Trial / Demo
In our latest guest blog, Tim Kohut, Director of Sustainable Design at National Community Renaissance (National CORE), explores the challenges of designing for resilience, sharing the workflow he uses in IESVE to evaluate critical loads, optimize PV and battery storage, and create affordable housing communities that can withstand the impacts of climate change.
It's hard to navigate through a day without hearing at least one news story on how climate change is impacting our world. Summer heatwaves seem to be hitting everywhere, and predictably seem to be becoming worse and more prolonged. Aside from modifying our professional behaviors, as energy codes are increasingly requiring us to do - requiring better energy performance and moving us closer to carbon neutrality - we now need to focus on the here and now. What weather conditions should our buildings be designed to withstand? How do we maximize heat avoidance at the lowest cost? What are the peak cooling loads, and when do they occur? What do we do if there's a power outage?
Throughout the world, there is a focus on how economically disadvantaged communities are particularly vulnerable to climate change. These communities often suffer from scarce or insufficient municipal infrastructure, often lack tree/foliage canopy sufficient to shield from the heat island effect, and suffer from economic blight. Interventions in these communities often aim at providing service centers, community centers, schools, libraries, and affordable housing. When the intervention does occur, the new building or amenity needs to do more than meet program requirements. These projects need to serve as catalysts for future development and as resource centers for the larger communities served.
National Community Renaissance (National CORE) is a developer/builder of affordable housing with portfolio properties in California, Texas, and Florida. Our primary focus is developing, building, owning, and operating the highest quality affordable housing at the lowest first cost, leveraging energy efficiency and renewable energy to lower long-term operating costs. We understand that the decisions we make during the design process will impact our residents for years to come. Because we develop and build at scale in California, we are also subject to the California Energy Code, which has pushed design teams toward all-electric buildings at the same time, targeting carbon-neutrality.
The 2022 California Energy Code went into effect on January 1, 2023, and is the current iteration in California's journey towards a decarbonized electricity grid. The new code brings with it new requirements for rooftop photovoltaic energy systems and battery storage for all multi-family buildings four stories and taller, as well as other commercial buildings. The size of the PV system is driven by either the conditioned floor area or the Solar Available Roof Area (SARA), whichever is smaller. The size of the battery is tied to the size of the PV system.
While the size of the rooftop PV system and battery storage are driven by Title 24, it is not enough to merely plan for and deploy them in plug-and-play fashion. Rather, it's important to first understand how much energy is produced and how much energy is used by the common area energy system (community room and office HVAC systems, common area lighting and plug loads, elevators, and laundry equipment).
In a previous case study (Santa Fe Senior Village), I described National CORE's approach to sub-metering energy within IESVE to better understand the economic implications of energy efficiency and renewable energy. To fully leverage the benefits of the Title 24 required rooftop PV system and battery storage, National CORE designs for resiliency.
The goal in designing for resiliency using PV and battery storage is to allow the system to charge from the sun and discharge on a daily basis. This requires a direct connection between the battery storage system and the critical loads panel, something that needs to be coordinated early on with the electrical engineer. Multi-family buildings consume a lot of energy and batteries, while important, cannot be sized to meet the whole building energy loads while at the same time charging from the sun. There just isn't enough roof space. Instead, the resiliency loads are smaller and are easier to manage. In some cases, depending on time-of-use utility charges, batteries may even provide significant savings to monthly electricity bills.
To give a recent example, Greenbrier Village is a four-story, 60-unit special needs project under construction in Oceanside, California. Once completed, it will house residents who were formerly homeless, providing ongoing supportive services. While the 60 studio units are individually metered for electricity, National CORE will be the owner of all electricity accounts and will pay for all utilities. Within the project, there is a 1,500 SF community room with connected supportive services offices. Using IESVE, National CORE designed Greenbrier Village (and other similar projects), using the following workflow:
Figure 1: Identify critical loads in IESVE
Figure 2: Identifying the critical energy period
Figure 3: IESVE Battery Storage Tool (inputs). Make sure you select the appropriate Apache simulation file. I ran several different PV sizes to optimize.
Figure 4: PV + battery storage on critical day
For Greenbrier Village, a 44 kW PV system (approximately 2,100 SF), coupled with a 30kW/60kWh battery storage system, should be enough to carry the critical loads areas through each day, in the event of a power outage. Equally important from an operations standpoint, the critical loads can be placed on a unique electrical panel so that they can be fed by the PV and a portion of the battery system on a daily basis. This will lower our operating costs. With affordable housing, saving money is as important as resiliency.
California, like other states and regions, moves closer and closer to zero net energy and carbon-neutral buildings. Rooftop PV and battery storage are now part of the Title 24 requirements for multi-family buildings four stories and taller. It's important to sharpen your analytics to better understand where your clients will get the most bang for their buck. At National Community Renaissance, we pride ourselves on being at the forefront of energy analytics and innovation. If we can do this with affordable housing projects, anyone can do it!
Interested to learn more about this project? Check out this feature in gb&d magazine.
You can also hear more about Tim's experiences using IESVE in our Meet the Front-Runners in the Race to Zero Energy Buildings video series.
