<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi, all--<div><br></div><div>Overheating usually happens within the particular room or space the windows are located in, not the whole house, which may limit the ability to compensate with outdoor air ventilation. In our PNW climate overheating can happen on a clear winter day, as well as during the shoulder months as John pointed out.</div><div><br></div><div>There may be two types of overheating as well, both the air temperature and the radiant temperature on the glazed side and where the sun's infrared is warming room surfaces.</div><div><br></div><div>Occupants in a space that overheats may also experience glare or excess brightness, which is uncomfortable regardless of the temperature or humidity.</div><div><br></div><div>All in all, I think a design that balances comfort and efficiency throughout the year makes sense.</div><div><br></div><div>Best,</div><div><br></div><div>Mike O'Brien<div apple-content-edited="true"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br></div></div></span></span>
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<br><div><div>On Aug 15, 2012, at 5:34 PM, Corwyn wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>On 8/15/2012 1:59 PM, John Straube wrote:<br><blockquote type="cite">Exterior shading of 24" overhanging a 8-9' high wall works, maybe, May<br></blockquote><blockquote type="cite">June July but does not help in April or September. These are the bigger<br></blockquote><blockquote type="cite">problems, as these months one can often have outdoor temperatures of 65<br></blockquote><blockquote type="cite">to 75 and full 200 Btu/hr/ft2 sun hitting windows.<br></blockquote><blockquote type="cite">Exterior shades are absolutely the answer. Unless you have a working<br></blockquote><blockquote type="cite">couple in the home who are not in the house during sunny hours. I guess<br></blockquote><blockquote type="cite">that is unlikely, eh? This can be solved with automatic controls on<br></blockquote><blockquote type="cite">automated shades. If you want to spend that kind of money.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Orrr, you could just use lower SHGC windows. But if you want to hit a<br></blockquote><blockquote type="cite">magic space heating (rather than total energy use) target using an<br></blockquote><blockquote type="cite">imprecise program (like PHPP) then I suppose that simple and low cost<br></blockquote><blockquote type="cite">solution wont work :)<br></blockquote><br>"Just" using lower SHGC windows, increases energy needed for heating. It is a trade-off. Opening windows at night (and other such measures) does NOT increase winter heating requirements. I would say that those should be where we start.<br><br>For this house, halving the SHGC on the windows, would lose 5M BTUs or so, at a cost of around $120 per year. I will note that my simulation shows that the worst overheating is in the spring, by the time the trees have leaved out, the problem is lessened.<br><br><br>Thank You Kindly,<br><br>Corwyn<br><br>-- <br>Topher Belknap<br>Green Fret Consulting<br>Kermit didn't know the half of it...<br><a href="http://www.greenfret.com/">http://www.greenfret.com/</a><br>topher@greenfret.com<br>(207) 882-7652<br><br>_______________________________________________<br>Greenbuilding mailing list<br>to Send a Message to the list, use the email address<br>Greenbuilding@bioenergylists.org<br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br>http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org<br><br></div></blockquote></div><br></div></body></html>