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The Empire State Realty Trust and their team of consultants shown above, followed the Playbook approach to define the decarbonization roadmap for their flagship office building: the Empire State Building. The iconic landmark consists of 102 stories totaling 2.8 million gross square feet, among which 1.8 million square feet of rentable space. |
Getting StartedThe ESRT management team took great care to assemble a project team with deep expertise that could handle the level of complexity, interdisciplinary thinking, and innovation needed to tackle the challenge of bringing the Empire State Building as close as possible to its carbon neutrality goal. The core project team consisted of:
Additional support was provided by:
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Building DiscoveryLearn the BuildingThe project team assessed the existing conditions and systems of the Empire State Building. The team reviewed the following items:
Here is a quick summary of the current building HVAC system:
Build the "Business-as-Usual" Base CaseUtility Analysis (Existing Condition) - The project team analyzed the building utility data for baseline year of 2019 to evaluate the breakdown of energy usage, utility costs and resulting carbon emissions by fuel source (i.e., gas, steam, and electricity – broadcast electricity usage was also broken out at the request of the owner). Electricity energy usage made up the majority of the energy consumption at 63.2%, while steam made up 35.1% of the energy used. While the energy cost profile is similar, the portion of electricity costs increases relative to the steam cost due to the tariff structures for the building. The results of the study are shown in the figure below: Figure - 2019 Baseline Building Energy Consumption (LEFT), Energy Cost (MIDDLE) and Carbon Emissions (RIGHT) by Fuel Type Building Performance Standard Impact Analysis - Important carbon-related project objectives were overlaid onto the base case to help the project team understand at a glance the scale of the reductions required. These included the LL97 emissions limits for 2024-2029, 2030-2035, and beyond 2035 as well as an 80% reduction from the 2007 baseline. Superimposing this information made it clear that while previous energy efficiency measures had significantly reduced emissions below the LL97 2024 limit, more work was needed to meet the remainder of the emissions limits and the 80% reduction target. Notably, achieving the 80% target would require more than just improving or even eliminating gas and steam usage, but also reducing the electrical usage. Figure - 2017 &. 2019 Baseline Carbon Emissions Compared to Project Objectives Identify Preliminary ECMs & Carbon Reduction StrategiesDuring the process, the team narrowed down over 200 energy and carbon conservation measures to 60 ECMs that have potential to be implemented over the next 15 years. |
Energy & Carbon ModelingBuild and Calibrate the Initial Energy ModelThe Empire State Building (ESB) energy model has been developed over the past 15 years. Each year, the energy model has been calibrated based on several factors including utility bills, hourly sub-metering, occupancy rates, new construction projects, etc. Create the Baseline Energy ModelThe baseline energy model for the Empire State Building was developed and is maintained by Quest Energy Group. In this latest version, the energy model was calibrated to the 2019 calendar year. The 2020 utility data was not used given the unique changes in occupancy and operation due to COVID-19. After the baseline model was calibrated, the eQUEST energy model outputs were then compared to the total monthly data from ConEdison. Calibration is maintained with statistical error and broken down by the various end uses in the building. Generate Detailed End-Use Breakdowns - The results from the baseline energy model allowed the project team to analyze energy usage on a deeper level. The energy usage breakdown showed that space heating, broadcast, and tenant loads were the largest contributors to energy usage. This analysis allowed the team to determine where there were opportunities for improvement. Figure - 2019 Baseline Energy Usage Load Breakdown by End-Use Figure - Baseline Model Electricity Usage (LEFT) and Steam Usage (RIGHT) Compared to Metered Data Overlay Carbon Emissions - Carbon emissions were broken out by fuel source, system, and ownership to help the project team understand the primary contributors and identify areas for reduction. From this analysis it became apparent that while optimization of base building systems like the central plant and steam system could provide significant emissions reductions, the project targets could not be achieved without addressing the contribution of tenant systems and equipment. Indeed, tenant plug loads are a significant component of the building’s baseline carbon emissions, with office and retail tenants accounting for almost 31% of total 2019 carbon emissions.
Figure - 2019 Baseline Carbon Emissions Breakdown by End-Use (LEFT) and by Ownership (RIGHT) Base building energy usage and carbon emissions include:
Analyze Individual ECMsThe team narrowed down over 200 energy and carbon conservation measures to 60 ECMs that have potential to be implemented over the next 15 years. Each ECM was vetted technically and identified as an opportunity to reduce energy consumption and further decarbonize the building. The energy modeler analyzed the ECMs through the baseline energy model to extract the associated energy, carbon and cost savings. As examples, below is a list of a few ECMs that the project team studied, with details on the energy modeling methodology used.
Group, Sequence, and Package ECMsRelated ECMs were grouped together into phases and sequenced in the modeling order such that savings for each ECM build on the last. These phases were then sequenced based on the logic of improving and optimizing existing systems first, then reducing loads, and finally replacing or updating the equipment. The sequence was also based on feasibility and expense, such that the phases that involved large system interventions like geothermal, DHW electrification, colocation of IT equipment, and chiller replacements are sequenced towards the end of the study period (phases 6-10). The team also developed a proposed implementation timeline for each of the phases. For example, the controls optimization measures in Phase 1 were proposed to be implemented immediately and completed in 1 year, while the Phase 5 ECMs that are intended to be implemented at tenant lease renewal extend over a period of 10 years. Figure - ECM Phasing and Implementation Timeline The ECMs were also grouped into 5 distinct packages which contain different combinations of ECMs, and an increasing number of them, in order to study their impact on CO2 reductions and Net Present Value (NPV). This allowed the team to review how different combinations of ECMs measure up against the project objectives. The NPV Max package contains the least amount of ECMs which are all NPV positive. On the opposite end of the scale, the CO2 Max package includes all the ECMs that were studied. Three additional packages were created to result in cost and carbon reductions in the middle of the scale. These were the CO2 Light, CO2 Mid, and CO2 High packages, which generally include all the measures that the project team recommends implementing with the major difference between them being that CO2 Light explores just optimizing the existing steam system, whereas CO2 Mid explores partial HVAC electrification, and CO2 High includes complete HVAC electrification plus a few other tenant measures. Figure - Relationship between Carbon Reductions and Net Present Value in ECM Packages Generate a Decarbonization RoadmapNow that the finalized ECMs have been grouped, sequenced, and packaged, the energy model can be run for each ECM package to obtain energy and carbon impacts. The project team compared the results of this analysis and calculated the energy and carbon savings from the baseline model. The results of this analysis are shown in the figures below. These results will be used in the detailed financial analysis and will represent a time-dependent decarbonization roadmap for the building. Figure - ECM Package Energy Savings Comparison Figure - ECM Package Carbon Savings Comparison Figure - ECM Package CO2 Emissions Projections Comparison Over Time (CLCPA Target Grid Scenario) While energy modeling was completed for all 5 packages of ECMs studied, the figures below focus on summarizing the results for the CO2 Mid Reduction Package which forms the Decarbonization Roadmap for the Empire State Building. The CO2 Mid Reduction Package provides the optimal techno-economic balance and is currently slated for implementation. However, certain ECMs in the CO2 High Reduction Package are recommended for further study to better assess their constructability, cost, and performance, and may be considered for implementation in the long term based on the outcomes of the planned pilots. Both packages meet ESRT’s goal of 80% carbon reductions compared to the 2007 benchmark year by 2030, as well as the average-long term Local Law 97 (LL97) limit by 2035. At the end of the 15-year study period, it is expected that the CO2 Mid Reduction Package will reduce energy consumption by 64.8% compared to the 2007 baseline (see Figure below). Phases 1, 2, and 5 (including steam phase out which is broken out separately) result in the largest energy reductions for this package with energy savings contributions of 6.1%, 8.0%, and 5.7% respectively. Figure - CO2 Mid Package Energy Reduction by Phase The Figure below shows the breakdown of the carbon reduction anticipated by phase for the CO2 Mid Reduction Package. The total carbon savings anticipated are 65% from the 2007 baseline, assuming the 2019 carbon coefficient. However, if the electrical grid continues to decarbonize in alignment with the CLCPA targets, the carbon savings can reach as much as 87% reduction from the 2007 baseline. Figure - CO2 Mid Package Carbon Emissions Reduction by Phase |
Economic & Financial AnalysisObtain Pricing and Run the AnalysisEnergy Cost Savings for all ECMs - A key part of the financial analysis was determining the energy cost savings of each of the ECMs. This is directly informed by the energy savings outputs from the energy model, as well as the advanced tariff analysis conducted by Luthin. As shown in the graph below, the measures with the highest energy cost savings are some of the more technically ambitious measures including steam phase-out, some of the envelope improvement measures, and the airside sequence optimization which eliminates a majority of the existing simultaneous heating and cooling. A key finding was that electrification does result in energy cost savings, even those the fuel source is being changed from steam to electricity. This is due to a strategy of implementing ECMs that reduce the heating load first, and then transitioning to electric heat pumps which produce more heat output per unit of energy input than electric resistance and fuel sources. Therefore, the increase in electrical cost is more than offset by the elimination of steam costs. Figure - Energy Cost Savings per ECM NPV for all ECMs - Individual NPV results for all ECMs are beneficial for the quick assessment and comparison between ECMs. The net present value of all the ECMs were calculated and used to inform the packaging of ECMs, which was an iterative process. The steam phase-out measures and envelope improvement measures were found to be the most NPV negative ECMs. Although these measures had some of the highest energy cost savings, the savings were overwhelmed by the high capital costs. For these measures the team also considered the impact on carbon reduction, simple payback, useful life of the system, and cost per ton of CO2 saved to provide a wholistic evaluation of the ECM performance. Figure - Net Present Value per ECM Energy Cost Savings of ECM Packages - The energy cost savings for each package are summarized in the graph below. As expected, after 2023 the annual energy cost savings for each package increase from the less intensive NPV Max package to the most intensive CO2 Max package, correlated with the ambition of each package. By the end of the study period, the annual energy cost savings associated with the CO2 Max package are significantly higher as compared to the remainder of the packages. Capital Costs of ECM Packages - Cost estimates were also completed for each ECM and package studied. The total capital costs (including and excluding escalation) for all packages are summarized in the table below. The total estimated capital costs associated with the CO2 Mid Reduction Package are $40,672,466 excluding escalation, and $51,628,387 including escalation. Table - Total Capital Cost for All Packages (Including & Excluding Escalation) Graphed over time, the annual capital costs for the CO2 Mid Reduction Package are expected to remain below $10M throughout the study period. The graph below shows the anticipated annual capital costs for each package, including escalation costs. These annual capital cost expenditures align with the implementation timeline designated for each ECM and shown in Table 3. Of note, the CO2 High Reduction Package has more than double the annual capital costs of CO2 Mid Reduction after 2021. Figure - Annual Capital Costs for Each Package (Including Construction Escalation) Refine Projections and Make RecommendationsUsing the Strategic Decarbonization Assessment (SDA) tool, the project team calculated the carbon emissions per year for three ECM packages compared to "business-as-usual" case. Figure - Carbon Emissions Per Year by Scenario The final financial results for each of the packages is illustrated in the NPV vs. CO2 Reduction figure below. The graph shows that three of the packages were NPV positive and 2 of the packages were NPV negative, but four out of five of the packages had a simple payback within the study period. The recommended package, CO2 Mid Reduction, has a positive NPV of $4,349,957 and a simple payback of 6.8 years. Implementing this package will require $40,672,466 (excluding escalation) of capital expenditure, and result in annual energy cost savings of $3,701,538 and operational savings of $546,000. This analysis accounted for $11,795,328 of available incentives from both Con Edison (Custom Commercial Electricity Program and Clean Heat Program) and NYSERDA, which makes up approximately 29% of the required expenditure. The major financial metrics for all the packages studied are summarized in the table below. Figure - NPV vs. CO2 Reduction over 15 Year Period for All Packages (CLCPA Grid Scenario) Figure - Summary of Financial Analysis Results for all ECM Packages |
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