Some highly energy efficient window attachment products are available today, but more rapid market adoption would be facilitated by fair performance metrics. It is important to have validated simulation tools to provide a basis for this analysis. This paper outlines a review and validation of the ISO 15099 center-of-glass zero-solar-load heat transfer correlations for windows with cellular shades. Thermal transmittance was measured experimentally, simulated using computational fluid dynamics (CFD) analysis, and simulated utilizing correlations from ISO 15099 as implemented in Berkeley Lab WINDOW and THERM software. CFD analysis showed ISO 15099 underestimates heat flux of rectangular cavities by up to 60% when aspect ratio (AR) = 1 and overestimates heat flux up to 20% when AR = 0.5. CFD analysis also showed that wave-type surfaces of cellular shades have less than 2% impact on heat flux through the cavities and less than 5% for natural convection of room-side surface. WINDOW was shown to accurately represent heat flux of the measured configurations to a mean relative error of 0.5% and standard deviation of 3.8%. Several shade parameters showed significant influence on correlation accuracy, including distance between shade and glass, inconsistency in cell stretch, size of perimeter gaps, and the mounting hardware.

%B Energy and Buildings %V 166 %P 358 - 371 %8 05/2018 %G eng %! Energy and Buildings %R 10.1016/j.enbuild.2018.02.017 %0 Journal Article %J Journal of Building Performance Simulation %D 2017 %T Experimental validation and model development for thermal transmittances of porous window screens and horizontal louvred blind systems %A Robert Hart %A Howdy Goudey %A D. Charlie Curcija %K Building energy %K Heat Transfer %K shading %K u-factor %K window attachment %K windows %XVirtually every home in the US has some form of shades, blinds, drapes, or other window attachment, but few have been designed for energy savings. In order to provide a common basis of comparison for thermal performance it is important to have validated simulation tools. This paper outlines a review and validation of the ISO 15099 centre-of-glass thermal transmittance correlations for naturally ventilated cavities through measurement and detailed simulations. The focus is on the impacts of room-side ventilated cavities, such as those found with solar screens and horizontal louvred blinds. The thermal transmittance of these systems is measured experimentally, simulated using computational fluid dynamics analysis, and simulated utilizing simplified correlations from ISO 15099. Correlation coefficients are proposed for the ISO 15099 algorithm that reduces the mean error between measured and simulated heat flux for typical solar screens from 16% to 3.5% and from 13% to 1% for horizontal blinds.

%B Journal of Building Performance Simulation %V 11 %P 190 - 204 %8 05/2017 %G eng %N 2 %2 LBNL-2001141 %! Journal of Building Performance Simulation %R 10.1080/19401493.2017.1323010 %0 Journal Article %J Building and Environment %D 2001 %T A Nodal Model for Displacement Ventilation and Chilled Ceiling Systems in Office Spaces %A Simon J. Rees %A Philip Haves %K Chilled ceilings %K commercial buildings %K Displacement ventilation %K energy %K Heat Transfer %K Nodal model %K simulation %XA 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.

%B Building and Environment %V 36 %P 753-762 %8 07/2001 %G eng %U http://www.ibpsa.org/proceedings/BS1999/BS99_D-05.pdf %N 6 %& 753 %R 10.1016/S0360-1323(00)00067-6 %0 Journal Article %J ASHRAE Transactions %D 1984 %T The Calculation of Natural Ventilation and Comfort %A Max H. Sherman %A S. Ashley %K Air Flow %K buildings %K ERDA/320100 %K Heat Transfer %K Humidity %K Scale Models %K The 1984 Winter Meeting, Atlanta, GA %K thermal comfort %K velocity %K ventilation %K Wind %K Wind Tunnels %K windows %XNatural ventilation can be used to greatly reduce cooling loads and increase human comfort in buildings in hot, humid climates. Airflow rates directly affect a building's heat balance by removing internal gains and directly affect comfort levels by increasing the body's convective and evaporative heat-transfer coefficients; these airflow rates are determined by the wind pressure on the faces of the building (which is calculated from the wind speed and pressure coefficient) and the amount of open area. Wind pressure coefficients can be obtained in three ways: (1) by direct field measurement, (2) by scale-model experiments in a wind-tunnel, and (3) by comparison with standard wind-tunnel data. In this report the authors describe measurements made on two buildings at the Kaneohe Marine Corps Air Station (KMCAS) on the island of Oahu, Hawaii, during the summer of 1982. These full-scale measurements of pressure coefficients will be compared to reduced-scale measurements made at the boundary-layer wind-tunnel at the Naval Civil Engineering Laboratory (NCEL). Estimates of the indoor comfort levels for different window conditions will be used as a basis for determining the acceptability of natural ventilation for cooling.

%B ASHRAE Transactions %V 90 %8 01/1984 %G eng %N 1B %M DE84009215 %2 LBL-16036