Beyond Code Compliance—Saving Money and Energy with Performance-Based Design: Q&A with CEA Hans Marsman

HANS MARSMAN: We typically only use the Performance Approach for any new projects, since it provides greater design flexibility and focuses on the energy efficiency measures with the greatest impact for each project and climate zone. This allows diverting funds to where it has the best ROI.

A performance-based process connects different stakeholders early in the project, enhancing understanding and aligning expectations to enable effective decision-making for optimized design:

• Determine the project goals (e.g., code compliance only, Zero Carbon, Zero Energy, CHPS, LEED).
• Build an energy model based on the current plans.
• Analyze energy efficiency measures to ensure the project complies with code and project goals.
• Provide feedback to the client regarding the impact of each measure.
• Implement all measures that are adopted.
• Generate code-compliant reports for submittal to DSA.
• Generate reports for above-code project goals.

The Performance Approach relies on building a strong partnership between the district and a multi-functional team of design and construction professionals. The best outcomes are the product of a collaborative process that connects the workflows of architects, engineers, modular manufacturers and project managers into a coordinated effort directed toward a common goal.

Successful teams share information in real-time, ensuring all members are contributing their resources and expertise toward an aligned vision. When the project team is continually communicating and collaborating, project performance can be optimized. Everyone has a clear role, design strategies reflect district needs and finished buildings deliver the shared vision as cost-effectively as possible.

HANS: Most school districts seem to prefer not to install the relatively small PV system that is prescriptively required for modular classroom buildings. This is mostly due to the high upfront cost of the PV system in combination with the current utility rate structure, which only slightly reduces operating costs.

Using the Performance Method, the project can often opt to optimize the envelope, HVAC or lighting efficiency (or a combination) for the local climate zone and trade off the prescriptive PV and/or battery requirements. This is especially true in the milder California climate zones. As long as the proposed energy use does not exceed the code allowance, the project complies. This approach allows for lower first costs while still meeting code-required energy usage targets.

HANS: Several projects have improved HVAC efficiency after energy analysis showed that this would have a much larger effect on energy use reduction than increasing envelope insulation to Title 24 prescriptive values. Since increasing envelope insulation has a diminishing effect and ventilation air is the largest source of heating requirements, improving the efficiency of the heat pump is key to achieving energy goals.

Furthermore, the moderate daytime weather in southern coastal California reduces the need for heating and cooling, while inland weather is more extreme. This means that energy efficiency measures should be tailored to the local climate, which is why we use the Performance Method.

HANS: Unlike the Prescriptive Approach, which requires that all aspects of a building meet a set of specific requirements (e.g., maximum U-factors, maximum lighting power density and minimum HVAC efficiency), the Performance Method allows for solutions that have a greater impact on a project’s energy use but are not prescriptively required. Examples of this are energy recovery ventilators, low wattage lighting or high-efficiency HVAC systems. Since these measures often have a greater impact than, for example, increasing envelope insulation, the result is a more efficient building even though each prescriptive requirement is sometimes not met.

HANS: The Performance Method allows for diverting funds from energy efficiency measures with a negligible impact to measures with a much better ROI. This reduces upfront costs and operating costs.

For example, installing a 1 kW PV system typically costs between $4,000 and $5,000. Engineering and electrical coordination fees can add $20,000 or more to a building’s upfront cost. So a district using the Prescriptive Method would spend around $50,000 or more to install a 6 kW system in a new school building. In comparison, a district using the Performance Method might not need to install a PV system at all, depending on design efficiency, building size and climate zone.

Performance-based design looks at the entire picture, creating cost-effective trade-offs that balance energy performance with project goals and district preferences. Instead of following a prescribed list, project engineers use energy analysis as a tool to help optimize the design energy efficiency and determine how much PV is required OR if the energy efficiency goals can be met without the need for solar PV. The ultimate goal is to create a solution that is optimized for performance, functionality, aesthetics and budget.

HANS: Performance-based design is mindful of long-term goals, giving districts the flexibility to utilize design strategies and energy efficiency measures that reduce building maintenance and repairs, in addition to electricity needs. Material selection, finishes, features and technologies can be combined to minimize annual operating costs. Savings can be diverted to other projects or used to fund salaries and supplies, purchase new equipment or add programming and other activities—enhancements that wouldn’t have been possible without the reallocated funding.

Cumulative savings can be significant, allowing districts to maximize performance potential while recouping as much as 100% of their upfront investment over the building’s 50-year lifecycle.

HANS: The easiest and most cost-effective way to reduce energy use is to lower lighting wattage (using LED fixtures) and employ daylight and motion sensor controls. This approach is recommended for every climate zone.

The impact of other options varies greatly depending on the local climate, building orientation and the goals of each school district. For example:

• Glazing: Using glazing with a low solar heat gain coefficient (SHGC) in combination with overhangs is effective in hot climates, especially when there are large windows facing south or west. Note that the impact of overhangs decreases as the glass SHGC reduces.
• Cool Roof: This can be a great option in extreme/hot climate zones as it reduces cooling loads. However, in colder climate zones, it may not have the desired effect.
• Increasing Envelope Insulation: This is only effective in extreme climate zones where there is a large difference between indoor and outdoor temperatures.
• HVAC Efficiency: Increasing heating and cooling efficiency is beneficial in extreme climate zones, while the impact in moderate climate zones will likely be small.
• HVAC Units with Variable Speed Fans: These are typically recommended since the fan operates mostly at part-load throughout the year.

HANS: Schools can and should go beyond code when designing a building. Eliminating fossil fuel usage should be a priority since burning fossil fuel has a negative impact on indoor air quality and the climate. Access to daylight and improved air quality have been shown to enhance the learning experience and each classroom should be optimized for this.

Sustainability programs such as CHPS and LEED are valuable resources when designing a better learning environment. Each California code cycle further improves building design and the indoor environment. The current direction of the upcoming 2025 code cycle seems to be a push for all-electric buildings, which is another step in the right direction.

HANS: Several studies have shown that good indoor air quality, access to natural daylight and optimized lighting levels improve student performance. A high-performance HVAC system with good filters will help maintain air quality, while optimizing window orientation, window areas and shading will reduce heating and cooling energy consumption. Daylight sensors adjust electric lighting based on available daylight, further reducing energy consumption.

Note that the grid in California is already predominantly powered by renewable energy during the daytime and is getting greener every year. (California’s goal is to have entirely renewable and zero-carbon electricity by 2045.) Switching to electric heat pumps and electric water heaters to eliminate fossil fuels from buildings dramatically reduces greenhouse gases. This strategy is highly recommended for districts that strive to reduce their carbon footprint.