>> >> Will there be sun in the eyes of people sitting on the north side of the table during winter? Column 7 computes an index of how easily solar heat gains from window glazing can be used to heat a building for each of the cities. /CS0 8 0 R In Table 2, it was noted that north-facing windows are always a net BTU loss, since heat losses exceed the meager solar heat gains for all 22 cities. (13) Design roof overhangs, patio or deck coverings, and landscaping to preserve unobstructed sunshine in winter, and shade west- and east-facing windows during summer months. 0000010399 00000 n These properties are the transmissivity "T" , absorptivity "A", emissivity (which is equal to the absorptivity for any given wavelength), and reflectivity all of which are dimensionless quantities that together sum to 1. At solar noon on Dec 21st, light from a south-facing window at typical height would cast direct sunlight about 13' into the home's interior. When architects (yes I've done it for clients) draw diagrams showing the solar exposure of south-facing windows, they often decide on the depth of overhangs for shading based on the angle of the sun at noon in both summer and winter. Which design principles from the 1970s are worth retaining, and which should be discarded? 0000058978 00000 n South-facing windows also have increased solar heat gain in late August to consider. 0000038693 00000 n Remember, Window Joe and the staff at WindowReplacement.net are always here to answer any questions. ( 0000023071 00000 n The following four cities are along the north central and western U.S. (Minneapolis; Salt Lake City; Bismarck, N.D.; and Billings, Montana) . 0000042979 00000 n ( 0000051730 00000 n Argon filled would be affordable and add about R-1. 0000059089 00000 n 0000038900 00000 n ) 0000027405 00000 n I think that the key design criteria for passive solar involves locating and sizing windows, thermal mass, and doing sufficient insulating and air-sealing so that only solar heat gain can provide most of the home's wintertime space heating, yet avoid summertime overheating. 0000021316 00000 n VT is expressed as a number between 0 and 1. 0000050946 00000 n ASHRAEs table of solar heat gain factors[2] provides the expected solar heat gain for clear float glass at different latitudes, orientations, and times, which can be multiplied by the shading coefficient to correct for differences in radiation properties. Passive solar designs typically employ large south facing windows with a high SHGC and overhangs that block sunlight in summer months and permit it to enter the window in the winter. 0000025994 00000 n 0000050037 00000 n 0000011092 00000 n /ColorSpace 27 0 R 0000021997 00000 n 0000056953 00000 n That indirect light comes in all directions, including from south-facing windows, though the direct sunlight is much stronger. hb``` , b-0.X)![)?OXjL ~E-AzMVk+u9:MX@qKpDa%E={d C=H:]JxrWur{. 0000022755 00000 n a product is at blocking unwanted heat gain. number between 0 and 1. 0000052866 00000 n In practice though, most g-values will range between 0.2 and 0.7, with solar control glazing having a g-value of less than 0.5. Solar, wind or other renewable energy source supplies not less than 80 percent of the energy for service water heating. 0000036867 00000 n Table 2 lists solar gain data for the 22 northern U.S. cities. 0000018449 00000 n Buffalo, Pittsburgh, and cities in the Pacific Northwest do not do as well as most other cities. SHGC also decreases with the number of glass panes used in a window. On a traditional southern plantation style home with porches and monster roof overhangs, you could design a south-facing overhang that would completely shade south-facing windows in June, yet not shade much of the top of the window during winter. If the TV were on the same wall, next to a south window around noontime mid-winter, the light from the window would be likely be much brighter than your TV or computer screen. Roof overhangs can shade the top of a window yet allow solar gain at the bottom. 645 0 obj<>stream 0000021224 00000 n 0000052240 00000 n (8) Unobstructed west-facing windows produce heat gains mostly in the afternoon. 0000030922 00000 n Solar Heat Gain Coefficient measures how well a product can resist unwanted heat gain, which is especially important during summer cooling season. 0000012329 00000 n 0000008386 00000 n 0000050694 00000 n 0000023549 00000 n 0000031934 00000 n Maybe some desiccant packets could help reduce fogging? 0 A U-factor of U-0.24 isn't bad, by the way. Go . Solar Heat Gain Coefficient (SHGC) Worksheet -For Non-HERS Registered Projects (Page 3 of 3) TABLE 110.6-B DEFAULT SOLAR HEAT GAIN COEFFICIENT (SHGC) FRAME TYPE PRODUCT GLAZING FENESTRATION PRODUCT SHGC . 0000019351 00000 n SHGC is expressed as a number between 0 and 1. (12) Consider different glazing for windows facing different directions. West-facing windows are a bigger concern, needing shading of some sort during hot late afternoons. The other climate zones underwent more stringent Energy Star qualifications that took effect on January 1, 2015. /TT6 17 0 R You build a simple house, and then you can set your latitude, and then choose the date/hour. The lower the SHGC, the better a product is at blocking unwanted heat gain. Avoiding south-facing windows because in rare cases people created window walls without considering the solar gain or glare impact would be a mistake. Subscribe to receive updates from Energy Saver, including new blogs, updated content, and seasonal energy saving tips for consumers and homeowners. endstream endobj 644 0 obj<> endobj 646 0 obj[647 0 R] endobj 647 0 obj<>>> endobj 648 0 obj<> endobj 649 0 obj<> endobj 650 0 obj<> endobj 651 0 obj<> endobj 652 0 obj<> endobj 653 0 obj<> endobj 654 0 obj<> endobj 655 0 obj<> endobj 656 0 obj<> endobj 657 0 obj<> endobj 658 0 obj<> endobj 659 0 obj<> endobj 660 0 obj<> endobj 661 0 obj<> endobj 662 0 obj<> endobj 663 0 obj<> endobj 664 0 obj<> endobj 665 0 obj<> endobj 666 0 obj<> endobj 667 0 obj<> endobj 668 0 obj<> endobj 669 0 obj<> endobj 670 0 obj<> endobj 671 0 obj<> endobj 672 0 obj<> endobj 673 0 obj<> endobj 674 0 obj<> endobj 675 0 obj<> endobj 676 0 obj<> endobj 677 0 obj<> endobj 678 0 obj<> endobj 679 0 obj<> endobj 680 0 obj<> endobj 681 0 obj<> endobj 682 0 obj<> endobj 683 0 obj<> endobj 684 0 obj<> endobj 685 0 obj<> endobj 686 0 obj<> endobj 687 0 obj<> endobj 688 0 obj<> endobj 689 0 obj<> endobj 690 0 obj<> endobj 691 0 obj<> endobj 692 0 obj<> endobj 693 0 obj<> endobj 694 0 obj<>/ProcSet[/PDF/Text]/ExtGState<>>> endobj 695 0 obj<> endobj 696 0 obj<> endobj 697 0 obj<> endobj 698 0 obj<> endobj 699 0 obj<> endobj 700 0 obj<>stream In Table 1, each city is listed with wintertime climate statistics. The challenge in selecting the appropriate SHGC is balancing out the ideal amount of incoming solar radiation in cold months (to heat your home from the sun's warmth and to lower heating bills), versus keeping solar heat out in hotter months of the year in order to save on air conditioning costs. It ranges from 0 to 1 and refers to the solar energy transmittance of a window or door as a whole, factoring in the glass, frame material, sash (if present), divided lite bars (if present) and screens (if present). I used double-pane windows, and four large double-pane IGUs (for site built fixed windows). It provides a gauge of the relative efficiency of different glass or glazing types in transmitting daylight while blocking heat gains. But hey nothing is perfect, so architects and builders could design roof overhangs to reduce summertime overheating. 0000034107 00000 n Passive solar heating is a design strategy that attempts to maximize the amount of solar gain in a building when additional heating is desired. The south-facing window advantage ranges from at least 140% (Indianapolis) and 144% (Denver), to the most extreme 179% (Seattle) and 338% (far-north Anchorage, Alaska). 0000060317 00000 n For double glazed windows SHGC is more often in the range of 0.42 - 0.55. NFRC U-factor ratings, however, represent the entire window performance, including frame and spacer material. That's good for south-facing windows, because during the hot summer, you don't want the sun beating in your windows, causing solar heat gain in your home's interior. Robert HUPTekzreUXT ey""E + efw# >XimcQLTs}w#HT^bo$kuYPU:)l {ewGJc'8qq`VHK'O]Hy&$z]=16FlN.S-$&uQ/:w An interesting result: It turns out that when these cities are ordered by average solar heat gain, they happen to be ordered somewhat by geographic areas: This geographic ordering is illustrated in the map in Figure 1. Personally, I think we should focus on better window shading methods than roof overhangs. You also may be able to increase the brightness of your screen, which some computer screens do automatically (depending upon ambient light levels). The cost-effectiveness of solar heating varies among regions as well. 0000019693 00000 n 5.8.2.2 Labeling of Fenestration Products . I think these recommendations are a mistake, as that high contrast of dark floor and white ceiling and walls adds to the perception of glare. The lower the rating, the less solar heat is transmitted through the glass, and the greater its shading ability. 0000036698 00000 n Overglazing, underinsulating, oversized HVAC and using stock home plans without site analysis, seem commonplace. Traditional metal windows allow heat to transfer along the metal into the home, so if you live in a hot climate region, metal isn't a great choice for your replacement window frame. 0000059651 00000 n 0000041718 00000 n June 21st, only sees direct sun in the early hours of the morning, and the window son the north-west side of the house in the late evening. So you could have a solar-tempered interior with tile or wood floors over wood frame construction, but not fully passive solar, unless you also have other significant thermal mass elsewhere. "oRD"wB=k:p!TcSm]L /ArtBox [0.0 0.0 612.0 792.0] 0000058284 00000 n These cities are geographically dispersed, with more cities located in the northeast and Great Lakes regions. 0000047504 00000 n 0000044364 00000 n 0000041950 00000 n Such devices can reduce the shading coefficient by blocking portions of the glazing with opaque or translucent material, thus reducing the overall transmissivity. stream The VT you need for a window, door, or skylight should be determined by your home's daylighting requirements and/or whether you need to reduce interior glare in a space. 0000045996 00000 n Table 1 lists 22 northern U.S. cities. Note that this article doesn't promote classic passive solar design, even though a well-designed passive solar home works great in dry cold winter climates (but not in climates with overcast winters). The manufacturers may have improved the materials that made up the frames or the coatings to the glass to meet demands. (Of course you could use a light filtering curtain or shade to fix this.). Annual heating degree days (HDD), an index of the amount of heating needed each winter season. You can use the energy performance ratings of windows, doors, and skylights to understand their potential for gaining and losing heat, as well as bringing sunlight into your home. http://www.cardinalcorp.com/products/coated-glass/loe-180-glass/, PPG Industries manufactures two low-e/high SHGC products: Sungate 500 and Sungate 100 window glass with SHGC of about 0.7. 0000022979 00000 n Kids in school and adults at work have been shown to have better moods and do complex work better with sunlight entering the room. To remain as Energy Star products, manufacturers had to either make changes to their effected products or lose the rating altogether. The winter climates in these cities differ not just in temperature ranges, but also in the amount of winter sunlight. 0000057764 00000 n Other factors like style, finish, hardware, and function can also play a big part in the curb appeal and aesthetics of your home. 0000020266 00000 n /C2_0 15 0 R ( 0000046898 00000 n How Do I Reduce Or Eliminate Condensation? [I notice that after I wrote this response, you edited your comment, changing "high U-value" to "low U-value." 0000013076 00000 n To minimize this and reduce cooling loads, several technologies exist for solar gain reduction. 0000052473 00000 n 0000010938 00000 n 0000028440 00000 n A passive solar building's south-facing windows need good solar access from 9 or 10AM through 2 or 3PM midwinter, when the sun is low on the horizon. The home show in the photo used ceramic floor tile which varied in color but overall was a coffee color. _________________________________________________________________________. 0.83 0.73 0.73 . The larger the net solar gains, the larger the amount of winter heating needed, and the higher the price of electricity, the better the score on the index. /Fm0 11 0 R Great article! 0000042551 00000 n Those principles work in all types of buildings, and unfortunately can be ignored in subdivision design, building design, and building orientation. This coefficient accounts for the time lag between the outdoor and indoor temperature peaks. 0000038260 00000 n Would seem 'Damn the torpedoes, full steam ahead' to catastrophic Global Warming. I look forward to reading your future articles. 0000029981 00000 n T Also for example, if I am to have brunch/lunch during daytime, where do I put dining table? 0000051079 00000 n MIT Press, 1992. North windows would be most desirable in cooling-dominated climates, or during hot summer periods anywhere in the U.S. but not during the cold and darker winters of northern U.S. locations. Very helpful. For more information, see All About Glazing Options. /GS0 3 0 R 0000014397 00000 n SHGC can either be estimated through simulation models or measured by recording the total heat flow through a window with a calorimeter chamber. /XObject Long stretches of overcast days produce large heat losses through large windows, with minimal solar heat gains to compensate. 0000053434 00000 n 0000044168 00000 n 0000020026 00000 n /Annots 26 0 R startxref , The warmer HDD numbers are highlighted in tan, and colder are highlighted in ice blue. The overall shading coefficient is thus given by the ratio: S product blocks heat from the sun. This article explores the viability of passive solar and solar-tempered space heating in northern U.S. regions and metro areas. cooling season. endstream endobj 701 0 obj<> endobj 702 0 obj<> endobj 703 0 obj<>stream Use our Energy Star climate zone tool to look up the specific combinations of u factor and solar heat gain coefficient for the county you live in. 0000058060 00000 n We have a passive solar house we designed and built ourselves in SE Michigan in the late 80's. [3] The transmittance of each component is calculated in a similar manner to the shading coefficient. What Is The Difference Between Convection And Drafts? Glare would not be the reason shades were drawn at that hour for south-facing windows in any home, unless someone needs a dark interior, like trying to sleep late. 0000038067 00000 n The shading coefficient depends on the radiation properties of the window assembly. 0000010707 00000 n Get building science and energy efficiency advice, plus special offers, in your inbox. A og = The skylight area. Fy(@k ,dKa`C]Ll*EWXhS %PDF-1.6 0000054151 00000 n A new, affordable but well-insulated window (with cellular blinds used at night) would attain values similar to those listed in the table. 0000030384 00000 n When the sun's rays hit an object, such as a window, some of the sun's energy is absorbed, warming that object, and allowed to pass through. 0000048656 00000 n 0000042713 00000 n In addition to glass properties, shading devices integrated into the window assembly are also included in the SC calculation. (1) To exploit solar heat gains from windows in mid-winter (and minimize heat gain in summer), we can build on a building lot that has good south-facing solar access during mid-winter, when the sun appears lower on the horizon mid-day. %PDF-1.3 % << Kansas City and cities along the northeast coast also look promising for wintertime daylighting, space heating, and PV. Is It Easier To Clean Replacement Windows? The home is a three story house, with a basement comprising the bottom floor. Cities in the table are listed in descending order of their mid-winter solar heat gain. , 0000053260 00000 n Will New Windows Save Money On Energy Bills? The lower the number, the less you'll spend on cooling. The product Passive solar design is a key element of creating resilient homes, Cold-climate glazing is surprisingly hard to find. << 0000031652 00000 n 0 To that end, glazing with a relatively high solar heat gain coefficient is often used so as not to block solar heat gains, especially in the sunny side of the house. Not sure when I took the photo, other than it shows AM shadows, and not during winter, as the deciduous plants had their leaves.