solar heat gain factor table

0000018593 00000 n 0000008360 00000 n 0000018860 00000 n 0000053952 00000 n In January, one south-facing window produces more solar heat gain than the solar gains from three windows facing north, east, and west for all 22 cities. That's where your observation about winter sun angles before and after solar noon is most critical. The maximum allowable fenestration U-factors in Table R402.1.2 (for the prescriptive compliance path) for climates zones 3 through 8 have been reduced from the values in the 2015 edition. 0000051599 00000 n 0000008467 00000 n Solar Gain Overheating Interiors In column 7, South Percentage of Total Gains, note that south-facing windows provide the majority of the total solar gains for every city in the list. 0000016860 00000 n E a9` zY ZOy 7!K?e. 0000026777 00000 n 0000053347 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. 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). Get building science and energy efficiency advice, plus special offers, in your inbox. standard low-E and about .40 for spectrally selective low- Continue readingat SOLAR GAIN TYPES, DEFINITIONS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX. 0000032810 00000 n Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly. 2 (b)] /a; + a~ ` g=r+URI h +Ra;I (5) where T is the total transmittivity; UR is the overall heat loss coefficient of the window; aj, aare, respectively, the absorptivities of the inner and outer glasses; R is the heat resistance of the glazing; and ho is Note that air leakage also depends on proper installation of a window, which is assumed in all ratings. {\displaystyle T=\int \limits _{350\ nm}^{3500\ nm}T(\lambda )E(\lambda )d\lambda }, Here /CS2 6 0 R Having lots of sunlight entering the home in the winter is a way to elevate mood when many folks find it hard to be outside like when it's warm. Can I Get Replacements For Odd Size Windows? 0000029050 00000 n Low-emissivity coating is another more recently developed option that offers greater specificity in the wavelengths reflected and re-emitted. /TT0 23 0 R 0000040032 00000 n SOLAR RADIATION Solar radiation has important effects on both the heat gain and heat loss of a building. How Do I Reduce Or Eliminate Condensation? They can work well in late summer hot weather, yet not block the sun on cooler days in the Spring. We pull tight insulating shades over the windows in the evening to reduce heat loss. 0000042410 00000 n Thanks for your comments. into a home or building through a product. The lower the U-Factor, the better the window insulates. /Metadata 9 0 R stream If you live in a hotter climate zone, an SHGC closer to 0 to block the heat is more appropriate. "Do the math!". However, a few strategically placed deciduous trees and i have all but eliminated my summertime window solar exposure. 0000047743 00000 n 0000026684 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. Long stretches of overcast days produce large heat losses through large windows, with minimal solar heat gains to compensate. on the climate, summer and winter fuels costs, and See ASHRAE Fundamentals, Chapter 27,for lists of solar heat gain factors. 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). This allows glass to block mainly short-wave infrared radiation without greatly reducing visible transmittance.[3]. Uncontrolled solar gain is undesirable in hot climates due to its potential for overheating a space. Unless I'm mistaken, the house has interior shades or curtains, and these are in use for many of the south-facing windows. 0000042224 00000 n In this example, of the window is covered with the venetian blind and is not; therefore, the solar heat gain factor equals of the overall factor + of the glass factor. Here, is the wavelength of radiation and is the angle of incidence. It is neat because you can pick a date, then move the hour from am to pm and watch the shadows dance across the house. Using window shades is not a defect of passive solar or other types of homes. Two cities along the Pacific northwest coast (Portland, Oregon; and Seattle). Thermal mass may be used to even out the fluctuations during the day, and to some extent between days. 0000009155 00000 n This feature has been temporarily disabled during the beta site preview. The following four cities are along the north central and western U.S. (Minneapolis; Salt Lake City; Bismarck, N.D.; and Billings, Montana) . If you were to draw a Dec 21st shading line for the top of the window, then draw a shading line for June 21st from the bottom of the window, the point of intersection could be used to set the lowest, farthest out point of the roof overhang. 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). endstream endobj 2226 0 obj <>/Metadata 59 0 R/Pages 2223 0 R/StructTreeRoot 113 0 R/Type/Catalog/ViewerPreferences<>>> endobj 2227 0 obj <>/MediaBox[0 0 612 792]/Parent 2223 0 R/Resources<>/Font<>/ProcSet[/PDF/Text/ImageC]/XObject<>>>/Rotate 0/StructParents 14/Tabs/S/Type/Page>> endobj 2228 0 obj <>stream About | Seattle, Washington. Will be adding solar panels on our large south facing roof when our city, state and utility stop punishing those with a solar tax who have. . 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. Canadian companies might be your best bet (e.g., Thermotech, Accurate Dorwin, Inline). This is also hugely effective. 0000036698 00000 n %PDF-1.6 % 0000024716 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. -- Seasonally, the coldest temps of winter, and the hottest temps of summer, lag the sun's seasonal changes in path and intensity. 8 , fgMPW'J[2JM2~&e@l3-9wDWj2bXec&X.!X095 The first five columns list each month of the year, and the daily solar heat gain per square foot of window glazing for windows facing south, north, and east, or west , and the average heat gain over the four window directions. /Font These cold sunny days the furnace rarely comes on all day long. There are a couple of ways that glass can maintain the indoor temperatures to keep you comfortable indoors. >> Modeling thermal mass performance seems difficult or approximate. The basement windows look out only on the east and south sides of the home where they barely see the light of day. 0000049884 00000 n 0000009311 00000 n /C2_0 15 0 R 0000047288 00000 n << %%EOF Average percent of sunlight shining in January (opposite of cloudiness). In climate-responsive design for cold and mixed climates, windows are typically sized and positioned in order to provide solar heat gains during the heating season. Here's some information not included in the article that provides background to those unfamiliar with the topic raised by Malcolm. (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. The lower the number, the less you'll spend on cooling. So if you have your heart set on high-solar-gain glazing, you should keep looking. << Shading analysis of the building site's landscaping and adjacent buildings is critically important. Note from the cells highlighted in yellow: During the winter, from November through February, one south-facing window would produce more light and solar heat gain than the total gain of three windows facing north, east, and west, respectively. [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. (12) Consider different glazing for windows facing different directions. South-facing window glazing may optimize heat gains with higher SHGC, and west-facing windows with lower SHGC glazing. 0000057599 00000 n 0000008611 00000 n /TT3 20 0 R What Is Solar Heat Gain Coefficient? 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. xSmHSQ~f:MLQBBQ20 XJ Unfortunately, whatever shading is caused by these roof overhangs also causes just as much shading on April 21st (two months before June 21st) as two months after (August 21st). 0000029417 00000 n ( Solar heat gain factor btu/hr calculator. Solar gain compared to Denver, the city with the highest solar heat gain in the list. The data on solar heat gains is summarized in Figure 2, below. Should homes with floor joist/subfloors opt for tile over wood? 0000018332 00000 n 0000055691 00000 n 350 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]. /TrimBox [0.0 0.0 612.0 792.0] /Height 99 0000009233 00000 n 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. 0000033945 00000 n Shades, overhangs, or many other alternatives can be used to cut down on solar heat gain during hot days in any type of home, to reduce AC or uncomfortable interior temps. 0000025308 00000 n 0000018030 00000 n The home show in the photo used ceramic floor tile which varied in color but overall was a coffee color. This is a particular concern in hot, tropical climates such as southern Florida, Georgia, Texas and other states in that experience extreme heat. 3M's Sungain Film brochure mentions "Solar Input," which represents the shading coefficient times 0.87. FIND A DEALER. (The result also is divided by 10 million so that numbers are transformed into the single digit range.). 0000043952 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. 0000009077 00000 n 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. Window specifications and climate data for your specific construction project are more important than the generalizations made here. [1] [5] The second factor is the CLF, or the cooling load factor. 0000037504 00000 n So I don't think glare around the dining table on the opposite side of the room would be much of a problem. N Much of the population of northern U.S. live in or near these metropolitan areas. Table 2 lists solar gain data for the 22 northern U.S. cities. 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. But overall, if values are changed to reflect other information sources, a similar overall pattern will emerge, unlikely changing any of the main conclusions of this modeling effort. Passive solar heat gains are more valuable in areas with higher costs for electricity or other heating fuels, or with occupants who are less affluent, or architects, owners, or builders more concerned with sustainable building. /Im0 10 0 R One shading method is to have roof overhangs stick out above the south-facing walls enough that they cast shade on south-facing windows in late August. 0000044364 00000 n Argon filled would be affordable and add about R-1. << 2252 0 obj <>/Filter/FlateDecode/ID[<83C04542AF040F4C833A7DC507AC7EE9><9975C82B1E27C340964B5370330FFFE6>]/Index[2225 55]/Info 2224 0 R/Length 124/Prev 708226/Root 2226 0 R/Size 2280/Type/XRef/W[1 3 1]>>stream A og = The skylight area. Heating Degree Days vary year-to-year, so other HDD numbers may be found. Key issues to be learned: a. 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. I used pleated or cellular shades at night, and sometimes insulating shutters to reduce heat loss during snowy days. comes through a product. Solar heat gain (SHG) describes the way radiation from the sun is turned into heat. For all other areas, solar heat gain through south-facing windows exceeds the heat lost through the glass. 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. {\displaystyle F(\lambda ,\theta )=T(\lambda ,\theta )+N*A(\lambda ,\theta )}. Our property has some young-ish maples that are already 30' tall and are perfect for transplanting into the exact spot that we need to maximise winter gains and reduce summer gains. 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. 0000027631 00000 n n Ideally, the goal is to not block wintertime sunlight on south-facing windows. David, Like Cardinal, PPG only manufactures window glass, and I don't think sell glass units retail, just to window manufacturers. [5], Apart from windows, walls and roofs also serve as pathways for solar gain. Even if there's only one south-facing window in the room at mid-day in winter, light will bounce off the window sill and floor and diffuse the light, especially at the other end of the room. 0000022755 00000 n Table 2 shows the amount of solar heat gain per square foot of window glass for the cities listed previously. The complete source for building, designing, and remodeling green homes. The lowest numbers are about double the highest. 0000050946 00000 n 0000053840 00000 n ) 0000048946 00000 n At home she is the first to pull them up on a sunny morning, maybe because we have more room at home. 0000026181 00000 n 0000020109 00000 n Will Vinyl Replacement Windows Stop Condensation? 0000018740 00000 n 0000051339 00000 n 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 . 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. How do you optimize this shading in a more so sophisticated way that the common arc diagram? At the bottom of the table, the yearly gains are totaled for south-, north-, 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. 0000050604 00000 n 0000028135 00000 n 0000019351 00000 n Cities in the table are listed in descending order of their mid-winter solar heat gain. The "solar input" in the 3M Sungain film brochure, also known as the solar heat gain coefficient, is the solar transmittance modified to account for re-radiated heat. 0000041454 00000 n number between 0 and 1. Personally, I think we should focus on better window shading methods than roof overhangs. What Is The Difference Between Convection And Drafts? /Resources I understand that some passivhaus builders pour 8 inch thick concrete slabs for heat distribution from solar gains. As indicated in the chart below, the EPA recommends . Like most things, you can have too much of a good thing. 10;I#l3*O@`0wo : 0000035843 00000 n Locations needing a lot of heating, that have high electricity prices, and that have good net solar gains, get higher scores. 0000014163 00000 n 0000014495 00000 n optional rating, and manufacturers can choose not to , Additional shading strategies such as vertical louvers may be needed. Is it possible to determine an appropriate period of shading for summertime sun that also allows peak wintertime solar gain? 0000011631 00000 n , Columns 1-3 lists the same city data, in the same order, as Table 1. 0 0000022435 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. What about glare? The specific microclimate of any building location should be used in building design, rather than the rough approximation of solar potential shown in this map or Table 1. be adjusted for thermal lag and time delay. First, thanks for sharing your many helpful comments and ideas on GBA articles on Q&A. 0000018449 00000 n << December 21st there is no shading from overhangs. Response to Davor Radman 0000038191 00000 n Generally she, me and the cat sit in the sun if we can. Will there be sun in the eyes of people sitting on the north side of the table during winter? The lower the U-factor, the more energy-efficient the window, door, or skylight. The window orientations were limited to true south, east, west, and north. Despite having minor differences in modeling standards compared to the SHGC, the two values are effectively the same. 5.8.2.2 Labeling of Fenestration Products . It can't be a problem for north-facing windows, which receive almost no direct sunlight any time of year. E At the bottom, Anchorage is the only city that has average net heat losses through south-facing windows. The SHGC is the measurement of how much radiant heat, or heat produced by the sun, comes in through a window. 0000019823 00000 n 0000053260 00000 n In addition to glass properties, shading devices integrated into the window assembly are also included in the SC calculation. 0000048108 00000 n 0000011092 00000 n Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia. Apologies for the delay. 0000036472 00000 n 0000021224 00000 n Blocking solar 0000047504 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. [5], Window design methods have moved away from the Shading Coefficient and towards the Solar Heat Gain Coefficient (SHGC), which is defined as the fraction of incident solar radiation that actually enters a building through the entire window assembly as heat gain (not just the glass portion). Technical Report: Solar Heat Gain Through Fenestration Systems Containing Shading: Procedures for Estimating Performance from Minimal Data Title: Solar Heat Gain Through Fenestration Systems Containing Shading: Procedures for Estimating Performance from Minimal Data Full Record Other RelatedResearch Abstract 0000011554 00000 n As such, the Energy Star Factors are as follows:Factors for Energy STAR Ratings in the South Central Climate Zone. (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. 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.

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