Greenhouse Window U-Factors Under Field Conditions

TitleGreenhouse Window U-Factors Under Field Conditions
Publication TypeJournal Article
Year of Publication1997
AuthorsJoseph H Klems
JournalASHRAE Transactions
Volume104, Part 1
Date Published01/1998
Call NumberLBNL-40448

Field measurements of U-factor are reported for two projecting greenhouse windows, each paired with a picture window of comparable insulation level during testing. A well-known calorimetric field test facility was used to make the measurements. The time-varying U-factors obtained are related to measurements of exterior conditions. For one of the greenhouse windows, which was the subject of a published laboratory hotbox test and simulation study, the results are compared with published test and simulation data and found to be in disagreement. Data on interior and exterior film coefficients are presented, and it is shown that the greenhouse window has a significantly lower interior film coefficient than a conventional window under the same interior conditions. This is advanced as a possible explanation of the disagreement.

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