A conversation about zero energy building with CALMAC CEO Mark MacCracken

January 22, 2016

Zero energy building is gaining momentum across the country as designers and building owners look to push the most effective sustainable practices even further. Recently CALMAC CEO Mark MacCracken, LEED Fellow and a leading expert on thermal energy storage, shared his views on the future of zero energy. He provided some insights into how the pursuit of zero energy is changing the way the industry looks at design, and why the ability to store energy is so vital to achieving the societal goals of the zero-energy standard.

Where is zero energy rapidly becoming a new standard for building design?

MacCracken: New construction is where I see the zero energy standard evolving the fastest. In new construction, zero energy is something that is attainable with good design, early commitment and the funds necessary to invest in renewable technology.

Renewable mandates, along with the dramatically lower costs of renewables, are pushing the trend along. It won't be long before we see more states mimicking California, where new building codes support zero energy construction. All new residential designs in the state must be net zero by 2020. Commercial buildings will be given until 2030.

Zero energy, like LEED in its early days, will act as a badge of honor and solid PR move for commercial building owners. Dozens of zero energy buildings are already in operation in the U.S. and being monitored for effectiveness, and that data has revealed that these facilities are generally meeting expectations. Zero energy has the buzz at the moment, with more and more companies recognizing that zero energy performance is the next step after meeting LEED. Eventually the masses will follow because the risk of being an early adopter will be gone and the value of a zero-energy building will become well proven.

How does energy storage play into the development of the zero energy standard?

MacCracken: I think the best way to explain is with an example. You can be sure that any Off-Grid Zero Energy Building will have multiple forms of energy storage to operate effectively. Back up fossil fuels (which are forms of stored energy), batteries and thermal energy storage technologies will most certainly be found on the same site. However, most zero energy buildings are connected to the grid and don't have energy storage on site. The problem with not having storage on site is that the grid itself has essentially no storage capabilities at this time. So presently, zero energy buildings are just outsourcing their storage needs to the grid and society, which just won't work as zero energy buildings increase in numbers.

In fact, we are seeing situations now in Texas because of renewables where electricity is being given away for free because the wind is mainly blowing at night instead of during the day when the schools and offices are operating. Renewables must have storage. As pointed out by Elon Musk and President Obama, storage is a vital ingredient to reducing our carbon emissions.

Hopefully the metrics of zero-energy building performance will soon again evolve to include a "capacitance" factor that measures and values storage. Current energy standards completely ignore capacitance when evaluating building performance, and this view of energy is limiting.

What challenges do building owners and designers face when integrating new solutions to achieve zero energy in retrofits?

MacCracken: When aiming for zero energy in an existing facility, the first step is always reducing the building's energy consumption: tighter envelope, great windows, effective shading, great lights, etc. Plug loads (energy consumed by screens, computers and copier machines) are now responsible for 50 percent of energy usage in office buildings. Retrofits must account for these "uncontrolled" loads if organizations hope to get their facilities to zero.
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Once you get these plug loads as low as possible, renewable resources must be added. However, achieving zero energy in retrofits becomes more difficult as you get into increasingly dense urban environments because of the limited access to local renewables. In suburban environments, it's common to see large retailers like Wal-Mart, typically single-story facilities with an expansive roof and a low-density energy load, offsetting their entire energy needs with rooftop PV panels.

Contrasting this to high-rise buildings in dense urban areas, which have limited surface area on their roofs and extremely dense energy profiles, PV on the roof will have little impact on the building's energy usage. It is the same with wind turbines in dense urban environments, which have been shown to perform with limited success when installed on New York City rooftops, simply because wind is too turbulent on the roofs of tall buildings. So in dense urban areas, it is likely that the energy will be collected off-site but stored within the building.

What best practices are involved in integrating zero-energy strategies from the onset of design?

MacCracken: Building controls are critical. Addressing plug-loads from the onset must be done as well as designing the building for "off" mode when people aren't in it. There also needs to be a certain amount of training of the building's occupants, though surveys report that this training very rarely happens. There has to be a balance between the technologies and users.

You must decide how automated you want things inside the building to be. Would you rather have employees involved and engaged, give them manual switches to control their own environment or automate the lights so things are done for them? A compromise must be achieved between the particular application you are using to manage energy consumption and its users. Human behavior always needs to be accounted for when designing zero-energy facilities.

Natural daylighting design strategies have been a popular means of reducing energy consumption by electric bulbs without compromising the indoor comfort of the facility. However, LED lighting has become so efficient that it may make more sense to simply power these devices with solar energy rather than design windows to maximize and control the intake of natural light. And of course, thermal energy storage, which helps manage energy flow, provides much-needed flexibility in energy management.