Measuring Progress toward Zero Energy

I was recently reading an article on Greenbiz.com relating to Zero Energy Buildings which got me thinking (again) about the challenges associated with any energy stewardship project. Chief among these is measurement and verification (M&V).
People want and need to know an answer to a very basic question: How much “X” did we save? The “X” can be any commodity, of course. But to talk about those savings, we have to have a common understanding and agreement on how we will assess them. And if the amount we save approaches the amount we use in our building, campus, portfolio, or community, we are closing in on zero energy.

The U.S. Department of Energy (DOE), in collaboration with the National Institute of Building Sciences, has made a helpful contribution in this area by preparing A Common Definition for Zero Energy Buildings. We’ll summarize this resource in today’s blog.

So what is a Zero Energy Building (ZEB) anyway? Obviously it’s not a building that doesn’t use energy. The DOE makes a convincing case for understanding Zero Energy as a balancing act with renewable and non-renewable energy assets in play. Those assets can either be produced or consumed onsite, and can be imported or exported. In one scenario, renewable energy assets can even be produced offsite and then purchased for onsite use and “credited” to the building’s energy “balance.” A zero energy building produces (or purchases) enough renewable energy to meet its own annual energy consumption requirements, thereby reducing the use of non-renewable energy in the building sector.

Here is the DOE’s definition of a zero energy building: An energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy.

To unpack this definition, the publication provides a helpful glossary of related terms:

Source Energy: Site energy plus the energy consumed in the extraction, processing and transport of primary fuels such as coal, oil and natural gas; energy losses in thermal combustion in power generation plants; and energy losses in transmission and distribution to the building site.
Delivered energy: Any type of energy that could be bought or sold for use as building energy, including electricity, steam, hot water or chilled water, natural gas, biogas, landfill gas, coal, coke, propane, petroleum and its derivatives, residual fuel oil, alcohol based fuels, wood, biomass and any other material consumed as fuel.
On-site Renewable Energy: Includes any renewable energy collected and generated within the site boundary that is used for building energy and the excess renewable energy could be exported outside the site boundary. The renewable energy certificates (RECs) associated with the renewable energy must be retained or retired by the building owner/lessee to be claimed as renewable energy.
Delivered energy: Any type of energy that could be bought or sold for use as building energy, including electricity, steam, hot water or chilled water, natural gas, biogas, landfill gas, coal, coke, propane, petroleum and its derivatives, residual fuel oil, alcohol based fuels, wood, biomass and any other material consumed as fuel.

These related definitions provide us with a helpful starting point for zero energy discussions. It is also important to point out that the DOE publication includes sample source energy calculations, a discussion of related “zero energy” terms currently in circulation, and a helpful bibliography of research materials (Appendix 1) that includes brief descriptions of each resource.

In our observation, EnergyCAP clients are becoming more savvy and creative in using the software to clearly distinguish renewable and non-renewable assets. Photovoltaics are a great example. An EnergyCAP best practice now includes setting up special meters to account for the renewable energy assets being generating onsite. When this is done correctly, it is very easy to quantify and account for onsite renewables when looking at energy consumption trends.

A more challenging task is determining cost savings associated with renewables. For a deep dive into various options for calculating the financial “bottom line,” see Steve Heinz’s blog on PV Solar and Wind. His closing thought is also appropriate for today’s blog: “The complexity of energy tracking and M&V reporting can be greatly compounded by an on-site renewable resource. That’s why a robust tracking tool like EnergyCAP is a good corporate investment strategy for a positive energy future.”