Zero Energy Buildings: Myth Or Must?

As the immediate needs for more environmentally friendly and energy efficient buildings become more and more apparent, a logical question begins to come into focus: Where does it end?

Many in the design and construction community believe the answer is Zero Energy Buildings.  Zero Energy is a term used to describe a building that consumes as much energy as it generates in a given year or net zero.  Conversely, carbon emissions, which are directly related to the energy consumed, are zero. This is not to be confused with the notion that the building consumes zero energy all together.  This would be nearly impossible given all of the HVAC, Lighting, and Life Safety System demands that are needed to operate a building, especially a commercial one.  The key is to reduce the amount of energy consumed to the lowest possible amount and then create that amount of energy on-site by renewable means.

Here is a DOE’s database of Zero Energy Buildings in the US Today: http://zeb.buildinggreen.com/

Science House (Minnesota) is a Net Zero Building Used as A Teaching Tool

It all starts with the building envelope and conservation: 

This encompasses the entire surrounding perimeter of the building including the roof, the walls, fenestration (windows/glass), and the foundation below.  The envelope is the first building system which must be optimized to achieve the most efficient building possible.  Several new building envelope concepts have emerged, most notably the use of air/vapor barriers and insulation on the outside of the building in lieu of the traditional installation on the interior of the building.  Driving this concept is the fact that thermal bridging has been found to drastically reduce the functional R-Value of an exterior wall when substrate and exterior finishes are attached directly to the framing of the building with no layer of thermal protection on the outside.  Not only must a building envelope be well insulated but it must also need to be sealed well enough to prevent air leakage.  Air leakage is one of the top reasons for energy loss in existing buildings today.

Click here for a link to a great resource, the passive haus institute on more information to maximize envelope efficiency: http://www.passivehouse.us/passiveHouse/PassiveHouseInfo.html

System Optimization & Proper Sizing: 

The next step to achieving net zero energy consumption in a building is through the optimization of the mechanical, electrical and plumbing systems that operate the building.  Virtually on a monthly basis new mechanical, electrical, lighting and plumbing equipment are released to the market with increased efficiencies.  Designers are finding new ways to integrate these systems and make them efficient as possible.  Also, these systems need to be engineered to be properly sized and configured based on the envelope and the anticipated demands of the occupants.  After occupancy, the use of building management systems, smart controls and variable settings on equipment have all helped to integrate these systems and provide constant feedback on the amount of energy being used at a given time.  The proper sizing and smart usage can combine to reduce the energy consumption by nearly 50% by using highly efficient systems and equipment.

For more information and great articles on optimizing energy efficiency in buildings:  Check out the M-Files Blog http://blog.mcclureco.com/

Note:
Studies and energy models have shown that maximizing both the envelope and the major building systems can reduce the energy consumption of a building by 70% (over the baseline energy usage established by ASHRAE 90.1).   Where does the remaining 30% come from?

On-Site Energy Generation:

The final step of achieving net zero energy consumption is through the generation of on-site energy for use by the building or the purchase of renewable energy through a green power provider.  The plausibility of generating your own energy or using renewable energy sources has increased recently due to a heightened awareness and a drop in costs (avg solar array runs between $3.50 and $5.00 per watt).  Systems that incorporate energy recovered from these various systems are becoming more of a common place for those planning to construct a new building: Solar, Geothermal, Cogeneration, Energy Recovery, Micro turbines, Wind and hydroelectricity.  Utilizing this energy locally first, at the building location, is where the remaining 30% reduction occurs.

Whether Net Zero is Feasible or Not, Raising the bar is a Must:

Buildings and optimizing their performance must be a focus for the design and construction communities because they have the single largest impact on the environment today (and the costs of operating our buildings).  Our collective commitment to creating buildings that perform optimally from a comfort, consumption and generative stance is imperative.  Finding creative ways to reduce energy (as much as fiscally possible) and then operating these buildings in an optimal manner is a must.  I am confident that the technologies and the strategies will continue to evolve and netzero will eventually become commonplace.

The Living Futures Institute (Creators of the Living Building Challenge) has now implemented a Net Zero Certification Program, for more information, go here: http://living-future.org/netzero/

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4 thoughts on “Zero Energy Buildings: Myth Or Must?

  1. Bill,
    Nice post and thanks for the blog referral. Another major contributor to net zero are O&M practices. I believe this is currently a bit of a blind spot in our industry. There’s a saying that “There aren’t zero energy buildings without zero energy people.” I think that’s an accurate statement.

    The National Renewable Energy Lab completed a study on the potential of achieving net zero energy buildings. According to their analysis we could achieve net zero in 22% of U.S. buildings with current technologies as of 2005, but that study doesn’t include any analysis of the economics – just technical potential. So we still have a ways to go. I wrote a post on the subject a while back: http://blog.mcclureco.com/net-zero-energy-buildings-legitimate-policy-or-hallucination/

    Hopefully we’ll see 22% NZEBs in our lifetime!
    Dan

  2. Amen! We must absolutely raise the bar on the way buildings use and generate energy. Our society has reached the point where we can no longer ignore the level at which our constructed environment consumes resources.

  3. Colleagues are realizing that Net-Zero Energy Building (NZEB) is central to the future of our profession. Currently, there isn’t a definition. Furthermore, the measuring science doesn’t exist. The National Institute of Standards and Testing has been conducting conferences to flush out a system. One idea is “Whole Building Metrics”. I drafted a definition of on a website I’ve developed for this purpose. The site is made up of 2 pages; the HOME page illustrates an example and on the 2nd page I drafted a definition. Please comment
    https://sites.google.com/site/zeroenergyconceptbuilding/home

  4. The goal of NZEB to generate at least the same amount of energy as buildings consume doesn’t solve the problem of how to construct buildings which are completely self sufficient. A more holistic approach is to reach beyond NZEB to Zero Energy Concept Building (ZECB). ZECB is a leap forward ahead of NZEB because Zero Energy Concept Building includes technology to purify waste water and improve indoor air quality by harnessing the power of Mother Nature to replenish these resources. ZECB addresses poor indoor air quality which has been linked to health problems, while at the same time applying natural processes defined as fixed-film ecology for waste water purification. With fixed-film ecology water is used and reused in diverse ways; continuously cycling through nature’s cleansing process through a series of wetland tanks which do double duty by scrubbing the indoor air through the process of photosynthesis. Photosynthesis is a natural charge particle technology that makes pollutants heavy causing them to drop out of the air which is the natural method of cleansing indoor air. For more about understanding this authors definition for ZECB click on this link https://sites.google.com/site/zeroenergyconceptbuilding/defining-zecb-for-the-green-collar-economy

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