Day 6: Net Zero Energy

RNL’s NREL RSF redefined the potential for achieving net zero energy (NZE) status in a commercial office building. Located in Golden, CO and completed in 2010, phase I was the largest office building in the nation to achieve net zero energy status.

The RSF is a 222,000 square foot Federal office building that is designed to be one of the largest net-zero energy buildings of its kind.

The RSF is a 222,000 square foot Federal office building that is designed to be one of the largest net-zero energy buildings of its kind.

Since the RSF we have been quietly building up our portfolio of next generation net zero energy buildings, and are currently working on two that have the potential for making waves in their respective building types. So stay tuned… While we can’t disclose the details of the projects, we can talk about the details of the process. 

Know your Numbers

In theory, any project can reach net zero energy if you buy enough photovoltaics (PV) and find somewhere on the site to put them. Is that the right way to approach it? Absolutely not. Besides, we have yet to find that unicorn of a project with an unlimited budget for on-site renewables. Instead, the key to NZE projects is reducing your energy use as much as possible first, and then making up the difference with on-site renewables. This math game requires knowing your numbers from the very start – the energy use intensity (EUI) of your design as soon as that first Sketch Up or Revit model is made, the amount of PV you will likely be able to fit on the site (and in the budget), and the EUI that you’ll need to hit to make the net zero energy equation work – and checking back in on those numbers regularly. 


While we have energy modeling consultants on most of our projects, it is important for the design team to also know not only the EUI of their design, but also how each component of the design impacts the EUI, where the biggest bang for your buck is in terms of lowering the EUI, and how even the smallest design decision impacts that number.This is especially important during the concept and schematic design phases when the bigger design moves are being made, sometimes in a matter of minutes during a charrette, and where energy consultants may not have started modeling yet. This is where our in-house energy modeling tools come in.

It’s important to know how even the smallest design decision impacts the EUI.

Have Cloud-Based Software, Will Travel (and Design)

The era of plug-ins and cloud-based software has made in-house conceptual energy modeling seamless with the design effort, and portable when traveling to client presentations or project meetings outside of the office; two key innovations. So far we have used Light Stanza, Sefaira and Fenestra Pro to get an early assessment of EUI, daylighting potential, and façade design in our projects.  The promise of every single member of the project team working off of one BIM model is still a ways out from being realized. And that’s fine. For now these software programs allow us, the architects, to know our numbers early on, update them quickly on the fly, and make more educated decisions on the drawing board.