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Solar Energy 81 (2007) 581–593 www.elsevier.com/locate/solener

Analysis of the thermal performance and comfort conditions produced by five different passive solar heating strategies in the United States midwest q
´ ´ Alfredo Fernandez-Gonzalez
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Natural Energies Advanced Technologies Laboratory, University of Nevada, Las Vegas, NV 89154-4018, United States Received 15 March 2005; received inrevised form 18 September 2006; accepted 26 September 2006 Available online 7 November 2006 Communicated by: Associate editor: Margot McDonald

Abstract This paper presents a summary of the thermal performance of five different passive solar test-cells (Direct Gain, Trombe-wall, Waterwall, Sunspace, and Roofpond) and a control test-cell during the 2002–2003 heating season in Muncie, Indiana. Theresults discussed in this article correspond to the initial phase of a longer study (data were collected from December of 2002 until August of 2004). The project’s original intent was to identify any barriers to achieving thermal comfort within a space when passive solar heating systems are employed in severe winter climates with predominant overcast sky conditions. Because of the originalintent of this project, the test-cells were arranged with their smaller facades oriented to the north and south and the longer facades facing east and west. This arrangement permitted to study temperature differences throughout the day (diurnal operative temperature swings) and also simultaneous temperature differences throughout the space (a simultaneous comparison of four points instrumented withineach cell to detect variations between the south side and the north side of the test-cells). The results of this phase of the study show that the Direct Gain strategy had the largest diurnal variations of temperature with an average operative temperature swing of 7.8 °C and a maximum variation during the reported period of 10.3 °C. By contrast, the Roofpond strategy had the smallest diurnalvariations of temperature with an average operative temperature swing of 1.2 °C and a maximum variation during the reported period of 1.4 °C. In terms of the simultaneous variations in the operative temperature between the south side and the north side of the test-cells, the Direct Gain strategy showed again the highest variations with an average simultaneous operative temperature difference between thesouth and north sides of the test-cell of 2.9 °C and a maximum variation during the reported period of 3.7 °C. The Roofpond strategy, on the other hand, had the smallest variations with an average simultaneous operative temperature difference between the south and north sides of the test-cell of 0.1 °C and a maximum variation during the reported period of 0.2 °C. The conclusions of this studydemonstrate that diurnal variations of the operative temperature are primarily determined by the type of passive solar strategy utilized (with direct gain producing the highest temperature swings and the indirect gain strategies producing the smallest temperature swings) and by the thermal storage capacity of the system (with a higher thermal storage producing a smaller temperature swing). Thesimultaneous variations of the operative temperature inside the test-cells during the daytime were mostly influenced by the type of passive solar strategy utilized (with direct gain producing the highest simultaneous differences in temperature between the south and north sides of the test-cell and the indirect gain strategies producing the smallest temperature swings). Ó 2006 Elsevier Ltd. All rightsreserved.
Keywords: Passive solar heating; Direct gain; Trombe-wall; Water-wall; Sunspace; Roofpond

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This paper was originally presented at the ASES Solar 2004 conference. Tel.: +1 702 895 1141; fax: +1 702 895 1119. E-mail address: Alfredo.Fernandez@unlv.edu

0038-092X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.solener.2006.09.010

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