Phius Associate Director Lisa White examines the interactivity between passive buildings and the future of the grid.
Our world of power and electricity is changing rapidly, from where and how we generate electricity to how we distribute, use, and sell it.
The distribution and transmission infrastructure is aging, the load on the grid is increasing due to electric vehicles and building electrification, and renewable generation resources are coming online at an unprecedented rate. It is estimated that the electric grid will undergo more change in the next decade than it has in the last century. And, building designers, owners, and operators are uniquely positioned to impact how quickly, and costly, the transition to a renewable energy future will be.
Over the last five years, I’ve focused my research at Phius on looking beyond the building: reviewing the existing and changing operations of the electrical grid; the trends, limitations, and challenges confronted within the electricity generation, transmission, and distribution space; and the profound impact our buildings have in that space. I often refer to Phius buildings as the capacitor or critical resource for the new grid (see “Passive Building 101”). No matter the framing, the core message is that the low-load passive building is critical for facilitating the grid transition away from using fossil-fueled resources to renewable resources (some refer to this as the “Mid-Transition”), and then for resilient operation once we’ve hit that goal (the renewable future). There is a ripple effect from conservation at the building level that perpetuates far beyond the building.
Image 1: Illustration of the ripple effect that conservation strategies have beyond the building boundary. Less energy consumed at a building site means less renewable energy required to operate it, less energy storage to re-shape the supply or demand profiles, and less transmission capacity required to carry the load to (and maybe from) the building.
Passive buildings are characterized as buildings that use passive conservation strategies to achieve extremely low loads for heating and cooling and also use significantly less annual energy than a typical building, resulting overall in less carbon emissions.
Image 2: A hypothetical annual load profile of a typical building versus a passive building. Passive conservation strategies bring down the peaks at the top of the curves (peak loads) as well as the area under the curve (annual loads).
At Phius, we’ve quantified and defined metrics for passive building. Our passive building standards are rooted in cost-optimization of conservation strategies and set targets for both peak and annual space conditioning loads. These targets vary based on climate, building size, occupant density, and the cost of delivered electricity. The goal is to reduce total cost (up-front and operational) over time, finding a sweet spot in investment.
We have two main certification tiers, Phius CORE and Phius ZERO. The CORE program targets that sweet spot for efficiency, through passive and active strategies to achieve that low-load building. The Phius ZERO program builds off that to not only target deep efficiency, but also uses a framework that accounts for the produced or procured renewable energy generation in order to net out the building’s energy use on an annual basis. It uses an annual “net” zero concept, meaning the amount of renewable energy produced must be equal to or greater than the amount of energy used in the building on an annual basis. This approach treats all units of energy the same, regardless of when energy is used or produced, which presents a stone left unturned on the path toward building decarbonization – I’ll get to that.
A main driver of Phius’ building certification program is to decarbonize the built environment. These buildings use conservation strategies to drive down operational energy use, and therefore drive down operational carbon emissions. But, we all know that we can’t conserve our way to zero energy use, and, after a certain point, investment in conservation measures may be better spent somewhere else if the true goal is to drive down emissions. After that sweet spot, our program suggests turning to renewable energy offsets to target net zero.
Now let’s get back to the grid.
The purpose of the electric grid is to provide power to buildings (and now some cars) – both instantaneously when called upon and uninterrupted. Grid operators are responsible for ensuring there are sufficient generation resources and sufficient transmission infrastructure to keep buildings running at all hours of the day and days of the year. And that is no small feat.
The grid is generally characterized by a “supply side” and a “demand side,” with a transmission and distribution network connecting the two. It currently consists mostly of large, centralized generation sources (supply side) that utilize long transmission and distribution networks that carry power to the building loads (demand side). For the most part, it’s run by a one way communication network – a building load increases and generation output must increase to match that load.
The supply side of the grid is made up of various generation resources and until recently, most of these were fossil-fuel based. These resources vary in terms of dispatchability and generation profiles.
The “profiles” I’m referring to here are “generation profiles” and “load profiles” - which are often graphically represented as a line chart with hours in the x-axis, and power in the y-axis. The top of the curve represents the peak, while the area under the curve represents energy (which is power consumed over time). Generation profiles are those that come from power generation and load profiles are those that result from building energy use.
Image 3: Conceptual Daily Generation Profiles, per season, of 50 MW of Different Renewable Resources.
Image Source: Peninsula Clean Energy
Traditional fuel-based power generation such as coal, natural gas, and nuclear are all considered “dispatchable,” which means that grid operators can control and dispatch them when it is needed to meet the load. But they don’t all have the same level of “dispatchability” or ramping capability. Coal and nuclear plants are restrained to very small changes in output, while natural gas is well-suited to ramp up and down quickly. Their generation profiles can look fairly similar but some can be shaped much more easily than others.
On the other hand, renewable energy resources on their own are not dispatchable. Grid operators cannot tell the sun when to shine, or the wind to blow. But their generation profiles are fairly predictable – we at least know when the sun does or does not have the potential to shine, and have past wind pattern data.
Image 4: Aggregated renewable energy generation profiles for the Peninsula Clean Energy CCA versus a (fairly flat) building load. Notice the mismatch between solar generation and demand, as well as when the CCA is required to buy central grid energy (in gray) due to lower renewable output.
Image Source: Peninsula Clean Energy
Renewable resources can become dispatchable when paired with energy storage, also allowing their generation profiles to be reshaped to meet the load. In other words, energy storage provides more control over when renewable energy can be used.
Image 5: To increase utilization of renewable resources, this scenario utilizes energy storage when renewable generation output is higher than the load on the grid, from the hours of ~8-16. In this hypothetical case, the excess solar production in the middle of the day is stored and discharged during times of lower renewable energy output (when the sun is down) to reduce reliability on fossil-fueled resources.
Image Source: Peninsula Clean Energy
How does a passive building assist this transition to renewable resources? To answer this question, we must take a closer look at the interdependency between buildings and today’s changing grid, which we will do in Part II of our Facilitating the Renewable Transition blog series. Stay tuned!
