This is a LEED NC v2.1 higher education, 240,000-sf student union building located in Washington State. We have provided Radiant Panels to service the heating and cooling loads of general office space. The radiant panels rely on a secondary water loop that supplies either hot or chilled water depending on the demand of the system. Outside air is being provided through operable windows or a dedicated 100% outside air handling unit. After doing some research on several energy modeling programs, we have not been able to find one that can model this approach. Instead, we used a four pipe fan coil unit and zeroed out the fan energy to try and mimic the water loads, but take away the fan motor loads. When we compare the proposed case with the base case for ASHRAE 90.1-1999, the proposed case in the energy model will call for a four pipe fan coil unit (system type 7), which in turn will designate the base case to be a four pipe fan coil system as well. It is our opinion that the base case does not need to be this. For a conventional office space in Washington, the industry standard is to provide a standard rooftop VAV unit and provide each zone with a fan powered terminal with reheat. Also, by using the Budget System Type flow chart in ASHRAE Standard 90.1-1999 and inserting data specific to our project (e.g. water cooled, fossil fuel heating, and non-residential space), we get System Type 2, which is a standard VAV with reheat system. Given this approach, can we use the standard VAV system as a base case for the radiant panels since we are not really using Fan Coils in this system?
The project team is seeking clarification regarding the appropriate Budget case system type selection for a non-residential building with radiant cooling and heating as its primary source of conditioning. Four pipe fan coils (System type 2) are the appropriate selection for a building with water-cooled chillers and fossil-fuel fired hot water boilers serving radiant panels. Radiant panel systems are generally considered to be single zone systems, since both the heating and cooling panels are located in each zone, and are separately controlled in each zone. Accordingly, the Budget system type would map to Water-cooled ? Single Zone Non-Residential ? Fossil Fuel. Per ASHRAE 90.1-1999 modeling requirements, the fans must be modeled with the same bhp/cfm in both the budget and proposed case (with the exception of savings allowed for premium efficiency motors). Therefore, if the fans from fan coils are modeled with zero power in the budget case, they must be modeled the same in the proposed case. Also, per ASHRAE 90.1-1999 requirements, the dedicated outside air unit providing ventilation to the building must include energy recovery in the budget case if required by Section 6.3.6.1. The project does have the option of pursuing credit for EAc1 using the LEED v2.2 requirements (as long as any submittals for EAp2, EAc2, and EAc6 are also submitted using the LEED v2.2 requirements). This would allow the project to reflect the fan energy savings associated with radiant heating / cooling systems, and to model the Baseline system as a VAV system with hot water reheat as requested in this CIR. Applicable Internationally.