Excellent Resource! 0000025511 00000 n Therefore, the sun is shining on your south-facing walls and windows during wintertime. 0000043195 00000 n Glare 0000019351 00000 n 0000028760 00000 n Solar, wind or other renewable energy source supplies not less than 80 percent of the energy for service water heating. On the flip side that means that cold air would normally go from outdoors to indoors with metal framed windows. 0000051467 00000 n 0000059464 00000 n Roof overhangs can shade the top of a window yet allow solar gain at the bottom. You build a simple house, and then you can set your latitude, and then choose the date/hour. Taking account of heat losses from the windows produces much more extreme results favoring south-facing glazing. 0000008360 00000 n /GS2 4 0 R [11] Materials with high SRI will reflect and emit a majority of heat energy, keeping them cooler than other exterior finishes. Apologies for the delay. >> Note (in the last two columns, #9 and #10) that Denver has better net solar heat gains than anywhere else in the list. 0000018593 00000 n + ) This won't delete the articles you've saved, just the list. If your TV screen is in direct sunlight, it would be difficult to see the screen. The highest percentages are highlighted in green, and the lowest red and pink. Engineering; Chemical Engineering; Chemical Engineering questions and answers; 400 TABLE 15 SOLAR HEAT GAIN THRU ORDINARY GLASS (Contd) Btu/(hr) (sq ft sash area) 400 East 110 102 47 90 40 NORTH LATITUDE . Passive solar heat gain through large south-facing windows provided most of the winter space heating energy. 0000029981 00000 n The window projection factor shall be . In buildings, excessive solar gain can lead to overheating within a space, but it can also be used as a passive heating strategy when heat is desired.[1]. 0000018276 00000 n 0000009545 00000 n I think glare would be a bigger problem if you were sitting in direct sunlight, not at the other end of the room. 0000054052 00000 n The lower the U-factor, the better the performance. Great Article! 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. 0000060317 00000 n 0000033028 00000 n Not that I watch it much (or at all) during daytime), but still :) The lower the rating, the less solar heat is transmitted through the glass, and the greater its shading ability. 0000021721 00000 n N sketchup /Annots 26 0 R 0000053085 00000 n Even for east- and west-facing windows, losses exceeded solar heat gains except for Denver. Passive solar heating is a design strategy that attempts to maximize the amount of solar gain in a building when additional heating is desired. 0000038067 00000 n I have not been able to find glass at local Vermont suppliers with both low U values and high SHGC. The following web resources were useful for gathering climate and solar gain data. The basement windows look out only on the east and south sides of the home where they barely see the light of day. Is this correct? stream This factor is used to represent the temperature difference between indoor and outdoor air with the inclusion of the heating effects of solar radiation. The Climate Zone 5 site has 5,600 heating degree days. 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). 0.80 0.70 0.70 . 0000009311 00000 n I know some others disagree with this perspective. 0000011785 00000 n Unfortunately in the US, most windows sold are low SHGC. For east- and west-facing windows, overhangs are not particularly effective in preventing unwanted heat gain. Q(summer) = U*A*(CLTD) using the CLTD method. 0000043781 00000 n 0000033229 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. In essence SC is an index of the effective solar rejection performance of a given glass type. 0000057926 00000 n You might find a double or triple pane sealed insulated glass unit (IGU) with no "heat mirror" low-e treatment on any of the panes, or rare low-e treatments that don't reduce solar gain as much. 0000038900 00000 n A vg The more you learn about energy efficiency in windows, the more you will be able to evaluate a quality window replacement installer. So if you have your heart set on high-solar-gain glazing, you should keep looking. /ArtBox [0.0 0.0 612.0 792.0] That's good for south-facing windows, because in the cold winter, you want the sun beating in your windows, warming your home's interior (and providing daylighting too). 0000027305 00000 n -- Seasonally, the coldest temps of winter, and the hottest temps of summer, lag the sun's seasonal changes in path and intensity. Kids in school and adults at work have been shown to have better moods and do complex work better with sunlight entering the room. /C2_3 12 0 R by A Bhatia Cited by 44 - Thermal Transmittance or Heat Transfer Coefficient (U-factor) - is the rate In determining the heating load, credit for solar heat gain or internal heat . While you may like having free heat in the winter, it might be too much of a good thing in the summer months if you live in a climate zone with extreme seasons. In summary, there are many things to consider when choosing the best window replacement options. 0000056254 00000 n %YYgeG&1'd$`0l sLqk>0h&b{g.\)o>KC\#F[T(Al'd X 0000031652 00000 n >> 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. 0000010245 00000 n I am having a hard time determining which specification to use when calculating solar heat gain through windows. 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) 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. 1 0 obj 0000029417 00000 n 0000045185 00000 n Modify the landscape of the property to optimize wintertime solar heat gain (and reduce summertime solar heat gain from the west). 0000016860 00000 n (10) Calculate solar heat gains when designing, and compare to heat losses. 0 Column 7 shows the percentage of the total amount of solar gain that comes from the south-facing glazing. That indirect light comes in all directions, including from south-facing windows, though the direct sunlight is much stronger. 0000009701 00000 n /Width 76 I would also like to hear more about your/GBA community's thoughts on thermal mass and its relationship with solar heat gain. In colorado I found Milgard and Pella had high SHGC, low E options. For any home design, heat loss, solar gain and other analysis needs to be done for best results, especially considering the high cost of building a home. In these components heat transfer is entirely due to absorptance, conduction, and re-radiation since all transmittance is blocked in opaque materials. Even during winter afternoons, additional space heating may not be needed by the afternoon. 3M's Sungain Film brochure mentions "Solar Input," which represents the shading coefficient times 0.87. glazing 0000028911 00000 n The higher the VT, the higher the Fixed Clear . m 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. Table 2 lists solar gain data for the 22 northern U.S. cities. 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. Davor, Most insulating glass units in windows sold in USA are closer to SGHC=0.3 for avoiding excess solar gains in summer. 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. 2225 0 obj <> endobj Solar heat gain coefficient (SHGC) is the fraction of solar radiation admitted through a window, door, or skylight -- either transmitted directly and/or absorbed, and subsequently released as heat inside a home. << (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. Operable Tinted Overcast winter conditions are more likely for cities west of large bodies of water. 0000023176 00000 n I saw that a lot: first, the designer included too much south-facing glazing; then the homeowners installed interior shades to cut down on the glare. The U-Factor measures how well the window in-sulates. Thank you so much for sharing The NFRC (National Fenestration Council) describes Solar Heat Gain Coefficient (SHGC) as: Solar Heat Gain Coefficient(SHGC) measures how well a We have about 2' overhangs on all south facing windows and doors which work well in this latitude. 0000054427 00000 n /TrimBox [0.0 0.0 612.0 792.0] 0000013076 00000 n Locations that lack significant net solar heat gain, or that require a lot of wintertime heating, score lower on this index. (15) Consider less costly minisplit heat pumps or even simpler resistance or radiant heating in energy-efficient high performance homes, which have a much lower heating load. Basically, any window frame material is going to insulate well whether it is wood, vinyl, aluminum clad wood, or fiberglass. However, a few strategically placed deciduous trees and i have all but eliminated my summertime window solar exposure. These cities are geographically dispersed, with more cities located in the northeast and Great Lakes regions. product blocks heat from the sun. 0000055784 00000 n Table 2 lists solar gain data for the 22 northern U.S. cities. The SHGC of the shaded vertical fenestration in the proposed building is permitted to then be reduced by using the multipliers in Table 5.5.4.4.1 for each fenestration product. I built and installed R20-30 closing shutters both internally and externally more than 5 years ago in Western Canada at 51 latitude north. This is a different figure from visible transmittance (VT) of light, also defined by the NFRC as follows: Visible Transmittance(VT) measures how much light 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. << 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. , E /GS0 3 0 R Here's some information not included in the article that provides background to those unfamiliar with the topic raised by Malcolm. E Note that the values in Table 6 highlighted in light blue show that south-facing windows gain less heat in June and July compared to east- or west-facing windows. Unless I'm mistaken, the house has interior shades or curtains, and these are in use for many of the south-facing windows. . I used pleated or cellular shades at night, and sometimes insulating shutters to reduce heat loss during snowy days. 0000020266 00000 n %%EOF Climate zone temperatures are important, as are available solar heat gains and utility prices. % The cost of electricity, natural gas, or other heating fuels can impact the use of passive solar heat gains for wintertime space heating. West-facing windows gain that heat in the afternoon, usually during the hottest time of the day, making west-facing windows particularly undesirable unless well shaded. Avoiding south-facing windows because in rare cases people created window walls without considering the solar gain or glare impact would be a mistake. However I don't believe they sell sealed glass units retail, just to window manufacturers. Next seven cities are all located in the northeast, along the Atlantic coast (Providence; Hartford; Boston; Portland, Maine; New York City; Philadelphia; and Concord, N.H.). I will quantify solar heating potential by looking at climate data for 22 large cities across the northern U.S. 0000048853 00000 n What about glare? 0000031802 00000 n The designer should distinguish between the maximum solar load on a surface which is important for load calculations against an average value that the surface experi-ences. << They fit the climate. Is it possible to determine an appropriate period of shading for summertime sun that also allows peak wintertime solar gain? [13] When designed properly, this can modulate temperature fluctuations. 0000031213 00000 n While the U-Factor can take any value, in general for windows it ranges from 0.20 to 1.20. North windows are a great example, since with the exception of dawn and sunset around June, there's no direct light through north-facing windows. Average January temperature (F), the coldest month of the year. %PDF-1.6 % 0000009155 00000 n Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia. Like most things, you can have too much of a good thing. Table 1 lists 22 northern U.S. cities. 0000033432 00000 n 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` cooling season. Though the original proposed changes to U-Factor and SHGC to Energy STAR would have cut the market share by 50% due to vastly increased costs of manufacturing that would have been passed on to the consumer. Locations in the northern U.S. are winter-heating-dominated (meaning that more energy is needed for winter heating and much less for summer cooling). << <]>> Table 1 shows wide variation in heating degree days, winter design temperatures, and Januarys average percentage of available sunlight. 0000043411 00000 n /TT7 16 0 R Beyond climate region, there are some other factors in place that impact how SHGC will affect your life. Would seem 'Damn the torpedoes, full steam ahead' to catastrophic Global Warming. Since I built that passive solar house back in the 1980's, there were no low-e windows available. This is quite significant in the design of roofs since dark roofing materials can often be as much as 50 C hotter than the surrounding air temperature, leading to large thermal stresses as well as heat transfer to interior space.[5]. MIT Press, 1992. 0000027631 00000 n ) T *dPeU|A#rJ]dwiuEZDu-KIVc"*f}*%,?bAL& GH D. That would provide ideal sun shading for those dates at solar noon. /ColorSpace Other cities in the list across the Midwest and northern central U.S. get about half the net solar heat gain of Denver. Heat gain during the summer months is usually undesirable, especially in cooling-dominated climates of the southeastern U.S. North-facing windows produce the least natural daylighting and solar heat gain for every month of the year. /MediaBox [0.0 0.0 612.0 792.0] This is a huge house over 10,000 sq ft with 1300 sq ft of double glaze windows. 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. 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. 0000018030 00000 n The home is a three story house, with a basement comprising the bottom floor. hb```g`` ,@Q ?>K kwlsEGyGG#h`@ %X The overall solar energy gain is expressed by the solar gain factor g and is given by [Fig. 0000022215 00000 n We would agree heat loss and solar gain calculations should be done to optimize any home design. https://www.greenbuildingadvisor.com/homes/passive-solar-home-1980s << Those principles work in all types of buildings, and unfortunately can be ignored in subdivision design, building design, and building orientation. But hey nothing is perfect, so architects and builders could design roof overhangs to reduce summertime overheating. This shows that a good percentage of the gains from south windows are retained, despite losses, except in Anchorage, Alaska. xSmHSQ~f:MLQBBQ20 XJ T The windows specifications used here might be typical for a Pretty Good House design, being relatively high-performance windows but in the affordable range. Is there anything else other than minding where you put your furniture? 0000034369 00000 n 0000050604 00000 n Appendix D, Degree Day and Design Temperatures. To minimize this and reduce cooling loads, several technologies exist for solar gain reduction. 0000047632 00000 n 0000055691 00000 n [4] Factors such as color, tint, and reflective coatings affect these properties, which is what prompted the development of the shading coefficient as a correction factor to account for this. Air leakage is the rate of air movement around a window, door, or skylight in the presence of a specific pressure difference across it. 0000020026 00000 n Those panels closed during the 15 hour nights of winter make far more difference than thermal mass or solar gain. 0000053952 00000 n /TT1 22 0 R You also may be able to increase the brightness of your screen, which some computer screens do automatically (depending upon ambient light levels). 0000025618 00000 n I'm old enough to remember the passive solar homes of the 1970s and 1980s. Argon filled would be affordable and add about R-1. %PDF-1.3 % 5.8.2.2 Labeling of Fenestration Products . 0000060982 00000 n Similar analysis could be performed by using web resources to compute solar gains for windows in other orientations. 0000059089 00000 n =J04pajo/7iv}F1&04 kkAVF/n0 The primary metric in opaque components is the Solar Reflectance Index which accounts for both solar reflectance (albedo) and emittance of a surface. 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 0000032457 00000 n However, I did have problems with too much solar heat gain from west-facing windows during hot summer days. (2005 ASHRAE Handbook : Fundamentals at Amazon). The design was intended to reduce supplementary space heating substantially and minimize utility bills. 0000032190 00000 n 0000039316 00000 n Additionally, the homeowner may choose to augment solar heat coming in the windows with exterior awnings or interior window blinds or curtains. /Filter /FlateDecode I enjoyed the bright sunlight and warm interior temps mid-winter too. 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). 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. Light-to-solar gain (LSG)is the ratio between the VT and SHGC. 0000023641 00000 n This quantity includes both energy that is transmitted directly through the glass as well as energy that is absorbed by the glass and frame and re-radiated into the space, and is given by the following equation:[4], F Thank you Bob for sharing this very thorough article! n Vinyl replacement windows, those with a vinyl window frame, are a great economic choice and also provide great energy efficiency for your home, lowering bills. In January, south-facing windows always account for more solar gain than east + west + north combined. 0000009467 00000 n 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. Blocking solar heat gain is particularly important during the summer cooling season. ( Used by solar PV installers for the most bang for the buck. /C2_2 13 0 R Glazing with lower U-factors (higher R-values) for north- and west-facing windows tend to have lower SHGC. 0000036017 00000 n Accompanying text is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. 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. West-facing windows are a bigger concern, needing shading of some sort during hot late afternoons. 0000014163 00000 n For windows, skylights, and glass doors, a U-factor may refer to just the glass or glazing alone. 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. 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. The other climate zones underwent more stringent Energy Star qualifications that took effect on January 1, 2015. South-facing windows gain about 3.5 times as much light and solar heat gain per square foot than either east- or west-facing windows in December and in January. lL)Cg4xo` =[3lhb$qrCcUT?iFgqH10L9e:Q` 8 Solar heat gain coefficients are expressed as decimals from 0.00 to 1.00. September 1st/March 1st modelling revealed modest exposure as the sun has dropped enough to negate most of the overhang benefit. 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. 0000048656 00000 n The product 0000034703 00000 n We don't have extensive open space, placing furniture near windows and glass doors. 0000036575 00000 n The thermal mass also will radiate stored heat when the sun isn't shining to keep interior temperatures from getting too cool.) Generally she, me and the cat sit in the sun if we can. I used Google Sketchup, the free version, to roughly model shadows on my soon to be built house. 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. 0000041586 00000 n Overall, it is best to take your time, build your knowledge, and scrutinize each portion of the process and product when choosing new replacement windows. In the early days, computer screens had hoods that blocked light from above and the sides. Annual heating degree days (HDD), an index of the amount of heating needed each winter season. 0000029142 00000 n /TT3 20 0 R This is also hugely effective. Fortunately, Energy STAR pulled back a bit, which means windows could remain a bit more affordable. 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. 0000048946 00000 n For all other areas, solar heat gain through south-facing windows exceeds the heat lost through the glass. 0000019823 00000 n xref ( For more information, see All About Glazing Options. Hours earlier and later, the light could extend further but would be less intense. 0000042713 00000 n [5], Apart from windows, walls and roofs also serve as pathways for solar gain. Many of us benefit significantly from each other's experiences and insights. b +{roFw@Qv.Pb=Z"3>!06&rhS8EnVw\/bw +rt|bSL6),W=^O *cAL^u'MH} ^D;p.'*{6OQYbS2tAD2)T=z 0!"Tl,|Am5q/Up+XwNM7}!/;yy6Q@=vjI~}krN>+e_CC-ccB: p7B . /BitsPerComponent 8 Locations needing a lot of heating, that have high electricity prices, and that have good net solar gains, get higher scores. . Thanks for your comments. Just that insulated door is shut at night and the porch is then isolated from the main heated building.

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