Overcoming Obstacles on the Path to Zero Net Energy (ZNE)

Zero Net Energy (ZNE) sounds very appealing doesn’t it?

This building only uses as much energy as it (cleanly) generates on-site!!!

ZNE quickly implies energy self-sufficiency. Efficient energy use plus some solar PV panels to match equals “we are doing our part!!”. Seems simple.

ZNE is hard. Sorry. Anyone who has got into the definitions and boundaries of ZNE knows it can look complicated really fast, especially when trying to develop broad policy.

Definitions are the easy part. Technically, yes, there are many means to get there. We can make extremely efficient buildings. We can install reliable, clean generation that is also cost-effective.

But in practice, ZNE is hard or impossible to achieve for many building types.

What building types make ZNE hard?

So, should we give up on buildings that can’t get to ZNE? Let’s keep it real. Data centers, high-rises, 24/7 facilities, medical centers – buildings with heavy energy use and/or small footprint for solar PV – are very hard to hit ZNE.

Targeting ZNE with Green Building Policy

We faced this question recently when helping a California municipality prepare their “Green Policy” for new buildings. The Board wanted to set a ZNE goal for all their new buildings, to do the ‘Right Thing’, and align with State goals. With some dozen or so new building projects in development, they needed to figure out a good policy quickly. They needed help.

We were brought in, alongside our trusted renewable energy partners, Sage Renewables. The municipality’s team tasked with creating the Green/ZNE Policy included many different folks involved in new building projects. Naturally enough, they first came to the conclusion that they should/could apply ZNE mandates only to projects where ZNE would be achievable. They developed a list of “exempted” buildings…and it was long. It was most projects.

We helped everyone step back from that disappointment to remind ourselves the reasons behind the ZNE goal. ZNE is a great motivator to push project teams to both achieve highly efficient use of energy, and to install on-site clean generation.

Striving for Energy Excellence

That’s why we set ZNE as a goal, to push for excellence on both ends – energy use and energy generation. We want excellence! So for a building project where ZNE cannot be reasonably mandated, why would we simply abandon those goals altogether? Of course, we would not.

Instead, we guided the team to a still-ambitious path, but where maximum efficiency and maximum clean generation will always be pursued. Where ZNE is shown by the design team to be impractical, the ZNE Policy still demands both maximum efficiency and maximum clean generation. The most that can be achieved at each site.

Appropriating Public Funds for ZNE

Since the ZNE Policy would impact spending of public funds, we built in concise financial tests to ensure sound, understandable lifetime financial results. We also developed specific efficiency goals set within the broader LEED® framework which they were already using. This way, buildings are indeed mandated to achieve ZNE where it is practical and financially justifiable.

Embracing the Maximum Renewable Path Ahead

The municipality’s Board adopted the Green/ZNE policy late last year. Though not every site is ZNE, EVERY building is required to reach to achieve excellence in both efficiency and generation. We call this the maximum “% Renewable” achievable for that site. For example, if clean generation on the site supplies 80% of the energy use of the building, then that is a wonderful achievement of “80% Renewable”. And we’ll happily take it!

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