Greenbuild Presenters Encourage Energy Efficiency in Much-Demanded Glass Buildings
October 7, 2011

By Megan Headley, mheadley@glass.com

Greenbuild featuerd a seminar on the many products and design techniques available to make today's glass buildings energy efficient.

"Everyone wants to be in a daylit space these days. When tenants are looking for a new space, it's all about how much light comes in," said Eric Duchon of Cushman and Wakefield during his presentation on "Transparency in the Service of Sustainability: Addressing the Market Demand for Glass Buildings." Duchon made his presentation on October 6, the last day of Greenbuild. His comment was based on an informal survey conducted by the company. The trick for Duchon and his peers presenting at Greenbuild was convincing their listeners that using today's technology and careful modeling, glass buildings can be energy-efficient.

In his survey, Duchon said that he found that energy efficiency was the most important consideration for any tenants in today's office buildings. However, he added that most tenants don't seem to be aware of energy efficiency challenges in glass buildings - a fact that many architects point out to their clients.

For John Hannum of Israel Berger & Associates (IBA) the goal of the presentation was"to show trends and redirect what the industry perceives as diverging interest in glass buildings and energy performance. Let's try and get people those glass buildings that they're used to, that they want, but let's do it better."

Some of the suggestions Hannum offered included using frit patterns to fine-tune glare issues, considering angling windows - as well as PV patterns - in the design stage, taking a look at the benefits of double-skin facades and considering the many options for building retrofits. He also pointed to up and coming technologies such as dynamic glazing and products that use a prismatic effect to direct certain parts of the light spectrum to the areas where it's wanted.

"And finally the frame. How do you address that thermal bridge which we all know is much more deleterious than the center of glass," Hannum asked. One suggestion he offered was getting rid of aluminum altogether, and replacing it with higher performing structural materials.

William Logan, AIA, with IBA, offered another suggestion. He pointed out that light shelves and mechanical shading devices can greatly impact energy savings. "In Europe, triple glazing is becoming much more common...it hasn't been used here traditionally but you're hearing much more talk about it."

Logan did caution, "With active facades to really reap the benefits, it needs to be integrated with lighting, mechanical, etc." He pointed out the client needs to be considered too.

James Brew of the Rocky Mountain Institute focused on just that.

"Many of you probably know about the top three most common complaints in buildings," Brew began. He listed: thermal comfort, glare and acoustics.

Taking these measures into account is a critical part of building performance, Brew said. "I think when we're thinking about building performance on the qualitative side [the focus] is the people. The only measure of a good building is the people who use it."

Brew pointed to research on the improvements in productivity, reduced absenteeism and reduced turnover as a result of natural daylighting, adding that even incremental improvements of that nature should dwarf the energy-efficiency benefits.

Hannum concluded the presentation with a case study in which he modeled a glass building on which IBA is working, and set it in different regions. With light dimming and mechanical shading, he was able to show significant cost savings in largely glass (75 percent) buildings.

You can get to a point where glass buildings have improved productivity, improved thermal comfort, etc., and still be cost effective, Hannum explained. "Energy efficiency is achievable for glass buildings, in other words," he said, but stressed, "Each solution is building specific.?" It has to be building specific. You have to focus on the whole building...you have to approach it systematically...and promote integrity in this analysis."

As the speakers explained, these options have to be explored by designers - and their design assist partners - because demand remains strong for glass buildings.

"Glass buildings are where we are now and it's what's going to continue based on tenant demand," Duchon said.

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