Scaling Energy Audits to Support Policy Planning for A Major City

qeatechmarkstg on March 20, 2025

As cities around the globe set decarbonization and net-zero goals to address the severe effects of climate change, ensuring energy efficient buildings is becoming an increasingly important priority for cities. Considering high-performing envelopes are the most effective way to reduce the thermal needs of buildings, understanding the energy usage and savings opportunities related to building envelopes is essential for cities in achieving their sustainability goals.

As such, a major capital city sought QEA Tech’s services to accelerate its ambitious energy transition strategy. Specifically, the City needed QEA Tech to validate assumptions it had made regarding the energy efficiency of its buildings. Aiming to reduce greenhouse gas emissions to zero by 2050, through key actions such as retrofitting existing residential and commercial buildings, QEA Tech’s analysis was necessary for the City to gain a clear understanding of the energy performance of its buildings. This analysis was also essential to tailoring retrofit programs and policies to meet the specific needs of the City’s built environment. QEA Tech collected thermal and visual data for the buildings identified by the City, then analyzed and compared the data to the City’s energy assumptions and targets.

QEA Tech conducted audits for 190 buildings, ranging from commercial to residential properties, within two large catchment areas. QEA Tech captured over 16,000 images in total, which our AI-powered software and team of building science specialists then analyzed. The scope of the analysis consisted of:

1. Number and percent of buildings considered to have major issues associated with their building envelope.

2. Number and percent of buildings with evidence of water ingress.

3. Average energy loss per meter square per building envelope.

4. Energy savings potential and GHG savings potential per square meter of building envelope element.

5. Identification of major patterns and trends in building envelope performance that need to be investigated further.

6. Average effective U-value for building envelope elements compared to the City’s energy assumptions and targets.

Thermal map of the first catchment area
 Façade scanning operation of the second catchment area

Key Findings: The Reality of Building Envelope Performance Across the City

QEA Tech’s audit of the two catchment areas found the City’s assumptions on the energy performance of its building envelopes to be more optimistic than the reality. QEA Tech’s audit revealed that:

1. 56% of average annual energy loss in megawatt-hours per meter squared (MWh/m2) from all building envelope elements can be avoided by upgrading building envelopes to building code.

2. 97% of buildings assessed across the two catchment areas did not meet the City’s initial performance assumptions.

3. 68-1123 tonnes of carbon dioxide equivalent (tCO2e) are avoidable annually per building.

4. 64% of the buildings assessed showed signs of water ingress.

Average U-Values (W/m2k) of Building Elements Compared to Building Code

QEA Tech found that the average building envelopes were performing 75% worse compared to current building code. Additionally, the City had assumed building envelope U-values were performing 50% better than the actuals measured by QEA Tech.

QEA Tech’s ability to calculate accurate and precise U-values for the building envelope enabled the City to have a clearer understanding on the actual performance of its buildings, allowing it to better plan energy efficiency measures.

Performance Trends and Patterns Across Building Envelopes

Occurrences of Building Envelope Issues

QEA Tech provided customized reports that identified issues specific to every building envelope for each of the 190 buildings in-scope of this engagement. Further, QEA Tech analyzed data across the 190 buildings to identify key trends and patterns in building envelope performance, supporting city benchmarking and policy planning. QEA Tech found that:

1. Building envelopes in the second catchment area performed slightly better than buildings in the first catchment area. The younger age of the buildings in the second catchment area are likely a contributing factor to their more efficient performance.

2. Key issues across building envelopes were heat loss due to connections between different materials, thermal bridging, inconsistent or decay of insulation, heat loss through doors and frames, and moisture accumulation.

3. Moisture accumulation issues were more common in buildings in the first catchment area and were more common in older buildings.

Building Envelope Issues: Closer Look

Heat Loss through Frames and IGUs

A staggering 158 of the buildings analyzed had instances of heat loss through window frames and insulated glass units (IGUs). Heat loss through IGUs occurs due to window assemblies failing to maintain an effective thermal barrier, allowing heating and cooling to escape from the building. This could be a result of seals between panes of glass degrading and allowing insulting gas to escape and moisture to enter, or inadequate window glazing. Heat loss through window frames often occurs due to frames being made from highly conductive materials (e.g. aluminum), allowing heat to easily transfer between the inside and outside of the building. Additionally, when frames are not sealed properly against the wall, it can lead to gaps that allow heat to escape.

For several instances, to mitigate heat loss through IGUs, building owners can implement window inserts, which are customized glass panes that can be placed on the inside or outside of the existing window. This creates a new thermal boundary that improves U-values. Window inserts are ideal for buildings throughout the two catchment areas that are interested in preserving their original frames for historical or aesthetic reasons, that are working with a constrained timeline and budget, or that want to maintain their window’s original size and operating style. Window inserts work best with structurally sound wood or aluminum frames. To decrease energy loss from uninsulated framing, energy efficient frames (e.g. vinyl frames) with improved glazing should be implemented.

Inconsistent and Decay of Insulation

QEA Tech identified instances of inconsistent and decay of insulation for 126 of the buildings analyzed. When insulation is poorly installed or compromised over time, it can lead to gaps that allow heating or cooling to escape, causing energy costs to increase. Considering the older ages of the buildings audited, it is also likely that insulation of most buildings settled, compressed, or degraded over time, leading to reduced effectiveness. Areas with inconsistent or decaying insulation contribute to drafts, cold spots, and moisture issues, causing tenant discomfort and further degrading building materials.

Depending on the building usage and architecture, interior insulation (e.g. Batt insulation) should be applied or recladding should be completed. Interior insulation is best to use for buildings that have a smaller budget and that are interested in maintaining their outward appearance. Recladding is optimal if the operations of the building cannot be disrupted (e.g. for hospitals).

A More Effective Path to Energy Transition

QEA Tech’s usage of our patented AI software and drones enabled us to collect and analyze building envelope data quickly, cost-effectively, and without disturbing city residents and building owners. Our technology also allowed our audit to be scalable, a necessity when collecting and analyzing data for large city blocks. QEA Tech’s efficient, detailed, and precise approach has provided the City with a clear picture of the energy performance of its building stock, allowing it to take informed action. The City now has accurate data to enhance its energy transition strategy to fit the actual needs of its building envelopes. Further, the City is able to tailor its programs and policies to make retrofits more accessible for building owners and maximize their return on investment. As an interim step, the City has published the energy performance of each building analyzed.

If you are interested in gaining a deeper understanding of the energy efficiency of building envelopes in your portfolio, connect with QEA Tech for a free quote.

Analyzing Energy Loss Across a Hospital Campus

Hannah Elhamahmy on November 18, 2024

QEA Tech completed detailed building envelope energy audits for a world-renowned hospital based in the US. The Hospital has numerous properties across a large dense city, provides a wide range of healthcare services, and includes a Level I trauma center. QEA Tech completed audits for 12 of the Hospital’s buildings, spanning multiple city blocks.

The Hospital enlisted QEA Tech’s services as it lacked the data it needed to integrate the building envelope into its decarbonization plan. The Hospital was motivated to enact decarbonization measures due to the old age of its buildings and high energy bills. Particularly, the Hospital suspected poor performance of its windows and sought data on their actual U-values. QEA Tech was selected as we provide detailed and actionable insights, which was optimal for the large size and number of the Hospital campus’s buildings.

Operations

QEA Tech’s drone operations spanned approximately 860,000 square feet with data being collected within 7 days. QEA Tech’s operations had to be efficient and non-intrusive to not disturb 24/7 hospital operations. The data collected was processed and analyzed by our AI-powered proprietary software, calculating the energy loss, greenhouse gas emissions, potential energy and greenhouse gas emissions savings, and actual effective U-values/ R-values for each building envelope element. Additionally, QEA Tech identified over 4800 issues related to the Hospital’s building envelopes, such as heat loss through connections of building envelope elements, thermal bridging, and heat loss through the window frame.

Key Findings

Through our audit, QEA Tech found that:

1. 62% of annual building envelope energy loss in megawatt-hours (MWh) can be avoided by upgrading the envelopes to building code.

2. >$850,000 in annual energy expenditures can be saved by upgrading building envelopes to building code.

3. 1451 tons of carbon dioxide equivalent (tCO2e) are avoidable annually by upgrading building envelopes to building code.

4. The average payback period to recoup costs of all the retrofits recommended in our audit is 7 years.

Total % of Energy Loss (MWh) from Each Building Envelope Element
Graph Insights

Heat loss due to connections of building envelope elements: Due to the old age of the Hospital campus’s buildings, this is likely caused by connections of building envelope elements not being continuously insulated or thermal layers decaying over time. Degradation of materials over time can lead to cracks or openings between building envelope elements, further increasing energy loss.

Inconsistent, decay of, or no insulation: Age and moisture accumulation throughout the building envelope has likely caused the insulation of the Hospital’s buildings to deteriorate, leading to reduced R-values and effectiveness.

Thermal bridging: As buildings age, settling and material degradation can lead to cracks or openings at junctions, amplifying thermal bridging issues. Thermal bridges occur when a more conductive material creates a direct pathway for heat transfer across less conductive areas of the building envelope, increasing energy loss.

Top Issues

Poorly Performing Windows

The average U-values calculated for the majority of the Hospital’s windows were performing significantly below building code, resulting in over $500,000 of annual heating and cooling loss attributed to windows. Some windows in the Hospital displayed heat loss through insulated glass units (IGUs), losing insulating gas fill due to failing seals.

QEA Tech recommended that the Hospital apply window inserts for the poorly performing windows identified by QEA Tech. These inserts are customized glass panes that can be placed on the inside or outside of the existing window. This creates a new thermal boundary that improves U-values while minimizing disruptions to hospital operations and patient care. Further, these inserts are more cost effective than traditional window replacement and take a fraction of the time to implement. The total potential energy savings of implementing this retrofit for the Hospital amounts to 7527 MWh. It will take approximately 10 years to recoup the costs of performing this retrofit.

Moisture Accumulation within Roofing Membrane and Tiles

Moisture accumulation on the Hospital’s roofs was likely caused by poorly ventilated roofing systems resulting in condensation beneath the roofing membrane and stagnant water from rainfall that was not properly drained. This is a significant issue as water trapped beneath the roofing membrane creates an environment for mold growth, rot, and deterioration of roofing material, negatively affecting the health of the Hospital’s occupants.

To address this issue, it is recommended that the drainage systems on the roof are regularly inspected and cleaned. In addition, the damaged areas of the roof should be remediated by applying an insulation layer and a durable roof membrane (e.g. bitumen layer). Lastly, the roof should be sealed against potential leaks. This approach is designed to provide the Hospital with a roof expected to last an additional 15-20 years, addressing existing leaks and other roofing issues. Moreover, this method is more cost-effective than a full roof replacement and better meets the needs of the Hospital by allowing it to remain fully operational during the renovation.