The Engineering Process of Decarbonization: Steps for… | P2S
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Decarbonization in
Educational Facilities

Decarbonization in
Educational Facilities

Decarbonization is a critical process to reduce our reliance on fossil fuels and decrease operational emissions from the built environment. As of 2020, buildings are responsible for roughly 40% of energy-related greenhouse gas emissions (ASHRAE 2022). Educational facilities in California are leading the way with initiatives to eliminate natural gas in new construction and funding modernizations to reduce or remove natural gas from existing buildings. But how are these initiatives actually executed from an engineering standpoint? This case study focuses on the key steps to turn a lofty goal into a reality:

  1. Site investigations and assessments
  2. Developing baselines, benchmarking, and current performance
  3. Implementing all-electric systems in building retrofits

Site Investigation and Assessment

No two buildings are the same and understanding the building you’re working with is critical to finding the best possible solution for each individual building. A thorough field investigation will review the building in its entirety to identify sources of existing emissions and opportunities to improve energy efficiency.

HVAC/Mechanical Systems

The building’s HVAC systems contribute to the carbon footprint more than just the direct emissions from gas-fired heating systems. Energy consumption from cooling systems also has a direct impact on the carbon footprint due to the emissions inherent in the current electrical grid. Furthermore, any savings in cooling energy can reduce the building’s electrical demand, which will be covered in the sections below.

When assessing mechanical systems, we start by identifying age, condition, and operational problems. By calculating the remaining useful life of a given piece of equipment, we can create a decarbonization plan that helps allocate capital at the right time to decarbonize these systems when they would need to be replaced regardless.

The site investigation will help develop a list of potential energy efficiency measures which, implemented correctly, will reduce the building’s energy consumption to free up capacity on the electrical system for electrification projects. Energy savings from installing Economizer and Controls upgrades can lead to significant savings before we start to implement major system changes.

In addition to the typical factors, when we are decarbonizing a building with an existing gas-fired boiler, we need to know the operating parameters of the boiler system, heating coils, and any connection to the domestic hot water system. Things such as pump configurations, number of reheat coil rows, and hot water setpoints allow us to review different heat pump hot water system configurations for feasibility. Air to Water Heat Pumps (or Heat Pump Boilers) typically operate efficiently at a much lower temperature (~110°F) than traditional gas-fired boilers (130-180°F), which limits the heat output from existing coils within the building.

Air to Water Heat Pumps need to be supplied with huge quantities of ambient air, so they are almost always installed outdoors, on roof or on grade. When assessing a building, the potential location of a heavy piece of Mechanical equipment should be considered.

Plumbing Systems

On-site natural gas distribution and other fuel piping systems are the key to locating sources of combustion within a building. Building heating and domestic hot water systems are the primary source of natural gas consumption, but other processes such as Laboratory and Kitchens can significantly contribute to a campus’s carbon footprint.

Gas-fired domestic hot water heaters must be catalogued and assessed as a part of the building assessment. Type is important, as instantaneous gas-fired water heaters have a very different design to tank-type. In either case, the available space within the existing water heater room is an important consideration. When replacing gas-fired water heaters with heat pumps, the room volume must be calculated to ensure that the heat pump has enough space to operate effectively. Heat Pump water heaters, specifically packaged heat pump units, need more space than gas-fired tank-type units due to the airflow required to operate efficiently. If space is limited, then alternative spaces for water heaters or external condensers should be identified in the field.

Electrical Systems

A building’s electrical service size can often be a challenging restraint on decarbonization efforts. Electrical service upgrades are a major financial investment, even just to upgrade campus-side infrastructure for colleges and universities. A field investigation needs to cover the size, condition, and usage of the building’s power distribution system. At least 12 months of meter data at the building is required to study the actual consumption patterns of the building and review available capacity. While Electrical Engineers can study the outside appearance of switchgear, transformers, and other electrical equipment, we can partner with electricians to provide a comprehensive evaluation of low and medium- voltage distribution equipment.

Lighting systems should also be assessed for energy efficiency upgrades. While LED lighting upgrades have been a low-hanging fruit for many years, most buildings with old incandescent lighting have already been upgraded, and more are being upgraded over time with LED drop-in lamps that work with existing fixtures without a single major project. All systems should still be considered, as lighting can still be an opportunity for efficiency improvements.

Building Envelope

A building’s envelope is its protection from the elements, and any weak points in that protection directly leads to wasted energy. A decarbonization assessment considers the existing envelope construction (walls, windows, roof) to evaluate the downstream benefits of upgrades. If you can reduce the size of the boilers and chillers by replacing single pane glass with insulated double-pane systems, you may avoid a multi-million-dollar electrical upgrade.

Most of these items are covered in an ASHRAE Level 1 energy audit. However, we typically recommend a Level 2 audit for a comprehensive look at a building’s energy consumption and recommendations cost impacts.

Baseline Development
& Benchmarking

Understanding a facility’s current energy use, emissions, and performance metrics is essential for setting a baseline to measure improvements and set realistic goals. This process includes gathering and analyzing data through utility bills, and metering and trend data. Once the overall building energy consumption is gathered, we continue on to benchmarking. Benchmarking is a powerful tool that can help the owners understand the facilities performance compared to similar and peer facilities with same occupancy type, climate, and size. Benchmark data is used to set long term and phased goals, aligning with institutional priorities and local or national emissions reduction targets.

A significant reason for careful trend data analysis is to correctly size the equipment. This analysis includes review of the granular trend data available for the building and campus. This analysis performed on several campuses showed that a substantial number of buildings in California have heating equipment that is grossly oversized for the actual building heating needs. The equipment was oversized by 50% to 250% when compared to the actual heating demand. This is very crucial to decarbonization planning. The size of the equipment has a large impact not only on the initial cost of the equipment and electrical service needed for the project but also impacts the operational efficiency of the equipment. The image on the right shows a HHW system load profile for a decarbonization project, in both operating hours and heating output, compared to the building’s original heating design value of 4,500 MBH. This image shows that most of the total heating energy used in a building was used when heating demand is less than 40% of the measured peak load of approximately 2,000 MBH, which is about 20% of the total designed capacity.

Implementing All-Electric
Systems in Building Retrofits

Transitioning to electric systems, such as heat pumps and energy-efficient HVAC solutions requires a holistic review of all aspects of the building. Challenges like space constraints and budget limitations are addressed with engineering solutions like modular systems and scalable technologies. Integration with renewable energy sources maximizes decarbonization potential and reduces grid reliance.

Our approach for existing building and facilities decarbonization focuses on reducing energy wasted through data analysis, providing Energy Efficiency Measures (EEMs) to reduce overall energy consumption, implementing an energy recovery system, being responsible for the electrification of fossil fuel burning equipment, minimizing embodied carbon footprint, and providing a clean source of energy.

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Moving Toward
Carbon-Neutral Campuses

A phased, collaborative approach considering infrastructure, staff capabilities, and budget is essential for decarbonization. Engineering plays a crucial role in creating sustainable, carbon-neutral educational facilities. Decarbonization is both an environmental responsibility and an opportunity to provide students with sustainable living and learning spaces.

After the analysis, our findings are summarized in a multi-factor decision-making matrix. The matrix will be utilized by P2S and the facility owners for prioritization of different strategies during current and future stages of the decarbonization efforts. This tool shows important metrics for each strategy such as:

  • Total Energy savings
  • Total Operational Cost Savings
  • Total Initial Investment
  • Construction Duration
  • BTU saved per dollar of initial investment.
  • Simple payback period
  • Pounds of carbon saved per dollar of initial investment.

We understand that a large-scale decarbonization project is implemented over a longer period of time and needs to be interactive and dynamic. The development of this tool enables the owners to re-prioritize the selected strategies for decarbonization based on different criteria and requirements at different stages of the process, while providing a clear pathway to carbon neutral future.

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01

Reduce energy wasted through data analysis

Looking at the trend data and utility bills can also provide valuable information about where energy consumption is larger than expected. As an example, during data analysis of a large campus project, our team noticed that the heating energy consumption was 2-3 times that of similar facilities, with more than anticipated consumption during cooling seasons. This led to a quick investigation that in turn led to the discovery of a broken temperature sensor in the HHW system. The broken sensor caused the boilers to run without a real heating demand. This is an example of a very low-cost, low effort fix that has huge energy and carbon emission savings in return.


On another campus project, we observed that during summertime, when the building was not occupied, the overall energy usage never fell below 60% of the peak energy consumption. This led to another short investigation that discovered that the building schedule has been modified and never switched back into “Summer mode”. With a quick change to the programming controls, the owner was able to reduce wasted energy during the summer months.

02

Providing Energy Efficiency Measures

After evaluating the existing systems through field investigation and data analysis, the next step is to evaluate Energy Efficiency Measures (EEMs) to find cost-effective ways to improve the building and reduce energy consumption and carbon emissions. A few common EEMs include:


  • Adding air-side economizers to systems not currently using their free-cooling benefit
  • Converting pumping systems from constant volume to variable volume through the use of Variable Frequency Drives
  • Reducing pumping energy by eliminating three-way valves and reducing flow requirements through the distribution systems
  • Implementing modern control sequences, including DP and static pressure resets, to reduce fan and pump energy further.
  • Upgrading Building lighting system and controls.
  • Retro-commissioning or Monitor Based Commissioning of building system are effective ways to reduce overall building energy consumption.

Evaluation of EEMs should include a cost-benefit analysis based on cost, energy saved, and emissions avoided to select the most feasible measures for a given project.

03

Implement energy recovery system.

With all the modern technology and heat recovery, we also review the trend data for any potential for energy recovery during the time that the overall campus is doing simultaneous heating and cooling. This can also have a significant impact on equipment sizing and initial project investment.

04

Responsible electrification of fossil fuel burning equipment

Once opportunities for energy efficiency improvements have been realized, the next step is to electrify remaining sources of gas-fired equipment. By aligning electrification projects with planned equipment replacement timelines, the systems remaining to be electrified will be smaller, more cost-effective, and easier to replace than if you try to replace all emissions sources in one go.

05

Minimize Embodied carbon footprint

One of the major benefits of electrifying existing buildings is the reduction in embodied carbon compared to demolishing it and rebuilding from scratch. Designing an all-electric new building is relatively simple when you have a clean slate, but the tradeoff is all the new concrete, steel, and other building materials and the carbon emissions associated with their production, known as embodied carbon. Repurposing and reusing existing buildings, or adaptive reuse, significantly reduces the embodied carbon associated with the project.

06

Provide clean source of energy

Electricity production with current grid utilities still contributes to overall greenhouse gas emissions, with a significant portion of grid energy being produced through fossil fuel power plants. Long-term building decarbonization efforts should be aligned with utility
decarbonization plans and supplemented with on-site renewables and energy storage efforts to ensure that the added demand on the power grid does not lead to more overall emissions.