03102nas a2200229 4500008004100000020002200041245008200063210006900145260004400214520234700258653001502605653001502620653002602635653001202661653001702673653001202690100002102702700002602723700002502749700002202774856007602796 2007 eng d a978-82-536-0970-600aState-of-the-Art Highly Insulating Window Frames - Research and Market Review0 aStateoftheArt Highly Insulating Window Frames Research and Marke aOlsobINTEF Building and Infrastructure3 a

This document reports the findings of a market and research review related to state-of-the-art highly insulating window frames. The market review focuses on window frames that satisfy the Passivhaus requirements (window U-value less or equal to 0.8 W/m2K), while other examples are also given in order to show the variety of materials and solutions that may be used for constructing window frames with a low thermal transmittance (U-value). The market search shows that several combinations of materials are used in order to obtain window frames with a low U-value. The most common insulating material seems to be Polyurethane (PUR), which is used together with most of the common structural materials such as wood, aluminum, and PVC.

The frame research review also shows examples of window frames developed in order to increase the energy efficiency of the frames and the glazings which the frames are to be used together with. The authors find that two main tracks are used in searching for better solutions. The first one is to minimize the heat losses through the frame itself. The result is that conductive materials are replaced by highly thermal insulating materials and air cavities. The other option is to reduce the window frame area to a minimum, which is done by focusing on the net energy gain by the entire window (frame, spacer and glazing). Literature shows that a window with a higher U-value may give a net energy gain to a building that is higher than a window with a smaller U-value. The net energy gain is calculated by subtracting the transmission losses through the window from the solar energy passing through the windows. The net energy gain depends on frame versus glazing area, solar factor, solar irradiance, calculation period and U-value.

The frame research review also discusses heat transfer modeling issues related to window frames. Thermal performance increasing measures, surface modeling, and frame cavity modeling are among the topics discussed. The review shows that the current knowledge gives the basis for improving the calculation procedures in the calculation standards. At the same time it is room for improvement within some areas, e.g. to fully understand the natural convection effects inside irregular vertical frame cavities (jambs) and ventilated frame cavities.

10aenergy use10aPassivhaus10athermal transmittance10aU-value10awindow frame10awindows1 aGustavsen, Arlid1 aJelle, Bjørn, Petter1 aArasteh, Dariush, K.1 aKohler, Christian uhttps://facades.lbl.gov/publications/state-art-highly-insulating-window02194nas a2200181 4500008004100000050001500041245007900056210006900135260003100204520156500235100002501800700002901825700001901854700002201873700002001895700002301915856007401938 1998 eng d aLBNL-4215100aState-of-the-Art Software for Window Energy-Efficiency Rating and Labeling0 aStateoftheArt Software for Window EnergyEfficiency Rating and La aPacific Grove, CAc08/19983 a

Measuring the thermal performance of windows in typical residential buildings is an expensive proposition. Not only is laboratory testing expensive, but each window manufacturer typically offers hundreds of individual products, each of which has different thermal performance properties. With over a thousand window manufacturers nationally, a testing-based rating system would be prohibitively expensive to the industry and to consumers.

Beginning in the early 1990s, simulation software began to be used as part of a national program for rating window U-values. The rating program has since been expanded to include Solar Hear Gain Coefficients and is now being extended to annual energy performance.

This paper describes four software packages available to the public from Lawrence Berkeley National Laboratory (LBNL). These software packages are used to evaluate window thermal performance: RESFEN (for evaluating annual energy costs), WINDOW (for calculating a products thermal performance properties), THERM (a preprocessor for WINDOW that determines two-dimensional heat-transfer effects), and Optics (a preprocessor for WINDOWs glass database).

Software not only offers a less expensive means than testing to evaluate window performance, it can also be used during the design process to help manufacturers produce windows that will meet target specifications. In addition, software can show small improvements in window performance that might not be detected in actual testing because of large uncertainties in test procedures.

1 aArasteh, Dariush, K.1 aFinlayson, Elizabeth, U.1 aHuang, Yu, Joe1 aHuizenga, Charlie1 aMitchell, Robin1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/state-art-software-window-energy01962nas a2200169 4500008004100000050001500041245010000056210006900156260003100225490001600256520135300272100002401625700002901649700002101678700002501699856006801724 1997 eng d aLBNL-4069000aThe Significance of Bolts in the Thermal Performance of Curtain-Wall Frames for Glazed Façades0 aSignificance of Bolts in the Thermal Performance of CurtainWall  aSan Francisco, CAc01/19980 v104, Part 13 a

Curtain walls are assemblies of glazings and metal frames that commonly form the exterior glass façades of commercial buildings. Evaluating the thermal performance of the bolts that hold curtain wall glazings in place is necessary to accurately rate the overall thermal performance of curtain walls. Using laboratory tests and computer simulations, we assessed the thermal performance of several different configurations of bolts and glazings. Curtain-wall samples were tested in the infrared thermography laboratory at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California. Experimental results were compared to two-dimensional simulations approximating the thermal effect of the bolts using the parallel path and the isothermal planes calculation methods. We conclude that stainless steel bolts minimally affect curtain-wall thermal performance (approximately 18%) when spaced at least nine inches apart, which is the industry standard. Performance is increasingly compromised when there is less than nine inches between bolts or when steel bolts are used. We also show that the isothermal planes method of approximating curtain wall thermal performance can be used with 2-D heat transfer software typical of that used in the window industry to give conservative results for the thermal bridging effect caused by bolts.

1 aGriffith, Brent, T.1 aFinlayson, Elizabeth, U.1 aYazdanian, Mehry1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/significance-bolts-thermal01611nas a2200157 4500008004100000024001100041245009900052210006900151260001200220490000800232520107300240100002401313700001901337700002501356856007201381 1995 eng d aTA-35200aSurface Temperatures of Insulated Glazing Units: Infrared Thermography Laboratory Measurements0 aSurface Temperatures of Insulated Glazing Units Infrared Thermog c12/19950 v1023 a

Data are presented for the distribution of surface temperatures on the warm-side surface of seven different insulated glazing units. Surface temperatures are measured using infrared thermography and an external referencing technique. This technique allows detailed mapping of surface temperatures that is non-intrusive. The glazings were placed between warm and cold environmental chambers that were operated at conditions corresponding to standard design conditions for winter heating. The temperatures conditions are 21.1 °C (70 °F) and -17.8 °C (0 °F) on the warm and cold sides, respectively. Film coefficients varied somewhat with average conditions of about 7.6 W/m2 K (1.34 Btu/h ft2 °F) for the warm-side and 28.9 W/m2 K (5.1 Btu/h ft2 °F) for the cold-side. Surface temperature data are plotted for the vertical distribution along the centerline of the IG and for the horizontal distribution along the centerline. This paper is part of larger collaborative effort that studied the same set of glazings.

1 aGriffith, Brent, T.1 aTurler, Daniel1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/surface-temperatures-insulated01994nas a2200265 4500008004100000245009000041210006900131490000800200520120800208653001201416653001301428653002401441653001201465653001201477653001601489653001501505653000801520653001201528100002101540700002101561700002301582700002501605700002701630856007101657 1994 eng d00aSpectrally Selective Glazings for Residential Retrofits in Cooling-Dominated Climates0 aSpectrally Selective Glazings for Residential Retrofits in Cooli0 v1003 a

Spectrally selective glazings can substantially reduce energy consumption and peak demand in residences by significantly reducing solar gains with minimal loss of illumination and view. In cooling-dominated climates, solar gains contribute 24–31% to electricity consumption and 40–43% to peak demand in homes with single pane clear glazing—standard practice for residential construction built before the implementation of building energy efficiency standards. The existing residential housing stock therefore offers a prime opportunity for significant demand-side management (DSM),but the energy and cost savings must be weighed against retrofit first costs in order for the technology to achieve full market penetration. Using DOE-2.1D for numerical simulation of building energy performance, we quantify the energy and peak demand reductions, cost savings, and HVAC capacity reductions using spectrally selective glazings for five cooling-dominated climates in California. The cost-effectiveness of various material and installation retrofit options is discussed. Glazing material improvements for retrofit applications that are needed to achieve a prescribed cost savings are also given.

10adeserts10adomestic10aenergy conservation10aGlazing10ahousing10amodernising10asubtropics10ausa10awindows1 aLee, Eleanor, S.1 aHopkins, Deborah1 aRubin, Michael, D.1 aArasteh, Dariush, K.1 aSelkowitz, Stephen, E. uhttps://facades.lbl.gov/publications/spectrally-selective-glazings01641nas a2200133 4500008004100000050001500041245013100056210006900187520111200256100002001368700002501388700002001413856007401433 1993 eng d aLBNL-3395600aSavings from Energy Efficient Windows: Current and Future Savings from New Fenestration Technologies in the Residential Market0 aSavings from Energy Efficient Windows Current and Future Savings3 a

Heating and cooling energy lost through windows in the residential sector (estimated at two-thirds of the energy lost through windows in all sectors) currently accounts for 3 percent (or 2.8 quads) of total US energy use, costing over $26 billion annually in energy bills. Installation of energy-efficient windows is acting to reduce the amount of energy lost per unit window area. Installation of more energy efficient windows since 1970 has resulted in an annual savings of approximately 0.6 quads. If all windows utilized existing cost effective energy conserving technologies, then residential window energy losses would amount to less than 0.8 quads, directly saving $18 billion per year in avoided energy costs. The nationwide installation of windows that are now being developed could actually turn this energy loss into a net energy gain. Considering only natural replacement of windows and new construction, appropriate fenestration policies could help realize this potential by reducing annual residential window energy losses to 2.2 quads by the year 2012, despite a growing housing stock.

1 aFrost, Karl, J.1 aArasteh, Dariush, K.1 aEto, Joseph, H. uhttps://facades.lbl.gov/publications/savings-energy-efficient-windows01348nas a2200145 4500008004100000050001400041245005600055210005600111260003200167520086300199100002501062700002101087700002101108856007301129 1984 eng d aLBL-1747600aSkylight Energy Performance and Design Optimization0 aSkylight Energy Performance and Design Optimization aGothenburg, Swedenc06/19843 a

Proper skylight utilization can significantly lower energy requirements and peak electrical loads for space conditioning and lighting in commercial buildings. In this study we systematically explore the energy effects of skylight systems in a prototypical officesbuilding and examine the savings from daylighting. We used the DOE-2.1B energy analysis computer program with its newly incorporated daylighting algorithims to generate more than 2000 parametric simulations for seven U.S. climates. The parameters varied include skylight-to-roof ratio, shading coefficient, visible transmittance, skylight well light loss, electric lighting powersdensity, roof heat transfer coefficient, and type of electric lighting control. For specific climates we identify roof/skylight characteristics that minimize total energy or peak electrical load requirements.

1 aArasteh, Dariush, K.1 aJohnson, Russell1 aSullivan, Robert uhttps://facades.lbl.gov/publications/skylight-energy-performance-and