So… what on earth does this blog have to do with death rays?!
Well, yesterday the story of the “Vdara Death Rays” flew through a couple building science mailing lists that I am on. Basically, the building designers put very reflective glass on the outside of a curved building, which wound up posing a problem for folks at a pool nearby (more below). However, it turns out that a building doesn’t have to be curved for highly reflective glazing to pose a hazard to nearby people or nearby buildings.
How does this fit into concerns about energy use? One of the reasons that the highly reflective glazing is used is to prevent heat gain and therefore reduce the amount of energy needed to keep a building cool.
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Image credit: Wikimedia Commons
The Las Vegas Review-Journal published a story a few days ago about the Vdara Hotel on the Strip in Las Vegas.
The tall, sleek, curving Vdara Hotel at CityCenter on the Strip is a thing of beauty. But the south-facing tower is also a collector and bouncer of sun rays, which — if you’re at the hotel’s swimming pool at the wrong time of day and season — can singe your hair and melt your plastic drink cups and shopping bags.
Hotel pool employees call the phenomenon the “Vdara death ray.” A spokesman for MGM Resorts International, which owns Vdara, said he prefers the term “hot spot” or “solar convergence” to describe it. He went on to say that designers are already working with resort staff to come up with solutions.
You can read the entire story here.
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Image credit: Wikimedia Commons
In Los Angeles, Walt Disney Concert Hall, by famous architect Frank Gehry, has had complaints about glare off the reflective surfaces.
While most of the building’s exterior was designed with stainless steel given a matte finish, the Founders Room and Children’s Amphitheater were designed with highly polished mirror-like panels. The reflective qualities of the surface were amplified by the concave sections of the Founders Room walls. Some residents of the neighboring condominiums suffered glare caused by sunlight that was reflected off these surfaces and concentrated in a manner similar to a parabolic mirror. The resulting heat made some rooms of nearby condominiums unbearably warm, caused the air-conditioning costs of these residents to skyrocket and created hot spots on adjacent sidewalks of as much as 60 °C (140 °F). After complaints from neighboring buildings and residents, the owners asked Gehry Partners to come up with a solution. Their response was a computer analysis of the building’s surfaces identifying the offending panels. In 2005 these were dulled by lightly sanding the panels to eliminate unwanted glare.
Frank Gehry had this to say when asked about potential for glare on a newer LA project (via the LA Times):
I had some bum rap at Disney Hall because of glare. That was 2% of the building had reflective stuff, and some pissed off lady (complained). So the County had to respond. (It took) A couple guys with steel wool and in about an hour and a half they fixed it. But it did appear as one of the 10 engineering disasters in the last ten years—talk about exaggerating. The county did a study of downtown LA that found 5 other buildings that were more reflective, but no one complained about them. So, we got to get more pissed off ladies.
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It has also been reported in Green Building Advisor that reflections from windows can melt residential vinyl siding.
Glass experts and home inspectors agree on one point: since vinyl siding can be melted by reflectance from conventional clear glass, a low-e window is not required… However, the use of low-e (or low-solar-gain) glass appears to increase the risk of melted siding. According to an article in the March 2007 issue of USGlass Magazine, “A study performed by Cardinal on this topic examined the impact of reflective coatings on this type of [vinyl siding] damage. ‘The more reflective coatings that are out there today, that are getting more popular, are going to create this problem,’ [Jeff Haberer] said. However, Cardinal found that even clear glass can become a significant heat source.”
Glass with a low solar heat-gain coefficient has a high solar reflectance. “What we are getting is very, very good windows,” said Jim Petersen, the director of R&D at Pulte Homes. “Now the energy that is not getting in the house has to go somewhere, and it’s being reflected.”
Read the entire story here.
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