Tag Archives: environmental building news

Alex Wilson, Founder of EBN – Part 3

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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 3 of my record of the presentation – residential ground source heat pumps. All portions are included in chronological order. Read Part 1 here. Read Part 2 here.

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.

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Let me move on the last issue – this is more at the residential scale. I’ve been frustrated for a while. This issue first struck me when I was a juror for a design competition maybe 10 years ago … almost without exception, these homes had ground source heat pumps. They went to extraordinary lengths to reduce heat loads…yet they didn’t benefit from that on the cost side by reducing the cost of the heating systems.

Ground source heat pumps are great … They can move heat from outside a house to inside, even if it’s colder outside than inside. That’s how a refrigerator works … does it by changing phases, alternately compressing and expanding the refrigerant …

Okay, so on the surface they’re very attractive, but they’re expensive. Let me explain the difference between an air source heat pump and ground source heat pump. Air source uses the air as a heat exchanger. Ground source uses the ground, which is more of a constant temperature during the year … if you’re heating, you want as warm a source as possible. The heat pumps can be operating in reverse in the summer to provide cooling. That’s the theory of why a ground source should be better than an air source heat pump. But there’s a lot of cost … either digging wells or trenching pipe … the costs are pretty high.

In our area in New England, we’re seeing ground source heat pumps for residences for about $30,000 … … As with wind turbines, there’s remarkably little data on the performance of ground source heat pumps. I don’t mean lab data, but actual in situ performance. There was a study just published by The Energy Saving Trust in the UK that compares ground source heat pumps with air source heat pumps. The results are pretty interesting … … There’s a pretty dramatic range in the performance of these systems … the range of performance is pretty identical, ground source to air source. That’s pretty interesting because air source is a lot cheaper to install. If you’re planning to spend a bunch of money on a heating system, you should instead take most of that money and invest it in the envelope and get the heating load down so low that you can meet the heating load with whatever system you want … A very efficient home can be heated with a few strips of electric baseboard heat or a small pellet stove … instead of a very expensive system. It’s the same argument I have about radiant floor heating systems– it’s a great way to distribute heat for a lousy building … I digress.

The basic argument with ground source heat pumps is take the money and put it into the building envelope. If you want a heat pump, get an air source heat pump …. these can be put in for a lots less money than ground source heat pumps. The performance is now neck and neck, and the performance of air source heat pumps keeps going up … I actually predict that the ground source heat pump industry disappears in the next ten years, it wouldn’t surprise me at all …

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This exchange was followed by a question and answer session with the audience.

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Part 1 is posted here. Part 2 is posted here.

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Alex Wilson, Founder of EBN – Part 2

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by profile • Tags: , , , , , , , , , , , , , , , , , , , ,

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 2 of my record of the presentation – building-integrated wind turbines. All portions are included in chronological order. Read Part 1 here.

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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I’ll move on to another issue … the idea of putting wind turbines on buildings. I started digging into this a few years ago … Going into it I had some skepticism about wind turbines in buildings, but I thought that as I got more into it, I’d get more enthusiastic. But what happened was that the more I dug into it, the harder it was to get data … I wrote an article titled “The Folly of Building-Integrated Wind”. After this article came out, I was interviewed by Melissa Block from NPR … I pointed out in the interview that for decades I’ve been a strong proponent of wind energy, but I feel that we need to be building wind farms where there’s lots of wind. But if someone builds a better mousetrap, I’ll be the first one to get excited about it …

So there are mostly small system that are being done on buildings, this is a big one – Bahrain World Trade Center … 225 kW wind turbines by Norwin … harvesting wind coming off the Persian Gulf which is very consistent directionally … but I believe that if these were effective, the architect and owner would want to boast about it, instead of not releasing any information about it.

Bahrain World Trade Center (Image credit: Wikimedia Commons)

Aerotecture, in Chicago … couldn’t get any data from them.

The only data I could find was from the UK, 25 installations.

The issues are several-fold … First, the benefits. Get a tall building, we know it’s windier up high … The electricity gets used right in the building … plus it makes a statement that you care about renewable energy and benefitting the environment. The problems are that we find the wind on top of buildings is very turbulent … wind turbines don’t like spiraling eddies. Next, the noise and vibration. Buildings, especially steel-framed commercial buildings, transmit vibrations through the superstructure … if you read the fine print of AeroVironment, they recommend them only on masonry buildings … Also the safety issue and the perception of safety … wonder if a building like the Bahrain World Trade Center, if the insurers in this country would have allowed them to put wind turbines on building where there’s the possibility of a blade coming off … like sometimes happens on a wind farm. And then there’s the issue of economy … In most cases, we’re limited to very small wind turbines. And we’ve learned that with wind turbines, there are huge economies of scale … the larger turbines are much more cost effective in terms of cost per delivered capacity … … Small wind turbines are pretty hard to justify economically even as stand-alones, and when we put them on buildings, the cost goes up significantly due to structural support and other issues.

[Looking at data from studies in the UK – the Warwick Wind Trials] Measured performance is extraordinarily low … In all cases the actual performance was significantly lower than the predicted …

Quietrevolution Wind Turbine (Image credit: Wikimedia Commons)

Any reputable manufacturer of a wind turbine has power curves – need to look at those very carefully … There isn’t a standardization for small wind turbines right now … you need to look at those numbers really carefully.

The Boston Museum of Science is doing some really neat data collection. Someone had the idea of putting some turbines on to make power – they did some analysis and decided it didn’t make sense economically … but they decided to do it anyway and collect data … They’re using five systems … They’ve got a great display in the building … by now they probably have some published results. The results they get should probably help put to rest this question of whether it makes sense to put turbines on buildings, and should show it doesn’t. They had quite a bit of expense to be able to support the turbines … it was a lot of additional installation cost for very low output.

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This exchange was followed by a question and answer session with the audience.

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Part 1 is posted here. Part 3 will be posted soon.

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Alex Wilson, Founder of EBN – Part 1

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by profile • Tags: , , , , , , , , , , , , , , , , , , , , , , , , ,

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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