Last week, I attended a driving event at the GM Proving Ground in Milford MI. Driving through the campus, there were several places where roads converged at roundabouts (sometimes also known as rotaries) rather than intersections with stop signs. (I’ll have more to say about the content of that event later.) But even before I arrived, I had gone through a couple more roundabouts on the roads in Milford, MI, where GM’s Proving Ground is located. That started me thinking about roundabouts, and how they are greener than standard intersections.
A modern roundabout … is a circle “designed for very low traffic speeds, about 15 mph.” Entrances and exits are curved so that motorists must travel slowly — far different from the rotaries of decades ago, which typically allowed drivers to enter at 35 mph or faster. The Institute says a modern roundabout typically needs to be about 100 feet across so that it can be properly designed to slow the entering traffic. (New Urban News)
Because the traffic only needs to slow down rather than stopping, all the cars traveling through a roundabout avoid the stop-and-go of a stop sign or a red light. Collectively, this adds up to thousands of gallons of fuel saved for each intersection. Avoiding a full stop also allows each driver to get through the intersection faster, which helps make overall travel times shorter.
<p><img src="/files/images/sol.jpg" border="0" alt="Advanced Glazings, Ltd." width="279" height="186" /><strong>solera : </strong>Image Credit: Advanced Glazings, Ltd.Lighting for buildings is a major part of their energy use. Increasingly, green building design is recognizing the importance of providing natural daylight as a means of lighting the building and reducing energy use. Not only does natural daylight reduce the building's energy use, but it also increases comfort for the people in the building. The LEED system includes credit for providing at least 75% of the spaces in the building with natural lighting and views, and the credit is increased if 90% of the spaces are naturally lit.<br /><br />Windows are good for providing views to the exterior. Skylights can be used to bring in more daylight, but they are not without issues. The problem with skylights is that they tend to create glare. The high contrast between areas where the daylight is streaming through the windows and other parts of the space that are not directly lit is visually (and sometimes even literally) uncomfortable. There's either too much light or too little. Diffuse light is more even and comfortable, and avoids areas of deep shadow and sharp glare. This is why so many older buildings had north oriented skylights or clerestory windows (or south-oriented in the southern hemisphere), and why those spaces were so well thought of as artists' spaces and galleries. The <a href="http://www.advancedglazings.com/ldp/index.php">light quality is much better</a> when it is from an indirect source.<br /><br />Most diffuser options do little to spread the light around. Typical etched or frosted glass has little effect. The light patterns are a little bit softer edged from frosted glass than they are from clear glass, but when it is directly lit, it is little better than clear glass. Advanced Glazings, Ltd. offers much better performance for incorporating daylighting into buildings with a line of insulated glazing called <a href="http://www.advancedglazings.com/index.html">Solera</a>. Architects have known of <a href="http://www.kalwall.com/windows.htm">Kalwall</a>, another company that has been making translucent panels for many years. Kalwall is a panel of polyester and fiberglass that offers translucency and some insulation.</p>