How a 249,754 sq. ft. Commercial Building Was Evaluated for 32.5% Potential Energy Savings

Project Overview

A 249,754 sq. ft., six-story commercial building in New York City underwent an ASHRAE Level II Energy Audit to evaluate its existing energy performance and identify opportunities for improvement.

The building relied on several systems contributing to its overall energy consumption, including district steam heating, air-cooled absorption chillers, cooling towers, domestic hot water, lighting, and building controls.

With multiple systems influencing energy performance, the challenge was not simply identifying what could be replaced. The more important question was which improvements could make the greatest difference and by how much.

A calibrated energy model was used to establish the building's existing performance and evaluate individual Energy Conservation Measures (ECMs). The analysis then compared broader upgrade strategies to understand how different improvements could perform when implemented together.

The Challenge

Multiple Systems Influenced Energy Performance

Heating, cooling, domestic hot water, lighting, controls, and the building envelope all contributed to the building's overall energy use.

This meant that improving one system could only address part of the building's energy performance.

Individual Improvements Had Different Levels of Impact

Not every ECM offered the same potential.

Major equipment upgrades, controls improvements, and operational changes could produce significantly different results. Their potential impact therefore needed to be quantified rather than assumed.

Combined Strategies Could Perform Differently

Individual measures were evaluated first, but the analysis also needed to determine how broader upgrade packages could perform when multiple improvements were considered together.

This provided a clearer comparison between electrification and non-electrification pathways.

Capital Improvements Needed a Measurable Basis

For a building of this scale, future improvements represent significant capital decisions.

The assessment needed to provide more than a list of possible upgrades. It needed to show their potential energy impact and create a measurable basis for prioritizing future improvements.

The Energy Engineering Approach

Establishing the Baseline

Before evaluating potential improvements, the building's existing energy performance needed to be represented accurately.

A calibrated energy model was developed using a one-year analysis period and TMY3 weather data to establish the baseline.

This created a consistent reference point for evaluating proposed ECMs.

The model became the testing ground for the potential improvements: change the system, run the model, and measure the potential impact.

Testing the Major Energy Systems

The existing building used district steam for heating and two air-cooled absorption chillers serving the AHUs for cooling.

One of the major opportunities evaluated was a Variable Refrigerant Flow (VRF) heating and cooling upgrade.

The modeled result showed a 29.11% potential reduction in total energy use, making it the highest-impact individual ECM evaluated.

An air-source heat pump domestic hot water system was also assessed, with the analysis identifying a potential 2-4× efficiency improvement.

These results helped distinguish major system opportunities from smaller operational improvements.

Finding the Smaller Opportunities

Not every improvement required a major equipment replacement.

The analysis also evaluated several measures that could contribute to the building's overall energy performance, including:

• Lighting controls
• Cooling tower optimization
• Free cooling
• Variable-frequency drives
• Demand-control ventilation
• Thermostatic radiator valves
• Building-envelope improvements
• Elevator upgrades

Each measure was evaluated based on its potential contribution to the building's energy performance.

This allowed the analysis to show where smaller improvements could complement larger system upgrades.

Comparing Individual Measures With Broader Strategies

Comparing Individual Measures With Broader Strategies

The electrification pathway produced the highest modeled overall impact.

This shifted the focus from asking “What can be upgraded?” to a more useful question:

“Which combination of changes can move the building's energy performance the furthest?”

Project Outcomes

32.5% Potential Energy Reduction

The Electrification Package produced the strongest modeled result, reducing annual modeled energy use from 28,378 MMBtu to 19,156 MMBtu.

That represents a potential reduction of 9,222 MMBtu, or 32.50% of modeled annual energy use.

29.11% Potential Reduction From One Major ECM

The VRF heating and cooling upgrade was the highest-impact individual ECM evaluated.

The model showed a potential reduction of 8,259 MMBtu, equivalent to a 29.11% potential reduction in total energy use.

9.53% Potential Reduction Without Electrification

The Non-Electrification Package provided an alternative pathway for improving building energy performance, with a modeled potential reduction of 2,704 MMBtu, or 9.53%.

Additional Savings Opportunities Quantified

The analysis also identified potential reductions from individual measures, including:

• 4.09% from a domestic hot water heat pump
• 3.08% from lighting controls
• 2.89% from cooling tower optimization
• 2.02% from free cooling

These measures provided additional opportunities to improve performance beyond the major HVAC strategy.

A Quantified Basis for Future Investment

The calibrated energy model established a consistent baseline against which individual upgrades and combined strategies could be evaluated.

Instead of relying on assumptions about which improvements might work, the building owner received a measurable framework for comparing potential strategies and prioritizing future capital improvements.

3-Week Delivery

The ASHRAE Level II audit and calibrated energy model were completed within 3 weeks with minimal revision.

The value of the assessment was not simply identifying potential improvements. It was showing which improvements could move the needle, how individual measures compared, and what broader strategies could achieve.