4558 (RP-1120) -- Development of Equivalent Full Load Heating and Cooling Hours for GCHPs ✓ Most Recent

The design of commercial ground–coupled heat pump systems (GCHP) requires knowledge of annual heating and cooling loads along with design loads to properly size the ground heat exchanger. Equivalent full load hours (EFLH) based on climate and building type provide a first estimate of annual loads that is useful in the initial feasibility assessment of GCHP systems. Through ASHRAE research project 1120- TRP we developed EFLHs for heating and cooling loads in GCHP systems. We used data from 20 buildings to develop building load models. These models provided the means to estimate heating and cooling loads across the range of climates depicted by the TMY2 data set and to subsequently develop EFLHs.

Our analysis of the EFLHs showed the need to normalize the equipment sizing among the buildings so that varying sizing practices did not add large variability to the EFLHs. We also found that variations in operating hours produced large variations in EFLHs, as the added operation of the building added load but did not increase peak loads. The operating hours are the main determinant in defining differing building types or uses. The operating hours also enhance variations in other parameters, such as internal gains, by changing the amount of time these loads are active. We used the models to investigate the EFLH variations and to ultimately generate EFLH tables for 35 climatic locations with four different occupancy schedules and two levels of internal gains.

Units: Dual