solar heat gain factor table

He was a psychology professor for five years, and a software and web site usability and design engineer for 20 years. 0000011708 00000 n 0000010245 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. High SHGC glazing /Contents 24 0 R /TT4 19 0 R 0000031934 00000 n However, in contrast to the shading coefficient, the total solar gain is calculated on a wavelength-by-wavelength basis where the directly 0000042040 00000 n 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. 0000032660 00000 n The most important factors are budget and energy efficiency. Argon filled would be affordable and add about R-1. How to calculate solar gain for a building: This article discusses the method for calculating solar heat gain through windows. /TT1 22 0 R 0000060552 00000 n The list of 22 northern U.S. cities can be re-ordered by the two indices for the ease of heating by solar gains and the value of solar heating. 0000012329 00000 n 1996 Ashrae Handbook Heating, Ventilating, and Air-Conditioning Systems and Equipment: Inch-Pound Edition (Hardcover), ISBN-10: 1883413346 or ISBN-13: 978-1883413347 , Principles of Heating, Ventilating, And Air Conditioning: A textbook with Design Data Based on 2005 AShrae Handbook - Fundamentals (Hardcover), Harry J., Jr. Sauer (Author), Ronald H. Howell, ISBN-10: 1931862923 or ISBN-13: 978-1931862929, 1993 ASHRAE Handbook Fundamentals (Hardcover), ISBN-10: 0910110964 or ISBN-13: 978-0910110969, Colloidal Materials, Inc., PO Box 696, Andover MA 01810, Pennwalt Corp., King of Prussia, PA 19406, The Passive Solar Design and Construction Handbook, Steven Winter Associates (Author), Michael J. Crosbie (Editor), Wiley & Sons, ISBN 978-047118382 or 0471183083, www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12850 is the base U.S. DOE website for these articles, Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the. 0000021224 00000 n I am having a hard time determining which specification to use when calculating solar heat gain through windows. . The other two factors related toSolar Heat Gain Coefficient when choosing replacement windows are: Window Joe went to look at a home recently that required different solar heat gain coefficients based on the two factors above. 0000045996 00000 n 0000060083 00000 n I would hope that we learn to manage solar gain better, to reduce our dependence on auxiliary heating and air-conditioning, on fossil fuel usage, and to reduce utility costs for those who can't afford it. 0000054516 00000 n Overcast winter conditions are more likely for cities west of large bodies of water. IMHO the typical USA under-insulated home with oversized fossil fuel heating and AC is the failed design in need of our greatest attention. SHGC vg = The solar heat gain coefficient of the vertical fenestration. 0000039839 00000 n Column 8 shows (with red negative numbers) the average January daily heat loss per square foot of glass (assuming glazing is rated R-5 or U=0.2, with window coverings adding some insulation during nighttime hours to attain U=0.15). /Metadata 9 0 R 0000008611 00000 n The following web resources were useful for gathering climate and solar gain data. 0000033229 00000 n 0 Locations that lack significant net solar heat gain, or that require a lot of wintertime heating, score lower on this index. It can range in value Most insulating glass units in windows sold in USA are closer to SGHC=0.3 for avoiding excess solar gains in summer. In the hotter summer season, solar heat gain through windows is usually undesirable. Very helpful. 0000021316 00000 n Unfortunately in the US, most windows sold are low SHGC. , 0000024834 00000 n My goal was to build an energy-efficient home using materials that cost no more in total than typical home construction. (8) Unobstructed west-facing windows produce heat gains mostly in the afternoon. I would hope this article would lead people to consider quantifying solar gains for any type of home, not just solar-oriented designs. Totally agree. We want to keep our solar heat, not lose it back through the same window that brought it in. 0000040500 00000 n 0000043195 00000 n 0000058589 00000 n 0000033574 00000 n Key issues to be learned: a. 0000058060 00000 n Unfortunately, by late August, it is still hot summer weather, but the sun's path has changed to be lower on the horizon than June 21st. Many more cities in the U.S., Canada, Europe, and elsewhere could be added to this list to compute comparative solar heating ease and value. If you live in a hotter climate zone, an SHGC closer to 0 to block the heat is more appropriate. 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. 0000008467 00000 n Worth remembering that those early-'80's houses are one of the main reasons we are having such fruitful discussions today! 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) Passive solar heat gain almost eliminated the need for space heating on the main floor. 0000044552 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. 0000020026 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. hbbd```b``v ;+) D,`RD&`!=D)`sJAdLdtDD2MU'I%R0H2Nd32p]4u~>0 ) Can I Get Replacements For Odd Size Windows? %PDF-1.3 % 8 times table chart up to 1000 . SOLAR RADIATION Solar radiation has important effects on both the heat gain and heat loss of a building. ( East- or west-facing windows produce the most heat gain from May through August. South-facing windows produce the most natural daylighting and solar heat gain from the month of September through the month of April. 0000010938 00000 n In January, south-facing windows always account for more solar gain than east + west + north combined. 0000018276 00000 n How Do I Reduce Or Eliminate Condensation? If not, how can I find a better alternative at a reasonable price? 0000034811 00000 n Overhangs, shading and sizing of west-facing and east-facing windows is most important to prevent summertime overheating! Fortunately, these days, thermal breaks which are small pieces of plastic, are built into the window frame, to "break" the conductivity, and therefore do a better job of insulating by disrupting the heat transfer through the frame material. So I don't think glare around the dining table on the opposite side of the room would be much of a problem. 0000033432 00000 n %YYgeG&1'd$`0l sLqk>0h&b{g.\)o>KC\#F[T(Al'd X 0000011477 00000 n 0000046682 00000 n Maybe we should not let the perfect be the enemy of the good. Low-E Type . 0000011938 00000 n << . About | 0000011246 00000 n Though the SHGC is more realistic than the SC, both are only rough approximations when they include complex elements such as shading devices, which offer more precise control over when fenestration is shaded from solar gain than glass treatments. Like most things, you can have too much of a good thing. Become a GBA Prime member and get full access to GBA articles, enyclopedia, videos, CAD library, and more. If glare is an issue, you could manage lighting levels with sheer curtains or partially drawn "buttom up, top down" cellular shades. 0000041950 00000 n Even for east- and west-facing windows, losses exceeded solar heat gains except for Denver. . 0000027028 00000 n Explained differently, the lower the SHGC ratio, the better the new window is at blocking the sun's heat from coming inside your home, the higher the SHGC ratio, the more heat is let in to your home. 0000058978 00000 n Sitemap | 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 this tends to provide a good estimate over a wide range of angles, up to 30 degrees from normal in most cases.[3]. % 0000012727 00000 n Despite having minor differences in modeling standards compared to the SHGC, the two values are effectively the same. /StructParents 1 %%EOF The lower the SHGC, the less solar heat it transmits and the greater its shading ability. One of the best I've read here. The SHGC measures how much of the sun's heat comes through the window. T comes through a product. Personally, I think we should focus on better window shading methods than roof overhangs. The lower the U-factor, the better the performance. 0000048563 00000 n 0000036366 00000 n NFRC is so well-trusted that its testing results inform Energy STAR ratings. >> I see lots of examples where people try things without "doing the math" beforehand. (If interested, see interior photos in this GBA article: ) /CropBox [0.0 0.0 612.0 792.0] Contrast between the direct sunlight and the TV screen needs to be avoided. When placed in the path of admitted sunlight, high thermal mass features such as concrete slabs or trombe walls store large amounts of solar radiation during the day and release it slowly into the space throughout the night. Objects struck by sunlight absorb its visible and short-wave infrared components, increase in temperature, and then re-radiate that heat at longer infrared wavelengths. 3M's Sungain Film brochure mentions "Solar Input," which represents the shading coefficient times 0.87. Because of this, the most common metrics for quantifying solar gain are used as a standard way of reporting the thermal properties of window assemblies. ) 0000042713 00000 n We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need. , 2225 0 obj <> endobj 0000008386 00000 n SHGC ratings are used to help in quantifying the energy efficiency of windows and skylights. 0000034904 00000 n I have 35 year old home-made fixed glass windows on the south side of my house that need to be replaced. 0000037935 00000 n xref = The solar heat gain coefficient of the skylights. Elevates mood in winter Most manufacturers worked to retrofit products to meet the new and more stringent standards. The higher the number, the more light transmitted without adding excessive amounts of heat. For windows, skylights, and glass doors, a U-factor may refer to just the glass or glazing alone. 0000034462 00000 n , Unlike the upstairs, the first floor has a tiled, concrete floor (with large amounts of thermal mass) to absorb heat to radiate later, stabilizing interior temperature fluctuations. (5) During mid-winter, south-facing windows can provide more than triple the amount of light and solar heat gain in winter than east- and west-facing windows. The solar heat gain coefficient (SHGC) is an index describing the proportion of light that is let through a window. /C2_3 12 0 R 0000059089 00000 n The U-Factor works in conjunction with the Solar Heat Gain Coefficient (SHGC). Get building science and energy efficiency advice, plus special offers, in your inbox. 0000039633 00000 n Using window shades is not a defect of passive solar or other types of homes. Glazing in conditioned spaces has a solar heat gain coefficient of less than or equal to 0.40, or has an overhang with a projection factor equal to or greater than 0.30. 0000032457 00000 n Windows orientation or direction (e.g., facing south, east, west or north); Solar Heat Gain Coefficient (SHGC), the solar gain potential, usually 0.35 to 0.7, or 35% to 70% for efficient new windows; and. Most consumers do not realize the extent to which window orientation affects the amount of light and solar heat gain. Would seem 'Damn the torpedoes, full steam ahead' to catastrophic Global Warming. Thanks for the kind words - and thanks for the explanation. 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. One quick note: It appears that you are assuming a SHGC of 0.5 for the heat gain calculations. startxref 0000040918 00000 n This simple computation provides a metric to rate locations for ease of using passive solar or solar tempered winter space heating. 0000047504 00000 n When integrated over the wavelengths of solar short-wave radiation, it yields the total fraction of transmitted solar energy across all solar wavelengths. /TT6 17 0 R 0000027723 00000 n This simple computation provides a metric to rate locations for the value or cost-effectiveness of passive solar or solar tempered winter space heating. Many had problems with glare. As indicated in the chart below, the EPA recommends . Not sure when I took the photo, other than it shows AM shadows, and not during winter, as the deciduous plants had their leaves. 0000043411 00000 n Which design principles from the 1970s are worth retaining, and which should be discarded? Balcomb, J.Douglas, editor. 0000053548 00000 n 0000025308 00000 n 0000045710 00000 n 0000060198 00000 n Tile floors over wood doesn't provide much thermal mass (about 1/2" vs. 4" slab), but more than wood floors. hbbd```b``A$cXDDr@3N,IF@L@s&00Lg`` How do you optimize this shading in a more so sophisticated way that the common arc diagram? 0000051599 00000 n Also for example, if I am to have brunch/lunch during daytime, where do I put dining table? Extending them would have an effect on the top of the window but not extend very far down the window. 0000008765 00000 n So thermal mass dampens daily temperature swings from solar gains, keeping interiors within about a ten degree Fahrenheit range (5 degrees C), if designed reasonably well. Thank you Bob for sharing this very thorough article! Here are added factors defined by the NFRC as of 2005: Air Leakage(AL) measures how much outside air comes Next, six cities in the Midwest and Great Lakes area (Chicago; Indianapolis; Detroit; Burlington, Vermont; Pittsburgh, Pennsylvania; and Buffalo, N.Y.). 0000031652 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. 2023 The Taunton Press, Inc. All rights reserved. As such, the Energy Star Factors are as follows:Factors for Energy STAR Ratings in the South Central Climate Zone. 0000052866 00000 n [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). The following four cities are along the north central and western U.S. (Minneapolis; Salt Lake City; Bismarck, N.D.; and Billings, Montana) . OR. 0000037750 00000 n 0000051079 00000 n 0000043512 00000 n a product is at blocking unwanted heat gain. In colorado I found Milgard and Pella had high SHGC, low E options. 0000047632 00000 n {\displaystyle F(\lambda ,\theta )=T(\lambda ,\theta )+N*A(\lambda ,\theta )}. Table 6 lists the BTUs per square foot of window glass per day for Providence, R.I. (the northeastern coastal city that looks most promising for solar heating). Providence, R.I., is not unique among northern U.S. cities. 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). /ExtGState For east- and west-facing windows, overhangs are not particularly effective in preventing unwanted heat gain. /Font Glare ( /GS1 5 0 R Table 1 lists 22 northern U.S. cities. K{0VBAt[)#vx_iNhR qD4;-u'6RW ]`\OEh5V9` MRN&G4dYd*=/?1c,C\M@RU2 L/HkY2(*bRX'eQ9/[Z" g,j1Mu(n|u -L$y(T*gR*x!~Uf* 5xPxU)gxF#\$@aX%IXV:RJ9 (C*[!/SUH;_) "~SQgbbL5*8GN%H*J_mI,sQ~d2L,#66H{k ^%Kd}%\XwME\)|MLVRu*{EoRAFxg";k*CNd oR6l1?]14} 5 {{h@LX!izyR<42:+p`XKml6s0 lwMn:%e7;L1sGw66Pp&X lXv[3;gk9`w` 0000041109 00000 n /Type /Page U-factor (inverse of R-value), which measures the rate of heat losses through that window to the cold outdoors. 0000049162 00000 n Meanwhile, the solar heat gain through east- and west-facing windows is more intense due to the greater amount of solar radiation around June (for the northern hemisphere). [4] Though the shading coefficient is still mentioned in manufacturer product literature and some industry computer software,[6] it is no longer mentioned as an option in industry-specific texts[2] or model building codes. 0000010476 00000 n In June, the sun is closer to overhead at noon, so south windows have far less solar heat gain. It's free and doesn't require a download. The complete source for building, designing, and remodeling green homes. 0000030603 00000 n Vinyl windows are generally made of one continuous piece. 0000022979 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. Here's some information not included in the article that provides background to those unfamiliar with the topic raised by Malcolm. This won't delete the articles you've saved, just the list. Thank you so much for sharing ;"\ h;; nM"O*]\_n}s54xBb;L";`fJq=.s5?puuus9Eq=7wWT|# LhH{\=vf}+W8?fX'Xgp8=ZHQ-oGA2mN~~k. This article also explores the difference in solar gain between south-facing windows and windows facing other directions. E The larger the SHGC, the more light that can enter through the window. 0000024598 00000 n Labels on products sold in markets outside the United The National Fenestration Rating Council (NFRC) operates a voluntary program that tests, certifies, and labels windows, doors, and skylights based on their energy performance ratings. Tables 4 and 5 show the re-ordered lists. 0000042410 00000 n Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia. Solar Pathfinder So for a traditional Cape style home, the small overhang doesn't shade the windows much in any season. << 143 0 obj <> endobj Their net solar heat gain is only about a quarter of Denvers. 0000033339 00000 n 0000011400 00000 n 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. 0000010399 00000 n The lowest numbers are about double the highest. For January solar heat gain from south-facing windows, the highest numbers are triple the lowest. For optimum absorption of solar heat in passive solar homes using a direct gain slab (like in the photo shown), many solar home designers recommended slab floors be a dark color. /GS2 4 0 R 0000009779 00000 n 0000029142 00000 n For more information about SHGC and windows, see. Solar heat gain is calculated with the solar shading coefficient and the solar heat gain factor (not to be confused with the solar heat gain coefficient - see below). 0000048656 00000 n Average January temperature (F), the coldest month of the year. The higher its solar transmittance or solar heat gain coefficient, the better a glazing is for solar heating use. 0000059744 00000 n hb``` , b-0.X)![)?OXjL ~E-AzMVk+u9:MX@qKpDa%E={d C=H:]JxrWur{. 0000057764 00000 n 0000060877 00000 n 0000035750 00000 n The larger the roof overhang, the more important it is to do shading analysis, as it makes a big difference in the size of the shadow. 0000042133 00000 n This article notes the importance of using south-facing windows to capture warmth (and natural lighting) in winter, yet not suffer as much heat gain in summer (vs. west and east-facing windows). See Table 6 for details. Re-allocating costs would reduce the cost and complexity of the space heating system, and can enable solar heating to provide a greater portion of space heating. 0000007296 00000 n He led a course in Sustainable Architecture for Lifelong Learning Collaborative, an adult ed organization in Providence, R.I. Bob has degrees in applied mathematics and in philosophy from Brown University, and psychology from UCLA. It is defined as the ratio of solar radiation at a given wavelength and angle of incidence passing through a glass unit to the radiation that would pass through a reference window of frameless 3 millimetres (0.12in) Clear Float Glass. (My apologies if these assumptions are printed and I overlooked them.). - Jeff Pendl, Enervision, Cincinnati OH. 0000035512 00000 n Hours earlier and later, the light could extend further but would be less intense. 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. 0000038526 00000 n Go . The solar transmittance of a window glazing or window is the percentage of visible and near-infrared light that passes directly through a window. The advantages of south-facing windows become even greater when losses are incorporated. 0000034200 00000 n Its likely that if the floors were a dark color, the house would have performed slightly better, but glare likely would been a much greater problem. Watch out: other very important factors need to be considered in arriving at an accurate picture of solar heat gain through windows.