A nodal model has been developed to represent room heat transfer in displacement ventilation and chilled ceiling systems. The model uses precalculated air flow rates to predict the air temperature distribution and the division of the cooling load between the ventilation air and the chilled ceiling. The air movements in the plumes and the rest of the room are represented separately using a network of ten air nodes. The values of the capacity rate parameters are calculated by solving the heat and mass balance equations for each node using measured temperatures as inputs. Correlations between parameter values for a range of cooling loads and supply air flow rates are presented.

10aChilled ceilings10acommercial buildings10aDisplacement ventilation10aenergy10aHeat Transfer10aNodal model10asimulation1 aRees, Simon, J.1 aHaves, Philip uhttp://www.ibpsa.org/proceedings/BS1999/BS99_D-05.pdf01528nas a2200157 4500008004100000245012300041210006900164260001200233300001400245490000700259520097200266100002001238700002301258700001801281856007101299 2001 eng d00aNumerical Investigation of Transient Buoyant Flow in a Room with a Displacement Ventilation and Chilled Ceiling System0 aNumerical Investigation of Transient Buoyant Flow in a Room with c08/2001 a3067-30800 v443 aThe air flow in the office ventilation system known as displacement ventilation is dominated by a gravity current from the inlet and buoyant plumes above internal heat sources. Calculations of the flow and heat transfer in a typical office room have been made for this type of ventilation system used in conjunction with chilled ceiling panels. These calculations have been made in parallel with full size test chamber experiments. It has been found that with higher values of internal load (45 and 72 W m^{−2} of floor area) the flow becomes quasi-periodic in nature. Complex lateral oscillations are seen in the plumes above the heat sources which impinge on the ceiling and induce significant recirculating flows in the room. The frequency spectra of the transient calculations show good agreement with those of the experimental results. Comparison is also made between calculated mean room air speeds and temperature profiles and measured values.

A qualitative comparison is presented between three current North American and U.K. design cooling load calculation methods. The methods compared are the ASHRAE Heat Balance Method, the Radiant Time Series Method and the Admittance Method, used in the U.K. The methods are compared and contrasted in terms of their overall structure. In order to generate the values of the 24 hourly cooling loads, comparison was also made in terms of the processing of the input data and the solution of the equations required. Specific comparisons are made between the approximations used by the three calculation methods to model some of the principal heat transfer mechanisms. Conclusions are drawn regarding the ability of the simplified methods to correctly predict peak-cooling loads compared to the Heat Balance Method predictions. Comment is also made on the potential for developing similar approaches to cooling load calculation in the U.K. and North America in the future.

1 aRees, Simon, J.1 aSpitler, Jeffrey, D.1 aDavies, Morris, G.1 aHaves, Philip uhttps://buildings.lbl.gov/publications/qualitative-comparison-north-american01143nas a2200121 4500008004100000245009200041210006900133260002600202520069700228100002000925700001800945856005800963 1999 eng d00aA Nodal Model for Displacement Ventilation and Chilled Ceiling Systems in Office Spaces0 aNodal Model for Displacement Ventilation and Chilled Ceiling Sys aKyoto, Japanc09/19993 aA nodal model has been developed to represent room heat transfer in displacement ventilation and chilled ceiling systems. The model uses precalculated air flow rates to predict the air temperature distribution and the division of the cooling load between the ventilation air and the chilled ceiling. The air movements in the plumes and the rest of the room are rep- resented separately using a network of ten air nodes. The values of the capacity rate parameters are calculated by solving the heat and mass balance equations for each node using measured temperatures as inputs. Correlations between parameter values for a range of cooling loads and supply air flow rates are presented.

1 aRees, Simon, J.1 aHaves, Philip uhttp://www.ibpsa.org/proceedings/BS1999/BS99_D-05.pdf01200nas a2200145 4500008004100000245008800041210006900129300001000198490000800208520069700216100002000913700002500933700001800958856007800976 1998 eng d00aComparison of North American and U.K. Cooling Load Calculation Procedures - Results0 aComparison of North American and UK Cooling Load Calculation Pro a36-460 v1043 aCalculation of design cooling loads is of critical concern to designers of HVAC systems. The work reported here has been carried out under a joint ASHRAE/CIBSE research project to compare design cooling calculation methods. Three calculation methods have been tested, the ASHRAE heat balance method and radiant time series method, and the admit- tance method, used in the U.K. The results presented in this paper show the general trends in over/underprediction of peak load in the simplified methods compared to the heat balance method. The performance of the simplified methods is explained in terms of some of the underlying assumptions in the methods and by reference to specific examples.1 aRees, Simon, J.1 aSpitler, Jeffrey, D.1 aHaves, Philip uhttps://buildings.lbl.gov/publications/comparison-north-american-and-uk-001637nas a2200145 4500008004100000245009200041210006900133300001000202490000800212520113200220100002501352700002001377700001801397856007601415 1998 eng d00aComparison of North American and U.K. Cooling Load Calculation Procedures - Methodology0 aComparison of North American and UK Cooling Load Calculation Pro a47-610 v1043 aThis paper describes the methodology used in a quanti- tative comparison between the current North American and United Kingdom cooling load calculation methods. Three calculation methods have been tested as part of a joint ASHRAE/CIBSE research project: the ASHRAE heat balance method and radiant time series method and the admittance method, used in the U.K. A companion paper (Rees et al.1998) describes the results of the study. The quantitative comparison is primarily organized as a parametric study—each building zone/weather day combination compared may be thought of as a combination of various parameters, e.g., exterior wall type, roof type, glazing area, etc. Specifically, this paper describes the overall organization of the study, the parameters and parameter levels that can be varied, and the tools developed to create input files, automate the load calculations, and extract the results. A brief descrip- tion of the cooling load calculation procedure implementa- tions is also given. The methodology presented and the tools described could also be used to make comparisons between other calculation methods.1 aSpitler, Jeffrey, D.1 aRees, Simon, J.1 aHaves, Philip uhttps://buildings.lbl.gov/publications/comparison-north-american-and-uk00475nas a2200109 4500008004100000245011100041210006900152260002500221100002000246700001800266856008100284 1995 eng d00aA Model of a Displacement Ventilation/Chilled Ceiling Cooling System Suitable for Annual Energy Simulation0 aModel of a Displacement VentilationChilled Ceiling Cooling Syste aMadison, WIc08/19951 aRees, Simon, J.1 aHaves, Philip uhttps://buildings.lbl.gov/publications/model-displacement-ventilationchilled00444nas a2200121 4500008004100000245005900041210005900100260002700159100001800186700002000204700001900224856007900243 1995 eng d00aModelling and Simulation of Low Energy Cooling Systems0 aModelling and Simulation of Low Energy Cooling Systems aBejing, Chinac09/19951 aHaves, Philip1 aRees, Simon, J.1 aHarrington, L. uhttps://buildings.lbl.gov/publications/modelling-and-simulation-low-energy