On Tuesday, September 28, I was in the audience at the Pacific Energy Center in San Francisco as Alex Wilson, Founder and Executive Editor of Environmental Building News, gave a presentation about misguided pursuits in green building. He covered all-glass buildings, building-integrated wind turbines, and residential ground source heat pumps.
The post below consists of Part 1 of my record of the presentation – all-glass buildings. All portions are included in chronological order.
An ellipsis (…) indicates that I was not able to capture the words or thoughts skipped. The presentation is transcribed as accurately as possible – punctuation choices are mine. I also added any photos or images.
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Today I’m going to talk about a couple strategies that get a lot of media play and that are widely perceived as being green. I’ll talk about three issues briefly – all-glass facades, building-integrated wind, and ground source heat pumps. Let’s dive in.
We do a lot of all glass buildings. There have been some high profile ones in recent years, like the Bank of America Building … can get some pretty dramatic effects with all glass … A lot of glass isn’t limited to this country … new tallest building is in Dubai … all glass in a desert environment … There is heavy use of glass in Las Vegas CityCenter where cooling loads dominate…
Burj Khalifa, Dubai (Image credit: Wikimedia Commons)
We did an article in Environmental Building News earlier this year … starting thinking about this because there are a lot of high-profile green buildings that are all glass … What we did … we wanted to present some pretty detailed info, some energy modeling info, and we went to … Arup to see if they would assist in some energy modeling … They graciously agreed. Looked at three cities … four glazing types … several different building footprints … four glazing percentages … and then calculated the net annual energy consumption. For each of the types of glass, the more that’s added, the higher the annual energy consumption … The worse the glazing, the higher the energy impact. Where the building was located had a big impact, New York being more dramatic than San Francisco of Miami … Looked at peak cooling and heating loads…This is significant because this is a first cost issue – the size of the chillers and the size of the heating plants…
When I talked with Steve Selkowitz … he said there are some other interesting things you can see in [the results] … can get a higher percentage of glazing if you improve the glazing, without an energy penalty …
We also looked at the impact of the footprint of the building – most of the modeling was done assuming a square building … We looked at square, elongated, and even more elongated. The more elongated, the higher the cooling load. For an elongated building, what is the effect of changing the orientation? … there are differences, but not as dramatic as I would have thought … With the more advanced glazing, the difference was greatly diminished … … …
I mentioned the issue of all-glass façade using curtain wall design compared to a masonry system with insert windows …
Something else we can do to improve performance if you want to use a lot of glass is shading. This is the David Brower building in Berkeley … You can see they used a number of different types of shading systems here and were quite effective with those. Another example is in Phoenix – the Burton Barr Central Library … this building has been up for 10 of 15 years, I think …
Burton Barr Central Library, Phoenix (Image credit: Wikimedia Commons)
We can also put blinds on the interior – it obviously affects the appearance of the building, but by using light-colored blinds, we can reflect some of that insolation back out before it becomes long-wave radiation … an advantage of interior blinds in controllability for office workers. They can control them individually … Savings are greater with automated blinds … The New York Times Building is using a combination of exterior shading, but then they also use interior blinds … There’s a pretty high degree of controllability in the building, and that lets them get away with a high glazing percentage. The architect went to great lengths to have a high glazing area and also very clear glass. Interior blinds can have problems – here’s the Yale Sculpture Museum. I walked through with someone who worked there are was pointing out all kinds of problems they were having … an issue of programming problems, not understanding client need.
New York Times Building, New York (Image credit: Wikimedia Commons)
Another thing we can do with glazings is to use dynamic glazings – these are glazings that are controlled, either passively or actively. There are different types – photochromic and thermochromic … More practical are the active control systems … It’s electrochromic that is the one that’s most actively being sold today … The basic idea is that you can apply a small amount of current and tint the glazing, dropping the transmittance from standard clear glass to down around 5 to 10%. Pretty dramatic reduction in solar gain … The interesting thing is that it’s expensive but the cost has been coming down and at the same time we’re understating what it takes to achieve this level of control with external and internal shading systems … and if you add it up, according to Sage, it’s more per square foot than if you went with an electrochromic system.
The other thing that can be done is a double envelope glazing system … have significant space between the layers of glazing … can ventilate the space in the summer to eliminate the heat gain. Can close the vents in the winter to keep the heat gain in. Fiona Cousins argues that for every project she’s done the modeling for, it’s been too expensive … She likes it form an engineering standpoint, but it doesn’t pencil out when they try to sell it to clients. The place that Fiona is more positive about double envelope is reskinning … just add an entire façade to the outside … dramatically improving of energy performance.
Vorderpfalz Bank, Ludwigshafen, Germany (Image credit: Wikimedia Commons)
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This exchange was followed by a question and answer session with the audience.
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Part 2 and Part 3 will be posted soon.
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