Changing Building Design for a Changing Electrical Grid

Renewable electricity generation has nearly doubled in the last 10 years. Ninety percent of that increase came from wind and solar generation (source: U.S. Energy Information Administration (EIA)). Costs have also declined rapidly. Oftentimes solar and wind generation is the cheapest option for new or replacement generation capacity (source: BloombergNEF (BNEF)). This capacity includes wind and solar generation and electric storage assets owned by utilities (“utility scale”) and those that are not owned or managed by utilities (“distributed energy resources” or “DERs,” which include net-zero-energy buildings).

Electricity generation from wind and solar is often termed a “Highly Variable Renewable Energy” generation asset, or “VRE” because electricity generated from these assets varies by time of day and season. Generally, solar electricity is most productive during the day, especially in the summer, and wind generation at night, especially in the spring (source: EIA). Of course, both solar and wind are dependent on daily, even hourly, local weather as well. The existing electricity sector—utility business models and grid infrastructure—were not designed for VREs. Building design and operation have also not been designed to optimize VREs.

When high penetrations of VRE generation occur, the grid goes out of balance. The shape of the net-load curves—the difference between electricity demand and VRE generation—in areas with high penetrations of VREs provides an easy visualization of the challenges, fondly referred to as “the zoo.” California has a “duck curve.” “Nene” the native goose is in Hawaii. Texas has an armadillo, and there’s an alligator in the upper Midwest. Each of these areas is a little different in terms of the degree of the problem, but they all illustrate a period of time in the late afternoon and early evening when electricity demand cannot be met by VRE generation. Utilities are forced to quickly ramp up “peaking generators” to address the mismatch between the profile of peak electricity generation by VREs and the typical afternoon/evening peak demand profile coming mostly from buildings. Utilities are required to meet that demand for electricity no matter the cost or the environmental and climate impacts. Their peaking generators are usually the most expensive, and sometimes the dirtiest, generation assets they have. Certainly, they are dirtier and more carbon intensive than VREs.

The problems illustrated by Hawaii’s Nene and California’s duck curve are even worse. Their net-load curves have bellies, which show that during some seasons, VRE generation is actually greater than demand in the middle of the day. Hawaii has no place to send that excess electricity, but California “curtails” it (sells it, gives it away, or pays to get rid of it). As utilities balance consumer and regulatory demand for low-carbon VRE electricity generation, they will be looking for rate structures and a variety of customer programs that incentivize building design and operation strategies to free the zoo animals and “flatten” those net-load curves.