Thermal Resistance of a Window with an Enclosed Venetian Blind: A Simplified Model

Wright, John L.; Collins, Michael R.; Huang, Ned Y. T.
May 2008
ASHRAE Transactions;2008, Vol. 114 Issue 1, p471
Academic Journal
Solar gain has a strong influence on building energy consumption and peak cooling load. Venetian blinds are routinely used to control solar gain. Software based on 1-D models is available to accurately predict the thermal performance of glazing systems but the development of models for shading devices is at a very early stage. An accurate model has been formulated to quantify the thermal resistance ofa glazing system with an enclosed venetian blind. It is possible to account for pane spacing, slat angle, alternate fill gases and the presence of a low-emissivity coating. Effective longwave optical properties are assigned to the blind layer in order to calculate radiant heat transfer. An exceptionally simple model for convective heat transfer, the reduced slat length (RSL) model, has been developed on the basis of guarded heater plate measurements. CFD results reveal reasons for the very close agreement between measurement and the RSL model. The new simulation capability can be applied to the quantification of U-factor and Solar Heat Gain Coefficient. The simplicity of the RSL model is particularly valuable in the context of building energy simulation where CPU time must be used sparingly.


Related Articles

  • Cooling Load Design Tool For UFAD. Bauman, Fred; Schiavon, Stefano; Webster, Tom; Kwang Ho Lee // ASHRAE Journal;Sep2010, Vol. 52 Issue 9, p62 

    The article presents an updated and more complete version of the cooling load design tools for underfloor air distribution(UFAD). It features the version 3.1 and the EnergyPlus, a publicly available whole building energy simulation program capable of modeling the more complex heat transfer...

  • Theoretical Analysis and Experimental Confirmation of the Performance of a Thermoelectric Refrigerator. Lingen Chen; Jianzheng Gong, Bjarne; Liangwen Sheng, Bjarne; Fengrui Sun; Chih Wu // Journal of Non-Equilibrium Thermodynamics;2001, Vol. 26 Issue 1, p85 

    The cooling load and coefficient of performance (COP) expressions for a thermoelectric refrigerator, which is composed of multi-elements, are derived with the consideration of heat transfer irreversibility in the heat exchangers between the refrigerator and the reservoirs. An experimental device...

  • Exergetic efficiency optimization of a thermoacoustic cooler. Chen, L.; Wu, F.; Li, Q.; Guo, F.; Su, A. // Proceedings of the Institution of Mechanical Engineers -- Part C;Nov2007, Vol. 221 Issue 11, p1339 

    A heat transfer model with a complex exponent between a thermoacoustic cooler and its surrounding heat reservoirs is established in the current paper. Both the real part and the imaginary part of the heat transfer exponent strongly affect the optimal performance of the cooler. The exergetic...

  • Validation of Solar/Optical Models for Louvered Shades Using a Broad Area Illumination Integrating Sphere. Collins, Michael R.; Tao Jiang // ASHRAE Transactions;2008, Vol. 114 Issue 1, p483 

    In recent years, much attention has been given to the analysis of windows with shading systems. If the solar and thermal performance of these systems can be accurately predicted, than building designers would be better able to include shading as an effective solar control device. In previous...

  • Pre-Cooling Ventilation Outdoor Air, By Heat Exchange With Cooling Coil Condensate Discharge. Namek, Ramzi Y. // Engineered Systems;Mar2005, Vol. 22 Issue 3, p68 

    This article investigates energy efficient systems related to energy recovery and the geographic regions where it might prove beneficial. The cool condensate from a large air conditioning process may be collected and used to reduce the cooling load in an independent and smaller air conditioning...

  • No Sweat. Bonar II, Henry B. // Process Cooling & Equipment;May2004, p16 

    Focuses on desiccant dehumidification. Areas conducive to desiccant and reheat use; Advantages and disadvantages of desiccant dehumidification; Possibility of using desiccant technology with industrial refrigeration systems.

  • How to Efficiently Cool or Condense. Demakos, Peter // Process Cooling & Equipment;May2004, p18 

    Focuses on the usage of wet-surface air coolers for auxiliary fluid cooling and vapor condensing. Basic principle of operation; Air requirements; Maintenance and repair; Design specification; Water use and disposal issues.

  • Reactions of Chiller Maintain Efficiency.  // Air Conditioning, Heating & Refrigeration News;5/1/2006, Vol. 228 Issue 1, p10 

    The article offers information on the advantages of variable speed technology to users of industrial chillers as well as chiller manufacturers. Variable speed, when applied to a refrigeration compressor works to always fit the compressor output to the demand for cooling. The compressor always...

  • We're on Deadline--Printing Press Heat Gain Is More (or Less) than Just Motor Load. Wessel, Dennis J. // ASHRAE Transactions;2004, Vol. 110 Issue 2, p871 

    Historically, heat gain from a newspaper printing press has been a conversion of input power to heat. This method of calculation has resulted in the installation of grossly oversized cooling equipment. Recently developed information from press vendors has resulted in the determination of...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics