Elevating the Principles of Net-Zero Buildings to Teach Us About Building Sustainable Communities


A few weeks ago, at the Greenbuild conference in San Francisco, I attended a session that featured NREL’s Research Support Facility (RSF) in Golden, CO. The session’s speakers described the design and construction process of the RSF, a net-zero energy building (NZEB) that today serves as a model for performance-based design.

The possibilities presented about achieving net-zero energy at scale were exciting: How do net-zero design strategies alter the discourse about how we design and build? Does NZEB necessitate a paradigm shift in the way we imagine and deliver buildings?

With my inner architecture geek fired up, I attended our own Congress of Cities Conference the following week. There, I had an opportunity to sit in on the Energy Efficiency workshop as Mayor Henrietta Davis of Cambridge, MA, along with Kurt Roth of Fraunhofer USA, presented the M.L.K School. This net-zero energy project, taken on by Cambridge Public Schools and the City of Cambridge in 2012, is to serve as a pilot project for achieving net-zero, specifically in schools.

“For Cambridge the process of planning and designing a net-zero school has changed the way we think about energy in all our buildings.  It has made us think about what energy we really need to use in our existing city buildings and will surely change some of what we do even in buildings not slated for full scale renovation or rebuilding.”

As Mayor Davis clearly states above, the process of planning for and designing net-zero buildings offers a new perspective on how we interact with and use energy in our communities.

Additionally, through the workshop sessions I realized that the focus on a life-cycle perspective (which the NZEB process elevates) offers principles applicable not only to energy efficiency in buildings, but also to the larger dialogue on taking sustainable communities to scale:

The Power of Integrated Design.  At the San Francisco Greenbuild session, speakers described the need to effectively integrate and coordinate the various building components and processes in order to achieve maximum energy efficiencies.  With NREL’s RSF, they spoke about the high level of coordination that took place between the various ‘designers’—the architect, engineer, contractor and operations/maintenance company—in order to ensure that energy efficiency was a prioritized goal (on par with scheduling and cost savings) throughout the process. Through open lines of communication, each ‘designer’ in the process ensured that their building component was as energy efficient as possible with relation to the various other components working in parallel.

Sustainable communities emerge from the thoughtful design and integration of the various components of a place.  While many of us are aware of this, do our planning practices actually encourage dialogue between the various ‘designers’ of the city—the architects, the transportation planners, the youth and the civic and faith-based organizers? Often, city planning is happenstance, pieces of communities clashing and colliding into places; and while there is beauty in the intersections that emerge, sustainable cities necessitate greater coordination and communication between these traditionally unlikely partners.  Create spaces that encourage open communication- the first step is to have everyone working together.

The Plug Load Problem.  In both sessions, the speakers used the example of plug loads—essentially the energy consumed by what you and I plug into a socket rather than the energy it takes to heat or light a room– to describe how much end users impact the overall building energy use.   To be able to achieve a NZEB, they emphasized 1) incorporating this variable into early energy modeling for the building and 2) creating an education process whereby end users (if known) understand the NZEB principles and the effects of their actions on overall building energy use.

Now this sounds quite simple, but how often do we forget that different communities are created for and occupied by different types of users?  While we may not ‘model’ a community like we do a building, we certainly envision outcomes early on.  So, in the design/visioning/ goal-setting process, the first step is identifying who the end users are (think: age, demographics, socioeconomic status) and how they already occupy spaces.  The second step is creating an educational component to the process so that “the users” understand the effects of their individual actions and are better equipped to make day-to-day decisions. Focus on the end user from the beginning—the key lies in the operation not just the planning.

The Passive Design Potential.  A critical component of designing a NZEB is incorporating passive design strategies—strategies that maximize the energy provided by natural systems as much as possible. Rather than defaulting to purchased energy, passive design creates a process whereby ambient sources of energy such as daylighting and natural ventilation are maximized. Both sets of speakers demonstrated that understanding the site and its “passive assets” was critical to minimizing the number of energy- consuming products that would make NZEB goals more difficult to achieve.

In the case of moving towards sustainable cities, how quickly do we assume that the ‘right’ answer in one place is the ‘right’ answer in another?  The fact is that each city has its own geographies, typologies, assets, and so forth. The strength of encouraging passive design strategies in net-zero building is that the excess addition of systems and components takes a second seat to the inherent assets of the site.

In the creation and implementation of a sustainability vision for a city, identifying those assets and qualities that already progress a city’s sustainability goals are not only low-hanging fruit, but often more successful in the long-term than imposing programs or policies that may not fit.  Build more with less-every community has untapped assets waiting to be utilized.

As NZEBs are still relatively recent in the sustainability conversation, I’m excited to see how building and energy rating systems develop and what lessons we continue to extract from the whole process!

Stay tuned and share your thoughts with us –comment below or email us at sustainability@nlc.org.

2 comments on “Elevating the Principles of Net-Zero Buildings to Teach Us About Building Sustainable Communities”

  1. My firm has been quietly working toward the goal of net-zero energy with some notable success. I believe a paradigm change is necessary, with or without plug loads. We’ve made that shift and are achieving reductions in energy usage approaching 85% based on completed facilities where we have a year or more utility use data and none of these facilities employ renewable resources. We believe we are on the cusp of achieving this goal, thermally, which has so far proven to be the most difficult part of the process.

    Conventional HVAC will not get you there, period. Many of the “sexy,” or as I prefer to describe them, “fad” solutions (air-side economizers, geothermal heat pumps, natural ventilation, VRF systems) are actually technological dead ends, more market hype than real solutions.

    Others, many not very sexy, show tremendous promise. The key to achieving true net-zero performance is cutting energy use by elimination of waste, and there is a tremendous amount of waste. We have documented ventilation energy use reductions as high as 97% with dedicated outdoor air systems based on multi-stage energy recovery and evaporative processes. Passive systems (radiant heating and cooling, day lighting, “cool” roofs) and adiabatic strategies (thermal storage, direct and indirect evaporative cooling) show tremendous potential, particularly in the area of heating and cooling.

    For primary heating and cooling, “central heat pumps” using hot and cold storage to capture and recycle waste heat energy typically disposed of with air-side economizers, use about 1/6th of the energy of distributed geothermal heat pump systems and require no wells.

    Couple these with cool roofs and fundamentally efficient heating and cooling strategies (DOAS Radiant or Regenerative Dual Duct) designed to make constructive use of plug loads instead of simply throwing the waste heat away and then, maybe, renewable resources can become an economically viable way to achieve real net-zero.

    But building designers need to be aware that using these processes introduce new challenges they must learn to deal with, and there is a steep learning curve. You don’t just decide to take these ideas and put them together and expect the contractor to make them work!

    Doing this requires very careful and very serious engineering!

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