solar heat gain factor table

/MC0 Next, six cities in the Midwest and Great Lakes area (Chicago; Indianapolis; Detroit; Burlington, Vermont; Pittsburgh, Pennsylvania; and Buffalo, N.Y.). 0000040032 00000 n /ColorSpace At home she is the first to pull them up on a sunny morning, maybe because we have more room at home. 0000019574 00000 n 0000029417 00000 n 0000056162 00000 n 0000029142 00000 n (17) Cities and towns can promote energy efficiency and public health by incorporating zoning laws and incentives that provide building lots with south-facing solar access, and protect solar access for existing buildings. The winter climates in these cities differ not just in temperature ranges, but also in the amount of winter sunlight. Worth remembering that those early-'80's houses are one of the main reasons we are having such fruitful discussions today! o 1 Try to design smaller and fewer west-facing windows. I used Google Sketchup, the free version, to roughly model shadows on my soon to be built house. << 0000050037 00000 n You want to shade your south-facing windows from the sun to avoid solar heat gain. Privacy | ) Other cities in the list across the Midwest and northern central U.S. get about half the net solar heat gain of Denver. a product is at blocking unwanted heat gain. Depending on how many changes a manufacturer had to make, it could have greatly impacted the retail price of your window replacement installation. Seattle, Washington. 0000048946 00000 n (11) Make adjustments to window locations, sizes, and glazing options (SHGC and U-factor) to optimize natural lighting and solar heat gain in winter and summer seasons. startxref What Is The Difference Between Convection And Drafts? , 0000008921 00000 n "oRD"wB=k:p!TcSm]L Q(summer) = U*A*(CLTD) using the CLTD method. Denver is the best location for wintertime daylighting, for using solar heat gain for space heating, and for PV. 0000025712 00000 n And if you design for best wintertime performance, you will get undesirable solar heat gain in the late summer. The most important factors are budget and energy efficiency. Unless I'm mistaken, the house has interior shades or curtains, and these are in use for many of the south-facing windows. The first six columns list the same 22 U.S. cities and other previously displayed data, which are helpful in determining the value and ease of using solar heat gains for space heating. So I don't think glare around the dining table on the opposite side of the room would be much of a problem. 0000011092 00000 n (6) South-facing windows have less undesirable solar gain during summer than west- or east-facing windows. 0000034369 00000 n For January solar heat gain from south-facing windows, the highest numbers are triple the lowest. 0000031802 00000 n The lower the SHGC, the better 0000034811 00000 n The lower the U-factor, the more energy-efficient the window, door, or skylight. >> 0000040580 00000 n Shading Coefficient (SC) SHADING COEFFICIENT (SC) is the ratio of the solar heat gain through a fenestration product to the solar heat gain through an unshaded 1/8-inch-thick clear double strength glass under the same set of conditions. 0000051467 00000 n The question-and-answer article above, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss. But it would not shade the window as much as you'd like by late August, or earlier or later during the day on June 21st, as you point out. 0000020469 00000 n Solar Heat Gain through Glass Internal Heat Gains from People, Lights, and Equipment ASHRAE Zones for Solar Cooling Load (SCL) Factors for Glass are based on: Floor Level and Room Location Single Story Building (Table 8.8-A) Top Floor (Table 8.8-B) First / Ground Floor (Table 8.8-C) Middle Floor (Table 8.8-D) Interior Rooms (Table 8.8-E) Office of Energy Efficiency & Renewable EnergyForrestal Building1000 Independence Avenue, SWWashington, DC 20585, Fuel Efficient & Alternative Fuel Vehicles, Independently Tested and Certified Energy Performance for Windows, Doors, and Skylights, Energy Performance Ratings for Windows, Doors, and Skylights, Direct conduction and convection heat transfer through the glass or multi-layer glazing and framing, Thermal radiation into a house and out of a house from room-temperature objects, such as exterior walls and windows, people, equipment, furniture, and interior walls, The solar radiation into a house, which is converted to heat when absorbed by building surfaces. I look forward to reading your future articles. Varying window sizes and numbers can increase or decrease solar gains and heat losses to affect overall energy performance. 0000051079 00000 n The lower the U-Factor, the better the window insulates. 0000034703 00000 n Passivhaus is known for having lots of foam insulation below slab floors (8" to 10" thickness might be common) to keep within their limited heat loss budget. 0000052997 00000 n 0000024359 00000 n The whole window; meaning the window frame and glazing (glass) or: Center of the glass; meaning it only includes the SHGC for the the glass, Coatings bounce heat and light out or inside the home to increase or decrease light and heat that enters the house, Glazing comes in single or multiple layers to keep mother nature outdoors. 0000058978 00000 n FIND A DEALER. , Reflections of the window or objects in direct sunlight (that are behind you) could be visible on your TV or computer screen as reflections on the screen. Thanks for all the great details and comments, and your work on this type of efficient home design. -- The lowest sun angle at noon is around Dec 21st,, when the sun is low on the southern horizon, even at noon. The solar gain is not stored near the windows to be lost at night but is captured through an open door into the main building. At the bottom of the table, the yearly gains are totaled for south-, north-, east-, and west-facing windows. One of the best I've read here. 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. 0000021316 00000 n 0000057117 00000 n 0000042410 00000 n UA Table = (U-factor from Table C402.1.4 or C402.4) x Area B = Sum of the (FL Dif) values for each distinct slab on grade perimeter condition of the building thermal . If the TV itself is not in or adjacent to direct sunlight, and at a 90 degree angle to the window receiving direct sunlight, it should be okay. In the context of passive solar building design, the aim of the designer is normally to maximize solar gain within the building in the winter (to reduce space heating demand), and to control it in summer (to minimize cooling requirements). 0000032457 00000 n Solar heat gain (SHG) describes the way radiation from the sun is turned into heat. Thanks for the kind words - and thanks for the explanation. /C2_1 14 0 R T [3] Since the quantities compared are functions of both wavelength and angle of incidence, the shading coefficient for a window assembly is typically reported for a single wavelength typical of solar radiation entering normal to the plane of glass. Higher SGHC=0.7 could be used on south-facing glazing to increase solar gains, but still get decent heat loss performance (e.g., Cardinal LoE-180 glass with SHGC=.69, U=26). 0000027631 00000 n 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. 0000060083 00000 n F 0000049380 00000 n He was a psychology professor for five years, and a software and web site usability and design engineer for 20 years. d ) Balcomb, J.Douglas, editor. The lower the number, the less you'll spend on cooling. E. Which type of glazing is optimal for a given project depends One quick note: It appears that you are assuming a SHGC of 0.5 for the heat gain calculations. In June, the sun is closer to overhead at noon, so south windows have far less solar heat gain. 0000044364 00000 n Other internet data sources may include somewhat different data, but the patterns of data would lead to similar conclusions. . Alaska, the Pacific Northwest, and Midwestern cities would not be good candidates to rely on wintertime solar heating. /TT7 16 0 R HUPTekzreUXT ey""E + efw# >XimcQLTs}w#HT^bo$kuYPU:)l {ewGJc'8qq`VHK'O]Hy&$z]=16FlN.S-$&uQ/:w Long stretches of overcast days produce large heat losses through large windows, with minimal solar heat gains to compensate. Their net solar heat gain is only about a quarter of Denvers. >> Low-emissivity coating is another more recently developed option that offers greater specificity in the wavelengths reflected and re-emitted. Industry technical experts recognized the limitations of SC and pushed towards SHGC in the United States (and the analogous g-value in Europe) before the early 1990s. Considering the dynamics of glass and solar energy, the simplest formula experts use to calculate the value for solar heat gain coefficient is: Solar heat gain coefficient = portion of solar energy transmitted + portion of absorbed solar energy that is emitted inside. 0000018860 00000 n Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Grid Type . It quantifies how some US climates (and not others) can use solar heat gain for space heating, or reduce utility bills cost-effectively, by designing to manage solar heat gain. 0000023459 00000 n 0000048656 00000 n 0000047288 00000 n AL is an South-facing windows produce the most natural daylighting and solar heat gain from the month of September through the month of April. Average January temperature (F), the coldest month of the year. /GS0 3 0 R is thus the portion of absorbed and re-emitted energy across all assembly components beyond just the glass. The shading coefficient (SC) is a measure of the radiative thermal performance of a glass unit (panel or window) in a building. 0000008689 00000 n Therefore, the sun is shining on your south-facing walls and windows during wintertime. If your TV screen is in direct sunlight, it would be difficult to see the screen. 0000026490 00000 n The glass on the TV or computer screen can also be highly reflective smooth glass for best visual screen performance, or can be less reflective glass for less interference with reflections on the screen. 0000010861 00000 n Although glare hadn't been much of a problem, that uniform interior color reduced color contrast, and did seem to reduce the perception of glare. Is it possible to determine an appropriate period of shading for summertime sun that also allows peak wintertime solar gain? The larger the SHGC, the more light that can enter through the window. A product with a low air leakage rating is tighter than one with a high air leakage rating. "T" is the transmissivity of the glass, "A" is its absorptivity, and "N" is the fraction of absorbed energy that is re-emitted into the space. Otherwise, the ordering remains similar to the previous ordering by amount of solar heat gain from south windows (Tables 1 through 3). /Properties %PDF-1.6 % And during this period, should the window be completely shaded, or just shaded at noon and partially on each side of that time? 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. "Do the math!". 0000027028 00000 n From what I've read, slab depth beyond 4" thick doesn't get you much additional heat storage or dampening of temperature fluctuations in direct gain passive solar designs. The overall solar energy gain is expressed by the solar gain factor g and is given by [Fig. The lowest numbers are about double the highest. I would also like to hear more about your/GBA community's thoughts on thermal mass and its relationship with solar heat gain. 0000011169 00000 n Gases are added between the layers of glazing to further increase insulation, the gases are heavier than air, making it less likely air will penetrate the glazing. 0000022435 00000 n 0000027305 00000 n 0000034610 00000 n -Bob Opaluch designed and built a passive solar home in Colorado, renovated two homes in Massachusetts, and has many years of renovation, maintenance, repair, and furniture-building experience. If you live in a climate where it is hot and sunny most of the year, then you may want to block more of the sun's heat with an SHGC closer to 1. This is also hugely effective. To optimize the heat gain through windows heavily insulated shutters will change all the numbers. 0000035843 00000 n endstream endobj 701 0 obj<> endobj 702 0 obj<> endobj 703 0 obj<>stream This is a very basic question I confess not knowing the answer to. Would seem 'Damn the torpedoes, full steam ahead' to catastrophic Global Warming. Excellent Resource! As well, 3 years ago, having been so pleased with the shutter effect, I built a "low mass, super insulated south facing solar porch. I'm old enough to remember the passive solar homes of the 1970s and 1980s. /TT6 17 0 R Kansas City and the seven northeastern seaboard cities do almost as well with average net solar heat gain in January. SHGC is influenced by the color or tint of glass and its degree of reflectivity. ) %3Qd Vw9k\1W7CL9tqM=~u5b&XfmFk!$"4c?9%fb|$N}0R16f]oqnDxo[hot;3Nq_fO-jldHA '*bIgdyfs[B[Z+^:E 9)Uii;/J PH( 6.u. w AL$/RB!)z&S7NOauE,|?q GQFSnD{.gTbPZsAFl rwxLCC C-bJD[F;#lTM5Xn"[. %PDF-1.6 % Thank you so much for sharing this with us. Designers and builders can use higher solar heat gain windows on south-facing windows and higher R-value (lower U-factor) windows on north, west, and east-facing windows to further increase solar gains and reduce heat losses overall. Even during winter afternoons, additional space heating may not be needed by the afternoon. (For Denver, east- and west-facing windows do have a net solar heat gain of 25%, which is positive, but only one-third as much as south-facing windows 75% net gain.). 0000022599 00000 n 0000054427 00000 n h[koG+`z?qN5A9 Y2dffIQMb?oE2+bXYkW6Dl-uJG%M}I2lF 9{lbbcJ*MZ&`S~PmQ9cU:VV)L+o/,7Z._}o.)?/o/\=|'7/>\?G{gN-`W>>llY9[Gyhenzvs=~zbW^z.67O_n2a}~s*y~ugg>g^=u|zrvqzbt -- The highest sun angle (for the northern hemisphere) is around June 21st, when the sun is nearly overhead at noon, just a little toward the southern horizon. 0000033229 00000 n << [3], The g-value (sometimes also called a Solar Factor or Total Solar Energy Transmittance) is the coefficient commonly used in Europe to measure the solar energy transmittance of windows. At the bottom, Anchorage is the only city that has average net heat losses through south-facing windows. For some locations, the heat is more pronounced and longer in duration than the short months of frigid temperatures with little snow. F 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. 0000057926 00000 n The larger the net solar gains, and the smaller the winter heating needed, the better the score on the index. 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. 0000053952 00000 n The tables and charts that follow provide solar radiation data in units of Btu / ft 2 / day for five surfaces: a horizontal (Figure 12.5) window and a vertical window . However, if shades are needed to reduce overheating mid-winter, likely there's a design error of over-glazing with west or south-facing windows. So I'd recommend designing overhangs for minimal shading mid-winter, and not worry so much about summer (for winter-dominated northern climates). 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 . 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. 0000011708 00000 n Avoiding south-facing windows because in rare cases people created window walls without considering the solar gain or glare impact would be a mistake. I will quantify solar heating potential by looking at climate data for 22 large cities across the northern U.S. Passive solar heating is a design strategy that attempts to maximize the amount of solar gain in a building when additional heating is desired. ) /Metadata 9 0 R 0000045996 00000 n {\displaystyle S.C.=F(\lambda ,\theta )_{1}/F(\lambda ,\theta )_{o}}. U-factor = 0.5, or R-2, very poor by today's standards. 0000052778 00000 n September 1st/March 1st modelling revealed modest exposure as the sun has dropped enough to negate most of the overhang benefit. 0000023337 00000 n Go . [I notice that after I wrote this response, you edited your comment, changing "high U-value" to "low U-value." 0000022215 00000 n Climate zone temperatures are important, as are available solar heat gains and utility prices. Kids in school and adults at work have been shown to have better moods and do complex work better with sunlight entering the room. Totally agree. A product with a higher VT transmits more visible light. For those trying to figure out directions and overhang sizes and angles, the best tool is the Solar Pathfinder and many new apps like that which show all angles and azimuths of the sun for any location throughout every day of the year. [8], A conversion from SC to SHGC is not necessarily straightforward, as they each take into account different heat transfer mechanisms and paths (window assembly vs. glass-only). Solar Heat Gain Coefficient, or SHGC, is the amount of solar radiation, or heat, that passes through windows into the home In other words, SHGC tells you how well the windows block the sun's heat from coming inside An SHGC closer to 0 means that little solar heat is let in An SHGC closer to 1 means more solar heat is let in 0000045401 00000 n 0000047504 00000 n This factor is used to represent the temperature difference between indoor and outdoor air with the inclusion of the heating effects of solar radiation.

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