What about glare? 0000027305 00000 n n 0000023760 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. 0000047504 00000 n (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). 0000035419 00000 n There is so little solar heat gain through all windows in Anchorage in January (and such large heat losses), that heat losses far exceed the gains, even for south-facing windows. IMHO the typical USA under-insulated home with oversized fossil fuel heating and AC is the failed design in need of our greatest attention. (3) Overall, unobstructed south-facing windows gain more heat than they lose during mid-winter in almost all U.S. climates. Most consumers do not realize the extent to which window orientation affects the amount of light and solar heat gain. potential for daylighting. {\displaystyle N*A(\lambda ,\theta )} OR. Solar gain compared to Denver, the city with the highest solar heat gain in the list. 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. MIT Press, 1992. 0000010476 00000 n 3500 0000058060 00000 n In contrast, the east, west, and north-facing windows lose more heat (column 8) than they gain in January (columns 4 or 5), except in Denver. Consequently, south-facing windows capture far more light, and thereby produce far more solar heat gain, than windows facing other directions. Many of us benefit significantly from each other's experiences and insights. 0000031405 00000 n Home | This is also hugely effective. Table 3 shows the net solar gain and value of solar gains in northern U.S. cities. Robert (8) Unobstructed west-facing windows produce heat gains mostly in the afternoon. 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. 1 0000050037 00000 n 0000050343 00000 n 350 Table 2 lists solar gain data for the 22 northern U.S. cities. Similar analysis could be performed by using web resources to compute solar gains for windows in other orientations. Even for east- and west-facing windows, losses exceeded solar heat gains except for Denver. 0000042317 00000 n 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. 0000024834 00000 n T 0000010630 00000 n n 0000057599 00000 n , But this angle represents a brief moment and most of the arch of the sun's path, while still influencing the solar gain, is much lower during the periods of time on both sides of noon. Is it possible to determine an appropriate period of shading for summertime sun that also allows peak wintertime solar gain? My wife has a small office at work with lots of south facing glass and pulls the shades on sunny days. 0000046682 00000 n 0000021134 00000 n For windows, skylights, and glass doors, a U-factor may refer to just the glass or glazing alone. At the bottom of the table, the yearly gains are totaled for south-, north-, east-, and west-facing windows. The question-and-answer article above, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss. /TT4 19 0 R 0000039839 00000 n 0000038900 00000 n 0000057378 00000 n The shading coefficient depends on the radiation properties of the window assembly. trailer December 21st there is no shading from overhangs. 0000035750 00000 n 0000009623 00000 n Varying window sizes and numbers can increase or decrease solar gains and heat losses to affect overall energy performance. . Annual heating degree days (HDD), an index of the amount of heating needed each winter season. ( N 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. 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. 0000049162 00000 n North windows would be most desirable in cooling-dominated climates, or during hot summer periods anywhere in the U.S. but not during the cold and darker winters of northern U.S. locations. I have 35 year old home-made fixed glass windows on the south side of my house that need to be replaced. 0000030116 00000 n In the hotter summer season, solar heat gain through windows is usually undesirable. Glare The last column (#10) shows the percent of net heat gain compared to the heat gain for window glass. into a home or building through a product. Window specifications and climate data for your specific construction project are more important than the generalizations made here. 0000029417 00000 n In Vermont you'd probably have difficulty with fogging due to moisture between glass layers. The SHGC measures how much of the sun's heat comes through the window. 0000033432 00000 n the street side of the street-level story does not exceed 20 ft . /Width 76 0000014495 00000 n 0000040500 00000 n lL)Cg4xo` =[3lhb$qrCcUT?iFgqH10L9e:Q` 8 {\displaystyle S.C.=F(\lambda ,\theta )_{1}/F(\lambda ,\theta )_{o}}. 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) (The result also is multiplied by 100 so that numbers are transformed into a simple single digit range.). 0000053548 00000 n /Properties It can't be a problem for north-facing windows, which receive almost no direct sunlight any time of year. Their net solar heat gain is only about a quarter of Denvers. Passive solar design is a key element of creating resilient homes, Cold-climate glazing is surprisingly hard to find. The product a product is at blocking unwanted heat gain. 0000046898 00000 n High-performance homes likely use these space heating appliances, since less space heating energy is required in well-insulated, airtight homes. Not just to design passive solar or solar-tempered buildings. 0000044828 00000 n 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. 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. Engineering-wise, this makes sense, but not for human perception. 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. 0000026181 00000 n Kansas City and cities along the northeast coast also look promising for wintertime daylighting, space heating, and PV. Maybe some desiccant packets could help reduce fogging? Note that northeastern coastal cities now rate highly along with Denver and Kansas City, for the value of solar heat gain (due to high electricity rates in the Northeast). 0000032190 00000 n The standard method for calculating the SHGC also uses a more realistic wavelength-by-wavelength method, rather than just providing a coefficient for a single wavelength like the shading coefficient does. 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. 0000043512 00000 n One of the best I've read here. Passive solar heating is a design strategy that attempts to maximize the amount of solar gain in a building when additional heating is desired. typically fall in a range between 0.1 and 0.3. 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. /Filter /FlateDecode 0000032660 00000 n HW=oFX72X?A(l5 $?ASN* Thanks for your comments. ) Table 1 shows wide variation in heating degree days, winter design temperatures, and Januarys average percentage of available sunlight. 0000059744 00000 n Those panels closed during the 15 hour nights of winter make far more difference than thermal mass or solar gain. Note that east- and west-facing glazing provide an equal amount of solar heat gain, but east gains mostly in the morning, and west mostly in the afternoon. 0000030489 00000 n % A cooling season. 0000027028 00000 n - Jeff Pendl, Enervision, Cincinnati OH. _________________________________________________________________________. [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). This feature has been temporarily disabled during the beta site preview. Blocking solar heat gain is particularly important during the summer cooling season. /CS1 7 0 R [11] Materials with high SRI will reflect and emit a majority of heat energy, keeping them cooler than other exterior finishes. Being in a solar home definitely cures the winter blues and Seasonal Affective Disorder (SAD). Thank you Bob for sharing this very thorough article! 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. 0000027723 00000 n /BitsPerComponent 8 Two cities along the Pacific northwest coast (Portland, Oregon; and Seattle). 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. 0000045996 00000 n Canadian companies might be your best bet (e.g., Thermotech, Accurate Dorwin, Inline). Different types of glass can be used to increase or to decrease solar heat gain through fenestration, but can also be more finely tuned by the proper orientation of windows and by the addition of shading devices such as overhangs, louvers, fins, porches, and other architectural shading elements. 0000008360 00000 n Cardinal glass makes LoE-180 for passive solar applications. A g-value of 1.0 represents full transmittance of all solar radiation while 0.0 represents a window with no solar energy transmittance. Response to Davor Radman 0000054151 00000 n 0000054052 00000 n [I notice that after I wrote this response, you edited your comment, changing "high U-value" to "low U-value." (My apologies if these assumptions are printed and I overlooked them.). 0000055475 00000 n The U-Factor measures how well the window in-sulates. The lower the 0 South-facing window glazing may optimize heat gains with higher SHGC, and west-facing windows with lower SHGC glazing. 165 0 obj <>stream << 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` Passive solar heat gain through large south-facing windows provided most of the winter space heating energy. 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). 645 0 obj<>stream 0000057117 00000 n So overhangs tend to keep the house cooler in the Spring as well as late summer.