Engineering Solutions

Building Discovery


Insights from Empire Building Challenge 

The discovery phase is intended to provide an initial understanding of the building’s existing conditions, current challenges, and potential opportunities. The data and insights gathered during this phase will be used to create the building’s calibrated energy model.  Key activities in this workstream include: 

  • Collecting and reviewing relevant building information 
  • Observing building operations under different conditions 
  • Testing subsystems and their interactions 
  • Creating the Business-as-Usual (BAU) base case 

This workstream is critical because it grounds the project team in the reality of the building’s current performance. It also helps build a jointly owned process for uncovering early energy or carbon reduction opportunities that can increase trust and enthusiasm to identify more complex measures as the project progresses.

At the end of this phase, the team should have a clear understanding of the building energy systems, its historical energy and carbon profile, the potential impact of local laws or other building requirements, opportunities for additional metering, and preliminary energy and carbon reduction opportunities. 

This workstream provides vital information on current challenges, near and longer-term carbon reduction opportunities, and the accuracy of the energy model. It also creates early wins that build momentum and trust. Getting the most out of this work requires trust-based collaboration between multiple stakeholders, including facilities managers, operations staff, the energy modeler, external contractors, and design engineers. Engaging with tenants to get insight into what drives their loads can also add value and inform this process. Data and insights on the building’s existing condition typically arise from four sources: 

  • Design documents 
  • Data from metered systems 
  • Direct observation and testing 
  • Building operations team feedback 

Each source is important, but it is the integration across these four categories of data that leads to deep operational insights and identification of major areas of opportunity. 

  • Cross-disciplinary, trust-based collaboration
  • Tenant insights

Gather Information:
In this phase, project teams should work with the building management and operations teams to collect key information using the sample checklist shown below.

Survey the Building:
Understanding a building’s existing conditions requires time on-site. Design drawings, operator interviews, and utility data all provide valuable insight, but do not capture the nuances of how the building runs day-in and day-out. Project teams should plan to conduct an initial site walkthrough to confirm high-level information about the building equipment, systems, and operations strategies shortly after project kickoff. As the study unfolds, additional site visits to verify information, gain additional clarity on certain conditions, or evaluate the feasibility of implementing ECMs will be necessary. The more time the project team spends in the building, the easier it will be to capture the building’s existing conditions in the building energy model and to develop ECMs that are feasible. When completing the building walkthrough, the project team should evaluate the following: 

  • Space temperatures: does the space temperature feel too low or too high?
  • Infiltration conditions: are there noticeable drafts within the space?  
  • Pipe trim and valving: is there proper instrumentation within the system?  
  • Unoccupied space conditions: is equipment running when it should be off?  
  • Central plant operations: is equipment running more often than it needs to be? 
  • Piping/duct conditions: are there noticeable leaks or inefficiencies within the distribution?  
  • Multiple controls for different equipment within a single space or physically grouped thermostats: is it possible that the controls are causing conflicting operation?  

Deploy Additional Metering (if required):
Collecting documentation and surveying the building will highlight gaps in data or information needed to build a calibrated energy model. To fill these gaps, the project team may elect to deploy additional metering to capture the missing information. Metering ultimately reduces speculation and provides real-time insight into the building’s operations. Project teams should execute the following steps when developing a metering strategy: 

  • Identify and create an inventory of existing meters, submeters and instrumentation. 
  • Verify the accuracy of existing meters and ensure they are properly connected and integrated in the building management system (BMS). 
  • Gain direct access to view the BMS data. Ideally, the team will have viewing access to real-time building operations during the entire duration of the project. 
  • Identify areas where additional meters will be required. 
  • Develop a deployment program for additional metering needs including preferred vendors, meter types, meter quantities, locations for placement, and an installation schedule. 

Observe and Test Systems:
Building system assessments and functional tests are great ways to capture operating parameters, evaluate performance, and identify issues that can be resolved with retro-commissioning. Project teams should conduct some or all the following building tests to further inform the study:

Building envelope performance and infiltrationUnderstand the conduction losses/gains through the envelope. This will inform potential envelope opportunities and the baseline energy model.Refer to ASTM E1186 – 17 for standard practices for air leakage site detection in building envelopes and air barrier systems. 
Tenant electric load disaggregation, i.e. plug loads, lighting, ITIdentify high consumption loads within tenant spaces to target critical loads and opportunities.Select one or two tenants and install submeters on their floor (can be temporary), separating out loads by lighting, IT, plug loads. Analyze consumption and data trends to develop energy conservation measures.
Setpoints and setbacks in all spaces (tenant areas, common area, IT rooms, MEP) during winter and summer seasonsDetermine the most energy efficient setpoint/setback while maintaining a comfortable space. Evaluate what is possible within each space. Evaluate the ability of the system to recover from the setback without causing excessive utility demand.Test potential setpoint and setback temperatures within each space type to determine the optimal energy efficient condition.
Airside controlsVerify that airside controls are configured to optimize energy and indoor air quality.  Identify easy-to-implement and inexpensive controls ECMs.Test procedures will vary based upon the type of airside equipment in use; however, the following assessments are applicable to many airside configurations and can act as a starting point: 
Step 1: Verify that static pressure setpoint controls are correct per the sequence of operations or current facility requirements.  
Step 2: Verify that supply air temperature resets are programmed and operating within the correct range.  
Step 3: Verify that terminal box minimum and maximum setpoint are appropriately set per the latest balancing report. 
Step 5: Confirm if outdoor airflow stations are installed, and if so, verify that the appropriate amount of outside air is being delivered per the design documents or current facility requirements.  
Step 6: Verify if a demand control ventilation (DCV) program is in place. If so, confirm that outside airflows are reduced as occupancy is reduced. 
Step 7: Verify that turndown controls are appropriately reducing equipment temperatures or flows in low load conditions.
Waterside controlsVerify that waterside controls are configured to optimize energy and are load-dependent.  

Identify easy-to-implement and inexpensive controls ECMs.

Test procedures will vary based upon the type of waterside equipment in use; however, the following assessments are applicable to many waterside configurations and can act as a starting point:  
Step 1: Verify that static pressure setpoint controls are correct per the sequence of operations or current facility requirements.  
Step 2: Verify that supply or return temperature resets are programmed and operating within the correct range.  
Step 3: Confirm if an economizer mode is available, and if so, verify that the system appropriately enables this mode in certain weather conditions.  
Step 4: Verify that turndown controls are appropriately reducing equipment temperatures or flows in low load conditions.
BMS anomalies and faultsIdentify discrepancies in what the BMS is outputting on the front-end versus the actual observed conditions. Identify easy-to-implement and inexpensive controls ECMs.For each tested system, compare the BMS outputs to the actual measured data or observed condition. Identify the root cause of the discrepancy and resolve.
  • An additional metering strategy with a timeline for installation and a plan for measurement & verification of new meters.  
  • A preliminary list of operational adjustments and retro-commissioning issues based upon building surveys and building system assessment/tests. 
  • A plan for implementing operational opportunities like setbacks and setpoint adjustments.

Lessons Learned and Key Considerations

Business operations are as important as facility operations:
Energy studies tend to focus only on the architectural and MEP operations within the building. Project teams spend a lot of time understanding how equipment and systems operate and perform, but often don’t spend enough time considering the building’s existing lease turnover schedules, existing capital plans, or hold strategy. These business considerations are critical to understanding the types of decarbonization strategies that building ownership are likely to invest in.

2. Build the “Business-as-Usual” Base Case

Building the business-as-usual (BAU) base case occurs between the Discovery and Energy Modeling phases and includes an analysis of the building’s utility data to gain insight into how the building uses energy at a high level and how that consumption translates to carbon emissions. From this analysis, the project team will be able to evaluate the building’s exposure to mandates such as Local Law 97. 


Building the BAU base case requires obtaining one full year of utility data, at a minimum.


Utility Analysis (Baseline Condition):
As the project team learns the building, one full year of utility data (at a minimum) will be collected. The project team should visualize this data monthly to further develop its understanding of how and when the building uses energy. The following list of questions can be used to guide the analysis: 

  • What fuel types are consumed by the building? 
  • When are fuel types used the most or the least and why? 
  • Are there unexpected usage peaks for certain fuel types? 
  • What is the building Energy Use Intensity (EUI) and how does it compare to peer buildings? 
  • What is the building Energy Cost Intensity (ECI) and how does it compare to buildings? 
  • What service class is the building in and what is the tariff structure for that service class? 
  • How does demand correlate with cost?  

Based on the results of this activity, the project team will begin to form hypotheses about how building systems interact, which end uses are the most energy intensive, and where deeper energy and carbon reduction strategies may be pursued.  

Building Performance Standard Impact Analysis:
Depending on the jurisdiction in which the deep energy retrofit study is taking place, it may be beneficial for the project team to evaluate the building’s current performance against mandates or building performance standards (BPS) that are in effect. In New York City, for example, Local Law 97 is a BPS that many building owners are focused on. Other jurisdictions may have energy use intensity (EUI) targets or other metrics for performance. The outcome of the impact analysis may help to inform the overall decarbonization approach for the building. Project teams should execute the following steps to conduct a BPS impact analysis: 

  • Step 1: Aggregate annual utility data by fuel type. 
  • Step 2: Convert raw data into the appropriate BPS metric. In the example of LL97, annual fuel consumption is converted to annual carbon emissions with carbon coefficients that are published in the law.  
  • Step 3: Compare the building’s annual performance against the BPS performance criteria. 
  • Step 4: Consider how the building’s performance might change over time as the electric grid decarbonizes. In the example of LL97, a building’s carbon emissions associated with electricity consumption will naturally decline over time as the grid decarbonizes. 
  • Step 5: Calculate impacts of compliance or non-compliance with the BPS. For LL97, building emissions in excess of the allowable carbon limit results in an annual financial penalty.   
  • Step 6: Share results with the building management and ownership teams to further inform that building decarbonization approach.

During the energy retrofit process, the team will discover simple ways to reduce energy consumption that can be implemented almost immediately. With real-time data, the BMS allows the team to analyze how effective the changes to the system are.


Deliverables for this task include the following: 

  • Energy, carbon & cost end use breakdowns (monthly) 
  • Demand and tariff structure analysis 
  • Mandate or Building Performance Standard impact analysis

Lessons Learned and Key Considerations

3. Identify Preliminary ECMs and Carbon Reduction Strategies


Based on the work completed during the “Learn the Building” and “Build the BAU Base Case” tasks, the project team should already have a sense of the ECMs that are a good fit for the building. The project team should review the outcomes of the work done up to this point and develop a list of preliminary strategies so the team can level set on an approach as the project enters the Energy & Carbon Modeling phase.  


• Develop a Tiered List of ECMs:
Through the document collection and building system assessments, the project team likely identified low or no-cost operational items that can be implemented immediately. These simple items should be grouped and presented as Tier 1 measures. Deeper measures that require more upfront capital and/or have a longer lead time should be separated out into Tier 2 items. Tiers can be based upon cost or timeframe for implementation. Categorizing measures in this way will support building owner decision-making. 

• Conduct a Qualitative Assessment of ECMs:
Once the measures are appropriately categorized into tiers, the project team should generate a qualitative assessment of each measure, based on metrics that are important to the building management team. For example, one building team may identify disruption to tenants as their primary go/no-go metric when deciding which strategies deserve deeper analysis. Metrics will vary from project to project. 

• Present and Solicit Feedback:
Present the tiered list of ECMs, along with the qualitative assessment, and solicit feedback from the building management team. Eliminate ideas that don’t meet the team’s decarbonization approach and welcome new items that the building team may want to pursue that were not originally considered. This process will bolster team engagement and ensure that time spent in the energy model is dedicated to measures that will be considered seriously by the building team for implementation.


The output of this task will be a finalized list of energy reduction strategies to study the next phase: the Energy & Carbon Modeling Phase.

Lessons Learned and Key Considerations