01287nas a2200133   4500008004100000050001500041245005500056210005400111260003100165490001600196520084400212100002201056856007501078       1997                        eng d  aLBNL-4044800aGreenhouse Window U-Factors Under Field Conditions0 aGreenhouse Window UFactors Under Field Conditions  aSan Francisco, CAc01/19980 v104, Part 13 a<p>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.</p>1 aKlems, Joseph, H.  uhttps://facades.lbl.gov/publications/greenhouse-window-u-factors-under