Week 4 Questions


Zero Net Energy (ZNE buildings) require more than a well-coordinated integrated design process and detailed, considered design; to truly reach zero net energy, a building also needs to be operated and occupied with a detailed, considered approach.

Building occupants use a great deal of energy that is difficult to account for accurately in the design process for several reasons, primarily the inherent variance in occupier use and the lack of inclusion of occupier energy use in regulatory codes.  To model energy use in the design phase of a ZNE building, occupant densities and hours of operation must be set through expectations and approximations.  Because these numbers are often higher than planned, the actual energy use of a building is equally as often higher than what was modeled.  Another major user of energy is plug loads.  When occupants plug in devices and equipment, and especially when items are continuously plugged in, energy use increases significantly.

There are several approaches to counteracting this occupant energy use.  One of the most important is occupant engagement and education, including awareness initiatives, that inform people of the energy that they are actually using.  Examples of this are green campaigns, dashboards that provide immediate user feedback regarding energy use by devices and lighting, and simple communication such as daily emails that remind occupants to shut down their computers at the end of the day.

The significant effect of plug loads upon overall energy use requires particular attention.  Advanced plug strips with schedule controls and controlled wall outlets both help a great deal in reducing the negative effect of continuous plug loads, especially while a building is unoccupied.  More efficient appliances and equipment also go a long way towards negating this issue.

Another important approach is the use of commissioning and monitoring, which allow for adjustments to be made quickly rather than after a standard annual cycle.  If energy use is much higher during the first several weeks of occupancy, and this is known, necessary adjustments can be made quickly to help the building reach ZNE status.  Involvement of the design team over the initial year of occupancy can contribute to this, as well as to the education and awareness efforts.


A crucial aspect to the continued development of the ZNE building market is data.  Currently, accurate and complete data is often difficult to find.  As more data becomes available, education of owners, developers, and designers will help to expand the ZNE building market and result in a much larger number of ZNE buildings.  Data also proves what a ZNE approach can achieve, thereby making it seem more attainable and desirable to a wider range of people.

Benchmarking, the submission of energy use data, is extremely important to the ZNE building movement as it leads to a more comprehensive understanding of actual energy use.  This then allows energy use goals to be set, and reveals the feasibility of ZNE strategies.  New York and Seattle have had success with benchmarking, and in the process have set a strong example for others to follow in the near future.