/electric heating system and ventilation air is provided by a DOAS. 

While the heating system is used to maintain the minimum allowed room temperature in the apartments, natural ventilation is allowed in Swedish codes as a method of keeping the temperature from exceeding the maximum allowed room temperature during summer.

Which of the following scenarios will be the best suited for this situation and a more conservative/acceptable approach according to USGBC:

    1) Choosing system-1/2 according to ASHRAE std. 90.1 2010 Appendix G. Sizing the system-1/2 air flow rate based on the:

           a. cooling demand that would be needed to maintain the maximum allowed room temperature based on a supply-air-to-room air temperature difference of -20 °F

           b. heating demand that would be needed to maintain the minimum allowed room temperature based on a supply-air-to-room air temperature difference of +20 °F

           c. minimum outdoor air flow rate

           (whichever is greater) and using that as the design maximum supply airflow.

           Then running the energy model with a high setpoint for the maximum allowed room temperature in both the proposed and the baseline since there is no cooling in reality. Opening the windows during the summer when there is a need for that in both proposed and baseline models

    2) Choosing system-1/2 according to ASHRAE std. 90.1 2010 Appendix G. Sizing the system-1/2 air flow rate based on the:

          a. cooling demand that would be needed to maintain the maximum allowed room temperature based on a supply-air-to-room air temperature difference of -20 °F

          b. heating demand that would be needed to maintain the minimum allowed room temperature based on a supply-air-to-room air temperature difference of +105 °F

          c. minimum outdoor air flow rate

         (whichever is greater) and use that as the design maximum supply airflow.

         Then running the energy model with a high setpoint for the maximum allowed room temperature in both the proposed and the baseline since there is no cooling demand in reality. Opening the windows during the summer when there is a need for that in both proposed and baseline models

   3) Choosing system-9/10. Opening the windows during the summer when there is a need for that in both proposed and baseline models.