TY - JOUR
T1 - Simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems
AU - Schiavon, Stefano
AU - Lee, Kwang Ho
AU - Bauman, Fred
AU - Webster, Tom
N1 - Funding Information:
For the help with energy simulations, the authors would like to thank Tyler Hoyt, Assistant Specialist, and Jingjuan Feng, Graduate Student Researcher; both are with the Center for the Built Environment. The present work was supported by the California Energy Commission (CEC) Public Interest Energy Research (PIER) Buildings Program and the Center for the Built Environment, University of California, Berkeley .
PY - 2011/2
Y1 - 2011/2
N2 - This paper describes the development of a simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems. The simplified design tool is able to account for key differences between UFAD and traditional mixing overhead (OH) systems. These include: (1) difference between design day cooling load profiles, (2) impact of a thermally stratified environment for UFAD versus well-mixed for OH, and (3) impact of heat transfer (temperature gain) in underfloor air supply plenums. The new design tool allows the use of a familiar load calculation procedure for OH mixing systems as input to the UFAD design tool. Based on 87 EnergyPlus simulations, four regression models have been developed to transform the OH cooling load into the UFAD cooling load, and then to split this total load between the supply plenum, zone (room), and return plenum. The regression models mainly depend on floor level, and position (interior or perimeter) and orientation of the zone under analysis. Although considered in the analysis, supply air temperature, window-to-wall ratio, internal heat gain, plenum configuration, climate, presence of the carpet and structure type do not strongly influence the developed models. The results show that, generally, UFAD has a peak cooling load 19% higher than an overhead cooling load and 22% and 37% of the total zone UFAD cooling load goes to the supply plenum in the perimeter and interior, respectively.
AB - This paper describes the development of a simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems. The simplified design tool is able to account for key differences between UFAD and traditional mixing overhead (OH) systems. These include: (1) difference between design day cooling load profiles, (2) impact of a thermally stratified environment for UFAD versus well-mixed for OH, and (3) impact of heat transfer (temperature gain) in underfloor air supply plenums. The new design tool allows the use of a familiar load calculation procedure for OH mixing systems as input to the UFAD design tool. Based on 87 EnergyPlus simulations, four regression models have been developed to transform the OH cooling load into the UFAD cooling load, and then to split this total load between the supply plenum, zone (room), and return plenum. The regression models mainly depend on floor level, and position (interior or perimeter) and orientation of the zone under analysis. Although considered in the analysis, supply air temperature, window-to-wall ratio, internal heat gain, plenum configuration, climate, presence of the carpet and structure type do not strongly influence the developed models. The results show that, generally, UFAD has a peak cooling load 19% higher than an overhead cooling load and 22% and 37% of the total zone UFAD cooling load goes to the supply plenum in the perimeter and interior, respectively.
KW - Cooling load
KW - HVAC sizing
KW - Mixing ventilation
KW - Overhead air distribution (OH)
KW - Underfloor air distribution (UFAD)
UR - http://www.scopus.com/inward/record.url?scp=78651435547&partnerID=8YFLogxK
U2 - 10.1016/j.enbuild.2010.10.017
DO - 10.1016/j.enbuild.2010.10.017
M3 - Article
AN - SCOPUS:78651435547
SN - 0378-7788
VL - 43
SP - 517
EP - 528
JO - Energy and Buildings
JF - Energy and Buildings
IS - 2-3
ER -