Culture and context: How to drive net zero design
By Jen Kinney
May 3, 2016
December’s historic Paris agreement on climate change has made governments, businesses, and ordinary people around the world more aware of the need to dramatically reduce greenhouse gas emissions. This has particular resonance within the design community, as over 30% of all emissions are related to buildings. The architecture, engineering, and construction professions must push for drastic change today.
Fortunately, leading green-building designers understand what it takes to reduce building energy use and, in turn, emissions. For new buildings this can mean getting to net zero energy use (or very close); for existing buildings it can mean significant reductions. In both cases, moving toward zero requires an integrated process that takes into account a given building’s context and life cycle.
Here are the main concepts designers need to keep in mind to hit this target.
As Arup principal Fiona Cousins explained, getting to zero requires building professionals to venture beyond their traditional skill set, thinking as much about psychology as physics. Designers may aim for ambitious energy conservation goals, but if the building’s operators and occupants don’t buy into the plan, their efforts can be wasted. “We know what the technical solutions are, but solutions are not only technical,” she said. “They are also personal and professional and political and organizational.”
For this reason, buildings that succeed with net zero are often mission-driven. The world’s first LEED Platinum building was built to house the Philip Merrill Environmental Center in Maryland, headquarters of the conservation-focused Chesapeake Bay Foundation. Here, energy efficiency isn’t an afterthought; it works in service of the organization’s core principles.
Of course, if global emissions targets are to be met, banks, universities, homes — all buildings — need to cut their energy use. Clarifying principles and setting priorities at the start can help all stakeholders understand their role in meeting this target, solidifying commitments from designers, users, and owners alike. “This whole integrated process is not just the design of the building, it’s quite often the design of the entire organization,” said Cousins. “You have to have net zero in mind all the way from the beginning of the process and include people from all of those groups.”
In some ways, this is more challenging in the United States and Canada than in other parts of the world, due to the omnipresence of air-conditioning and central heating. Asking people in Cleveland to wear a sweater inside on cold days, for instance, represents something of a paradigm shift.
Just enough of everything
From a demand standpoint, user energy requirements need to be pared down as much as possible. This can take many forms: for instance, selecting energy-efficient equipment, reducing the amount of square footage, and thinking carefully about the power requirements.
The latter is particularly important. Market pressures often lead tenants and owners to request far more power per square foot than is necessary for a building’s intended use. This has far-reaching implications for the overall design. “Every little bucket of electricity you use produces heat, so for every little bucket of electricity you add you have to put in more mechanical systems to take the heat away,” Cousins said. As a result, even if the occupants never use all the power they have access to, the damage has been done. “You’ve made the electrical wires bigger, and you’ve probably got more of them. You’ve made the mechanical system bigger, and it will probably take more space in the building, which may be enlarged as a result. So everything gets larger, which means your embodied energy goes up.”
Getting to zero requires building professionals to think as much about psychology as physics.
The solution: stakeholders need to agree on what they are actually designing for and plan energy needs around that, without pushing capacity so low that the building can’t be adapted for different uses in the future. Spaces with significant computing needs — bank trading floors, for example — need access to large amounts of energy, but most can function perfectly well with only one-third of the wattage commonly provided today.
In addition to intended use, buildings must be tailored for the local climate. A residential building in Saskatchewan needs to retain heat during most of the year, while an office building in Tennessee will be extremely uncomfortable in most months unless it sheds heat generated by computers, occupants, and lights. A warehouse owner in New Jersey has little use for windows, while a beachfront hotel developer in Miami wants to make the most of the view. Zero-net-energy design requires careful consideration of these factors and how they relate to one another.
Passive design techniques allow architects and engineers to create comfortable conditions with minimal reliance on energy-using equipment. Paying attention to issues like building orientation, daylighting, and building envelope ventilation and insulation is key.
The Chesapeake Bay Foundation’s headquarters, for example, is situated to take maximum advantage of natural light, equipped with sensor-enabled windows that open to let in bay breezes and heated and cooled by ground-source heat pumps. The mechanical temperature-control systems run only about two-thirds of the year — a massive improvement over standard buildings in the region.
Appropriate sizing of mechanical equipment such as boilers and chillers is a must. “Imagine that you have an extra-large sweater and you want to make it fit you,” Cousins explained. “It doesn’t, because you’re skinny. You might put a belt around it, but it will be basically a mess, because it will be just too big. It’s kind of the same thing with a mechanical system.”
Correct sizing is critical to keeping building occupants comfortable while staying within energy targets. Get this wrong, and proper heating and cooling suddenly become much more difficult and energy-intensive to achieve.
If following these fairly straightforward guidelines will lead to nearly net zero buildings, why aren’t more people pursing this goal?
The answer comes down largely to culture. Expectations about things most of us take for granted need to change: Lights in hotel hallways don’t need to be on when no one’s around, for instance. Thankfully, design interventions such as the installation of sensor-driven light switches can have the added benefit of making people think more about their energy use.
A similar effect can be seen at larger scales. If cities or countries set carbon-emission-reduction goals, mandatory public reporting on building emissions might prompt owners to consider conservation retrofits. This is increasingly a reality: the European Union passed its Energy Performance of Buildings Directive in 2010, and New York City has been requiring that buildings report energy (and water) data since 2012.
Today’s most forward-looking buildings generate their own energy with renewable sources rather than pulling it off the grid. Hopefully, designers will take net zero for granted in the not-too-distant future, focusing instead on using excess power generated by buildings to benefit the wider community.