Zero Net Energy Buildings Explained

In our previous post, we talked about the idea of Zero Net Energy buildings and how it could lead to a carbon free future. In this post, we look at the different types of Zero Net Energy buildings and the latest measure for calculating the energy performance.

The market for zero net energy buildings is growing with innovative designers, building owners and government working together to create a minimum carbon future. This is also evident by the increase in the number of projects not only in US, but also in New Zealand, Canada, Singapore and India. While a range of energy efficient strategies are being incorporated in commercial and lately in residential buildings, corporate stakeholders such as Walgreens and McDonalds are looking towards creating zero energy retail outlets in quick-serve spaces/restaurants. ZNE buildings are categorized as per the energy requirements that have been met over the course of a year.

Categories of ZNE Buildings:

ZNE verified buildings:

These are high-energy efficient buildings that have achieved ZNE status as the energy requirements have been met by onsite renewable energy sources for one year; i.e. their renewables could produce the energy required to power themselves for a year without depending on any fossil fuels. Eg. 231 Main Street, Suncoast Credit Union etc.

ZNE Emerging Buildings:

These buildings are usually in the planning, design or construction phase and/or have been in operation for less than twelve months, hence have not achieved
ZNE status. Buildings that have been in operation for more than twelve months but have not
yet achieved ZNE status are also known as & emerging buildings.  Eg. St. Jamers Intermediate School, Sustainable Energy Fund etc.

ZNE Districts:

These constitute buildings in a community or campus and could be ZNE emerging or verified.Eg. Boulder Commons, Mark Day School etc.

Ultra-low energy verified buildings:

These buildings are technologically moving towards reducing energy use of fossil fuels and investing in on-site renewable energy sources and/or do not have a stated goal of ZNE. Eg. Alvaton Elementary School, Everett Municipal Court Replacement etc.

How is the energy usage calculated for onsite renewables?

The scale: Zero Energy Performance Index – zEPI – provides a new dimension of analyzing and
observing a holistic approach to energy use in buildings.

To work around and reach the goal of increasing the buildings energy efficiency by 2030, zEPI has been developed as a metrics for setting the energy requirements. It provides owners, designers, and other stakeholders a new way/benchmark to fulfill the 2030 challenge. The zEPI score of zero (0) of a building implies a zero-net energy building. This is based on location, supply, cost, emissions etc. 100 is the score of an average energy consumption building , the base year for comparison being the year 2000. For eg. if a building uses double the amount of energy it receives, it will be given a score of 200; whereas a building that uses
half the amount of energy as an average building, will be awarded a score of 50. zEPI is outcome based and a lower score signifies less energy utilization. zEPI sets energy targets for actual energy consumption rather than predictive analysis wherein the performance rating is established on source energy and not site energy further adjusting for climate. Adoption of 2015 International Green Construction Code (IgCC) sets the zEPI goal to be 51 while lowering it every year till zero by the year 2030. For eg. if a buildings energy code is 48 and the buildings code setting body wishes it to become zero in the next 12 years (2018-2030), zEPI would set the goal as 36, 24, 12 and zero on the zEPI scale. Not only does zEPI measure energy milestones, it also evaluates the performance of single projects/policies. Also, for buildings occupied between 2015 and 2020, the zEPI score is 39. These energy codes also include a renewable energy component (at lower zEPI target levels) present in the IgCC.

What is in store for the future ?

The revenue for ZNE buildings by 2035 is expected to exceed $1.4 trillion annually, according to a study by Navigant . ZNE buildings show us the future – 20 years and after; and provide an excellent opportunity with a relatively great pay off. The varying economics of renewable energy, the growing interest of the private sector, environmental demands, and governments
policies towards building an energy efficient future is accelerating the growth of completely self-generating energy/zero net energy buildings. One could even say that the goal of a ZNE building is that nothing exceeds zero’ . ZNE buildings – a step towards a cleaner and greener future.

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