This CASE Report consists of four submeasures: controlled environment horticulture, refrigeration system opportunities, steam trap monitoring, and pipe sizing and leak testing for compressed air systems.
Controlled Environment Horticulture
This CASE Report will analyze several controlled environment horticulture measures for inclusion in the 2022 update cycle of Title 24, Part 6, Building Energy Efficiency Standards. Similar to other covered processes, maintaining product quality and production amounts are critical to controlled environment horticulture. The analysis will account for these critical parameters and include metrics pertinent to controlled environment horticulture and plant growth. The measures analyzed can be utilized for several different crop types, and analysis will include variations in energy input requirements for different crop types. The proposed requirements will be developed as part of the CASE effort with input from a wide range of stakeholders. Primary energy uses for indoor agriculture include lighting, HVAC and dehumidification, and irrigation, and measures analyzed for Title 24, Part 6 inclusion will focus on measures related to these energy end uses. Since Title 24, Part 6 does not currently include requirements for indoor agriculture, this measure will define building types and/or space types in which the proposed requirements apply.
This CASE Report will include the following submeasures for indoor cultivation spaces.
Increased prescriptive skylight to floor ratio
- Requirements may differ between retrofits and new construction – cost-effectiveness of both will be evaluated. This evaluation will include structural impacts in the stiffness of the roof diaphragm.
- Cost-effectiveness may include considering the cost of skylight shutters for forcing growing cycles.
- Evaluate the energy savings potential, including any HVAC load increase penalties due to reduced building envelope insulation values. Use energy modeling to evaluate the savings associated with this potential code change.
Lighting power density requirements have two tiers
- Lighting power density based on that for warehouses for standard lighting systems.
- Higher allowed lighting power density for light sources with a Photosynthetic Photon Efficacy (Photosynthetic Photon Flux / Watts) greater than xx.
- Air to air heat recovery and desiccant regeneration from condenser waste heat.
- Dehumidification system specification: Explore a limit or ban to stand alone dehumidifiers. These systems are not designed for large-scale commercial dehumidification and are not energy efficient for this use.
Optimized economizer usage for growing systems that are not using CO2 injection
- Account for biosecurity concerns of utilizing outdoor air and analyze the requirements for exchanging air without introducing airborne contaminants such as mold and bacteria.
- Evaluate economizer operation specific to plant growth.
Lighting for plant growth
Building codes have historically defined lighting requirements around humans and human-centric lighting. Define the efficacy metrics used for plant growth lighting to be consistent with ANSI/ASABE S640: Quantities and Units of Electromagnetic Radiation for Plants (Photosynthetic Organisms). The submeasure proposed code change will also set light efficacy levels using the defined plant growth lighting metrics to be consistent with the proposed IECC 2021 code change “C405.4 Lighting for Plant Growth and Maintenance.”
- Define light performance metrics in accordance with American National Standards Institute/American Society of Agricultural and Biological Engineers (ANSI/ASABE) S640.
- Adopt proposed IECC 2021 lighting code: Not less than 95 percent of the permanently installed luminaires used for plant growth and maintenance shall have a photon efficiency of not less than 1.6 micromole per joule μmol/J rated in accordance with ANSI/ASABE S640. Utilize ANSI/ASABE S640 to define light requirements for various crop types.
- Possible requirements for timer controls.
Ventilation for plant growth
Ventilation requirements in building codes have historically been centered around human occupancy. Defining ventilation requirements specific to plants is needed.
- Specify ventilation and circulation fan specifications to be consistent with the Bioenvironmental and Structural Systems (BESS) Laboratory Agricultural Ventilation Fans, Performance and Efficiencies ratings.
- Explore setting a minimum fan performance rating utilizing Bioenvironmental and Structural Systems BESS Labs performance ratings.
Environmental controls for controlled environment horticulture
- Specify the monitoring parameters specific to plant growth, such as CO2 levels, temperature, and humidity. Consider the value of utilizing vapor pressure deficit as a control parameter and potential energy savings associated with higher temperature settings combined with optimum vapor pressure deficit levels.
- Identify optimum parameters for several crop types.
Refrigeration System Opportunities
The California Energy Code (Title 24, Part 6) currently includes mandatory efficiency requirements for refrigeration systems serving refrigerated warehouses and retail spaces with walk-in coolers or freezers or refrigerated display cases. This CASE Report proposes code change proposals that will improve energy performance end reduce greenhouse gas (GHG) emissions from refrigeration systems in refrigerated warehouse, retail stores, and commercial kitchens. Requirements for commercial kitchens would apply to a variety of building types including restaurants, schools, and hospitals.
This CASE Report will include five submeasures: design and control requirements for transcritical CO2 systems and large packaged systems, evaporator minimum specific efficiency for refrigerated warehouses, self-contained hydrocarbon display case heat rejection for grocery stores, require automatic door closers, and acceptance testing for commercial refrigeration.
Establish design and control requirements for transcritical CO2 systems and large packaged systems
- Will establish design and control requirements for two types of refrigeration systems that are gaining market share: transcritical CO2 systems and large packaged systems. The current requirements in Title 24, Part 6 are appropriate for traditional vapor compression refrigeration, but they are not appropriate for transcritical CO2 systems or large packaged systems. This submeasure would not mandate that either system be used in any situation, but it would establish mandatory design and control requirements that will optimize energy performance should a designer elect to use these systems.
- Historically, refrigeration systems have used halocarbon refrigerants that have high global warming potential (GWP), but use of these high GWP refrigerants is being phased out in California (Health and Safety Code Section 39730.5). Many types of refrigerants will no longer be allowed for us in supermarket refrigeration or refrigerated cold storage by the time the 2022 Title 24, Part 6 standards take effect in January 2023. As high GWP refrigerants are being phased out, transcritical CO2 systems are becoming more prominent. Specific code requirements will be determined as part of the advocacy effort but may include requirements for sizing and efficiency of gas coolers for heat rejection, implementing parallel compression system configuration, and heat pressure control strategies. The requirements would apply to refrigeration systems in refrigerated warehouses, retail spaces (e.g., supermarkets), and commercial kitchens.
Evaporator minimum specific efficiency for refrigerated warehouses
- Will define mandatory minimum specific efficiency requirements for evaporators in refrigerated warehouses. Specific efficiency is a metric that determines the amount of cooling an evaporator can provide per unit of input power required. This is similar to the metric of specific efficiency currently defined in Title 24 for evaporative, air cooled, and adiabatic condensers.
Self-contained hydrocarbon display case heat rejection for grocery stores
- Will explore prohibiting self-contained air-cooled refrigeration systems in stores above a certain size threshold and require external heat rejection. This measure will also consider requirements to help optimize heat rejection control strategies using variable speed fans and floating head pressure.
Require automatic door closers
- Will require walk-in coolers to have automatic door closures and include two types. One is the spring or gravity/cam hinge that closes the door from a standing-open position to a closed position. The second is the closure devices that snaps the door tightly closed (when magnetic gaskets are not applicable). This will define both types of closures and require them both for walk-ins.
Acceptance testing for commercial refrigeration
- Will add acceptance testing to verify compliance with existing code requirements for commercial refrigeration systems.
Steam Trap Monitoring
This CASE Report for the steam traps will require mandatory automatic monitoring equipment in new construction and alterations for large installations on all steam trap types. The change impacts all industries using steam traps from oil and gas producers to food processing, hospitals, and universities. Automatic steam trap monitoring involves attaching sensors to steam traps which monitor the process conditions of the traps. When steam traps fail open steam is vented to the atmosphere through the condensate return system losing significant amounts of energy. Automated monitoring provides a method that reports any failure instantly and eliminates the labor required to manually check the traps.
Pipe Sizing and Leak Testing for Compressed Air Systems
This CASE Report will establish requirements for pipe sizing and leak testing for compressed air systems in the form of two submeasures.
Pipe sizing: This submeasure would standardize the diameter of the air compressor distribution piping according to the system pressure and flow at different points in the system. Improper pipe sizing can decrease energy efficiency in several ways. Smaller-diameter pipe will result in higher air friction and turbulence compared to larger-sized pipe. Also, pipe diameter should be optimized across the air distribution system since constant diameter pipe results in decreasing air pressure with distance from the compressor. Since air pressure needs to be high enough to serve the constraining load, which is furthest out on the distribution line, a constant pipe diameter results in higher pressure upstream of the constraining load, which then must be managed by releasing compressed air, wasting energy.
Leak Testing: This submeasure will focus on proactive leak detection through pressure testing and inspection. Compressed air system leaks can waste up to 20 to 30 percent of a compressor’s output. Leaks not only waste energy but can cause other operational losses, such as decreased functionality and efficiency of air tools, and longer run times, which can shorten the system’s lifetime, increase system maintenance, and lower productivity. According to the Compressed Air Challenge, proactive leak detection and repair can limit leaks to no more than 10 percent of compressor output. In case of a pressure drop during the test, the location of the leak would be detected using a tool, such as an ultrasonic acoustic detector, and fixed.
Give Us Your Feedback
The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.
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