Four Strategies for Decarbonization, Electrification in Comm

Decarbonization efforts are a critical part in meeting the goals pledged by President Biden during the 2021 Leaders Summit on Climate — reducing the nation’s greenhouse gas emissions 50% by 2030 and net-zero by 2050 (2005 emissions as basis).

The U.S. Department of Energy decarbonization roadmap is a set of strategies including energy efficiency, clean energy supply, clean fuel sources and direct air capture of carbon. Of these strategies, energy efficiency is the “beginning of the pipe,” improving efficiency which reduces the need for clean energy and fuel and results in lower carbon emissions. Energy efficiency is vital in the world’s journey to net zero and keeping global warming at 1.5 degrees Celsius. The International Energy Agency (IEA), nicknamed it “the first fuel.”

To develop actional processes and to reinforce the importance of energy efficiency, the New Building Institute (NBI) published the “Existing Building Decarbonization Code.” According to the NBI, the code is “… a new way for jurisdictions to reduce carbon emissions and meet Climate Action Plan and public health and equity goals. The need to address existing building stock is great, with 5.9 million existing commercial buildings in the U.S. comprising 97 billion square feet”.

Electrification of buildings

Electrification is a strategy that falls under the decarbonization umbrella. It can play a major role in reducing the carbon emissions from commercial buildings when the source grid is sufficiently clean. In 2020, the American Council for an Energy-Efficient Economy produced a study that showed commercial buildings that replace their gas-burning heating systems with electric heat pumps could reduce their total greenhouse emissions by 44%.

Commercial buildings account for 35% of all electricity use in the U.S and 16% of carbon dioxide (CO2) emissions. And according to the U.S. Department of Energy (DOE), 30% of the energy used in commercial buildings is wasted. Furthermore, in commercial office buildings, the heating and cooling systems, including air handling equipment, consume more energy for air conditioning than any other building type.

The good news is that energy use in commercial buildings continues to drop. The data show that from 2018 the energy use intensity has decreased by 12% (see Figure 1).

Energy consumption of air conditioning in buildings

Air conditioning systems are one of largest electricity consumers in commercial buildings. Across the buildings sector, purchased electricity accounted for 94% of delivered energy for air conditioning in 2019. These systems range from central built-up systems to packaged rooftop units. Breaking down a typical heating, ventilation and air conditioning (HVAC) system into smaller categories, ventilation, cooling and heating systems are the largest energy consumer of all the other sub-systems. When building owners are looking for ways to reduce energy consumption, implementing energy efficiency measures (EEM) specifically for air handling equipment can yield significant savings.

Small- and medium-sized businesses may have difficulty finding capital funds or using cash reserves for HVAC system upgrades, but there are options for funding that can reduce the need for securing loans. Most states have energy efficiency policies, which are generally managed by the state’s public utility commission. Electric and natural gas utilities are responsible for developing a ratepayer funded energy efficiency program.

The programs are designed to incentivize residential, commercial and industrial customers as they implement energy reduction projects. Depending on the scope of the customer’s project, the incentives can provide a significant funding source for capital-intensive air-handling unit (AHU) upgrade projects.

Regulatory energy policy

Regulatory policy can have a significant impact on investments for improving energy efficiency in commercial, institutional and industrial buildings. Electric and natural gas utilities have a key role in making sure the end use of the energy is efficient, with the goal of lowering energy demand (electricity and natural gas). State utility regulators use a variety of incentives to address the inherent conflict that exists — lowering energy use can have an adverse financial impact on the utility. Policies enacted by the state encourage the utility to play a role in lowering overall energy consumption and set a foundation for implementing cost-effective EEM.

The state public utility commission (PUC) is responsible for the developing and updating the technical reference manual (TRM). The technical parameters and calculation steps in the TRM are essential for state regulators, utilities, program administrators and implementation teams for estimating and validating the energy and demand savings of end-use EEM. TRMs can be used exclusively by a state, by utilities or shared with other states and alliances.

Some TRMs include requirements to validate nonenergy impacts (such as water use and secondary CO2 emissions). Some measures include processes and calculations to validate the cost-effectiveness of a measures focusing on the useful life of equipment intended to be replaced.

The state PUC approves the TRMs, giving it a legal framework. For example, in Illinois, the PUC approves the contract of an independent third-party organization whose primary responsibility is administering the TRC. In this scenario the third-party organization works for and is paid by the utility. But ultimately, the PUC has the final say.

In simple terms, the TRM is the “rulebook” for ratepayer-funded energy efficiency programs. When examining different EEMs, many are straightforward with little math required. Others are more complex using a series of calculations that include multiple variables such as age and capacity of existing equipment, type of flow control, location of project, operating characteristics and others. All these details ensure that requirements are consistent and fair since the different utilities may use the same TRM for programs in other service areas.

Deemed energy savings method

When comparing AHU measures from different TRMs, weather data and hours of operation are two common values used in calculating savings. The TRM provides instruction on how to obtain these and other variables. For outside sources, the measure lists the technical reference that must be used (e.g., ASHRAE). In other cases, the values are defined in the TRM.

The TRM measures discussed in this article are classified “deemed” or “partially deemed.” Typically, deemed measures are thoroughly vetted and reviewed on a regular interval by the utility’s third-party evaluator and the utility commission and updated as necessary. The authors of the measures are required to use reliable and transparent data sources and established analytical methods to calculate energy savings. Some of the measures (such as lighting upgrades) have minimal calculations and might use fixture count to determine energy savings, as an example.

Deemed savings measures have different components:

Deemed variables: Examples of a deemed variable included weather assumptions and hours of operation
Deemed factors: These include factors are dependent on the measure, such as measure cost and effective useful life
Deemed calculations: These included stipulated calculations for determine the economic aspects and energy impacts of the measure

However, measures for HVAC efficiency upgrades use different methods to calculate energy savings. These types of measures generally use a more detailed approach to determine energy use reduction. Some of these measures are used for straightforward efficiency projects such as one-for-one equipment replacement – AHUs, chillers, pumps, split-system A/C units and motors are some common examples.

Partially deemed and custom measures

Deemed measures are used to ensure uniformity in documenting energy efficiency. As such, the engineer uses a pre-defined roadmap that determines the energy savings. This method allows the use of the TRM across cities, states or regions and creates a level playing field when determining incentives for the building owner.

Measures for more complex AHU efficiency upgrades, depending on the jurisdiction, require the engineer to demonstrate savings using a pre-defined set of calculations and assumptions. These measures are defined as partially deemed. Although these require deeper analysis, the measures contain pre-defined specific calculation steps and requirements for documenting savings.

Although this method to generate savings is more clear-cut, the engineer must understand what the calculation steps mean and if the energy savings is realistic base on the project criteria. Although not discussed in this article, custom measures require fully documented energy savings calculations with little guidance from the TRM compared to a deemed measure. Custom measures are calculation-intensive and the engineer must define (and defend) their approach in detail.

It must be noted that TRMs present challenges that must be overcome. TRMs do not eliminate the need for applying fundamental engineering principals and investigation of the data presented in the TRM. Also, the energy savings generated from the calculations in the TRM must be validated to ensure accuracy.

State TRMs and EEMs for air-handling equipment

For air-handling equipment and systems, the measures in the TRMs apply to replacing existing equipment with high-efficiency systems, mostly for packaged AHUs. Additionally, there are measures for each item such as economizers, airflow control and advanced control strategies. Depending on the situation, more than one of these measures can be used to determine energy savings. Also, energy-efficient products with low market penetration are used to stimulate the marketplace and stay ahead of future codes that require efficiency increases.

Knowing that a measure can span several pages in a TRM and include very detailed energy efficiency compliance requirements, the data presented here is a summary only. The reader is encouraged to review a specific TRM for more information. To illustrate how measures are structured, examples relating to AHUs and ancillary equipment are outlined in this article.

Four Strategies for Decarbonization, Electrification in Commercial Buildings