Maybe someone can answer this for me:
?Using ASHRAE 90.1-1999 at the reference standard, what is the HVAC system
for the baseline building if the proposed building is a ground-source heat
pump with radiant heating and cooling? In Figure 11.4.3, the standard
indicates that System 6 should be used. System 6 is listed as a
water-source heat pump with direct expansion for cooling and electric heat
pump and boiler for heating. Is System 6 distributed water-source heat
pumps with a boiler for heat and a fluid cooler for cooling? Or is it a
ground-source heat pump with a boiler for peak demand and domestic hot
water??
Thanks.
Chris Flood BSc (Eng)
Hi Chris,
Using Figure 11.4.3, the first step is to identify the principle heating
source (I would assume there are backup boilers for the ground-source heat
pumps in the proposed design). Per ASHRAE 90.1-1999 - 11.4.3.k.2, for
systems with mixed fuel heating sources, the principle heating source is the
one with the largest total installed output capacity. Hence, the Baseline
Case should be modeled as system 6 only if the total output capacity of the
geothermal heat pumps is larger than the total output capacity of the backup
boilers.
In response to your second question, system 6 is distributed water-source
heat pumps with an atmospheric boiler (80% efficiency) and an axial fan
cooling tower with two-speed fans.
Regards,
Ali Nazari, M.A.Sc.