02476nas a2200325 4500008003900000245007600039210006900115260001200184300001200196490000700208520149100215653001701706653001601723653004601739653002201785653001001807653003301817653001301850653001201863100001901875700002301894700001901917700002201936700002801958700002101986700002102007700002102028700002402049856007702073 2013 d00aU.S. energy savings potential from dynamic daylighting control glazings0 aUS energy savings potential from dynamic daylighting control gla c11/2013 a415-4230 v663 a

Daylighting controls have the potential to reduce the substantial amount of electricity consumed for lighting in commercial buildings. Material science research is now pursuing the development of a dynamic prismatic optical element (dPOE) window coating that can continuously readjust incoming light to maximize the performance and energy savings available from daylighting controls. This study estimates the technical potential for energy savings available from vertical daylighting strategies and explores additional savings that may be available if current dPOE research culminates in a successful market-ready product. Radiance daylight simulations are conducted with a multi-shape prismatic window coating. Simulated lighting energy savings are then applied to perimeter floorspace estimates generated from U.S. commercial building stock data. Results indicate that fully functional dPOE coatings, when paired with conventional vertical daylight strategies, have the potential to reduce energy use associated with U.S. commercial electric lighting demand by as much as 930 TBtu. This reduction in electric lighting demand represents an approximately 85% increase in the energy savings estimated from implementing conventional vertical daylight strategies alone. Results presented in this study provide insight into energy and cost performance targets for dPOE coatings, which can help accelerate the development process and establish a successful new daylighting technology.

10aClerestories10adaylighting10aDynamic prismatic optical elements (dPOE)10aenergy efficiency10aGlare10aindoor environmental quality10aradiance10awindows1 aShehabi, Arman1 aDeForest, Nicholas1 aMcNeil, Andrew1 aMasanet, Eric, R.1 aGreenblatt, Jeffery, B.1 aLee, Eleanor, S.1 aMasson, Georgeta1 aHelms, Brett, A.1 aMilliron, Delia, J. uhttps://facades.lbl.gov/publications/us-energy-savings-potential-dynamic00422nas a2200109 4500008004100000245007600041210006900117260001200186100001900198700002100217856007400238 2012 eng d00aUsing Radiance and GenOpt to design static daylight redirection systems0 aUsing Radiance and GenOpt to design static daylight redirection  c09/20121 aMcNeil, Andrew1 aLee, Eleanor, S. uhttps://facades.lbl.gov/publications/using-radiance-and-genopt-design00421nas a2200097 4500008004100000245007300041210006900114260003500183100002700218856007800245 2011 eng d00aUsing Helmholtz reciprocity in variable resolution BSDFs in Radiance0 aUsing Helmholtz reciprocity in variable resolution BSDFs in Radi bBartenbach L-chtLaborc11/20111 aGeisler-Moroder, David uhttps://facades.lbl.gov/publications/using-helmholtz-reciprocity-variable01115nas a2200121 4500008004100000245004100041210004000082260003600122490001600158520072200174100002200896856007500918 2000 eng d00aU-Values of Flat and Domed Skylights0 aUValues of Flat and Domed Skylights aMinneapolis, Minnesotac06/20000 v106, Part 23 a

Data from nighttime measurements of the net heat flow through several types of skylights is presented. A well-known thermal test facility was reconfigured to measure the net heat flow through the bottom of a skylight/light well combination. Use of this data to determine the U-factor of the skylight is considerably more complicated than the analogous problem of a vertical fenestration contained in a test mask. Correction of the data for heat flow through the skylight well surfaces and evidence for the nature of the heat transfer between the skylight and the bottom of the well is discussed. The resulting measured U-values are presented and compared with calculations using the WINDOW4 and THERM programs.

1 aKlems, Joseph, H. uhttps://facades.lbl.gov/publications/u-values-flat-and-domed-skylights02870nas a2200157 4500008004100000050001400041245013200055210006900187260002900256520225900285100002202544700002402566700001902590700002502609856007802634 1995 eng d aLBL-3697500aUsing Infrared Thermography for the Creation of a Window Surface Temperature Database to Validate Computer Heat Transfer Models0 aUsing Infrared Thermography for the Creation of a Window Surface aToronto, Canadac06/19953 a

Infrared thermography is a non-invasive, non-destructive technique for measuring surface temperatures of an object. These surface temperatures can be used to understand the thermal performance of window components and complete window systems. Infrared (IR) thermography has long been used for qualitative field assessment of window thermal performance, and is now being used in the laboratory for quantitative assessments of window thermal performance. As windows become better and better, more refined test methods and/or simulation tools are required to accurately detect performance changes and make comparisons between products. While hot box calorimetery has worked well to characterize the thermal performance of conventional insulating products, differences in the thermal performance of new highly insulating systems are often less than the resolution of conventional hot box calorimeters. Infrared imaging techniques offer the opportunity to resolve small differences in the thermal performance of components of highly insulating window systems that hot box measurements are not able to identify.

Lawrence Berkeley Laboratory (LBL), a U.S. national research laboratory, is currently using infrared thermography to develop a database of measured surface temperature profiles for a number of different fenestration products for use in validating both basic and advanced two- and three-dimensional finite element method (FEM) and finite difference method (FDM) fenestration heat transfer simulation programs. IR surface temperature data, when taken under controlled laboratory conditions, can be used to direct the development of these simulation codes, identify their strengths and weaknesses, set research priorities, and validate finished modeling tools. Simulation of fenestration heat transfer is faster and less expensive than hot box testing of fenestration products, and forms the basis of window energy codes being implemented, developed, or considered in the US, Canada, the Former Soviet Union, Europe, and Australia. The National Fenestration Rating Council (U. S.) has developed a simulation-based standard which is used to rate and label window U-values for a published directory of over 10,000 different window products.

1 aBeck, Fredric, A.1 aGriffith, Brent, T.1 aTurler, Daniel1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/using-infrared-thermography-creation