solar heat gain factor table

potential for daylighting. It comes down to three ways windows are improved with the use of glass technology, coatings and gases: Review in-depth information on energy efficient glass for your window replacements. The answer to this question depends on where you live. The other climate zones underwent more stringent Energy Star qualifications that took effect on January 1, 2015. (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. 0000033121 00000 n Window Joe says to always keep it simple and follow NFRC and Energy STAR ratings that are suggested for your specific county. SHGC can either be estimated through simulation models or measured by recording the total heat flow through a window with a calorimeter chamber. The intense summer sun on the east side of the building in the morning, and the west in the hot afternoon, is greater than the sunlight striking the south side. Those panels closed during the 15 hour nights of winter make far more difference than thermal mass or solar gain. Table 2 lists solar gain data for the 22 northern U.S. cities. Designing roof overhangs to avoid shading windows at noon on Dec 21st results in some shading at the top of the window at noon in January, February and November, when you still want that sunlight (though at 10AM or 2PM you won't be shading the top of the window since the sun is lower on the horizon at that time of day). _________________________________________________________________________. Uncontrolled solar gain is undesirable in hot climates due to its potential for overheating a space. (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.). typically fall in a range between 0.1 and 0.3. You bring up an important point. be adjusted for thermal lag and time delay. The highest percentages are highlighted in green, and the lowest red and pink. The shading coefficient depends on the radiation properties of the window assembly. The lower the number, the less you'll spend on cooling. 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. The Southern Climate Zone has hot summers and mild winters. [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. InspectAPedia tolerates no conflicts of interest. . 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. 0000058060 00000 n Getting free heat and sunlight to raise mood is great. 3500 We have white walls and flat white ceilings in the main living spaces. Being in a solar home definitely cures the winter blues and Seasonal Affective Disorder (SAD). The following web resources were useful for gathering climate and solar gain data. 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. However, I did have problems with too much solar heat gain from west-facing windows during hot summer days. (4) South-facing windows can provide about fifteen times as much light and solar heat gain in winter as north-facing windows. The lower those numbers are, the more suitable a glazing is for cooling. 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. So I'd recommend designing overhangs for minimal shading mid-winter, and not worry so much about summer (for winter-dominated northern climates). What about glare? We have a passive solar house we designed and built ourselves in SE Michigan in the late 80's. The lower the 0000055784 00000 n 0000029557 00000 n In colorado I found Milgard and Pella had high SHGC, low E options. I enjoyed the bright sunlight and warm interior temps mid-winter too. Malcolm. 0000009311 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. The further north, the greater the percentage of gain from the south-facing windows vs. other directions during mid-winter. 0000034369 00000 n 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. (Plus the low utility bills and resilience in case of power outages.). In January, south-facing windows always account for more solar gain than east + west + north combined. However this tends to provide a good estimate over a wide range of angles, up to 30 degrees from normal in most cases.[3]. 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. 0000011477 00000 n 0000049715 00000 n This is a particular concern in hot, tropical climates such as southern Florida, Georgia, Texas and other states in that experience extreme heat. 0000031405 00000 n PDF ASHRAE STANDARD Energy Standard for Buildings Except Buildings The complete source for building, designing, and remodeling green homes. 0000018332 00000 n http://www.vitrowindowglass.com/lowe_glass/sungate_500.aspx. Our energy use for the area is almost off the chart lower than other homes mainly due to passive solar design at not much/or no higher cost than conventional. Cities in the table are listed in descending order of their mid-winter solar heat gain. 0000047743 00000 n 0000049162 00000 n Figure 1 depicts the grouping of northern U.S. cities by solar heating potential, as listed in Table 1. 0000000016 00000 n Varying window sizes and numbers can increase or decrease solar gains and heat losses to affect overall energy performance. 0000025214 00000 n 0000032457 00000 n Florida Energy Code . 643 350 This raises the question: Could a passive solar home be built successfully and cost-effectively in other cold, northern climates climates more challenging than the sunny but cold climate of the Rocky Mountain Front Range? 0000036216 00000 n 0000029142 00000 n glazing has an SHGC of about .75 versus .60 to .70 for 0000030116 00000 n <]>> /CS0 8 0 R Table 1 lists 22 northern U.S. cities. The lower the U-factor, the more energy-efficient the window, door, or skylight. 0000037304 00000 n My goal was to build an energy-efficient home using materials that cost no more in total than typical home construction. The sun is even lower before and after noon. Home | 0000010476 00000 n 0000052649 00000 n 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. 8 times table chart up to 1000 . 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. 0000024129 00000 n 0000010707 00000 n (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 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. /TT7 16 0 R Solar heat gain factors and heat loss coefficients for passive heating (10) Calculate solar heat gains when designing, and compare to heat losses. 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. Single Pane SHGC Double Pane SHGC Glass Block SHGC Metal Operable Clear . Would seem 'Damn the torpedoes, full steam ahead' to catastrophic Global Warming. << 0000011708 00000 n You build a simple house, and then you can set your latitude, and then choose the date/hour. 0000019232 00000 n This energy performance rating isn't always provided. Passive solar design is a key element of creating resilient homes, Cold-climate glazing is surprisingly hard to find. Is it, say, the angle of the sun at 11:00am and 1:00 pm? 0000031018 00000 n In June, the sun is closer to overhead at noon, so south windows have far less solar heat gain. /GS2 4 0 R The U-Factor measures how well the window in-sulates. I'll address passive solar and other home design issues in the next article. 0000036698 00000 n The higher its solar transmittance or solar heat gain coefficient, the better a glazing is for solar heating use. 0000060771 00000 n The lower the U-Factor, the better the window insulates. If windows get direct sun in mid-winter, solar heat gain might provide the majority of needed space heating energy for a well-insulated, airtight building. Again, the northeastern coastal cities look promising for using solar heat gains for wintertime space heating. 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. Avoiding south-facing windows because in rare cases people created window walls without considering the solar gain or glare impact would be a mistake. "Do the math!". 0000011862 00000 n 0000021997 00000 n This article explores the viability of passive solar and solar-tempered space heating in northern U.S. regions and metro areas. 0000055475 00000 n OR. 0000053548 00000 n ( Fortunately, retailers will tailor their stock to homes in your area. (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. Totally agree. /CS2 6 0 R If you started shopping prior to January 1, 2016, then you might notice some of the windows you were considering buying no longer carry the Energy STAR sticker. Providence, R.I., is not unique among northern U.S. cities. 0000030922 00000 n 0000014163 00000 n Comparable data was not readily available for Canada or Europe, and limits on the length of the article and readable table size limited the cities listed. 0000043952 00000 n . >> For the months of December and January, the sun is low on the horizon during midday. 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. Solar Heat Gain Through Fenestration Systems Containing Shading 0000037504 00000 n 0000011400 00000 n E 0000011554 00000 n Visible transmittance (VT)is a fraction of the visible spectrum of sunlight (380 to 720 nanometers), weighted by the sensitivity of the human eye, that is transmitted through the glazing of a window, door, or skylight. C Those principles work in all types of buildings, and unfortunately can be ignored in subdivision design, building design, and building orientation. Solar heat gain coefficient or SHGC primarily reflects the percentage of solar radiation or sunlight admitted through a door, skylight, or a window, either directly or absorbed, only to release a fraction of heat inside the house to keep it warm. Note that the photo at the top of the page shows a passive solar house from 1982. = Great Article! 0000039534 00000 n trailer See ASHRAE Fundamentals, Chapter 27,for lists of solar heat gain factors. From this ordering of cities by average mid-winter solar heat gain potential, we may begin to conclude: Next, we need to explore solar heat gains and losses in more detail for each metro area. Passive solar heat gain almost eliminated the need for space heating on the main floor. (2) To exploit solar heat gains from windows in mid-winter (and minimize heat gain in summer), we can, as much as practical, locate more and larger windows facing within 15 degrees of south, and try to reduce the glazing on walls facing north and west (and perhaps east). 0000024834 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 . 0000026490 00000 n 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. 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. 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. Is It Easier To Clean Replacement Windows? 0000008432 00000 n 0000021486 00000 n 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. 0000040918 00000 n

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