This is a report on the zero emissions building virtual design charrette that took place on August 26, 2009. HOK and The Weidt Group participants in San Francisco, Toronto, St. Louis and Minneapolis used Cisco Telepresence Technology, Polyvision THUNDER Express, WebEx and HOK’s Advanced Collaboration Rooms to communicate.

In this meeting The Weidt Group’s Chris Baker and Vinay Ghatti pushed the team closer to a zero emissions office building design by talking the group through a whopping 89-page Strategy Report describing the potential energy use, carbon emissions and cost implications of hundreds of specific energy conservation strategies.

The report documented the results of DOE-2 building simulations for each strategy compared to a code-level building. The DOE-2 software performs thermal and luminous calculations on an hourly basis, using typical yearly climatic data to determine the building’s energy loads and system requirements.

In a half-day session that HOK Chairman Bill Valentine later described as “painstakingly long and detailed but incredibly worthwhile,” the team looked at envelope insulation strategies, other envelope strategies (from white roof to shading effect of a PV array), window glazing strategies, window design strategies, daylighting control strategies, lighting control strategies, lighting design strategies, lighting technology strategies, cooling efficiency strategies, heating efficiency strategies, alternative HVAC system strategies, fan and pump strategies, conditioning of outside air strategies, miscellaneous mechanical strategies, service hot water strategies and plug load strategies.

The design team assembled bundles of strategies representing four potential building options, ranging from minimal to maximum savings. A spreadsheet added the savings for each isolated strategy and factored the results by 68% to account for strategy interactions.

Attaching hard numbers to each strategy enabled the team to start making energy-related decisions about the design. “But I don’t want to be in the role of saying any specific strategy is the right answer,” cautioned Baker during his review. “Energy analysis alone doesn’t get us to a zero emissions design. The value comes from discussing these strategies and the numbers together. We need to include architectural and mechanical strategies and look at this building holistically.”

One interesting result in the window glazing review was the substantial energy savings offered by wood window frames.

“We are trying to design a zero carbon building that is as frugal and buildable as possible, so idea of using wood instead of a special high-tech window wall is appealing,” said Valentine.

During the plug loads discussion, the team debated whether tenants would accept a reduced equipment load. “It doesn’t worry me,” said Valentine. “One message with these kinds of buildings is that everybody needs to work on their strategies and behaviors to get zero carbon to work. We need some owner and tenant participation. Tenants that use more energy than they have been allocated will have to offset the rest. We need some behavioral changes in our culture to get down to zero carbon.”

Late in the review, as the team went through the service hot water strategies, hunger kicked in and energy began to wane. HOK Director of Integrated Design Gerry Faubert urged the team to keep going, pointing out that this was the type of detail typically not thoroughly discussed by a design team. “Then we get buildings that don’t perform the way we thought they would.”

HOK Sustainable Design Director Mary Ann Lazarus asked the team to use these numbers to start making conclusions about the design. “Even if we don’t like the numbers, we have to live with them,” she said. “They are all about performance.”

Daylighting Analysis

The team also discussed the results of a daylighting analysis completed with RADIANCE software. After reviewing the energy results of four options, the group decided to proceed with Option 3: a 36.6% window/wall area with a vision window from 3′ to 8′ and a daylight window from 8′-6″ to 12.’

“Daylighting is important,” said Baker. “But next we will look at the daylighting savings offset by the energy penalty of increased floor-to-floor and glass area.”

Valentine asked about the impact of using 15 instead of 30 foot candles to calculate the daylight autonomy. “I think the difference will difficult to detect with the human eye.”

The Results: Pushing the Envelope of Energy Efficiency

The four bundles of potential strategies showed energy cost savings ranging from 78-83% and a reduction of carbon dioxide emissions of 84-89% compared to a code level base building. Such a building would use just 18-19 KTBUs per square foot per year.

“That’s more energy efficiency than we have ever tried to squeeze into a building,” admitted Baker. “It’s exciting to push the boundaries. Though the number may jump around a little when we build the virtual building and all the strategies interact, this range is close to that 80 percent energy savings we have been aiming for.”

The team projected a need for 79,000-86,000 square feet of photovoltaic panels on the roofs of the buildings to offset the energy that the building will use and get down to zero emissions.

While all agreed that while it would be ideal to put all the photovoltaic and solar thermal solutions on the surfaces of the two buildings without using the garage, they also agreed that, if necessary, using the garage roof for PVs would not be cheating.

“This building is in St. Louis so it needs a garage,” said Lazarus. “In Manhattan it would not.”

The Aftermath

“I am encouraged by our results today,” Valentine said. “Our goal is to design a realistic building that will really conserve. I wouldn’t want to be any less aggressive.”

“This has been a great experience,” said Ghatti. “It’s a testament to what we can all achieve if we collaborate with this particular design approach.”

“This type of energy analysis and collaboration before pen hits paper should be a no-brainer for design teams,” said Colin Rohlfing, HOK Chicago’s director of sustainable design.

“I had been concerned about the bar building design scheme,” said Faubert, “but the sketches I’m seeing all look very elegant.”

“Let’s make sure we hold the design to the same high level of scrutiny as we have for the energy analysis,” added HOK Chicago’s Jeff Sanner.

“The challenge for the architecture is to live within and embrace those limits presented by the daylighting and energy analyses,” said Lazarus. “Developing creative, innovative design solutions that keep to the parameters we are establishing can result in something truly extraordinary. That is the gauntlet we are running.”

Before deciding on preferred approaches for the final design, the team will review an incremental construction cost report from cost estimator Frank Kutilek of HOK Construction Services. Onward to zero…

Previous ZEB posts (in chronological order):

1. Onward to Zero Emissions
2. Onward to Zero Emissions – Part 2
3. Weidt Light
4. Zero Emissions Building Charrette #2 — The Paradigm Shift
5. Passing Virtual Notes
6. Zero Emissions Building Team Using Biomimicry as a Design Filter
7. Challenging the Frontier of Carbon Neutrality
8. Zero Emissions Building Charrette: Bar Length, Core Configuration + More!